As your season comes down to the last few races, many of you will be trying to gain points on your competitors to either move up in the rankings, or maybe even win the championship. A strong finish is critical to ending a season well.

This issue is dedicated to helping race teams plan out how to finish strong, and maybe win that championship. We’ll cover both the mechanics of the car, as well as the philosophy of finishing strong, and how to adjust to new tracks that you might be running for the first time.

In many parts of the country, there are big money and prestige races at tracks not too distant, which your team might want to attempt a run. If you have never run those tracks, we’ll tell you how to adjust your setup to be more competitive.

But first we need to finish races and gain the most points possible. If we have a parts failure, we lose valuable points and position in the rankings. Here are some tips on items that can fail and cost you a race or more. These include things I have seen go wrong and tales I have heard about things others have had go wrong.

We list here what we consider the most important items for late-season maintenance. Based on this general guide, make your own list of maintenance items that you think you’ll need to pay attention to. After all, you know your car much better than we do.

Our list is intended to instill the notion that any mechanical device can—and will—fail without proper maintenance and replacement. Our race cars and tools are subjected to extreme conditions, and all of the moving parts will eventually wear out or fail if we do not make frequent checks and repair or replace parts.

Suspension and Steering

Suspension failures include broken Heim joints, bent ball joints, bent axle tubes, binding in the control arm bushings, loose bolts, worn steering parts, and more. If you normally spend a night at the shop going over the car for the next race weekend, this process is different.

This time, we need to dedicate more time and put in more effort. If you really are in a position to win a championship, you’ll need to really go over the car as if it were the start of the season. You cannot afford a suspension failure now.

To start out, thoroughly clean the chassis. We need to remove all of the control arms, steering assembly, spindles, rear trailing arms, shocks, and springs. Lay the parts out on the garage floor and carefully inspect each one for any signs of cracking, bending, or breaks at the welded seams.

Remove all of the Heim joints, ball joints, idler arm assemblies on a drag-link system, and test for excess play and wear. Replace all of the joints that are worn. Check the steering box or rack for excess play and worn seals. If it is suspect, now is a good time to overhaul it, not after it fails. I’ve had that happen to me. The steering began to lock up on a car I was engineering, and it ruined our weekend.

Inspect the engine mounts, front hoop tubing, upper control arm mounts, and any areas where fatigue might have caused cracking or breaking of the metal. Make sure you inspect the components for the rear suspension, too. The Heim joints, shock brackets, pull bars, lift arms, and other devises need to be checked out and cleaned and serviced. Most of these parts take a lot of abuse and damage is not only possible, it is likely.

Bolts that have been loosened and tightened repeatedly need to be replaced. High-stress parts such as third-link Heims, the tubing, and the rear-end brackets could have damage and cracking. Don’t overlook your J-bar or panhard bar. This part is stressed quite a bit over the course of an entire season. I’ve heard of them failing, and it is not pretty when it happens at high speeds.

Driveline Assembly

Remove and inspect the entire driveline. If the driveshaft is not damaged, then just remove and replace the U-joints. This should be done at least once a season. These parts are subject to high stress and are way too cheap to take a chance on failure.

Inspect the yokes and transmission tailshaft to make sure everything fits all right. There are high-performance shafts and yokes available that weren’t around a few years ago. If you are looking for a little more performance and reliability, check out some of the new stuff.

The rear end should be removed, and all mounts cleaned and inspected. If necessary, replace leaking grease seals, axle bearings, and pinion bearings if they are suspect. Check the axle tubes for damage and if they are straight. Inspect shock brackets and trailing arm brackets for damage or wear. All Heim joints should be looked at and replaced if worn excessively.

Rear End Maintenance

The rear ends and the differentials have really cause me a lot of headaches in the past. No rear diff, except the spool, can go for very long without maintenance. Some types of traction enhancing rear diffs are especially prone to failure if not maintained. Some require rebuilding, or at least inspection, after about 10 races. The locker diffs can go a half a season, but if you go longer than that without changing out the springs, you are taking a chance.

When disassembling your rear end, make sure you note the condition of all of the parts. When first draining the rear end grease, run it through a filter to see if there are any telltale metal bits or pieces that may indicate a part failure or excessive wear.

Look over the gear wear pattern as well as the bearing play and any obvious cracks in the housing that may only be seen from the inside. Now is the time to decide whether to replace the centersection, a right or left bell side, or one of the axle tubes.

Apply the same attention to the transmission. The bushings and bearings in the tranny will wear out. Don’t expect a transmission to last a lifetime. Be sure to match that tailshaft bearing to the proper yoke. Roller bearings require a special hardened slip yoke.

Check your shifter links and attachment points. A broken shifter has ended many a racers night. We seldom think of these types of parts as maintenance items. That is, until they fail mid-race.

Brake Systems

Brake failure is high on the list of known momentum killers. How many times have you heard of a driver having to pump the brakes to finish a race? If the pedal goes to the floor, it’s game over. This cannot happen with well-maintained systems.

The brake system should be completely gone through at mid-season. If it has not, then now is absolutely the time to do it. Remove the brake and clutch master cylinders, inspect and flush the lines, and do a rebuild of the cylinders. The last thing you need is brake failure.

If your brake lines have been banged up or otherwise damaged, consider replacement of the damaged line, or all the lines. At least replace all of the flex lines, which may contain degradable synthetic hose inside the woven stainless steel.

Your brake adjuster is only intended to be used for fine tuning the bias. If you don’t think your brake bias has been totally correct during the season, and the adjuster is far to one side, now is a good time to rethink the master cylinder and caliper sizes. Adjusting the sizes of those components can bring your brake bias into a more balanced state, and your race car might feel better now than it did at the start of the season. You’ll have adjustability you never had before.

Clutch Hydraulic Systems

Clutch failure is another area that surprises most racers. We tend to avoid maintenance on the clutch, mainly because it is so hard to get to. Forget all of that. Think of the frustration of having a clutch failure during a race, or a practice before a race for that matter. You’ll end up servicing the clutch anyhow, might as well do it now in a more relaxed atmosphere at the shop.

Pull the transmission and remove the pressure plate and disc assembly. We are checking for wear or any other anomaly. Look over the hydraulic lines, or mechanical links if so designed. Replace all the components if there are any leaks, not just the ones that leak. If one leaks, others will eventually leak, it’s just a matter of time. Check the master cylinder that serves the clutch.

Check the flywheel for excessive wear, cracks, or warping. While you are there, check the outer edge for cracked teeth or excessive wear from the starter. In our Project Modified, the outer gears came apart and flew off at high speed, putting holes in the body and windshield just like they were shot with a gun.

Cooling System

Radiators take abuse, more with some types of racing than others, but all suffer. During the past season, the radiator may have suffered from collisions, beating, and banging or just nicks and scrapes from working on the car. Remove and pressure test it. Inspect it thoroughly to make sure it will perform for the remainder of the year.

Replace hoses, belts, pressure caps, and anything else that might give you problems at the worst time, such as when leading the race. Nothing is more frustrating than those little annoyances like a water leak or thrown water-pump belt.

How old is your water pump? This is another neglected item. If there is any play at all in the shaft, replace it whether there is leakage or not. Water pumps are not that expensive, certainly not as much as an engine.

Wiring and Switches

To insure your car doesn’t stop running at the wrong moment, all wiring and switches must be fresh and free of corrosion. The vibrations that go on during a race can cause the wire connections to break or come loose. We wrote an entire article on how to rewire your race car.

Recheck the grommets where the wires pass through the firewall or other panels. Cycle the switches and notice if they feel tight or corroded. Replace the ones that are suspect. Many races have been lost due to the failure of an inexpensive switch or connector. Make sure your negative lead from the ignition box is secure. Most permanent failures of the ignition box occur because the negative lead comes loose.

Carburetor Maintenance

Remove your carburetor and disassemble it. Do a thorough cleaning, at the very least. Inspect all of the moving parts. Install a new gasket kit and consider replacement of all of the parts that can, and do, go wrong at some point in time. These include the power valves, the accelerator pump, seals, and such.

Look outside the carb and inspect the linkage from the gas pedal to the carb. Replace the return springs no matter what they look like, as well as the ball sockets if they appear to be worn. Inspect your sparkplugs and if they show signs of the engine running rich or lean, now is the time to change the jets. Consult your carburetor specialist for information on this process.

Shocks

I cannot tell you how many times a race cars performance has suffered due to having the wrong shock rate on the car or suffering a shock internal failure. If you have the capacity or know someone who does, have your shocks tested on a shock dyno to ferret out any problems internally. If you have one or more shocks going bad, your whole season goes up in smoke.

Shocks are one of those items that can make your setup ideal, or when they fail, ruin an otherwise great package. You must check every shock regularly to make sure they are not leaking and that the internal parts are functioning properly.

If you are not sure about your shocks, then either send them to a repair facility or re-build them yourself. Change the oil and replace the seals. These parts are not intended to last indefinitely. The heat and force the shock is subjected to is extreme. Once the shocks have been re-built, make sure they are run on a shock dyno and keep a record of the rates.

Wheels and Lug Nuts

This is a simple item, but one that can destroy a race car. It goes without saying that the wheel takes a lot of loading and abuse. There is a good chance of failure with the wheels, no matter how well they are made.

Remove the wheels from the car and remove the tires. Make a thorough inspection of the welds, the bead areas and the stud holes. Check to see if the wheel is bent. You can do that by bolting just the wheel onto the hub and spinning it while holding a reference point next to the bead area. If it is bent, you’ll see it.

Safety First

An injury to your driver can and will end your season. Even an incident that can be repaired before the next race might be moot if the driver cannot drive the car. Seemingly minor hits can turn into major problems if a seat belt breaks or a head-and-neck restraint fails.

Look over the seatbelts and seats on a regular basis. Stress from hard racing might have damaged your seatbelt system. Inspect the rollbar padding and install new pieces where necessary. Completely remove all belts, the seat, and the window net. There should be no fraying or tears to the material. The mounts must be stress free and not bent from the original location. The seat should be crack free. If not, send it back to the manufacturer for repair or replacement.

Inspect your head-and-neck restraint system and your helmet. Hard hits will dent the Styrofoam material inside your helmet, which is what it is supposed to do to prevent damage to your skull. But this is only a one-time deal. Once it has been compressed, it will not rebound back into the original shape. The shell must be replaced. Most helmet makers will repair their helmets at a fraction of the cost of a new helmet.

Fuel cells are a definite safety check item. Inspect the containment structure for rust or damage that might compromise the cell itself. The fill tube assembly should tight and in good condition. It might be a good idea to remove and clean the inside of the cell and get all of the dirt or other foreign material out that might have crept in. A clogged fuel inlet has often caused fuel feed problems and lost races.

The fuel pickup should be inspected and cleaned. If you have a fuel pump that pushes fuel to the engine, as some cars do, inspect the wiring and general condition of the pump.

Don’t forget to recheck that fire-suppression system to see that it is fully charged and will work properly when needed. The fire bottle is rarely needed, but when it is, if it doesn’t do its job, things can get real ugly in a hurry.

If you don’t have a brake-pressure-activated engine kill switch, this would be a good time to purchase and install one. Stuck throttles can happen for many reasons and at any time. Be prepared and have a switch installed that will kill the engine in the event of a stuck throttle. It could save a lot of damage and serious injury.

Final Checks

The most important thing to remember is that we need to find any structural or mechanical problems related to the chassis or other components bolted onto the chassis. Correct any driver safety-related problems that involve wear or age of the seatbelts, restraints, fire-suppression system, helmet, or seat.

The point is this, towards the end of each season, we need to thoroughly go over our race car. Later, during the winter months, we can do a complete overhaul. When we hit the track again in the spring, it will be just like a new car. But for now, let’s finish those races and collect more points so we can finish higher in rankings and possibly win that championship.

The post Late-Season Maintenance appeared first on Hot Rod Network.

It’s time to talk about this. A recent event whereby one John Hunter Nemechek, who by some accounts, ran over Cole Custer at a truck race at Ontario brought to mind a discussion I have wanted to have for some time. And I invite any of you to chime in by emailing me directly.

In case you haven’t seen it, here is the video:

With the influx of youth into our sport combined with the obvious lack of proper parenting in some cases, the racing has become overly rough. It seems to many observers, that too many of our younger drivers push too hard and drive rough simply because there are no consequences.

The fact that John Hunter was awarded that win speaks volumes about how some officials deal with rough driving. They evidently are willing to look the other way. That does nothing to curb that kind of behavior.

The youngsters are too young to give a good butt whoopin’ to. I think they call that a crime, whereas among older drivers, a good fight sends a message that the receiving drivers will not take it anymore. What can you do to a 14 year old? Even Dalton Zehr, our test driver few years ago said then jokingly, “What are they going to do, beat me up, I’m only fifteen.”

The result of the Custer vs. Nemechek dustup was Cole running out to John Hunter and tackling him in the grass. Team members and NASCAR officials intervened before any real damage could be done. And maybe Cole was not intent on hurting John, but he did send a message that most viewers agreed with. He just wasn’t going to take it anymore.

The point is, this does not have to happen this way. John Hunter Nemechek is by many accounts a good kid and races hard and wants to win. That is a good thing. What he needs is for the officials to do the right thing and not reward that kind of behavior. He should have been relegated to some position behind Cole, not awarded the win. The officials are not doing a good job providing consequences and the drivers are not learning accountability.

Where are the parents when all of this is going on? John’s father was a racer. He knows what that was and how wrong it is. We don’t know what went on between father and son, but we know what should have been discussed. The most love and direction you can give your child is to show them where they have gone wrong and explain how to do it right the next time.

So, now we have the video of the run-up and aftermath of the encounter on Facebook getting tens of thousands of views. Many of those viewers are youngsters who are, or will become, race car drivers. What message does that send to them? I can tell you what I think. The message is clear, you can drive like that and get away with it. Hey, John Hunter did, period.

This message goes out to all of the officials out there who tolerate this kind of behavior. You are doing the sport no good whatsoever. In fact, in some ways, you are ruining the sport. Older drivers cannot by law knock some sense into these young drivers and the parents evidently are not doing their part.

Who is left? You got it, you the official. Use that black flag as often as is necessary to send a message to whoever needs it. Make it known that rough driving will not be tolerated. You definitely have the power to stop this kind of behavior. You can be the consequences. Then maybe the drivers will learn to have more accountability.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1733 Alton Parkway, Suite 100, Irvine, CA.

The post Accountability and Consequences appeared first on Hot Rod Network.

Helping A Driver Learn Better Skills

As a part of my new project car Pro Late Model, I began to work with the driver to develop better techniques and habits. What I observed is common to many drivers, young and old. What this presentation will do hopefully, is open your eyes to a better way to drive.

Much of the information contained here is copied from a piece John Block wrote for CT in 2006 and is preached in other places by some very knowledgeable racing instructors. John went a bit further and used data acquisition graphs to better explain the dos and don’ts of throttle modulation and braking skills.

I will pass this information along to my driver as I hope you will pass it along to someone you know who drives a race car. A lot of the teams John works with now are involved in road racing and the very same skills are important to them. He has improved lap times by 1-2 seconds on some courses. You can improve your circle track lap times by 2-4 tenths just by applying and using these tips.

In John’s previous piece, he explained how there are basically three parts to performance. The first is the car’s performance level compared to the competition. Of course, the driver can only drive the car as fast as it will allow him/her to go. For the most part, the top fifteen percent of the cars in your division are probably very close in performance.

The next part is the driver’s skill.  However, unlike the race cars that end up being relatively close in performance, drivers vary widely in skill levels.  It is common at the local level to see a driver with a higher skill level competing against a comparatively low skill level driver.  In such a case, even if the lower skilled driver had the better race car, the higher skilled driver would place higher on a consistent basis.

The final part, according to John’s analysis, is the driver’s performance on any given day.   Everybody has good days and bad days.  A death in the family, divorce or even the flu can throw you off your game.  So on a great day you could perform at 100% of your skill level and on a bad day you would perform at a lower percentage of your given skill.

As for my project driver, we raced at the newly renovated Citrus County Speedway last Saturday night and the brake bias was way off due to a malfunction. The rear brakes were dominant to the point he would go very loose on entry using adequate braking. So, during the race, he had to use much less brake and allow the car to roll through the turns.

At the end of the 75 lap race, he was turning laps a half a second faster than he had done in the best practice times on similar age tires. The gain was due to his having to change his driving style to one that was faster. The techniques explained here are what caused my driver to go faster, and these same tips will help you or your driver do the same.

Technology to the Rescue

A very basic fundamental that all engineers and scientists live by is, “You can’t have improvement without measurement.”  This is where technology fills the bill. Race car data acquisition is nothing more than an electronic measuring system, which often is associated with the first part of the three performance ingredients.  The secrets you will learn here will show how data acquisition is crucial for improving the other two parts.

It is important to measure and record what the driver is doing because what may feel fast in the seat isn’t always fast on the stopwatch.  Often, the exact opposite is true.  This is exactly what Mike Loescher taught in his driving school that I attended years ago.

The system necessary to measure the driver will need a throttle sensor, steering sensor, G force, and vehicle speed sensors.  Basic data acquisition systems typically have these sensors, but if you pick up a used system make sure these sensors are included.

How to Improve Throttle Control

Drivers may think they are in total control of their body, but many times this is not the case.  It has been proven many times in testing that a driver will say, “I never lifted that lap,” but when you check the data this is not the case.  There seems to be a brain to foot disconnect, as if the foot has a mind of its own.  This is why many crew chiefs laughingly call data systems “The Lie Detector.”

Smokey Yunick told me a story one time about Curtis Turner, his driver at Daytona one year. He could hear Curtis lifting going into turn one in practice and when the car came in, he told the driver he was lifting. Curtis swore he was not and even threatened Smokey with a butt whipping.

Smokey said, “You can whoop me if you want, but if you lift one more time, I’m taking this car to the shop.” Curtis went out again and when he came in, he told Smokey, “You know what, I would have swore I wasn’t lifting, but when I paid attention, my foot got real light going into that corner.”

Using data acquisition, graphs can be constructed to display throttle position all the way around the track. We need to watch for specific patterns when reading data graphs for throttle skills.  Often the patterns will get nicknames like cliffs vs. roller coasters and pancakes vs. high valleys.

An example of throttle cliffs can be seen in Graph #1. This graph clearly shows that entering turn one the driver quickly dropped the throttle in less than one second.  Likewise, in turn 3 the driver dropped the throttle in roughly 0.7 seconds.  Especially on pavement, this tends to be less than desirable throttle control.

Another non-desirable throttle aspect is the pancake, or flat line, following the cliff. This data shows the driver is completely off the throttle for roughly 250 feet in each corner. Often times the pancake is a result of the throttle cliff. Suddenly dropping the throttle upsets the car’s balance and the driver must wait longer to get back on the throttle.

Graph # 2 is a different driver with good throttle habits. You can see the throttle pattern looks much more like a roller coaster than the cliffs in the previous two graphs. Also notice the driver manages to keep the throttle open between 20% and 25% in the middle of the corners. These high valleys will result in more overall average turn speed than the pancakes in the previous graphs.

There are many aspects of throttle control that can be improved with data acquisition. The graphs show the driver what is actually happening and helps him tune his driving style. Remember that what feels fast in the seat in not always fast on the stopwatch.

How to Improve Steering Control

Conversations about driving often address the “line” (the path you want the car to travel), but never how to manipulate the steering wheel to achieve a given line. Most drivers are not aware they are causing a handling problem because of their lack of driving skills, and this includes steering.

Graph #4 is an example of a driver that misses the timing when steering for the corners. The steering trace for both corners has a leading spike rather than a rounded plateau. The leading spike is where the driver is trying to get to the bottom of the track too soon.

In this case the race car gets to the bottom quickly and the driver must reduce the steering for the remainder of the turn or end up in the infield. The steering input for turns 3 & 4 shows the timing was error was bad enough on this lap that a second big “cut” on the steering wheel was necessary to finish the corner.

Some drivers appear to be force oriented by increasing/decreasing the wheel angle to maintain a specific torque on the wheel. Other drivers are displacement oriented, turning the wheel to a specific angle but not aware of the speed the wheel was turned. Here, again, is where data acquisition can do wonders in developing steering skills.

An example of “force responding” to wheel feel can be seen in Graph #5.  Here the data shows what is often called “sawing on the wheel.”  You can see a big overall hump on the graph for each turn, but there are lots of wiggles in the line indicating a back and forth motion on the steering wheel.  Graph #6 shows the same driver after the “sawing” was brought to his attention via the data acquisition.  Here you notice the trace is much smoother.

Also, when the driver made a conscious effort to smooth out the steering input the car settled down and the lap time went from 21.129 in the first example to 20.846 in this example.

While smoothing out your steering motion sounds quite easy, in reality it is very hard to do.  The above examples are from a full time professional driver on a half-mile racetrack.  Graph #6 is a weekend driver with several Championships to his credit on a half-mile track.  Notice here there are no big jags in the steering trace.

Another example of a weekend dirt track racer is displayed in Graph #7.  This, too, is a Champion racer with many pole positions and wins to his credit.  Notice this steering trace is fairly jagged. As mentioned in the three part concept, a track champion typically has better skills than a racer in the middle or back of the pack, but you can see a full time professional race has better skills, yet.

How to Improve Braking Control

Braking control tends to be more difficult than throttle or steering control.  One of the reasons braking is so difficult is there are actually two brakes on a racecar.  Everybody is aware of the brake pedal; however, the engine is also a brake.

The total slowing of the racecar is a result of both the engine brake and friction brakes.  It’s the blending of engine brake and foot brake that makes this skill more challenging and why “left foot” braking typically yields the best results.

Most drivers are unaware of how they use the brake pedal.  Some may be able to identify using a large amount of pedal force for a short duration or a lower pedal force for a longer duration, but beyond that they are typically unsure of what their foot is doing.  Just like throttle and steering control, the subtleties of highly skilled braking seldom come naturally and must be developed.

How the pedal is pressed to reach the maximum force is an important skill.  To illustrate this point, examine Graph #8.  Here you will see a very quick and smooth increase in force to a peak value.  Also, the peak braking force for each end of the racetrack is virtually the same.

The slower release of the brakes allows the car to maintain the maximum speed that is capable of through the range of decreasing radius. This is where the overall lap speed is improved. If we brake hard enough initially to get down to the mid-turn speed too early, then we give up the speed in that transition area. The driver should slow the car in relation to the turn radius and maintain as much speed as the cars resistance to lateral forces will allow.

This is a skill many weekend drivers lack. The graph is from a full time pro.  Oftentimes you will find brake force varies from lap to lap and in each turn.  The ability to repeat the same force is paramount in improving lap times and solving set-up problems with your chassis.

Another braking skill is the release. In Graph #8 you can see that overall the driver had a steady and uniform release of the brake.  However, in Graph #9 this driver did not release the brakes smoothly, which many drivers do without realizing what they have done.  This can lead to bad handling which typically gets blamed on chassis set-up rather than the real source, the driver. I quit working on the setup when I see bad driving habits.

Again, combining the brake pedal motion with the throttle motion is the key to mastering braking skills.  You can slow down by simply taking your foot off the throttle, or slow down faster by pressing on the brake pedal.  Both actions work together for the total slowing and data acquisition can be used to measure the overall results.

Conclusion – In the past, some drivers were said to be naturals.  Some excelled in their racing career and some never made it out of the local level.  It was also believed that a struggling driver just needed more seat time to improve.  However, practice doesn’t make perfect, only perfect practice makes perfect.  Otherwise, just practicing may reinforce bad habits and good race driving skills may never be developed.

Now, with the availability of affordable data acquisition, even local racers can develop the skills necessary to win or move up the racing ladder. You have now been exposed to some specific race driving skills that should be goals for your driver to try to achieve in the seat.

The bonus to approaching racing performance in this fashion is that you may discover that either there is nothing wrong with your racecar’s set-up/power and that many of your set-up/power problems disappear with the development of good driving skills. I have proven that to be true time after time.

John Block, who contributed to this story, is the founder of Auto-Ware, a company focused on using technology to improve racing performance.  Starting in 1992, the company developed and sold computer software just for racers. As time progressed data acquisition became an obvious advantage, so, the company began selling data systems.

However, as more vendors entered the market selling data systems, it became obvious that what races really needed was training on how to use the data.  So, in 2004 Auto-Ware started and is still a main provider of data training for racers all across the country and around the world.

Several years ago they began providing “Remote Data Analysis” services that provides racers the speed and experience of a professional race engineer without the cost of having someone on staff.  Today, the company has evolved to offer services for racers that include driver coaching, race engineering solutions and product/parts prototyping.  You can read more about them at their website www.auto-ware.com.

Sources:

Auto-Ware

www.auto-ware.com

505-890-8708

Competition Data Systems

www.competitiondata.com

205-948-7317

Performance Trends

www.performancetrends.com

248-473-9230

Photos: Courtesy of Tyler Sontag, Performance Trends, and Competition Data Systems

The post Using Data to Improve Driving appeared first on Hot Rod Network.

We modified the anti-squat design in our project Pro Late Model recently. We used a method to distribute more loading onto the left rear tire and a modification of that method is being used to promote rear bite on acceleration with great success. Let me explain.

Anti-Squat (AS) is one of those mechanical tools that we know can add traction off the corners and today we know more than ever about how it works. We can utilize that knowledge to further enhance our turn exit performance.

Anti-squat is associated mostly with three link rear suspension systems where we mount the upper third link so that it is at an angle to the ground with the front end of the link attached lower than the rear heim. There is also an AS affect from lift arm devices as well as to a limited degree the truck arm suspension systems. We will illustrate how the effect works using the three link system.

How AS Works

Upon acceleration, the rear end pinion gear is trying to climb the ring gear in the differential and that causes the rear end housing to want to rotate in a clockwise direction when viewed from the left side. There is a considerable amount of force, about 3,000 pounds or more, that is applied to the third link of the three link system upon acceleration that pulls on the bar trying to stretch it. This is where the term “pull bars” came from that is commonly used to refer to links that have torque absorbing springs or rubber disk.

The lower trailing arms have a small affect on Anti-squat. They are usually mounted fairly level up to two or three degrees and are in compression during acceleration. Because the angle of these links is critical to rear steer characteristics and therefore not considered an adjustable item, we only speak of regulating the angle of the third link to adjust the amount of AS in our cars.

Many of us have assumed over the years that by applying AS to our rear suspensions, we were causing more load to be applied to the rear tires by the mechanical effect produced through the third link. This is not true.

What the mechanical effect of AS does is to cause a portion of the loading on the rear springs to be moved to the rear end through the third link. This means that we exchange some of the load off of the rear springs and onto the rear end where the link is attached. Since this is an equal tradeoff, there is no more load on the rear tires than before.

The physical law that states for every reaction there is an equal and opposite reaction means AS cannot add load onto the rear tires. This is understandable because where would the added load come from? In the mechanical world we cannot “receive” additional load without “taking” from somewhere the same amount of load. So, we receive the load from the action of the AS and it is taken from the rear springs, to ultimately find itself back on the rear tires.

Let’s look at it another way. If we had zero AS effect, the car would transfer a certain load or weight onto the rear springs as we accelerated and they would compress to carry that added load and the car would squat. If we apply 100% AS meaning the effect would prevent the car from squatting at all upon acceleration, then the springs would not have compressed and therefore do not carry any more load. The load the springs would have carried is now applied to the rear end through the third link because it has to go somewhere.

Adjusting Amount/Location Of AS

There are several ways to adjust the magnitude of the force that is applied to the rear end through the third link. One is the angle of the third link and the other is the distance that the upper link is mounted from the lower links. The greater the distance between upper and lower rear mounts, the less mechanical force the system has and therefore the less AS effect.

Adding angle to the third link will increase the AS effect but this has its limits because the effect is reversed when we decelerate and brake into the corners. Instead of transferring load onto the rear tires, the reverse means that we reduce load on the rear tires when entering the turns and that can make the car very loose.

Usually an 8 to 10 degree angle is sufficient to cause the desired effect while not being excessive. If more AS affect is needed, we can lower the third link and/or raise the lower trailing arms while maintaining the angles of all of the links.

If we position the third link laterally half way between the centers of the rear tires, then whatever amount of load that is being applied to the rear end will be equally distributed between the rear tires upon acceleration. They will take the vertical load from AS in equal proportion.

If we move the third link laterally and closer to one side of the car, more of the vertical AS load will be applied to the closer tire. In this way we can cause a greater load to be applied to one of the rear tires upon acceleration if that is a desired goal.

So, if we don’t end up with more overall load on the rear tires by using AS than if we did not, how does the car gain traction by using AS. The answer lies in how we design the system so that we can redistribute the loads onto the rear tires.

Lateral Location Of The Front Of The Third Link

To achieve maximum traction from the rear tires, they must be equally loaded. Most of the time in the turns, the RR tire will have more vertical load due to the load transfer from the turning left. We therefore need to cause a shift in loading from the RR tire to the LR tire upon acceleration in order to better equalize the loading on the rear tires.

Here is the trick that has been discovered recently. If you move the location of the front end of the third link, you can affect the roll stiffness so to speak of the rear of the car. We would leave the rear location where it’s at for this process.

When we talked about the loading force of the third link onto the rear end, there is an equal and opposite force being applied upwards to the front of the link on the chassis. This is what constitutes the anti-squat force that keeps the car from squatting.

If we now locate our third link end attached to the chassis more to the left, what happens? It tries to assist in rolling the rear of the car just like if we pick up on the left side of the car. When we cause the rear to roll more, it creates a tighter setup condition that would cause the car to be tight in the middle if it were applied throughout the corner.

Since it is only applied upon acceleration, the tight condition helps to increase the rear bite much like if you lowered the panhard bar upon acceleration. This is advanced thinking and seems to work out well.

While it does nothing to redistribute the loading on the rear tires directly, indirectly it does by changing the setups dynamic balance. You now have more equally loaded rear tires than ever before and therefore more basic traction.

On our project Pro Late Model car, we added a new link box next to the old one. This moved the link end left about three or four inches. Some teams are moving the forward mount more than that to somewhere behind the drivers back.

The closer you can get to flat-footing it off the corners, the faster you will be. The third link location is just one design effect that can help you achieve that. There are others, but remember that if you have as much bite as you need, don’t overdo it. You can have too much of a good thing and start to overload the LR tire.

The post Advanced Anti-Squat Techniques appeared first on Hot Rod Network.

Many times, people get a funny feeling that something bad is going to happen in the near future. Call it a premonition or vision, but they know. When you do get the feeling that things are not going to be good, I think you need to pay attention and act.

Acting can take various forms, from not doing what doesn’t feel right to being more careful knowing that there could be problems. This discussion is all about recognizing when that feeling comes upon you and acting on it. It’s a bit serious, but then again, some things in life are.

I’ve had it happen to me. I raced Karts for about five years, and the last year I raced, I was running a summer road racing series in Savannah, Georgia, at the Roebling Road course. About two weeks before the next races, I had the strong feeling something was going to go wrong. Up to that point, I had never had a crash or gotten hurt racing, but this felt different.

So, I went anyway—without my Karts—and helped my friends with their efforts. I was asked many times, “Why aren’t you racing?” My answer was just that I didn’t want to, and I didn’t have to. It’s as simple as that.

Did anything happen? Yes, in a race I would have been running in, it rained, but only down in turn 1 at the end of a long dry straightaway. It was a very fast, wide-open 4G turn, and all of the participants went off track, some crashing into other Karts and drivers. My good friend Terry whom I was helping hit another Kart, flipped, and broke his collarbone. I had to take him to the hospital.

Would I have been in that one? Yes. Would I have been hurt? I don’t know. All I do know is I wasn’t involved. I had made a tough decision, and it probably paid off. I guess we’ll never know. Here is another example.

I really like watching films showing Aryton Senna, the F1 driver who died in a crash in 1994. I think he might just be the greatest race driver of all time, and I liked who he was as a person. I have watched documentaries of his life, and I especially studied the parts showing the weekend of his last race, and the morning of that race. Looking at his demeanor and his face, I am convinced he knew something bad was going to happen.

Fellow driver Roland Ratzenberger had died in a violent crash just the day before. The F1 doctor, Sid Watkins, was a good friend of Ayrtons, and had been aware of his concerns. He was quoted as saying essentially, Aryton, you don’t have to do this. We can just go fishing. Senna replied, you know that I have to do it. He felt he owed his fans, sponsors, and team the race. I believe in making that decision, he was going against his better judgment. We’ll never know.

But now you are reading this, and you might have your own special feelings before a big race. Or, you might have repeated symptoms of concussion as we have related in an earlier story. If you have second thoughts and think it might be better to not race for whatever the reason, I am here to tell you that you don’t have to.

I sincerely hope that if and when the time comes, you will have the courage to just say no, to walk away. Reconsider what you are doing and maybe do it a different way. Jeff Vochaska, who I mentioned in my concussion story, did just that. He stopped driving and became a car owner and crew chief. He is still enjoying the sport, so no one can say he quit. He just does it in a different way.

Right now, Junior—and if you don’t know whom I am talking about find another sport—is deciding what to do with his racing future. By the time you read this, he will have decided. The direction he takes will speak to our current and future short-track drivers and influence how they decide their future.

We really don’t know how many racers at short tracks across the country are affected by concussions, but as we spread awareness of this problem and especially its symptoms, maybe more of you will make an informed decision to just say no.

We really don’t know how many other drivers have had that funny feeling, but said yes when they should have said no. The decision that is ultimately made affects not only you as a driver, it affects your entire family, your fans, and your fellow participants. No one wants to see anything bad happen to anyone.

Racing is like all sports, and as such, will not last forever for any of us who drive, or play fullback, or pitcher or forward guard. Playing has its limits physically. We need to understand that, accept it, and be willing and ready to move on when it comes time to quit. I hope you will have the courage.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1821 E. Dyer Rd., Ste. 150, Santa Ana, CA 92705.

CTRP-170100-QA-01
This is Bob back in 1988 during a practice for a one-off race at New Smyrna, which he won. He never lifted from the green flag on. We would not recommend racing Karts on a track with concrete walls. He was hitting speeds upwards of 100mph with basically no protection.

CT Needs More Detail
Hello Circle Track Staff,
I have been involved in racing since 1964, enjoy reading everything you print, overall, and think it’s terrific! I would like to point out in some of your articles on articles like bumpsteer, roll centers, and more tend to be written for engineering grads.

Many of the folks looking into this stuff haven’t the background to really comprehend it. Secondly, several of the articles are left open ended without explaining exactly how to make the adjustments necessary.

A good example here was the piece done on brakes and rotors. You mentioned everything there is to it except the principle of bias, balance bars and their installation, adjustment, fluid pressure and such. It would have been a great idea to also have given where to obtain the heat paint for checking the rotor temps.

Don Alford

Don,
Thanks for pointing that out. Funny thing, we have started to put more detail into the subject matter we present. I recently have written shorter “how to” articles explaining in detail how to accomplish the things we tout as being important to your cars performance.

The two brake articles that were in the September issue were the result of asking industry brake experts questions about the use and maintenance of racing brake systems. You are correct, we should have asked them about balance bars and brake-line pressure bias on different types of cars.

There is a division between explaining theory and explaining how to accomplish what the theory is trying to get you to do. I promise to be more diligent in the future as to how I explain things and more thorough by not leaving anything out. Take a look at our next few issues, and you can see where I do more step-by-step explanation of how to make the theory work.

Years Ago it Was Better
I just got Circle Track Magazine yesterday in the mail. I’m not a stock-car driver, but I am an auto-racing fan. I started off in 1968 going to Lancaster Speedway, and from there, numerous race tracks within a two- to three-hour drive from Buffalo, New York. I still go, and most of the people I meet at the racetrack are much younger. If you mention Holland Speedway, they say they don’t like it as it has only one middle groove. Spencer Speedway, they say, is too flat to race side by side. They have never seen Lancaster when it was a separate speedway from the drag strip nor have they ever been to Cayuga Speedway.

My point, back in the late ’60s to early ’70s every one of these tracks had side-by-side racing, and the drivers were more gentlemenly racers. The Modified cars came with very wide racing rubber, and although they had a side crash bar, it was usually flush against the body. If you made contact with another car, someone went airborne, and quite a few times ended up flying out of the speedway.

The Late Models with full bodies still had much wider rubber that extended outside the body. These cars also could get airborne if they touched wheels. I believe they raced more cautiously because of what might happen, and they also had racing rubber that controlled the cars a lot better than today.

Then, the Modified cars came up with a side nerf bar that extended out to match the outside wheel. Once this happened, the drivers could make side contact without having to worry about flipping and drove them more like Late Models. Then, you had the tire width reduced both on Open Wheel and Late Model cars. That change was supposed to save on the cost of a set of tires by what, a hundred dollars, making it more affordable to the race teams. Nobody slowed down, and it effectively killed side-by-side racing as I saw it. The guys that tried it, ended up causing major accidents.

I went to Spencer Speedway recently, and ended up talking to a guy who used to help out Richie Evans with his race cars. I mentioned that they change to smaller width tires, while saving some tire costs and ended up with what looked like thousands of dollars in damaged race cars. He agreed, and said it started what I would call freight-train racing, and a great reduction in the number of race cars due to crash costs. Neither of us understands it.

All the drivers coming up through the ranks are dirtier drivers than back in the ’60s, but it’s the rules themselves that have caused such a change in the racing action—not necessarily for the better. At Martinsville back when the Modified cars ran the day, before the NASCAR stock cars raced on Sunday, Geoff Bodine put a set of his Modified tires on his Late Model and knocked off a couple of seconds in his lap times. He said, “Now that’s the way a stock car should be”. NASCAR promptly told him to mind his own business or go back to running Modifieds. Whether or not you agree with me, I’m not sure. But as a fan watching the races for the past 40-some years, this is what I have seen from the bleachers.
Chet Olen
Buffalo, New York

Chet,
I do agree with you. The changes made to the cars and tire size did have an effect on the racing. But I believe the officiating has a lot to do with the way modern drivers act. It’s a lot like raising children, if you allow bad behavior, or don’t correct it early on, immediately, and especially consistently, it just gets worse.

Today’s promoters are so worried about losing racers, they put up with bad driving and even intentional assault with a race car. No other way to put it. I just witnessed an incident at a local speedway where one team’s spotter told one of the driver’s mothers, during a race, that his driver was going to put him out. And he did just that a few laps later. The officials were told before it happened and said, “We’re watching it”. Afterwards, they did nothing. Now, the team who was intentionally crashed and others who witnessed it might not come back. So much for not wanting to lose competitors, right?

Loose-In Problem
What could it be the problem when you get loose in after 15 to 20 laps? The temperature split is good, and the tire temps are fine. It happens on both new and used tires.
Garrett

Garrett,
This is something that would take some checking into. I’ll offer some of my thoughts. Loose-in usually happens when the left rear tire looses grip. It often comes as a result of a LR shock that has too much rebound resistance. But your loose-in doesn’t come until after 15 to 20 laps.

It could still be shocks. If the right front shock works to control movement on entry braking, turning left, and the rise in banking, then the car would be fine until it stopped working. If that shock were to fade from heat after that length of time, the quicker movement of the RF on entry would take more load off the LR tire than before, causing the loose-in condition.

You don’t mention what type of shocks you are running, so it’s hard to diagnose this problem with so little information. But logically, it has to be associated with a change caused by heat or function. Springs don’t change that fast, and tires usually won’t cause this type of problem, especially when you say the temperatures are fine.

If you are running a twin-tube shock on the RF, you might want to change to a gas-pressure shock that can handle heat more efficiently. Or, if you are running gas-pressure shocks, maybe the pressure you are running in the RF shock is insufficient to prevent cavitations. These are just a few of my thoughts.

The post Making Race Decisions – Will You Have the Courage? appeared first on Hot Rod Network.

The process and consideration I am about to discuss is maybe one of the most important thing you will learn in your entire racing career. It was for me. And it works for dirt or asphalt racing. My normal commentary that goes along with the QA section of Circle Track involves discussing issues about our sport. Not this time. This is tech and a necessary tool for your setup development.

Some years ago when I was doing much more consulting, I would make sure that what I was working on, the improvement of turn speeds and chassis dynamic balance, could be measured. I did that by taking and recording turn segment times.

I went to Bristol in 1999 with a part time NASCAR truck team who had good equipment including a newly built 9:1 motor by an experienced motor builder who had just moved from Cup to the truck series. Long story short, we were six tenths off on lap times during early practice. But when I looked at our turn segment times, we were as quick as the fastest truck.

We found out that the motor guys had little experience with the 9:1 motor and had leaned it down to where it had no power. We kept putting bigger jets in the carb until we were finally competitive and he finished the race in the top fifteen as a rookie driver.

Recently when working with my newest project Pro Late Model car, I had to resort back to the methods I had used in the past. In developing this cars setup, I had covered all of the bases I have preached about for some fifteen years in CT and the car looked good and was easy to drive.

Along the way we had to resolve non-setup issues like brake bias, driver related performance, and shock rates that were out of sync with the spring rates being used. It took several races and a night test session to dial all of that in, but we finally did.

Then came the deciding moment, a race that I thought we would be very competitive in. We were not. In qualifying, we were a good five tenths off of what would have put us Second or Third. Our driver was not yet up to pole performance, but close. It then dawned on me that I needed to measure the performance in segments to tell me where we were losing that speed.

So, I told the dad I was going to turns 3-4 to take segment times during the race and he went to turns 1-2 to do the same. The result was that I had segment times very close to those of the eventual winner early in the race and a bit quicker in the closing laps.

The dad recorded segment times a tenth quicker than the leader throughout the race. So, we were losing the five tenths on the straightaways in qualifying and during the race. Something was hurting our acceleration.

Our job now is to find where we are losing power. Some of the things we have already checked are compression (it was very good on all cylinders), timing (it was a little high and will be corrected), fuel pressure (checked good but if it were high could have flooded the carb), and gear ratio. There is also the issue of a cam lobe or more being worn off.

In the process of driver development, I tried to get him to stop dive bombing the corners and to lift earlier, brake smoother and accelerate sooner, which he learned to do very well. To help that, I had them install a lower gear to get the engine onto the chip sooner. That takes HP away from the motor just before entry and forces an early end to acceleration so the corner entry is smoother.

Once he learned how to do that without the crutch of the gear, we never went back to the old gear. It is possible that this engine, a spec motor originally built to make power at a higher RPM is now choked down due to the officials mandating use of a 6800 RPM chip.

If the motor makes its maximum HP from say 6200 to 7400 RMP, then we can’t even get to half of the power range it was designed to operate in and that may be our problem. It didn’t help that we have a gear that hit the chip early.

At any rate, by measuring the performance in the turn segments, we were able to eliminate setup as an issue holding us back. We could then concentrate on the real issue that was lack of straightaway performance for whatever reason.

I encourage you to periodically record your turn segment times and compare them to the fastest cars you compete against. This will tell you where you need to look if your lap times are not what they should be.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1733 Alton Parkway, Suite 100, Irvine, CA.

The post Measure Of Performance appeared first on Hot Rod Network.

Why Your Handling Does Not Change

Have you ever wondered why fuel burn-off typically does not change the handling of a race car, at least not a great deal? I have been asked many times when helping teams setup their cars, what will the car do when the fuel burns off? My standard answer is, I have never seen much change. And that remains true, at least when we have achieved a more balanced setup.

I have setup cars that have run 200 lap races on one load of fuel and not seen any appreciable change in handling. The car burned almost twenty gallons of race fuel, or 120 pounds of loss of loading behind the rear axle. Why didn’t the handling balance change with such a large loss of rear loading and dramatic change in front to rear percent?

I thought – the same as you are probably now thinking – there must be a reason why such a dramatic change in rear weight, front to rear percent, and overall weight does not seriously affect the handling. So, I studied this at length and came up with a probable cause concluding that there are compensating and offsetting effects from fuel burn-off.

To understand what changes in the car when fuel burns off and we lose load at the point where the fuel tank is mounted, we need to understand the whole picture of what is going on with our race cars.

Suppose we have a car that has equal load on the two axles when the fuel tank is full. This would represent a 50/50 weight distribution front to rear measured at the axles. The Center of Gravity (CG) would then be midway between the two axles. When we go through the turns, the lateral force trying to take the car to the wall is centered at the CG. The force, and the resisting tire forces, would be equally distributed between the two axles.

Understanding The Moment – There is a concept called Moment Arm (MA). There is an influences on the car associated with MA related to the force acting at the CG verses its distance from the axles. Since the CG is centered between the two axles in our example, there is equal force applied to each axle. The moment is equal distant in front of and behind the CG. Whenever the CG moves closer to one of the axles, those tires will have more lateral force applied to them and be more stressed.

If the car is truly balanced with a centered CG, then there will be equal distribution of the lateral force at both ends and the car will remain neutral in handling. If the lateral force exceeded the traction we have, the car would slide, but equally front and rear.

Also, if the CG was moved forward, then the lateral force would cause the front tires to lose traction first as the force overcame the traction. That is the essence of moment arm, the closer to an axle, the more force is applied to that axle as a percent of the total lateral force. Are you staying with me so far?

Traction Verses Vertical Loading – The amount of traction a set of tires will produce is partially determined by the amount of load those tires have on them. The more load, the more grip. We can easily understand that when fuel burns off, the rear tires won’t have as much load on them and the rear tires will lose grip. The front to rear percent changes also to more front percent.

At the same time, since the fuel load is cantilevered behind the rear axle, as we lose load in the tank, we gain an even greater percent of load on the front tires. It’s a double whammy. This car should go loose with less rear loading and more front loading, but it doesn’t.

Here is where teams become confused as I was initially until I figured this out. So, here we are, losing rear weight and rear percent of sprung loading. That loss of rear weight and resulting move of the CG towards the front changes the lateral moment too.

The lateral force is now located closer to the front axle and those tires have to resist the greater lateral force. Since the load is also increasing, they are able to resist the extra lateral force.

At the rear, we have less loading due to the fuel burn-off reducing the traction of the rear tires. At the same time, those tires have less lateral force to deal with since the CG moved forward, so they do not lose grip. This is because they are less influenced by the moment affect, so the loss of grip is offset by the loss of lateral force.

Balance of Losses – The changes caused by movement of the center of force coupled with the change in rear loading and percent of load will equal out for the most part. The tradeoff might not be exactly equal, but both changes move in the same direction, the gain of grip to resist the gain in lateral force at the front and loss of grip to go along with the loss of lateral force at the rear helps to maintain a neutral handling car.

Different setups may experience different results. I believe that a balanced setup is less prone to handling changes due to the effects described above and maybe that is why some cars can lose performance the longer the race goes on while others don’t.

Movement of the fuel load, or fuel tank, forward will not change the offsetting affect. This is because if the fuel load were over the rear axle, that would remove the cantilever affect as fuel burns off. So, the front will gain less percent of sprung weight per pound of fuel burn-off.

At the same time, the movement of the CG forward will be reduced and so as the change in rear load becomes less, the change of CG movement forward becomes less. Again we are closer to equal in the trade-off.

Different Designs of Cars – All of this does not change with the different designs of cars for the most part. If we run a high rear percent like some dirt cars do, the center of lateral force, or CG, is closer to the rear tires than if the car were a 50/50 weight distribution car.

With a high rear percent car, initially the rear tires will be over loaded as more of the lateral force will be acting on the rear tires because the CG is more to the rear. Especially on dirt, they may break loose sooner than the front tires due to the overall lack of grip on dirt.

Even though they will be somewhat more heavily loaded than the front tires, the lack of grip won’t translate to more resistance to the lateral force. Maybe that is why teams with a loose car, that is in reality a tight car that goes loose, will run more rear percent and end up with a more neutral car. They are fixing the tight condition and that solves the loose condition.

The problem with that is this. As the fuel burns off, the loading moves to the front giving the front tires more grip while the CG also moves forward towards the center of the car which puts more equal lateral force on the two axles. As the front gains grip, the car will go loose later in the race.

I’ve always said that dirt cars should run less rear percent and it has always worked out better that way to keep the car more neutral throughout the race. Adding rear percent is a crutch for a car that won’t turn. Like we said, most cars that won’t turn end up tight/loose. That is usually wrongly interpreted as a loose car that seems to be fixed by adding rear percent.

Conclusion – So, the next time someone asks you how your cars handling will change as the fuel burns off, tell them it won’t. If they ask why, tell them you have worked hard to create a balanced setup and that there are compensating factors that prevent the car from changing its handling balance. If they want to know more, refer them to this article.

Sources:

Coleman Racing
www.colemanracing.com
800-221-1851

Smileys Racing Products
www.smileysracing.com
866-959-7223

The post Fuel Burn-Off and the Trade-Off with Your Car’s Handling appeared first on Hot Rod Network.

I see many different types of setup these days and racers trying to do things that the laws of physics just won’t allow. You don’t have to be an engineer to understand the problems that can come as a result of this. With just a basic understanding of how the dynamics of the race car work, we can all choose our shock rates correctly to complement our setups.

In the modern world of short track racing for both dirt and asphalt competition, shocks have become one of the most important tuning tools we have. They can complement the current setups, especially the radical bump setups if applied correctly.

Just recently I was involved with setting up a Pro Late Model running bump springs on the front. The team had inherited a set of shocks that were valved correctly at the front for the bumps, but all wrong at the back for the rates of springs we were using. I then used the information contained herein to solve my problem and it improved the performance of the car quite a bit.

The following information is useful whether you are running more conventional setups or the more radical ones. Think along with me as I discuss how shocks affect the speed of movement and the load distribution at the four corners of the car as we transition from high speed to minimum mid-turn, and then to up high speed again.

One of the most basic and important things to remember is this: Shocks do not affect the handling of the car if they are not in motion. To say that you can tune your mid-turn, steady state, handling with shock changes is just wrong. Any competent shock expert will tell you that up front.

Shocks Work With Springs – Controlling wheel movement would be much easier if all we had to work with was the shocks. But in reality, our race cars are supported by a set of springs. Basically, we always want to match our shock rates to the spring rates, and/or the bump device you might be using. In all situations, the shocks rebound rate will always be greater than the compression rate for any racing shock because the spring helps resist compression and promotes rebound.

As we install stiffer springs, we would naturally need to increase the rebound resistance and decrease the compression resistance. Stiffer springs would include adding bumps to one or more corners of the car. Each bump device has a spring rate in the range of motion it is operating in. Bump springs have a constant rate that is just added to the equivalent ride spring rate.

So, we may say we have a soft spring setup because we install 150 ppi ride springs at the front in our coil-over car, but when we add the stiff bumps to that, we end up with 1200-1500 ppi or more spring rates. That is why I am avoiding saying, soft spring setups when referring to bumps setups.

Therefore, with those setups, keeping with the idea that the shocks must control the installed spring rate, we must run shocks with a rebound rate upwards of 1200-1500 pounds at 3-5 inches per second of speed.

“Tie-Down” Shock Terminology – This brings us to an important discussion. The use of the term “tie-down” has been around for some time to describe shocks that are high in rebound resistance. The idea initially was that if we install these high rebound shocks, we can tie that corner of the car down and keep the tire tied to the track. This is completely wrong.

First off, a tire is not connected to the track surface, it is free to rise and fall according to what the other three corners of the car are doing at that instant on the track. If our setup wants that corner to move vertically because load has shifted off of it, then the load will come off regardless of how much we “tie down” with shocks. You just won’t see much suspension movement.

So, we might be fooled into thinking that it indeed did work. No it did not. If enough load comes off that corner, or the setup is unbalanced enough, the tire might well come off the track surface even without suspension movement.

This unloading of the tire will occur on the left front or left rear normally. So, we cannot tie the left front tire down and we cannot tie the left rear corner down, although I’ve seen some teams try. Lack of movement of the suspension does not mean the load remains on the tire.

What we can do is control the spring rate of the ride spring plus any bumps we have installed. If your left rear spring is a 175 ppi spring, then you need to use a normal shock rebound rate associated with that spring or risk taking much of the load off that tire on entry into the corners. On some tracks when using too much rebound, not only will you be loose in, but also loose off due to the way the track banking transitions.

Entry Tuning – If we split the front shock compression rates with a RF shock using a stiffer compression rate than the LF shock, then, while the suspension is in motion due to load being transferred to the front on entry, the RF suspension will move slower than the LF suspension. Additional load will be transferred onto the RF and LR tires causing a momentary increase in the cross weight percent in the car.

This obviously tightens the car. The affect is more pronounced with conventional setups that might be used now days in the classes that are restricted from using bumps, or the stock classes. But it can still affect the bump setup cars.

It is important to note here that the load transfers almost immediately when a force is presented to enact that transfer such as applying the brakes. As we apply brakes entering the corner, the load transfer happens quickly. If on entry we transfer 300 pounds from the rear to the front, the 300 pounds goes to the front in an instant.

The distribution of that 300 pounds between the two front tires, while the suspension is in motion, assuming a new attitude that will support the additional load, will depend entirely on differences in stiffness of the suspension systems at all four corners. Stiffness is defined as the resistance to movement influenced by the shocks and springs.

The result of all of the above is this. The slower moving (or stiffer) corner will momentarily retain more of the transferred load while the suspension is in motion traveling to a new attitude.

Cross weight, as we know, is defined as the percent of the combined RF and LR weight divided by the total vehicle weight. If the cross weight percent increases, then the car will be tighter on entry and the car might be faster if that is the desired effect. This is exactly why it has been said that a stiffer RF shock will speed up load transfer to that corner.

Later in the entry event, some of the load that has been transferred onto the RF due to that corner being stiffer in compression will transfer to the LF tire as the car reaches a steady state at mid-turn. Then the normal cross weight you set the car at will apply.

If the car is already tight on entry, after having eliminated common causes of tight entry such as rear miss-alignment, rear steer or brake bias issues, then an opposite effect can be utilized. If we install a LF shock that is stiffer than the RF shock, and/or run a stiffer LF spring than on the RF, then we can effectively reduce the cross weight in the car on entry while the suspension is in transition by loading the opposite diagonal, the LF and RR. As one diagonal goes up in percentage of supported weight the other goes down.

Modern bump setups use much lower front compression settings due to the high spring rate of the bumps. We can still utilize this method by creating a compression split. The effect will be less than with a conventional setup, but still somewhat effective.

Once the shocks are firmly on the bumps, the load distribution will equalize and the advantage of shock compression split will be nullified. If the shock rebound settings are high enough, the shock will never leave the bump and no amount of compression split will work because there will be very little shock movement.

Exit Tuning Using Split Valve Shocks – Corner exit performance can be improved by utilizing the shocks. This is done by either splitting the compression settings in the rear shocks and/or utilizing the rebound settings in the front shocks. In a car with equal rear spring rates, a stiffer compression setting in the LR shock than in the RR shock will load the LR and RF corners. Load is transferred to the rear under acceleration and while the rear suspension is in motion, this split will tighten the car by increasing the cross weight percent.

For non-bump setups, a shock with a stiffer rebound rate at the LF corner can help accomplish the same effect by causing a slower movement of that suspension and a more rapid transfer of load off of that corner which in turn increases the percentage of load supported by the RF and LR tires.

With the bump setups, the rear compression settings can really help a car that is otherwise limited in adjustments. If the RR spring is somewhat stiffer than the LR spring, and this is very common with bump setups, there will be a loosening affect on acceleration when load transfers to the rear. The stiffer RR spring causes load to be placed on the RR and LF corners reducing the cross weight percent.

By installing LR shock with a much stiffer compression rate, and a RR shock with a much softer compression rate, you can nullify the negative effect of the stiffer RR spring. This serves to equalize the unequal resistance to compression due to the dissimilar spring rates and helps keep the car tight on exit.

Putting All Of This to Use – In order to utilize the configurations we have discussed here, we must be able to use a range of different rates of shocks in order to find the right combination for our car at a particular race track for a particular setup. For a team that races at only one track, the process is fairly simple.

You would experiment to find the fastest set of shocks and ones that suit the driver’s style and stick to those staying within the boundaries of physics. For teams that travel to different tracks, some changes might be necessary if the setup (read as spring rates) needs to change and/or the track layout is different from track to track.

Most shock experts agree with certain basics, such as:

1) The shock package should be softer overall when racing on dirt and when the track is flatter when on asphalt for the conventional setups.

2) Get your basic setup close to being balanced before trying to tune with shocks. Shocks cannot solve basic handling balance problems.

3) Higher banked tracks require a higher overall rate of shocks and springs as opposed to flat tracks. This is because of the higher speeds and the extreme amount of down force.

4) Shocks that are mounted farther from the ball joint should be stiffer than if they were mounted close to the ball joint. That is because with each inch of travel of the wheel, the shock mounted farther away will move at a slower speed which means less resistance in both rebound and compression. This is also true of shocks mounted at high angles to the direction of motion.

5) Of the two transitions, tune entry performance first. If there are no entry problems, make small changes if you want to experiment to see if entry speeds can be improved. Entry problems include a tight or a loose car. By far the worst problem would be the loose-in condition. This can involve an alignment problem, but far too many times, I have discovered a LR shock that is too stiff in rebound.

6) Tune exit performance last. If there are no exit problems, don’t make any significant changes. Exit problems can include a car that pushes under acceleration or one that goes loose under power. Be sure that you do not have a Tight / Loose condition where the car is basically tight in the middle and goes loose just past mid-turn. This is fixed with spring rate and/or panhard bar adjustment, etc.

7) On dirt race tracks, reduce rebound settings on the left side and decrease the compression rates on the right side for dry slick surfaces to promote more chassis movement. This helps to maintain grip as the car goes through the transitional phases of entry and exit.

8) For the bump setups on asphalt, the whole shock package must be much different than when running conventional or soft conventional setups. The bump spring rates (either bump rubbers, bump stops, or bump springs) will be very high and so the shock rebound rates must match those high rates in order to control the ride spring and bump device.

Using a bump that is rated in the 1000 pound per inch spring rate range will need a shock that is rated at around 1000 ppi at 3 – 5 inches of movement per second. Usually the low speed rate of the shock will be comparatively high too and we often see a “nose” rate of between 500 and 800 ppi or more at less than one inch per second speed of movement.

A Closing Caution – The suggestions provided here are representative of trends that can enhance your handling package. Before any of this can work, the setup must be balanced, the steering characteristics must be ideal and the car must be aligned properly. If not, you will probably chase the setup and experience a lot of frustration and expense.

Shock tuning is the last thing to experiment with in order to try to increase your race cars performance, but it is nonetheless a necessary step in finding the ideal total handling package. That said, before you setup your car and chose your shocks, evaluate what you will need as far as shock rates that will match the spring rates you will run.

If you are experimenting with the bump setups, consult your shock expert so that you can match your shocks to the spring rates you will be using. Most racing shock companies have technicians who are very familiar with those setups and can advise you as to the best rates to use to match your bumps.

Sources:

AFCO Racing
www.afcoracing.com
(800) 632-2320

Integra Shocks and Springs
www.integrashocksandsprings.com
(800) 472-3464

Penske Racing Shocks
www.penskeshocks.com
(610) 375-6180

RE Suspension
www.resuspension.com
(704) 664-2277

QA1
www.qa1.net
(800) 721-7761

The post Matching Your Shocks appeared first on Hot Rod Network.

In order for the rear of our race cars to steer, there must be vertical motion. For most dirt cars using the traditional four-link rear suspension system, the motion can be created and controlled through several means. There are three basic methods that can cause rear movement on a dirt car. One is the use of lift arms, or lift bars, second is the use of the angled panhard bar with the left side mounted to the frame and the right side much lower and mounted to the rear end. Third is the use of the left rear four link angles that cause the LR wheel to be pushed up under the front mounts lifting the LR corner of the car.

The extent and use of the four-link angles in all of the above depends on what the racers goals are and somewhat the track conditions that must be dealt with. There are a lot of different settings involved with the rear four-link suspension and most racers are overwhelmed with the complexity. So, let’s examine how the angles affect rear steer and learn when and how much steer we need to use.

Explaining The Four-Link System – The parallel 4-link rear suspension is common to Dirt Late Model, Dirt Modified and Sprint Cars. The original purpose for using the 4-link suspension was to have a suspension system that produced very little, even zero, rear steer as the chassis moved vertically. Racers, being true to their nature decided to experiment with various angles in the 4-link and found that zero rear steer might not be the most efficient way to go under all circumstances.

Today, we have various schools of thought on where to position the links on a 4-link system and many more theories on why. Let’s examine what happens with the various changes and look at the big picture to try to understand what is really happening to our cars. Even though the current trend among top Dirt Late Model racers is to minimize the steering characteristics of the rear suspension, there are times when even these teams must get a little more radical.

Basic 4-Link Designs – There are two basic designs of the 4-link rear suspension, the “standard” 4-link where both links are forward of the rear end axle tubes and then there is the “Z” link where the top link is rearward and the bottom link runs forward. Both of these designs can be positioned to produce near zero rear steer and by far the most common is the 4-link. The 4-Link design can be made to produce somewhat more rear steer than the Z-link.

One of the big differences between these systems is ability to create weight jacking and forced loading of the left rear tire that is common with the 4-link system whereas the Z-link cannot. As we introduce more rear steer which moves the left rear wheel forward, the angle of the bars is such that the wheel is forced down and is trying to lift the chassis, so load is transferred onto the left rear tire. This loading is desired by some in order to produce more bite under dry and slick conditions.

If you look at the way the car is situated when the rear is severely steered to the right, the left rear tire is pointed more to the middle of the front tires and is driving from the middle of the car. Because of the added loading of this tire, most of the rear weight is on this tire. The right rear tire is helping to locate the rear of the car, but does little to drive it off the corners.

Both of the suspension types are usually attached to a bird cage that may or may not be locked to the rear axle tube and where the rear end may be free to rotate. A separate structure is attached to the rear end to control rotational movement of the rear end upon acceleration and braking. This could be a “third” link or pull bar, similar to that used on a three link suspension, a lift arm that runs forward and is attached well in front of the rear end or a combination of several systems.

If the bird cage link brackets at both sides were mounted solid to the rear axle tube, then as the car rolled in the turns, there would be a significant amount of binding going on because the bird cages would be trying to move different amounts and possibly in different directions. The suspension would be trying to twist the rear end as each axle tube would be rotated differently.

If we change the angles of the links so that one side of the car produces more fore/aft movement at the bird cage, we cause that end of the rear end to move in a direction that will cause the rear of the car to steer away from straight ahead. This is called Rear Steer and most of what is used for dirt racing is steering to the right.

Under some conditions, rear steer is less desirable, especially on hard and tight dirt tracks that act more like asphalt than dirt. Rear steer on dirt tracks that are slick is not only acceptable, but could be useful under certain conditions.

Understanding Rear Steer – To even begin to understand how the car will rear-steer and to what extent, we first need to completely understand the movement of the chassis and what causes this movement. The chassis mounting points of the 4-link and Z-link will move vertically as the car transitions into and out of the turns and even down the straightaway and the amount of movement dictates the degree of rear steer.

As a chassis rolls in the turns, three basic things can be happening overall: 1) the left side of the chassis may move up while the right side may move down, 2) the right side may move down and the left side may stay near that static location, or 3) the left side may move up and the right side may remain unchanged. With the same set of suspension link locations at each side, a car may well produce very different rear steer characteristics from each of the three scenarios.

A 4-link can be made to produce varying amounts of fore and aft movement of each end of the rear axle, depending on the combined angles of the links. By starting at a neutral setting for the links, meaning that for a certain range of movement up or down, the axle will not move fore and aft, we will show you how we can produce axle movement.

If, on a 4-link, we move the chassis mount for the bottom link up, then as the chassis moves up, the rear axle will move more forward. On the Z-link, we see the same effect for the bottom link. The opposite is true if the chassis moves down. For both systems, the axle would move to the rear. That is exactly why we need to know which way the chassis is moving at each side of the car under all conditions.

Knowledge of the extent and direction of shock travels will come in handy as we plan out our rear geometry. We can translate shock movement to suspension movement. Using either shock travel indicators or data acquisition will tell us what is really happening. I don’t see wide spread use of electronic data gathering on dirt cars, so some mechanical device must be used to help us understand our true movements.

Effect Of Panhard Bar Angle – A direct influence on chassis movement in the turns is the J-bar or panhard bar angle. If the bar is mounted more parallel to the ground, then it will have little influence on the vertical location of the chassis in the turns. If there is a lot of angle in the bar with the left end mounted on the chassis and higher than the right end, then as the car turns left, the bar angle will have a jacking affect causing the left side of the bar to want to ride up over the right side of the bar. This movement would raise the entire rear of the car.

Under those conditions, if the car rolls, and we know it does, and the whole chassis rises up, as we too can visually see, then the right side links may well remain in their static locations producing near zero rear steer at that side. On the other side of the chassis, there will be a combined vertical movement of the front mounts of those links to where the lift associated with the bar angle will be combined with the roll lift so that together these two effects can produce a large amount of forward movement of the left rear wheel. This movement pulls that end of the axle forward and the rear end will steer to the right.

Upon acceleration off the corners, the rear end will be driven forward and if the forward mounts of the links are higher than the rear mounts, there is a further movement of the chassis to a higher level through a jacking affect.

If we just look at the way the car steers, we might conclude that this is not a very good idea. On asphalt this would produce a very loose car that would be un-drivable. But if we look at the whole picture, including the aerodynamics of the body, we start to see why our lap times may be improved by doing this on dirt, especially on a very dry slick race track.

Side Force Flat Plate Aerodynamics – Winged Sprint Cars will generally run at an angle to the direction they are moving through the turns. The tall side plates on the wing catch a lot of air and will produce a lateral force that is the opposite of the centrifugal force that tries to take the car to the wall. Long story short, the aero force counteracts the lateral G-force and helps the car go faster through the turns, just like having more tire grip.

Another good example of this are the unlimited asphalt Late Models that sometimes run at Kalamazoo Speedway in Michigan trying to set the world record short track lap speed. They run very large panels on each side similar to the ones on a sprint car, only bigger, and those produce the same effect of countering the lateral forces using the air.

The combined effects that raise the whole rear of the car also put the rear spoiler higher into the wind stream and that can produce more aero downforce at the rear. This helps give us more traction to provide better bite off the corners.

Necessity Of Making Changes – If the track has a lot of grip, then we need much less rear steer and the associated aero help and so we make changes to our rear links so that less rear steer occurs. We may even benefit from creating opposite rear steer in small amounts, to the left, to gain more rear traction, just like we do on asphalt. The operative word here is CHANGE. We must be willing to make changes and a more thorough understanding of what happens with each change will make it easier to do with better results.

What happens at many dirt tracks is that the track is wet and tacky as the day starts out. A car that is jacked up and rear steered to the max just won’t get through the mud as well as one that is more level with all four tires on the ground. We can position the links so that there is very little rear-steer for these conditions.

As the track dries out and becomes slicker, we may need more rear steer and rear jacking to get the rear spoiler up into the air stream for more rear downforce and to drive the left rear tire into the track. The rear steer has more effect on the angle of the body related to the direction that the car is traveling and an aero side force helps pull the car to the left to keep it from sliding. Putting more angle in the J-bar is warranted now.

Measuring 4-Link Rear Steer – You can measure your rear steer in your shop. I have had racers I know do this with their NE big block Modifieds. This is an easy process and can be accomplished in one evening at the shop.

Put the front and rear link mounts in the “neutral” adjusting holes, or the middle holes for the range of adjustment. Then set the car at ride height and take a measurement level to the ground from the rear wheel rim on each side to the front say 50 or 60 inches. Put tape on the body and mark the distance.

Then jack up the left side in one inch increments and take measurements and record the height change and measurement. Go as far as you need to go to replicate the movement of the chassis on the track you run on. The difference in your measurements from the original static measurement is the rear steer amount. It will be fore or aft.

Go then to the right rear and raise and lower the chassis in one inch increments again recording the results. This corner of the car will either be lower or higher through the turns depending on your overall setup.

You can move the front and/or rear mounts up or down to see how the left and right wheels move with chassis movement. This process will teach you much of what you need to know about your car’s rear steer. Find and mark the holes that will produce Zero Rear Steer. Then chose holes that will steer the rear end the amounts that you think necessary to deal with slick conditions and anything in between.

Creating Setup Sheets – Once we fully understand how link angle changes produce rear steer at each side, we can make helpful adjustments at the track as the conditions change. We need to plan out which changes to make and be able to do them fast with little effort. A setup sheet that shows which holes to mount the links to for each set of conditions would help the crew make fast changes. If you don’t want your crew to know why you are doing things (secrecy is an asset at times) then just number the different sheets and tell them to set the car to sheet “3”, period.

Because we need to adjust other parameters on the car for changing conditions, we can include spring rate changes, shock changes and fifth and sixth coil changes as well when we make up the setup sheets. Once we develop our setup sheets, as we race the car, we can tweak the numbers according to the results.

The process of dialing in the car to the conditions using our setup sheets may take a few races, but at least we will have a plan that takes us in a positive direction. Remember that tacky tracks require less rear steer than when it goes dry and slick and plan accordingly. This will take much of the confusion out of the process of making changes when the track conditions change.

Sources:

Beak Built Chassis
(828) 478-4400
Facebook.com/beakbuilt

The post Explaining the Dirt 4-Link Rear Suspension appeared first on Hot Rod Network.

Virginia Research Center Gives Hands-On Instruction

SoVa Motion is presenting a thre- part seminar series and we attended part one. SoVa is a division of the GCAPS center located near Danville, VA on the grounds of the Virginia International Raceway. GCAPS stands for Global Center for Automotive Performance Simulation, and they have some of the most sophisticated testing equipment available anywhere in the world.

Frank Della Pia is the Executive Director of GCAPS and spent 35 years in various positions relating to vehicle performance at General Motors. The Technical Director is Kevin Kefauver, Ph.D. who in the past has worked for Dale Earnhardt, Inc. racing managing the shaker rig test program.

As related to circle track racing and stock cars, SoVa Motion has available an Eight Post rig used to re-create the dynamics of the motion of the car when circling a race track. They also have the most advanced tire simulation machine in the world and they have tested and have data on the actual tires being used at short tracks like you run on.

They can also measure race cars for geometry and do simulation runs and reports on the eight post rig. They offer track testing and data acquisition with two engineers and will come to your shop to assist you in setup preparation. They also provide race day consulting. Now that you know a little about SoVa Motion, let us tell you a little about their seminar series.

As of this writing, Keith Montgomery, the motor sports director at SoVa Motion, is conducting a series of seminars designed to help racers understand more about race car dynamics and introduce them to the tools available that can improve their setups.

I attended the first of three one day seminar on October 11th and observed as Keith and guest speaker Shane Huffman, spoke to those in attendance. They told the attendees of the most important aspects of race car preparation and setups. Keith is a long time crew member of NASCAR teams climbing the ladder from short track racing up to crew chief in NASCAR Cup competition.

Shane, as you might recall, is a very successful driver who excelled in the Pro Cup Series for a number of years and is now a crew chief for a top NASCAR Camping World Truck team. His extensive range of experience was apparent as he described in terms every racer can understand, the critical steps race teams need to take to become more successful.

We visited the nearby NTRC facility (National Tire Research Center) and observed as the crew tested a passenger car tire for a major tire manufacturer. The NTRC facility is another division of GCAPS. Keith explained how the tire rig simulates life on the road using a rolling road, flat belt simulation technique that produces a tire shape and contact patch true to the reality of everyday use. It has done the same true testing for race tires.

We then moved to the Eight Post rig where Keith had mounted up a NASCAR Late Model Stock car so that the attendees could watch and participate in testing the setup. The car was “run” through a typical lap re-enacted from data taken from an actual race car running a local track.

Check out SoVa’s Promotional Video of their capabilities:

We made changes to the car to see what the rig showed as a performance difference and the data correlated with what we knew should be the results of those changes. If we weren’t sure what the changes would result in, the data would show us and we could decide if that were a positive or negative change.

The seminar series consists of three sessions, all presented on Tuesdays. The second part was an on-track demonstration of data acquisition on location at Orange County Speedway in Rougemont, NC. This is a very fast, 16 degree banking, 3/8ths mile track. The seminar took place on October 25th.

At this seminar session, racers observed firsthand how the data gathering equipment was installed and what were the most important types of data to record. At this test, steering, shock movement, throttle, RPM, lap plus segment times and speed were recorded.

As a plus, the engineering team also installed load sensors on the bumps to record when they were on and off the bumps and how much loading was taking place throughout the lap. This data represents the most essential areas of data you would need to evaluate your setup performance and how the driver reacts to the setup conditions.

As changes are made, the data shows the results not only in lap times, but steering input, chassis motion (shock and spring travel) and chassis balance. It’s one thing to talk about these tools and how they can benefit the racer, but quite another to actually see how they work and to observe the process of reading, evaluating and making changes based on those results.

The third and final seminar session will take place on Tuesday, November 8th at the SoVa Motion building at VIR. Keith will present information and analysis using the ChassisSim software program as well as tire reports on the Hoosier 45 race tire. He will show the students how that data can be used to improve the cars setup and performance before going to the race track.

Even if you were not able to attend the first two seminar sessions, part three will be very useful because it will provide new and innovative information using data from earlier test sessions to go the extra distance by putting all of that to use.

Source:

SoVa Motion
1020 Lotus Drive
Alton, VA 24520
434-766-6644
www.sovamotion.com

The post A Look at the SoVA Motion Series of Seminars appeared first on Hot Rod Network.

A Discussion About Ethics: What Part of Illegal Don’t You Understand

I’ve been aware of this problem for some time and decided now is the time to speak out. Traction Control products are advertised in certain media and I have a problem with that. As a part of the racing community, publications should, and do for the most part, promote a healthy racing environment and that health is based on making racing more affordable, safer, and more equally competitive.

It’s the last of those health items I have a problem with in relation to traction control. And I will explain my thinking on this in more detail. But for now, I can tell you I had a very interesting and informative discussion with a fellow editor and friend of mine (at least he used to be) where he and I discussed the ethics and effects of traction control products in our sport.

He explained that the people who develop and sell those products are good people and are just trying to do business in the sport. He explained that a test was conducted whereby several drivers drove cars that were equipped with TC. Evidently, at this particular track, there was not much performance gain for whatever reason.

One of the drivers was a very experienced and well known driver of that region and he said he didn’t like what it felt like and would prefer not to use it, in so many words. The argument being that if it doesn’t do much, why worry about it, right? The truth is this driver didn’t need TC. He has already learned throttle control based on his years of experience.

The very first thing to consider when talking about TC is that it is illegal. There is only one other product that is widely advertised that is illegal and that is tire treatment. One could argue that tire treatment is legal, or not enforced as it may be, at some racing venues and in some series, so the offering of it is not really considered offering a cheating or illegal product.

That is not so with TC. I don’t know of any series or track that openly allows TC for any of its divisions.  It would be like offering services to get inside a sealed motor and make modifications that are illegal. We don’t see much of that because it would point a finger at the teams using motors from that vendor, and it is illegal.

Here is the real problem, aside from the legal issue. In years past, drivers came up from humble beginnings racing in lower classes with low horsepower. As they progress up the racing ladder, the engines became more powerful and the drivers had to learn throttle control in order to manage tire spin. That is if they were to be successful, and many did not ever master the technique.

The ones who did became so successful that they were able to do well when they got the call to drive in the upper divisions of NASCAR. Drivers like Dale Earnhardt, Sr. were masters of throttle control. I have heard first hand stories from data engineers who observed and recorded his throttle movements that showed he controlled tire slip with his foot, not a chip.

Now fast forward to today’s racing. A youngster who is well financed comes along and daddy wants Jr. to do well so he can move up the ladder faster. Papa is willing to do anything within monetary limits to make that happen. TC is one of those things that can help Jr, initially do well, but later on hurt his/her chances when they get to the big leagues and haven’t learned throttle control.

Now the quick rise to the top stops cold in its tracks. We’ve all seen where an up and coming driver who really dominated on the short tracks just cannot cut the mustard in the big leagues and we all wonder what went wrong. Could it be that Jr. had a helping hand in those early years? It’s possible. It’s not just that TC is illegal; it is harmful to driver development.

Many years ago I thought about inventing an analog traction control device that would detect wheel spin. It would be connected to a sensitive part of the driver’s body with electrodes much like a taser. If the wheels started to spin, a low voltage shock would be administered to the body part and gradually get more intense as the tire slip increased.

That way, the driver would really feel the event and be forced to develop an educated foot, or suffer the consequences.  Maybe we could still do that. Would it be illegal? Probably so.

As a long time consultant to race teams, I personally don’t want to compete against teams who run illegal equipment, whether those are illegal engines or TC or any other non-approved parts. I’ve lost races to teams who by everyone’s account were running TC and it pissed me off.

I have nothing against the owners of the companies who choose to offer to sell illegal racing parts, I just don’t want to compete against those products. So, I’ll do everything in my power to rat you out every chance I get. And I will never be caught using any of those products or working with anyone who does. It’s all about integrity my friend.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1821 E Dyer Road, Suite 150, Santa Ana, CA 92705.

Sprint Car Safety

Bob,

Let me start by saying that I think safety should be the number one concern in racing. I crushed my C2 and T3 vertebra in a crash on a 1/4 mile dirt track. I flipped and my cage collapsed and have been paralyzed since. As you can imagine, I now look at ways that could prevent this type of injury.

I know that head and neck restraints are great for preventing certain types of injuries but I don’t see where they would be of much help in a compression type injury like mine. It seems to me that most serious racing related injuries to the spinal cord come from these types of injuries and a H&N device would have done little to prevent any of the injuries that have occurred on short tracks.

I’m not downing H&N devices at all, I think they’re great, but is there any device that provides protection from the head/helmet moving forward and protection from compression type injuries at the same time?

Russ

Russ,

From your description of the injuries and the crash, in my opinion, there is no device that a driver could wear that would prevent that injury. The problem is the collapse of the roll cage. The spine would be compressed even with some kind of device on. 

If the cage held up, there still needs to be room for the movement of the upper body trying to come out of the seat due to seat belt stretch. The current design doesn’t provide enough of that kind of space for taller drivers. 

Another problem with the current design is that the drivers sit too straight up. There is too much compression loading on the spine whereas if the driver were sitting in a more inclined position, the forces would be greatly reduced on the spine.

That’s about all I’ve got on the subject. Most of what would help the situation would be very hard to change for those cars.

Russ Response,

Thanks for your response. My cage was definitely poorly designed even though it was a “professionally” built chassis. It didn’t have the bar that goes from the door bars up to the a-pillar bar. If it had I believe I would have walked away.

I had never thought about the driver sitting up straighter causing more loading to the spinal cord, great point. Even though I no longer drive, I help a couple friends with their cars and we are putting a street stock together for my nephews to drive so I want to be as safe as possible. Thanks again for the information!

Front Weight Distribution

Bob,

Throughout your years of setting up cars, what can you tell me about wheel weight differences on the front? Most discussions pertain to bite on rear tires but little is discussed on the front.

I have had past successful setups regardless of front spring rates using equal amounts of weight on front, for example 725 lf 725 rf. As of now I am carrying a lot more weight on the LF than the RF and wondering what affect this has in comparison other than more Left Side %. Thanks for any input.

Jason

Jason,

The equal front weights are associated with running a cross weight equal to the left side percent. When you do that, you always end up with equal front weights. That high cross weight percent adds load onto the left rear tire, and that may help with bite off the corners on a flatter track.

There is a lower range you can run that is about 5-6 percent below that. This lower range is usually much better for higher banked tracks. If your LF weight is higher now, then your cross weight percent is lower considering the same overall weight. So, you are moving in the direction of the lower range. Just go all the way, not part of the way.

Tire Balancing For Dirt Mods

Bob,

I wonder what your take is on balancing dirt modified tires like the big blocks in the northeast run. At Syracuse most guys balanced. Now with it going to Oswego some may wonder if it’s still needed. My opinion is a balanced assembly should accelerate and decelerate fast.

Also it should put less harmonic vibrations through the drive line and shock absorbers which should aid in dependability.  For $8 a tire would you recommend?

David Surace

David,

I’m not sure your car will accelerate or decelerate faster unless the tire is bouncing noticeably. But balancing will reduce the vibrations through the driveline and that could help reliability.

It is always a good idea to balance tires, even on dirt. There are simple ways to do that. You can make a balancer yourself. When I raced karts, we used a simple balancer that utilized a free bearing system. If you could get a hub and spindle pin, you could make a balancer for your racing. Mount the hub somewhere where you can mount the tire/wheel to it easily.

The key is to use a very light oil on the hub bearings for your homemade balancer and don’t preload the bearings much at all. That way, the tire and rim mounted to it will be free to spin easily. If greased, it would not move as freely.

Just mount the tire and rim to the hub and rotate it 45 degrees at a time and see if it wants to rotate on its own. If one side is heavier (i.e. unbalanced), that side will move to the bottom. Just add weights to the light side (high side) until it won’t want to spin.

Right Front Tire Wear

Hello,

I’m struggling for wear on the right front wheel. It’s on the inside of the tyre and I cannot work out what’s wrong with the car to make it happen. Would it possibly be because I’m running the wrong scrub angle or is it something else? I’ve just bought software to try a new front end layout but want to sort this tyre situation out before I get to far into it.

My car runs on 10″ Hoosier slicks. My roll centers are 3.76 high and 7.74 to the right and dynamically they are 2.75 high and 8.50 to the right after about 1″ of dive and roll. Camber for the right front is -2.8 deg. and -3.57 deg. dynamic. And Ackermann is 0 to 0.42 deg. dynamic. And scrub radius is 3.55 and 3.38 dynamic.  Any help is much appreciated.

Many thanks,

Carl

Carl,

 It could be that your setup is not balanced. With a roll center right of centerline, most of the loading at the front in the turns ends up on the right front tire and it becomes overworked.

You might be running a lower pressure than needed on the RF tire. Check your tire temperatures and see if the inside temp. is cooler than the average of the outside and inside temps. If so, you need more pressure. Low pressure causes the tire to roll over and put excess wear on the inside edge, like you show in your photo.

Try to adjust your setup to be more balanced by moving the roll center to the left of centerline. Also, increase the roll stiffness of the rear suspension by increasing the RR spring rate, and/or lowering the LR spring rate. You could also raise the panhard bar if so equipped.

The Ackermann should be near zero. You have 0.42 degrees of Ackermann and that produces another ¼ inch of toe when the wheels are turned. Scrub radius is not a performance item in circle track racing for the most part.

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When a local Pro Late model team posted an in-car video of their last race on their facebook page early in the season, I knew immediately they had some serious problems. The car was very tight-loose and the driver was really struggling with the car, but doing an amazing job of holding on. I couldn’t help myself, I commented, “I can fix that”.

Blaise Hetznecker, the driver, responded that he would love for me to help, and so began a journey that taught me a little more about what I already know something about. This may be of great interest for those who have already converted from conventional to bump setups and are struggling, or anyone who contemplates making the change.

The car the video was shot in was involved in a crash and basically destroyed and Blaise’s father, Rainey, was able to pick up a seldom used, but older design, late model that hadn’t worked very well for the previous owners. We’ll tell you why that was so.

In this story, I will provide as much detail as I can so that you can understand the problems you might encounter when trying to convert a car that may not have been designed to run bumps into one that is. There was a period of time between five to ten years ago that the chassis manufacturers were converting to the new style front ends, but some were sold that still had the conventional design. This car was one of those.

About The Car – This is a Port City chassis circa 2005. The car came with everything the team needed except the motor and tranny. Those would be salvaged out of the old car and were perfectly fine. A very good set of adjustable shocks came with the car also and that helped us when it came time to do the setup.

First we needed to look at the previous setup to see what went wrong. That front end design was very similar to the new car, so any problems I could identify would carry over to the new one. And we did find significant problems.

First off, the front top and bottom shock mounts were not spaced far enough apart to allow room to mount the shocks so that there was enough shock shaft showing at ride height to allow bump stops or bumps springs. On the old car, they were trying to run bump stops and they set the static cambers like everyone else does. Without the required shock travel, the dynamic cambers were all wrong.

When I realized what the cambers were that Blaise was trying to steer the car with through the turns, I was more amazed that he was able to hold on and not wreck the car. The actual wreck that totaled the car was due to getting caught up in someone else’s mess.

Shock Mount Changes – So, the first thing I suggested was to modify the upper shock mounts to do two things. One was to raise the upper shock mount to allow room for bumps so that the car would travel enough to get down low in the turns while also allowing the tire cambers to be correct. The second was we needed to be able to quickly adjust the upper shock mount height so that we could adjust the spacing between the shock body and the bumps.

Being do-it-yourself kind of guys, they proceeded to fabricate upper mounts that were a bit large, but very effective for our use. By using screw jack upper coil-over mounts, they didn’t need to run packers, or spacers to tune the point where the shock lays on the bumps.

That done, the next thing I suggested was for them to run on bump springs instead of the bump stops. I donated a pair of 1500 ppi bump springs I had left over from my foray into the bump spring market a few years ago and we installed a pair of 175 ppi ride springs.

The car also had a nice Nascar style, three piece sway bar that was 1.25” diameter, which seems small in today’s bump world, but it had 0.375” walls. That made it a stiff bar that when installed in this car amounted to a 600 lb/in rate.

Bump springs don’t like high sway bar rates and this one was too much. So we installed a 0.75” diameter solid sway bar that rated around 120 lb/in. This would free up the bumps springs to do their job, plus we could pre-load the bar without jacking the ride heights around like happens with a stiff bar.

We also measured the front end for moment center location and found that this car was very close to what I wanted. With a little tweaking, we were able to get the dynamic location to 0.2” high and 14.0” left of centerline. For all of you “jacking force” people out there, this is a good location for you too.

Once we got the ride springs and bump springs installed, we “hand” tested the front shocks for rebound. We did that by pushing the front down onto the bump springs and then releasing the car. How quickly it rises tells us something about the rebound rate since the low speed jets mostly affect low speed shock movement.  If the LF moves about an inch or a little less per second, it is in the ballpark and can be adjusted further once we test the car. This one was fine and we ended up adding a little more rebound to the LF once we tested the car.

At the back, what they were running for springs on the old car was too stiff at the right rear. Many teams overdo this aspect of bump setups. Granted, the bumps make the front very stiff and roll resistant. So, you have to make the back as stiff, or roll resistant, as the front in order to attain the balanced setup.

But many teams will overdo the spring split that serves to reduce rear roll and install a very stiff RR spring. On this car, they had run a 200 ppi LR spring and a 450 ppi RR spring. That 250 ppi spring split is too much for most cars. We went with something less.

Of course, the panhard bar can compensate for the spring split, and I like to run a lower bar, but this car didn’t have the mounts mounted low enough to get where I like to run, so the rear spring rates we chose matched the panhard bar height we were force to run.

Here I will explain that there is a large combination of spring rates, spring split, and panhard bar heights that will work to produce the same rear roll resistance. That is why I’m not telling you what we ran because it may not work the same in your car.

Other Things To Check – There were other items on my list to go over with this car that I highly recommend you consider too. We checked the Ackermann and this car had too much. We adjusted that to near zero by moving the left outer tie rod forward ¼ inch.

The rear alignment was nearly perfect and I don’t think we changed that at all. The rear trailing arm angles were adjusted a little so that we got no steer from the RR, and a little steer back from the LR by using a higher arm angle.

We also adjusted our pinion angle to equal and opposite to reduce driveline vibrations. As we progressed through the alignment process, I discovered that the engine was almost an inch high from what the rules allow, and too far left by 0.75”. We would deal with the tech officials later on about that.

Setting Cross Weight – I knew from using a setup tool I have what cross weight works for the weights of this car. But before we put it on the scales, I needed to check the shop floor for level. We used a long piece of 1×2 steel placed on blocks of wood at each end sitting where the scales would be placed and a set a smart level on top of the steel.

The floor doesn’t need to be perfectly level, but both ends need to be the same angle in the same direction. We’re talking about +/- 0.5 degrees or so being OK. This floor amazed me. It was dead on perfectly the same front and rear. I think it read zero too. One less thing I guess.

We weighed the car with the sway bar loose and set the cross and ride heights. Then we set the sway bar snug to neutral and pushed the car down onto the bumps. Sure enough, the bar was loaded about two turns. We see this a lot and you can keep that preload like we did using this small bar, or set the bar to snug while down on the bumps.

The next step is setting the cross weight on the bump springs. This is commonly referred to as setting the timing of the bumps, but in reality, we don’t want the car to have any different cross weight while on the bumps than what it is has ride height.

To do this, we removed the ride springs, set the bar loose and allowed the car to sit on the bumps springs. Remember that the front end will travel more this way than it will on the track because we don’t have the ride springs to help hold the car up.

Now check the scales for cross weight and either shim between the bumps and the shock body or turn the screw adjusters until the cross weight is the same as when at ride height on the ride springs.

This is an important step because if we don’t check the weight distribution when on the bumps, it could be anything. We could go from 52.4% cross at ride height to 56.8% on the bumps, or to 48.3% on the bumps. We just don’t know unless we check it.

There is a movement afoot to design the car so that the weight distribution is different when on and off the bumps, but that is more advanced than this presentation and we might address that later on. We basically knew what the car wanted for cross and I want to maintain that cross weight throughout the lap.

Time To Go Testing – In initial testing, the car reacted well enough, but the driver reported a push on entry. It was significant enough to affect the other parts of the turn, so I decided to observe from turns three and four at New Smyrna Speedway where this car would mostly race.

In his youthful excitement, Blaise was over-driving the entry by about two to three car lengths. I used the lift points I saw being used by the top two finishers at most of his races as a reference. Late braking on entry can upset any car and I went through a process of backing him up on his entry and the push went away.

In The Race – It was time to go racing. In the first race, the car started out looking very good, but quickly went loose off turn four to the point that his previous dirt racing experience came into play. He saved the car lap after lap and finished in the top five, but this wasn’t good. This track has a shape off turn four that tends to unload the LR corner and if the rebound is too much in that shock, it can cause the car to go loose.

I needed to know how the back shocks were built because that was the only unknown on the car to that point. I had a friend named Vic Kangas, who had been a very successful crew chief in Nascar racing and who lives near me and is semi-retired. He volunteered to help.

He had a shock dyno and when we ran the rates, I knew immediately what the problem was. The rear shocks had been built as tie-down shocks, or with much more rebound than the spring rates would justify. I had him rebuild the shocks to “normal” rates. In the old days we would call these a three LR and a four RR shock.

At the next race we found that we had fixed the problem. In subsequent races we timed the car in the segments and were as fast, or a little quicker through the turns than the lead cars, but our lap times were off by several tenths.

NSS is a horsepower track by everyone’s account and we were down on speed. The next step is to try to identify the deficit and make corrections. I have a theory as to why we are off. This engine is a “built” motor that when it was built probably was designed for a maximum power RPM range of 6800 to 7400 RPM. Back a few years ago, that was what was allowed in his class.

Since then, the class started allowing crate motors to compete and to level the playing field, the maximum allowable RPM for built motors is now only 6800. This puts his motor out of the power band that the engine was designed to run in and it now puts out much less HP. A different cam profile might level out the power curve and give more HP in the 6000 to 6800 RPM range.

That said, for this presentation, I will say I did my job. The segment times proved that and this car will be competitive once the team rectifies the power problem. As for the conversion, if this had been a car that had suffered some abuse in its past life, I would have recommended that they install a new clip and one that was designed for bump setups.

As it was, the car had very little track time on it and was never bent or crashed. So, this was a perfect candidate for cutting up and re-designing as we did. If you are thinking of going the bump route, or have tried and failed, think about making changes to your car to make it more bump friendly.

How To Deal With Tech Officials – Now I need to address something I alluded to earlier. Our chassis had engine mounts designed for the super late model class. It put the motor too far to the left, at a point that in the rules was legal for SLM, but not for this class and it involved pulling the motor to correct it.

Before we ran the first race, I talked to the tech officials and explained the problem. It would have been very difficult to make the changes necessary to move the motor over and it was getting late in the season. They said that if we added 25 pounds, then the car would be legal and that is what we did.

I want to point out here that they really appreciated my honesty coming forward before we might have had to explain the situation in tech after a good finish. The solution we came to was agreeable and if and when we had to go through tech, which we did later on, there were no surprises.

If you have a situation that is hard to immediately correct, I firmly believe your tech officials will be understanding and work with you. If you try to hide it, you are in for a rough time. It’s like when you are pulled over for speeding. You may as well tell them how fast you were going, they already know. Honesty is always the best policy.

Conclusion – There are numerous teams who have already switched their cars from conventional setups to bumps and are struggling. And there are still ones that want to convert, but are nervous about the process. It doesn’t have to be that way.

If you follow the steps outlined here, you will be in the ball park with bumps. Remember, the camber change is much greater with bumps setups than what you are used to with conventional. And, you need more front shock shaft travel and shock length for bump setups.

Your car needs to travel until the cross member is about a half inch off the ground when you push the car down onto the bumps. On the track the front end will travel about a quarter inch or so more than that from bump compression.

Don’t over shock the car either. The LF front shock will be the highest for rebound and the RF shock will be about half the rebound rate of the LF. At the rear, the shock rebound rate should match the spring rate at 3-4 inches per second of shock speed and no more.

Get all of the other parameters right such as alignment and moment center and then go racing. Tune with the panhard bar for balance watching the LF tire temperatures. The goal is to equal the left side tires for average temperatures. Then tune the handling balance with the cross weight.

Sources:

Powertrain Technology
Butlerbuilt Seats

The post From Conventional To Bump Setup appeared first on Hot Rod Network.

Of all the rules related problems we have encountered over the years, specifying and matching different engines has been at or near the top of the list. Some sanctions just cannot get a handle on making common sense rules when it comes to what they allow for motors. And so, teams who get the setup right can often suffer from lack of performance on the engine side.

The problem is what is referred to in some circles as Balance of Performance. This is a common term in the old Grand-Am racing series, forever in NASCAR racing and now in IMSA racing as you incorporate different brands and configurations of motors. It is done to equal out the competition so that some teams do not end up with way more performance than the other teams.

That is all understandable as far as it goes, but what if they get it wrong. And what if there are politics involved whereby the tech official is swayed by one or more engine builders against other types of engines (insert crate motors here).

And even where only one type of motor is allowed, there is sometimes differences in those motors power output (insert cheating here). A certain mid-west motor builder who has become very frustrated recently said in a Facebook presentation, that after much research he believed 40-50% of a certain brand of sealed crate engine “had work done” to them.

He went on to say that aftermarket companies readily offer cheater valve springs, cams, pistons, and cranks. And, the seal bolts and tags are also available. So, even if you have good intentions at your track or in a series or sanction, it still happens, cheating that is. This disrupts the Balance of Performance we want and need.

In at least one sanction in the Carolinas, when you bring a sealed crate motor to the track the first time, they ask you to remove the seals and bolts and leave the motor “open” for inspection. This is something I have advocated for many years now. Just remove the “sealed” from the description of those motors and let the tech officials have at it.

In another example, one track allowed the sealed crate motors into a class that had previously only had a spec motor allowance. To create a BoP, where the crates were at a horsepower disadvantage, the spec motor teams were asked to install a 6800 RPM chip when the motor was originally designed to run up to 7400 RPM. This then put the spec motor at a disadvantage to the crate motor because it dropped its HP down below that of the crate.

In the TUNDRA series in and around Wisconsin, you can run any approved motor you want. They can create the BoP by requiring you to have the engine dyno’d at a specified shop and certified as to the horsepower output. Then they have a formula for adding weight to the cars whose teams run the higher HP motors, and it’s not just adding 25 pounds that won’t really do anything, it’s more. For example, the GM 604 crate motor can run 250 pounds lighter than the built motors at certain tracks.

In this way, you are allowed to run your spec or crate motor and still compete without having to worry about the BoP. If the motor has been certified, it is legal if you meet the weight criteria. But, there is a cost some might point out. The teams have to pay the dyno shop around $400 for the certification.

As you can see from reading the above, things get messy in a hurry when you start looking into the motor situation in circle track racing. I’m not sure what the perfect answer to all of this is right now. I do know certain things that are indisputable. Here are a few.

Sealed motors need to be un-sealed. We know by now that up to half or more of the sealed motors are cheated up. Chipping down the maximum RPM of a spec motor designed to run efficiently at a higher RPM does not work well. Adding sufficient weight does. Cheater motor builders need to be caught and punished severely. And, the tech officials are the only ones who can make a difference with the cheater motor problem. Do your jobs.

GM and Ford have put a lot of effort and money into providing cost effective competitive motors for short track racing. Their plan was a good one whereby racers would spend less money for adequate performance. The only problem was that there is an entire industry built around engine builders making money building motors and engine parts manufactures making money selling engine parts.

Surely, we can understand how the crate motor program disrupted that industry and many who write the rules for short track racing are still trying to navigate through this mess without running anyone out of business. And it’s a difficult task. Just ask those who must decide.

The TUNDRA series seems to have found the perfect answer to all of this with their certification program.  I’m not sure other sanctions have the infrastructure to pull this off, but they would do well to try. Otherwise, we remain in a very convoluted situation that is in many cases unfair to the honest racer who just wants to race on an equal basis.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1733 Alton Parkway, Suite 100, Irvine, CA.

Consequences Comment

Bob,

That is a great article in the Feb 2017 CT.  The behavior young Mr. Nemechek exhibited isn’t new to NASCAR.  Dale Sr. made a career out of it.  Remember Bristol when on the last lap Dale was just going to get to Terry Labonte’s bumper and “rough him up a little bit”?  Or one of the last races on the ½ mile at the old Richmond track where I think Petty, Waltrip and Earnhardt took themselves out and Kyle Petty won his first race.  Or maybe you didn’t see Jeff Gordon win a dozen or so races with the “bump and run”?  And what got NASCAR on the map with the final lap of the first flag to flag coverage of the Daytona 500 in 1979? A classic, old school short track scuffle, that’s what.

We have two scenarios here to base this type of driving upon.  Back in the day when you earned your way into a ride and you were older than 25 by then to get a ride, racing still had a behind the scenes before cameras and social media didn’t capture every fart and utterance of a driver or race team.

That said, if you chose to pull that kind of crap and dish it out like a man (which you were by then) you had to take it like a man, which meant you had to deal with the other driver or the owner of the car kicking your ass.  If that didn’t resolve it then it got resolved on the track.  If you were a good enough driver or were as big or bad as a Buddy Baker, you could save yourself.  Sponsors only cared about where their logo finished the race because those were the only events that got media attention.  The key phrase here is “media attention.”  That used to be TV – if that.

No doubt you’ve noticed the empty stands at NASCAR’s big three traveling series as of late.  Butts in the seats aren’t paying the bills these days for racing purses.  Richard Childress Racing doesn’t have a competitive driver, they are all drivers whose families are footing the bill to buy them rides (Brendan Gaughan!).  Almost all of the trucks are being driven by those who bring their own sponsors (Nemechek Jr. drives for his dad).

The XFINITY series isn’t much better.  Justin Allgaier has got to be paying his own way. The point here is clear.  NASCAR needs any and all exposure it can get to attract sponsors and will therefore allow this behavior to continue, thereby promoting it.  Since most of these young drivers are now driving for their own sponsors, what risk is there to losing a sponsor?  Not much.  What did Joe Nemechek say to Jr. after this wreck?  In the trailer, behind closed doors it probably went like this, “Thank God we’re in the chase now”.

So it boils down to this, what is there to lose or gain by driving like this?  For Nemechek Jr.  it looks like it got him a sponsor.  There isn’t one in the picture in your article but there was soon after and into the chase.

 Mark Tustin

Mark,

You make some good points. The politics dictate the consequences in many cases. So, understanding the behind the scenes goings on helps us to understand the events. I still don’t like the lack of consequences. Any publicity might be good publicity, but in the long run, it isn’t working evidenced by what you referred to, empty seats.

Consequences Comment II

Bob,

Who do many fans and media say is the best NASCAR driver of all time, the Intimidator (Bully), Dale Earnhardt, Sr.  Richard Petty after exiting the Care Center at Darlington, a few years back, said on TV, “The wreck was my fault, I know better than to race with Earnhardt.”

When Dale wrecked Terry Labonte in turn 3 at Bristol (and won the race) he said, “Last time I wrecked him coming out of 4 and he won.”  Ken Schrader summed up Earnhardt’s approach, ” I just hit him; it’s his problem if he doesn’t have the driving talent to save it.”

If a young driver wants to be the best, he needs to model his driving style after the best.  Why should young Nemechek drive like his Dad?  Joe drove hard, clean and got the best out of his equipment.  He didn’t make millions of dollars or make anyone’s “all time list”. I completely agree with your article; however, the media and fans can’t have it both ways.

 Don W. Wolfe, St. Augustine, FL

Don,

I’ll refer your comments to the ones above. There were usually consequences in the pits after those actions. But for some reason, by that time, Dale and others seemed to be immune from retaliation, maybe because he had big guys like Chocolate Myers in his pits.

I guess the answer for short track racers is to never be first on the last lap! At Daytona for years, it was understood that if you wanted to win the 500 or the 400, you want to be second on the last lap and draft by for the win.

With the current bump and run tactics, the same holds true. Find a way to be second on the last lap, then bump and win? Something about that doesn’t sound right. Yes, you might win, but where is your integrity. More times than not, Dale, Sr. could and did get to the guys bumper and bump and ran. He did it with finesse and he didn’t wreck the other guy, most of the time.

We tend to only remember when it went wrong. Richard Petty didn’t win his last, 200^th, race by bumping Cale Yarborough, he did what no one thought possible at the time. He drove his butt off to re-passed Cale in turn four after the master of “second on the last lap” Cale had drafted by going into turn three. That, my friends, is how it’s done.

Gear Changes

Bob,

First off, I am a big fan of your technical articles. The design and proper setup of a race car have intrigued me since my late teens. I am in my late sixties now and not currently involved with a car, but still like to stay on top of the curve as much as possible. I have a question regarding your article in the Feb 2017 issue of Circle Track titled “Gear Selection Science”.

As a dirt track goes dry/slick you state that one should go to a taller (lower numerically) gear to make it easier for the driver to control wheel spin. Are there any easier ways to kill the torque the tire contact patch sees by engine tuning? Retarding the timing would help and is a lot easier and not near as messy as a gear change.

You also state that if lap times slow a lot because the track went from heavy/tacky to dry/slick, that would warrant a gear change to put engine back into its proper power band on corner exit. If the track has slowed for the main event due to going dry slick, hasn’t this in effect put a taller gear in the car because exit corner exit speed is now slower, or am I wrong with this line of thought?

I helped a number of drivers locally for a total of about 25 years in my younger years. We didn’t have quick changes in the classes involved. Attempts were made to throttle linkage geometry to have as much pedal travel as was comfortable for driver and also progressive, meaning the first half or two thirds of application happened at a slower rate than the remaining amount.

Also your article on anti-squat in same issue also helped me understand some missing pieces that I had wondered about for many years. Thanks again for sharing your knowledge and experience.

Brian Ratzlaff, Merced, California

Brian,

The article was about gearing, but yes, there are other ways to deal with lack of grip on dry slick tracks. The first that comes to mind is unhooking the secondary throttle bodies and only running on two instead of four barrels. That is a trick many successful dirt teams have been doing for years.

Yes, when the car slows down, it would seem that the RPM changes into a range out of the maximum power range. But, when it is dry and slick, it is easy to break the tires loose, even in the lower RPM range. With the higher gear, the wheels will spin faster and the situation gets worse, which negates what I said in the first place.

I like the idea of the progressive throttle and actually discussed that with a racer at PRI this past year. That and throttle control and having plenty of throttle throw to work with are the most effective ways to deal with slick conditions.

The post Engine Control Needed and Q&A with Bob Bolles appeared first on Hot Rod Network.

Bumps – One Or Two?

In the world of bump stops, bump springs or air bumps, there are two ways to set these up, using one bump or two at the front. For now we’ll not talk about the rear as that is another story all together. In asphalt racing the one-bump crowd generally will use the left front as the bump corner and in dirt racing it is the right front that has the one bump. Is it generally better to use one or two bumps? Let’s investigate that.

Let’s take a look at the dynamics of the front end on a race car and what the differences between running one bump or two is. We’ll mostly cover entry into the corner, and some of mid-turn. Exit off the corners is much less affected and is a separate event.

I am going into this discussion without a bias as far as my thinking is concerned, but that said, I have always advocated running two bumps on the front end when working with teams. As we go along here, I will either convince myself that using one is best, or that two are best. Let’s see how it goes.

Using One Bump – The influence on the handling between using one bump or two is most evident on entry to the corners. At steady state mid-corner there is still an influence, but much less. On entry to the corners, we are letting off the throttle, then braking, then letting off the brake and then entering mid-turn. During all of that, weight is transferred onto the front corners and loading the front springs and bumps.

If we have one bump up front, much of that load will find its way onto the corner that has the bump. It has to because that corner has a much stiffer spring rate due to the bump spring rate added to the ride spring rate. So, the corner that has the bump will load up.

If it is the left front, as on asphalt, then the LF and RR corners will gain load. We cannot load one corner without affecting the other three corners. Loading the LF and RR will necessarily take load away from the RF and LR corners. There is only so much loading to go around. The car doesn’t gain or lose weight, it just gets redistributed.

So if the RF and LR corners lose load, the cross weight that those corners represent goes down. And here is where it gets tricky. One would think lowering the cross weight will loosen the car. That is not necessarily true.

The amount the car is “loosened up” depends on how much cross weight is taken out of the car. We know from studying the dynamics of a race car that there are ranges of cross weight that will still make the car neutral in handling. A dirt car for example can run 50-75 pounds of LR, or 200-250 pounds of LR and still be neutral in handling.

The same is true for asphalt cars. A car I have worked with can run either 52.3 or 58.0 percent and still be neutral in handling. For both types of cars, an even lower cross might be possible going from 52.3 to 46.6 or so.

Now let’s get back to our single bump car. If we are running dirt and bumping the RF corner, as we enter the corner, we increase the RF and LR corner loading and raise the cross weight. But what if we raise it the same as in our example to go to the next cross weight range? The handling might not change at all. Here is why that is possible.

I did some calculations and for a typical asphalt car, on braking we transfer about 310 pounds of weight from the rear to the front. If the LF bump corner were to take 75% of that load, that is 232 lbs., or 8.3 percent of cross weight based on a 2800 pound car.

If we are running a cross weight of say, 58%, then our cross on entry would be 58 minus 8.3 = 49.7%. If for this car the lower range were 52.3%, then we would definitely be loosening our car on entry, which might be the desired result. We are just in a different cross weight range and the percent of change varies with how hard we brake.

For dirt, it is the opposite scenario. We would be gaining 205 pounds at the front and if 75% of that were added to the RF, then that would represent a 5.9% increase in cross weight percent. At the low range of 50% cross weight (52lb. LR weight), we could be going to 55.9% cross weight, or 210 pounds of LR weight. That again puts us in a different cross weight range only higher in this example. Again, the change varies as the braking force changes.

At any rate, using one bump changes both our cross weight range and percent and depending on how hard we brake for how long, that percent change is different meaning our handling could be in a constant state of change.

Using Two Bumps – Now let’s see what happens when we have two bumps. With both front corners having bumps, it is like having more equal but much stiffer springs on the front. As we brake into the corner, load transfers onto the front end and is taken by the two corners. If the spring rates of the front corners are similar, then the load that is transferred will be more equally distributed.

If our goal is to affect our entry handling, then using two bumps won’t necessarily accomplish that goal. Because the load transfer is more equal, our cross weight percent stays the same as it was before entry braking.

If we need to tune entry handling, such as a car that is tight in, we need to find other ways to do that. And we have discussed many different ways to cause the car to be either tighter or looser into the corner while it is in transition.

We could use different rates of bump springs or bump stops for each corner to facilitate a change in handling, a stiffer RF to tighten the car or a stiffer LF to loosen the car. Those changes would cause much less change in cross weight percent and probably be more predictable than if we were running only one bump.

Mid-turn Handling One Verses Two – We need to get into the mid-turn handling aspect of this because there will be an influence on handling between the two scenarios. The changes in cross weight percent and the roll stiffness in the front will be different between the two scenarios.

The cross weight will change at mid-turn when using only one bump. For the dirt example, the car will be tighter and adjustments must be made statically so that it is not too tight. This is caused by load transfer laterally from turning left and more of that load ends up on the RF verses the RR tire.

The stiffer RF corner will also make the front more roll resistant therefore creating a tight setup condition. The large spring split, very stiff RF verses much softer LF, equals more roll resistance at the front. So, changes to the rear spring rates and/or rear J-bar height may be needed.

In our asphalt situation, the stiffer LF corner of the car using one bump causes the opposite effect as the dirt car description. The stiffer LF loosens the car through the middle by adding load to the LF corner due to the stiffer spring rate. This is most evident on banked tracks whereas on flatter tracks it might not be as much of an influence.

The large spring split of a stiffer LF verses the much softer RF spring rate promotes roll and lessens roll resistance. This car would be looser through the mid-turn segment and adjustments must be made to compensate.

We might lower the panhard bar, soften the RR spring, etc. in order to improve the mid-turn handling while using the single bump on asphalt. At any rate, changes must be made to compensate for the effect.

As for using two bumps, none of the above changes in weight distribution or roll resistance happens when using two bumps on the front. We don’t have the load distribution or cross weight change going on and we don’t have a change in the roll stiffness happening either.

So, Why Run Either – Now that we have examined the effects of the two situations, let’s go over the Pro’s and Con’s of each one and see which might be a better choice.
As for the single front bump setup direction, we can see there will be a lot of changes in weight distribution and roll stiffness going on. It is possible that you could utilize these changes to your advantage to improve corner entry and possibly corner exit.

To do that, you would need to do a lot of experimentation and/or understand exactly what is happening in your situation with your cars design. The teams that have the resources to do this testing might find an advantage, or not. I just cannot say right now with what I know.

For those who like to experiment, have at it. But remember that when you get this all figured out for one track, going to a different track that is designed differently will change your results. You would need to tune the car differently.

When using two bumps on the front, we see where there is much more consistency in the load distribution and roll stiffness. This consistency will not enhance transitional handling like improving turn entry or exit. You’ll need to find other ways to accomplish those if that is your goal. But the transition from track to track will be much more predictable with less overall setup changes needed.

So there you have it, information about running two bumps verses one and why. Only you can determine if either would suit your situation. There are teams doing well with both of these approaches, so we won’t necessarily push you in either direction. As for me, having thought this out just now, I would still go with simplicity and two bumps looks like it is simpler and easier to manage. But that is just my choice.

Sources:

Allstar Performance
www.allstarperformance.com
269-463-8000

Coleman Racing
www.colemanracing.com
800-221-1851

Eibach Springs
www.eibach.com
800-507-2338

Hyperco Springs
www.hypercoils.com
800-365-2645

Keyser Manufacturing
www.keysermanufacturing.com
800-472-2464

Pac Suspension Springs
www.keysermanufacturing.com
866-799-9417

RE Suspension
www.resuspension.com
704-664-2277

The post Comparison of Dirt and Asphalt Bump Setups appeared first on Hot Rod Network.

Roll-Control Tech

Many stock cars use a one-piece sway bar and find it more than adequate for normal setups on average racetracks. There can be some disadvantages to the one-piece bar, and there is an alternative. A common trend among asphalt Late Model teams is to run setups that use a bigger diameter sway bar in combination with softer springs and bumps to control the roll of the car. Along with this development, it has been discovered that certain components and settings on the cars need to evolve along with the radical change in the setup.

Bump Setups Necessitate Rethinking our Designs

Racers have learned that in order to gain full benefit of the bump setups, they need to address certain issues. Items like their front geometry Moment Center design, camber change issues and associated clearance problems can arise from using very soft springs. They create increased dive, and you need to perform certain component modifications when it comes to suspension parts like the sway-bar assembly.

A big bar can mean the installation of anything from a 1 3/8-inch diameter sway bar to upwards of a 2-inch bar. The lower limit on diameter for a one-piece sway bar is 1 3/8 inches. One the other hand, if we were to install what we call a NASCAR-style or splined sway bar, our options on diameter selection become much greater. And this fits with the more current trend of using much smaller sway bars with bumpspring setups.

Many teams have already opted to convert their cars from a one-piece style sway bar to the splined style. We talked with a few teams that have converted their Super Late Model cars over and learned a few tips in the process that we will pass along.

Why Switch to a Three-Piece Sway Bar

A properly installed three-piece sway bar will offer the team a smoother operating bar devoid of much of the binding associated with the one-piece bar along with plenty of adjustability. Because the three-piece unit uses bushings or bearings at the end of the sway bar, the movement in both roll and dive of the chassis is much smoother. The sway bar arms are more ridged with the spline style, as compared to the one-piece bar where those arms can flex quite a bit. This causes a reduction in the bar rate of the whole assembly.

Binding can be a major source of problems when we are sorting out our handling balance. One of the things we always need to do is make sure all of our pivot points are free of bind and the whole suspension operates freely, even the sway bar.

The splined sway bars are usually enclosed inside a tube. For larger diameter bars, the tube will need to be large enough to accommodate up to 2-inch-diameter bars. The roller bearing bushings used for these bars are 1 1/4-inch inside diameter and that matches the splined end diameter of the larger sway bars. A bushing spacer is installed in the end of the tube to match the bearing or bushing to the tubing.

Clearance Matters

Clearance is an issue when installing the sway bar. If the crossmember is, say, 4 inches off the ground at ride height, and then the sway bar components will need to clear 4 inches, too. The end of the sway bar arms at the control arm can be lower because the control arm will hold it off the ground when the car dives.

One of our example cars had a piece of square tubing welded to the front chassis rail directly under the spot where the old one-piece bar adjuster was fixed. The length of this tubing for your application will vary depending on clearance for both chassis dive, as well as clearance between the sway bar arm and the tie rod. You will most likely have to use an offset, dropped arm here.

Right Side Connection

The best connection at the control arm end of the sway bar arm on the right side is the double Heim (left and right hand threads) joined with a threaded length of rod, or a threaded tube, and two lock nuts. Remember that the Heim connector must be vertical and perpendicular to both the sway bar arm and the lower control arm. If this connection is not made at 90 degrees, a severe bind will take place and affect the setup.

The end connections should be placed as close to the lower ball joint as practical. This increases the rate of resistance of the bar assembly to the roll tendency of the suspension. A motion ratio applies here, just the same as the spring to lower control arm mounting motion ratio. The farther the spring or sway bar is from the ball joint, the less effect the spring or sway bar will have.

Left-Side Connection

The connection at the left side consists of a flat sway-bar bumper that rests on a plate welded to the lower control arm. This bumper should be lightly lubricated as it will slide around slightly as the car goes through dive and roll.

An added touch is a unique adjuster that attaches to the end of the sway bar and the sway bar arm. This unit allows easy adjustment of the height of the end of the arm, so you can precisely align the sway bar when setting up the weight distribution of the car at the shop. It also eliminates the need for a dropped arm. This team used a straight arm that was made lower in the car by the adjuster.

The fact is, the car will get on the bar immediately when the driver turns into the corner and stay there all throughout the turn. Preload on larger bars would only serve to ruin your carefully planned out weight distribution and legal ride heights. For smaller bars less than 1.25 inches, preload is a viable option.

The choice of material for the sway-bar arms is important, too. For larger, high-roll resistance bars, a more ridged arm is needed. The steel arms are really the only ones that will do the job without bending. They do weigh more, but this weight is very low in the car and can be a substitute for other ballast.

The addition of a free-moving, splined sway bar is an improvement to any Stock Car that uses a sway bar. You don’t necessarily need to run the bump setups to benefit from this suspension component. Sway bar size changes and adjustments are quick and easy. Most dealers now stock, or can get, the parts needed to build the splined sway-bar attachments. Once completed, you’ll wonder why you didn’t make the switch earlier.

Sources:

Allstar Performance
(269) 463-8000
www.allstarperformance.com

Coleman Racing
(800) 221-1851
www.colemanracng.com

Right Foot Performance
(920) 832-2322
www.rightfootperformance.net

The post Steps and Tips on Installing a Three-Piece Sway Bar appeared first on Hot Rod Network.

S.E.A.L. Makes Rules Changes For GM 604

In last month’s QA commentary, I discussed Balance of Performance and ways sanctions try to equal out the power influence of different engines. I say power influence because the value of a particular engine depends somewhat on what track it is running on and how that power is regulated.

I outlined how adding a small amount of weight to a higher horsepower motor car does little to equal the competition. Adding sufficient weight is more effective in providing equal acceleration down the straights. But what about differences in performance in the corners? The penalized car now has to try to get through the corners with a lot more weight that wants to go to the wall.

If we consider that penalty, then we add less weight to make up for the turns and the higher HP car runs down the lower HP car on the straights. They then each have advantages at separate parts of the track. Maybe that is good and maybe not.

Now we see where S.E.A.L. has changed its rules to allow an improved performance cam for the GM 604 crate motor. S.E.A.L. stands for the Sealed Engine Alliance Leaders and is comprised of a group of promoters and tech officials. Their purpose is to regulate and certify sealed short track engines.

Tech official Ricky Brooks told me that he was the driving force behind this move and that he personally spoke with Bill Martens who oversees the GM crate motor program and urged him to approve the change. It is not clear if GM will make changes to their production motors to include this replacement cam. Here is some history.

It has been suspected and pointed out by numerous engine builders who have dyno’d both the GM 604 motor and the Ford equivalent motor over the years that the Ford had more HP. It has been said too that the Ford was easier to cheat up, not my words, just repeating what I heard. So, for some time, and at an accelerated rate lately, many teams who had been running the GM motors are switching to the Ford motors. Two of the top Pro Late Model teams at New Smyrna did indeed switch to Ford for the 2016 season.

The change allowing the new cam, GM part number 24502586, is said to be a response to Fords recent upgrade in their ring/piston package. As reported in a January 4^th, 2017 S.E.A.L. press release, there were evidently a series of dyno testing runs made with both engines that resulted in the decision.

As a concession to teams not able to make the change to the new cam immediately, a 25 lb. weight break has been approved. The rules change goes into effect for this year and we’ll see how many teams take advantage of it.

For reference, the going price for this cam is around $256 at most racing retailers and the cost to install it at your approved sealed crate motor shop is around $400-$500. Of course, the builder will need to be installing this cam in a motor they previously sealed, or we’re talking about a complete rebuild/refresh which goes for a lot more money.

And, if GM does not make changes to the production crate 604, then plan on adding about $700 to the cost of a new motor for installation of the cam if you plan on being competitive. But, I did a rough check on pricing and it seems that the Ford motor lists for about $1,500 more than the GM 604. So, with the cam upgrade to the 604 motor, your still ahead $800 on cost by going with the GM motor.

Getting back to last month’s column, we see where again the engine issue gets more complicated. At least tech people like Ricky Brooks understand the problem and are trying to make things better and more equal in the engine department.

Early on, and many years ago, when GM introduced the sealed crate motor program, it was a good plan with no complications, and no competition. Then Ford got involved and it makes sense that it would be hard to end up with two identically powered motors, especially when these two companies are historically so competitive.

Since the motors have been dyno’d at several facilities and found to be very close to equal in power output, maybe now we can get back to what we do and that is go racing. We’re going to try to get one of these 604 motors with the new cam onto a dyno in the near future. When we do, we’ll provide you with the results.

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1733 Alton Parkway, Suite 100, Irvine, CA.

Comment On “Engine Control Needed”

Bob,

I have been doing this for years.  Many Super Late Model classes up here in the Upper Midwest use the Midwest Tour rules.  In fact if you look at TUNDRA’s rules package they are 90 percent rules I wrote over the years.

It is very important to people who have Super Late Models that the rules are very close.  It is not like it was at one time when you had people who traveled weekly to many events. The days of Trickle, Reffner, Sauter and others have come to an end. We at one time raced five nights a week. We could very simply add or deduct weight and change the set up to go.  Now it is a much bigger deal for the teams to do that.  But again if we all stay close it is best for all.

But with your story you also forgot a very important part.  At least up here in the great white northland, Tire Wear. Most tracks up here have a tire banking system for weekly shows.  Also I believe TUNDRA has a tire system where you have to use tires more than one race.

So to me the tire wear on a weekly car and even in a TUNDRA Series car would be much better when your car is 250 pounds lighter than another car.  That also helps the lighter weight car in the next event, and most of the time it’s a crate car.

So to me that amount of weight is pretty hard to swallow plus it may get to be cutting things away that are in place for the safety and integrity of the chassis.  All and all crates engine cars can race with Super Lates but the laps of the race also then becomes a factor.   Each tracks size, type, and banking is also not the same as far as weights for crate and Super Late cars to make them compete together.

I guess I am saying that it is a lot harder to run them together than most people think, with the lighter weight of the crate cars rolling in the center. But to me a crate engine car should not be used as a weight advantage.  It should be used by a smaller team trying to compete.  A crate in the right place is great, but should not be used as a tool for an advantage.

Thanx, Mike (Lumpy) Lemke

Mike,

Thanks so much for your comments. This is a complicated issue that many who mandate the rules struggle with and you make some very valid points.  There is no perfect solution, only good attempts. What usually tells the story is how the season progresses for those running different motor combinations at the same track as well as in touring series.

If a more even combination of success for built/spec verse crate motors occurs and wins are split between the two, then you probably have a good set of rules. On the other hand, if one or the other dominates, then you have to take a good look at the rules and make changes where necessary to make everything more equal. That only makes sense.

What those who write the rules shouldn’t do is penalize one or the other for the sake of their personal beliefs as to what is best for the sport. Leave it up to the race teams to decide which they want and produce a set of rules that will allow more equal competition. There are two sides to this issue and then there is fairness and equality.

Consequences Comment

Bob:

I’ve been racing on local dirt short tracks in Colorado since the age of 14 and grew up idolizing drivers like Kelly Boen, Keith Roush, my father Don Schweitzer, and a number of other clean drivers. Among lack of decent parenting, I believe most of the problem lies with the fact that a lot of younger drivers never even touch a bolt on their machine which results in careless decisions behind the wheel.

It might be too late to save some of the drivers in the activity but the best thing you can do for your kid is to form a bond between he/she and their equipment. Respect the equipment, drivers and the future of the sport.

Josh Schweitzer, IMCA Stock Car One17s

Josh,

I completely agree. Many of the “fast track” drivers who have big money families and/or famous racing fathers, have not spent sufficient time behind a wrench. I’m not talking about all of them. I’m sure some of these drivers had to turn wrenches plenty when they were starting out.

The lesson would be, bend it or break it and you fix it, if it’s your fault. Then there would be a measure of appreciation for what it takes to build and repair these cars. I bet the next time a decision comes along whether to chance wrecking the car they would be much more inclined to wait for a better and less troublesome time to try to pass.

As an example, not to toot our own horn because we had nothing to do with it, is Dalton Zehr, our past test driver on many CT projects. He, working alongside his dad Marty, has played a big part in building his cars for as long as I can remember. Marty instilled in him the basic work ethic and they worked together building every car he drove for the family. That is where he learned that.

Right now, as I write this, he is building his new short track car from a bare frame/chassis in the shop in Menominee. If you’ve ever seen him race, he rarely ever gets caught up in a fracas or bends any “sheet metal”. One big reason for that is that he has to fix it come Monday.

Traction Control

Bob Bolles,

I enjoyed your article about Traction Control which I read through my Hot Rod Network email. I have not reached a conclusion on the subject which is as settled as yours (“don’t use it”). However, and you’ve heard this rap, technology is very difficult to keep out of things. In the interest of brevity, I’ll put some thoughts down in a list:

Keeping technology out of racing may have prohibited even synchromesh transmissions or rev limiters. Isn’t part of racing the development of new technologies?

Traction control did exist in Formula One, got banned, then unbanned and finally banned again (in 2008) when they went to a standard ECU. Standard anything is difficult, expensive and enforceable only in the most organized and policed series.

Traction control for drag racing is the best. I never could master getting a set of MTs heated up and then hooked for a great start but that didn’t mean I couldn’t enjoy being a klutz. However, when I got a car with AWD and traction control, a 1.7 sixty foot time was relatively easy (yes, the reaction time isn’t exactly zero).

Has traction control increased the enjoyment of my vehicle? Absolutely. The summary of my wandering here is: let some classes or racing groups or whatever’s, use traction control if it makes for more enjoyable racing for the competitors.

The problem is the extension of this thinking: we may soon have self driving race cars, where the driver merely monitors vehicle voltage. Would that work, maybe? In any event, “Just say no”, or somehow being completely negative on a technology may not be the answer in all cases.

Very truly yours, Joe Bagel, Chicago, IL

Joe,

If you have followed short track racing for any length of time you would have seen a great deal of innovation and invention along the way. The technology in many areas of performance is allowed within the rules and is ever changing for the better. All tracks and sanctions have rules and what you are arguing is for the rules makers to change the rules. This is not at all what I was talking about.

My two points were, one that the use of TC is against the rules. Secondly, the use of TC does not help a driver learn to control wheel spin through throttle control, which in Cup racing where TC is strictly outlawed, is essential to doing well. You of all people should know that.

You stated that when you were able to use TC in your drag car, your times improved quite a bit. You didn’t say you learned how to manage tire spin, you leaned on a crutch called TC. What that does is hurt all of the drivers who have talent and can control tire spin on their own. Let’s give out participation trophies next and see how that works out. Like you pointed out, before you know it, we’ll only need for the drivers to steer the car, and on a drag strip, that isn’t too awful hard.

Traction Control From Across The Pond

Bob,

From a European (English ) point of view, this subject takes me back several years. Most of our road cars and competition cars have TC as OEM fit. Virtually all the aftermarket ECU’s have TC on their menu. It does reduce the driver skill in driving, but interestingly, in the loose surface disciplines I follow (Rally and dirt track), it has not caught on.

Particularly in Grass Track , where the cars are 250kg missiles powered by 1300cc Hayabusa motors, the top drivers have tried TC in testing (it is banned) and say that, with track conditions so variable, it is impossible to set up correctly. So, long live the right foot! Mind you, in our hill climbs (one mile or so), the ex. F1 (stock car, not Formula One) engines and turbo ‘busas don’t half need it the wet!

Arthur Heaton, Yorkshire, and proud of it.

Arthur,

Thanks for chiming in. The sport of circle track racing in Europe is extremely varied and exciting. It seems to me like you guys have tried to find any and all ways to compete going in a “circle”, and I find it very interesting to watch in YouTube videos.

Many racers here have learned the same thing, it’s sometimes hard to tune. Maybe they would be better served to forget TC and get on with learning how to drive. That is how it always was long before TC ever came along. It worked then and it works now.

The post Matching Sealed Motors appeared first on Hot Rod Network.

We want to provide tips on how to do various things while at the race track. Many things are easily done at the shop where we have a mostly sterile environment, but things get messy when we go racing. Here is why.

When I walk around the pits, I either see techniques I never saw or knew before that are a better way to do it, or I see things that are done wrong, in my opinion. I like to think of myself as a student of processes. That means I am forever looking to do things in a more organized way, more accurately, and easier, the emphasis on easy.

So, here are seven processes that we hope you can learn from us how to do better. If you see where any of these could be further improved or you disagree with what we are saying, please let me know and I’ll make adjustments in future presentations. The idea is to get you thinking about each process and to establish a routine and more efficient way to do them.

Set Track Ride Heights – Every race car needs a set of constant ride heights. You normally set these at the shop and maintain them for the life of your car using your setup according to your track rules and common sense.

If you ever have to replace the right front upper and lower control arms, spindle and maybe a front clip, you will go back to your original ride heights to reset your cambers, casters, weight distribution, bump to shock spacing, etc.

When you get to the track, you may be making changes to your spring rates or other settings. So, you need to measure your track ride heights. The problem with the track setting is that the ground, or concrete if you’re lucky, is not level like your shop was.

Pick a place to park your four tires and mark those spots so that when the car is in the pits, it is always on those spots. That is the first step. Then measure your ride heights in a different way than you did in the shop.

In the shop, we usually measure from the floor to the frame at four points. At the track we need to measure this differently. You can do this a number of ways, but try to understand the process and why we are doing it and find the best method for your car.

Many teams measure from the bottom of the rim to the wheel opening directly above that. Or, you can measure from the bottom of the rim to a mark on tape on the fender and set the mark to an even inch. If you don’t have fenders on the front, you can measure from the top of the ball joint stud to a point on the tubing near the shock mount or wherever is convenient.

Recording these height references helps us when it comes time to make changes so that we don’t change our weight distribution either statically or dynamically once we have determined what works best for our car.

Spring Changes – After doing the above process, we can now make spring changes without affecting anything else. The most common thing that goes wrong with making a spring change is inadvertently changing the weight distribution. To prevent that, we refer back to the original ride heights.

Once you have established the track ride height references, you can make spring changes, one at a time. Never try to change two springs at the same time. It might work, or it might not. Just do one at a time.
With the car on the pit marks, jack up the corner that you want to make a spring change. If the spring is stiffer than what was in it previously, you’ll need to back off on the spring adjuster because it won’t compress as far with the same loading. Here is how to calculate the difference to speed things up with the change.

If the old spring were a 10 inch spring and its compressed height at ride height were 8 inches, then it compressed 2 inches to support the load. If the old spring were a 300 pounds-per-inch rate (ppi) and the new one is a 400ppi 10 inch spring, divide the old by the new. You get 0.75. Multiply that times the 2 inches to get 1.5 inches.

The new spring will compress a half inch less than the old spring, so back off a half inch on your adjuster ring or screw. For your springs, just substitute your spring rates and compression amount to determine how much to change your adjuster. You’re not done yet.

Once you have lowered the car back on the ground, shake it down and re-measure the ride height using the references and make changes to the spring height as needed to get your ride height back. It shouldn’t take much if you did the calculations.

Ride Height Changes – As you test your car in practice, it might be necessary to change your ride heights. This can get complicated if you are running bumps, There is a way to do this without messing up other settings in the car.

Most of the time when we feel the need to make ride height changes, it is with the front end because the frame or cross member is hitting the track. This goes for dirt or asphalt. So let’s discuss doing this with and without bumps.

First off, with bumps, we are hitting the track because we are contacting the bumps too late or allowing the shock to compress too far. If we add packers, or spacers, to the area between the shock and the bump, we can raise the car when on the bumps, which is when we are in the turns and the part of the track where we are bottoming out.

When running bumps on both sides, always add the same amount of spacing to each of the front shocks or you will alter the load distribution through the turns and your handling will change as a result.

If you are only running one bump, you have to do this differently. Add the amount of spacing you think will keep the frame off the track on the bump side. On the other side, add the amount of turns on your ride spring adjuster that will equal the amount of spacing. If the bumps spacing were increased ¼”, then adjust your other side spring down ¼” too. This may not perfectly compensate for load changes, but it will get you closer.

For teams with cars having shock screw jack adjusters and running bumps on both sides in the front, you would screw the shock down the amount you think necessary to keep the frame off the track and then move the coil-over adjuster ring up the same amount. Do the same amount of movement to both sides of the car.

Because you are changing the dynamic ride height, your dynamic cambers will change, and so the static cambers will need to change. You are traveling less, so the RF camber will need to be increased in the negative direction and the LF camber will need to be increased in the positive direction.

If you are running soft conventional without bumps, this is your process. In the above examples, we made changes to the static camber settings based on ending up in a different place, or having less overall travel. Not so for conventional setups.

When you raise your ride height to keep the frame from hitting the track, the front will travel the same amount as before, so your camber change will be the same. So, you only need to change your static camber back to where it was before the change to ride height and you’ll be good to go.

Checking Your Alignment – There are several alignment settings we might need to check when at the track. There is front toe, rear toe, and rear alignment related to the front tires. In all of those cases, we need to prepare the car first. In this example we are assuming you are using the tire sidewall to check the alignments.

Every tire has sidewalls that are irregular in shape to a certain extent, or could be. We need to find what we call the high side and position that side of the tire to the top at each wheel. So, we jack the car up and rotate each tire to find the high side, or part which sticks out the most.

Once you have the tire off the ground, place a jack stand next to the tire sidewall and place a screw driver or other object onto the jack as a reference point to where the tip is very close to the sidewall away from the lettering.

Next, have someone rotate the tire while you observe the gap between the reference point and the sidewall. For most tires, the gap will change. Move the reference in towards the tire until it touches the high point. Mark that point and move it to the top. Do this for every tire you will be working with.

Now you will be able to check your toe settings without errors caused by sidewall irregularities. You can also check your rear alignment more accurately. But before checking that , be sure to check the rear toe.

If the rear toe is very near zero, we can go ahead and check the rear alignment. Run a string beyond the two tires on the right side of the car. Tie it to two jack stands and at a height equal to the center of the hubs past both right side tires. Move the string to where it is a reference distance off the front and rear tire sidewalls. For the rear, use the back sidewall only for now.

Here is where it gets a little tricky. If you want the front and rear tire contact patches to line up, you will need to add the cambered offset from the front tires to the reference distance. For an 85 inch tire with 5 degrees of camber, the offset is 1 1/8” based on making an adjustment for the rear tires having 1/4″ degree of camber due to tire stagger. Estimate from that what you need to add. If you want the rear tire contact patch to be offset from inline with the front tire contact patch, then add or subtract further to establish the front offset.

At the front, you will need to turn the steering wheel so that the distance from the front and rear sidewalls are the same after you add the offset. As you do this, you’ll need to recheck and readjust the rear string position off the rear tire. Now take a measurement from the string to the front sidewall at the rear. It should be the same distance as the rear offset for that tire. If it is more, the rear end is aligned to the left. If it is less, then the rear end is aligned to the right from straight ahead.

Changing Gear Ratio – We often need to change our gear ratio to regulate our top RPM, or where we hit the chip if we are restricted to a defined high RPM amount. If we know what RPM we need to achieve, we can do a calculation to find the right gear, but it is not a direct ratio because of the power curve.

Say we have been running a limit of 6800 RPM and we change the chip to a 7200 RPM chip. What gear will it take to top out at the higher RPM at the same point on the race track?

For an example, let’s say we are running a 4.69 gear and want to make the above change in RPM. If the engine power were the same for each RPM, then we just divide the higher RPM by the lower and multiply that number times the old gear ratio to get the new ratio. In this case it is 7200/6800=1.0588. That number times 4.69 gives us 4.96. That’s easy, right?

But what if we have 5 or 10 more HP at the higher RPM? The car will gain speed faster and get to the new RPM quicker and at a point on the track back from where we need it to be. The engine will over-rev past the 7200 RPM or hit the chip sooner than we want.

If the engine were producing 410 HP at 6800 and 420 at 7200, we could divide the lower HP by the higher to get 0.976. We know we need to run less gear to keep from over-revving, but by how much? Multiply the RPM ratio by the HP ratio: 1.0588 times 0.976 = 1.034. That new number times the old gear ratio of 4.69 = 4.85.

This is what happens when we change gears. We move to a new part of the power curve and either gain power or lose it. When making gear changes, we need to compensate for the power difference in order to reach the desired RPM goals.

How To Use A Spring Pre-Loader – It is becoming popular to use a spring pre-loader to facilitate using a softer spring in the RR corner of an asphalt late model or possibly other classes. The reason this is done is to provide the support that the car needs to be balanced through the turns, but allows a softer rate for acceleration off the corners.

The idea is that a preloaded softer spring will have the same force as a higher rate spring. For bump setups, the RR spring is usually a good 100 to 125 pounds stiffer than the LR spring. When loaded statically and through the turns, it has a pre-determined amount of force that it needs to do the job. Let’s investigate how much force is required and how much we need to pre-load the spring.

If our example car normally has a 275ppi spring in the RR corner and it supports 550 pounds of load, then the spring will compress 2.0 inches at ride height. If through the turns it compresses another 1.0 inch, then there is another 275 pounds of force on that spring. So, total, we need to generate 825 pounds of force.

If our LR spring is a 175ppi spring, then we need to make the RR spring less than the LR spring to aid in acceleration off the corners. If we install a 150ppi spring in the RR, we need to pre-load it to 825 pounds or so. Then once the car accelerates and more load transfers to the RR, the spring will compress like a 150ppi spring beyond the pre-load amount.

To get 825 pounds of force into the spring, we need to compress it 5.50 inches. The only way that spring will move is if that corner has to support more than 825 pounds of force such as when the car accelerates and causes load transfer off the front to the rear.

It is possible for a modern late model to transfer 300 pounds upon acceleration. If half of that transferred load ends up on the RR corner, then that is 150 pounds more load and the RR corner will compress another inch. The LR corner will compress only 0.85”, so there will be a slight increase in cross weight for the car that will tighten it off the corners.

An added benefit to this scenario is that if you can make the RR spring compress more and help the RR corner travel more, the right side panhard bar will be lower causing the car to have a lower rear moment center for even more tightness off the corners.

How To Measure Stagger, The Easy Way – Many of you will read this and say, oh, I knew that. Just the same, this is about teaching methods that you may or may not be aware of. This is one trick that I learned years ago and I still see people doing it the hard way.

When measuring stagger, you don’t need to subtract the two measurements to find the stagger amount. You just have to remember one number and that is much easier. If you need to remember tire sizes, just write down that one number.

The magic number is the size of the largest tire for each axle, being the right side for left turning circle track cars. First measure the right side (larger) tire circumference. Remember that number and/or write it down.

Then measure the left side tire for that same end of the car. Let the tape overlap the end of the tape and read from the end where the larger tire size lays on the tape. If the larger tire were 85 1/4 inches and that measurement falls on the 2 3/16 inch mark, then the stagger is 2 3/16”. It’s that simple.

If you remember, or write down the large tire size number for the right side tires, later on if you think you need to swap the right side tires to change the stagger, you’ll know what those tires sizes are for analysis purposes.

HOW Photos and Captions

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Cutting Edge Information For Modern Dirt Racing

Many aspects of the parts and pieces of dirt cars have evolved over the past twenty years or so. We’ve seen almost every part of the car evolve from fairly primitive designs to the most advanced configurations possible. The brake systems historically have been among the least evolved, mainly because in years past, dirt racers used very little braking. That has now changed.

A big influence in the change in how brakes are used in dirt racing has to do with the way the cars are setup and raced. The setups offer a more balanced approach whereby all of the four tires are doing work. We now rarely see the left front tire up in the air.

This is true for the top three types of dirt cars by popularity, the dirt late model, UMP/IMCA dirt modifieds and the NE big block modifieds. I have purposely not included the dirt sprint cars as that is another story altogether.

So, with this balance comes a more straight ahead driving style that has been popularized by the top winners in each division. Drivers like Billy Moyer, Scott Bloomquist, Ken Schrader, Kenny Wallace, Kenny Tremont, Brett Hearn and our own David Reutimann and his father Buzzy all have more of a straight ahead style that brings success.

What has helped bring about the change in setups is a better understanding of the balance concept. Whereas in the early to mid 1990’s we saw cars running a softer right rear spring than the left rear, we now see stiffer right rear springs over the left rear.

Shock technology has evolved a great deal. In 1995 it was rare indeed to see a dirt late model running gas pressure shocks. Now it is rare to see one not running gas pressure. I think the modifieds ran them before the late models did using “stock” configuration Bilstein gas pressure shocks.

We have redesigned the front geometry on most all current brands of dirt cars, a process that began in the late 1990’s and one in which I assisted several top car builders in their transition. Now the cars turn much better than before and we can utilize higher rear grip and bite than ever before because of it.

The engines are much more powerful and last much longer at very high RPM levels. All of that torque has to be controlled and the drivers are now needing to use the brakes to keep the motor from overpowering the tires. Here is where much of the brake evolution comes in.

With all of those improvements I have listed, it is high time we start looking at what has recently changed in the way the teams utilize the brake system to take advantage of the new designs of cars and the new way drivers drive.

One of the things drivers are doing more so today than in the past is using the brakes to slow the cars down rather than pitching the car sideways and letting the sliding of the tires and aero drag slow the car. If you see a car accelerating off the turns and gaining speed very quickly, then slowing and entering the turn without going sideways, there is only one way that is happening. It is from the use of the brakes.

To regulate wheel spin coming off the corners and to keep the rear bars loaded, many winning drives will stay on the brakes at varying pressures the entire race. This increased use of the brakes can cause problems if the brake systems are not designed correctly.

We spoke with Randy Keene, a dirt racer who also works for PFC brakes and consults with dirt race teams on their application and designs. Performance Friction has been around a long time and their involvement in racing extends all of the way from the local short tracks up to the high tech world of Formula One, Indycar, Nascar Cup, Porsche and IMSA endurance racing.

Because of that wide range of involvement and participation, they are an excellent source of information. What they have developed can be directly applied to the problems associated with the conditions we see in dirt racing today.

Although their friction (pads) products have been used for years on dirt cars, it is more recently that they have pursued a greater involvement due to the opportunity presented by the evolution of the setups and driving styles I mentioned above. Now PFC offers rotors and calipers specifically for dirt racing in addition to the pad line.

So my conversation with Randy forms the basis of the information I will present now. Much of this coincides with what I personally have seen and heard from other insiders throughout the industry.

Without giving away any secrets, I will tell you what areas teams are working in and how they are using the components to improve their performance. Here are the areas of most importance.

Endurance – Today’s brake pads, rotors and calipers must endure higher heat ranges and longer duration of heating than ever before. The calipers must remain cooler to help survive a longer event such as a 100 lap race and week after week of competition.

The rotor can be light, or for some applications heavier, and strong enough to take repeated heat cycles. And the pads must endure too so that they provide consistent braking forces from start to finish. With some drivers reporting the use of brakes continually throughout a race, we can begin to understand how important the endurance aspect is for dirt race teams.

Engagement – The brake system on a dirt car must engage quickly and release just as quickly. The “feel” that the driver has in the brake pedal related to how the system is build and arranged is critical. And that feel must stay consistent over the course of a race.

If the brakes change in any area of performance such as engagement quickness, release timing, grip levels or wear, the drivers must adjust the way they use and apply the brakes. Along with everything else going on within the race, that is very hard to do.

The drivers themselves report that what they need most is consistency in the operation and feel of the braking system. Driving a dirt car successfully depends on how well the driver feels the car and reacts to the inter-connect between the tires and the racing surface. It is a lot to deal with a brake system that changes and that distracts from the drivers concentration and slows them down.

Adaptability – The brake system and components you choose must be adaptable to the changing track conditions. Whoever supplies your brake parts must understand that as the track changes, so must the setup and braking components. And they must have the right selection of parts available for you to use.

A high grip track surface, such as at the beginning of an event, allows the use of a much higher grip compound in the brake pads that will operate at a lower temperature. This helps the driver during short practice sessions, qualifying and shorter heat races. That is because the runs are shorter, the track has more grip and there will be less use of the brakes. These types of pads will provide more braking force before the tires break loose and slide.

As the track dries out and the runs become longer, the tires grip level is diminished and the pads must be changed to a compound that will be less aggressive while providing the endurance needed when the driver uses more brake to help the car though the transitions from entry to exit. In longer races, these compounds must stay consistent.

Staggering Grip Levels – Racers are now experimenting with staggering the grip levels not only from side to side, but front to rear. This is not to be confused with bias adjustment because it involves the selection of different designs of brake pads and calipers and the mechanics of the system.

I acknowledge that this concept is nothing new, so don’t send emails telling me so. But we have never had a better selection of pad and caliper designs as we have now. The tuning aspect of the brakes is so much more advanced and useful in today’s market place.

Timing Of Braking – There are tricks being utilized to adjust the timing of when the front and rear brakes are applied. This helps the racer regulate when and how much rear braking occurs.

Although we want our brakes to engage quickly and disengage just as quickly, the timing of the application to each when the driver pushes on the pedal is a fine tuning tool that has found popularity among the top drivers in all of the divisions.

Trail Braking Technique – One of the most significant developments in today’s racing is the use of Trail Braking. This is not a new concept either, but one that has taken on new interest and is being used much more than in the past.

As Randy told me, “The guys out there winning now from your Bloomquist and Chris Madden’s all of them, they probably never take their foot off the brake.” Many of the top winners in dirt late model will tell you that they “drag” the brake the entire 100 lap race. In reality, they are modulating the brake pressures based on where the car is on the track and what they want it to do.

This TB technique can be very hard on the brakes. It creates heat and wear. The heat needs to be dealt with by using pads that can withstand high and prolonged heat. You also need calipers that isolate the heat of the pistons from the seals and fluid helping to maintain zero drag.

PFC has developed free floating rotors that will compensate for the heat induced re-shaping of components like the rotor hat and caliper mounts. In this way, drag is eliminated and the brakes become very consistent from start to finish.

Accomplishing The Goals – The goals for dirt braking systems are simple in concept, but complicated in application. First off, the components must be manufactured to do the job at hand. Simply put, the master cylinders must be sized to provide the brake pressures to the front and rear in proportion to what is needed.

What we don’t want is to have to run a bias to the master cylinders that places the balance bar way off center. We regulate the bias with the master cylinder sizes only. Then minor adjustments using the balance bar adjuster can be made during the runs.

The calipers must be ridged and not prone to changes when subjected to high and prolonged heat. PFC created the one piece caliper for that reason. And, the pistons are coated to isolate the heat of the pad from the fluid and seals.

Next we need a wide selection of different friction levels in the pads we use. That way we can run a bias laterally between say the right rear and left rear brakes. This is becoming more and more popular because of certain rules changes and the way some teams arrange their four bar rear suspensions.

The next thing we need is to time the application of the rear brakes verses the front brakes. I’m not talking about bias because that is a regulation of pressures. What I mean is the timing of when the rear brakes are engaged verses when the front brakes come in. Most teams will want the rear brakes to engage first, and much of the time the driver is trail braking, the rear brakes will be the only ones affected.

This is done by adjusting the length of the pushrod going to the rear brake master cylinder. In that way, the rear brakes are engaged first when going from zero pedal pressure up to a slightly higher pedal pressure. Then when the driver needs to apply brakes to the fronts and rears, a higher pedal force will accomplish that with a consistent predetermined line pressure to all four wheels.

Making Changes At The Event – As we said earlier, teams must be willing and able to make changes to the brake pad friction, i.e. different compounds, in order to match the brakes to the track conditions. In almost every case, the dirt track will start off tight with lots of grip. The early events such as hot laps, qualifying and heat races will be much shorter in length than the feature.

The team would make a pad selection that will provide grip under the reduce heat levels. Not having the opportunity to make longer runs means having cooler brakes. Many pad compounds will not make grip until they reach a certain higher heat level. The ones you need early will make good grip at the lower temperatures.

Once the preliminary stages of the racing event are out of the way, we need to prepare for the race itself. Depending on the length of the race, we would select pads with compounds that will operate in the heat range we think we’ll see on the track. For regular Saturday night racing, most features will be in the 30 lap range.

If there are several cautions along the way, we now have two or three shorter races within the race. That has to be taken into consideration and predicted. For longer events of 50 to 100 laps, once the race gets underway, there are seldom any breaks and a driver might have to run a continuous 70 to 80 laps under green.

Now you need pads designed to stand up to all of that heat. They may come in more slowly, but once heated, they will stay consistent until the end if they are designed correctly. If your pads are fading or wearing unevenly or excessively, maybe you need to look for ones that will hold up.

Evolution Is Taking Place – From everything I have heard, the industry is in transition and teams are looking for better braking systems. The way the setups have evolved and the way the drivers feel the need to drive differently dictates more use of the brakes in ways never before imagined. Something has to give.

And so, as we get into the situation where dirt brakes must endure conditions very similar to endurance racing. It is only natural that we look to the companies that have provided products to those types of racing where the same conditions exist. That way, the compounds have already been developed and can be utilized right away.

The components like calipers and rotors also need to be up to the task. In the same way as the pads were developed for high heat applications like 24 hour races and Nascar events like Martinsville, the same basic designs can be utilized for dirt racing, and are.

I find all of this very interesting. It’s not like I am reporting on what has transpired a few years ago or even last season, this is all happening right now. Numerous teams are doing pre-season testing of brake systems and pad compounds within weeks of the date of this writing.

It is common in racing that evolution takes place that makes cars quicker. The more innovative teams will catch on sooner than others who wait to see how things develop. The lag in time can be several years. I would say that by the end of this season, most dirt teams will have seen the light and feel the need to move up to brake components that will match the conditions the cars have to endure. Which type of team will you be?

Sources:

PFC Brakes
269-463-8000
www.pfcbrakes.com

The post Dirt Brake Selection and Application appeared first on Hot Rod Network.

How Far is Too Far

It’s a problem I have encountered many times in my consulting career. Teams just cannot be satisfied with what they have that many times is very successful. Either they miss-apply new technology or apply it to cars that do not need to have it. At any rate, the cars performance suffers as a result.

Early on in the 1990’s, teams whose cars were loose off tried to make them tighter until the cars pushed “like a dump truck” so to speak. No one understood dynamic balance meaning if they solved the tight condition first, the car would naturally exit without being loose.

Then we began to see the Big Bar and Soft Spring setups along about year 2000. This got out of hand in a hurry. Teams that experimented with those setups put softer springs on the front end, a bigger sway bar, and a stiffer right rear spring than anyone had previously run.

The soft springs were there to allow the front end to run lower and the bigger sway bar was there to reduce front roll to make the cars more level to the track. The bigger RR spring was needed to reduce roll in the rear to match the low roll in the front.

All was well and good for a time. Then the racers said, “If that works, let’s go bigger still.” The sway bars got bigger, up to two inches or more in diameter. The right rear spring rate got bigger too, up to 600 to 800 ppi spring rates. All of this was overkill.

To limit the front travel and keep the cars from hitting the track, we saw bump stops come into the picture. Now we could run even softer springs up front and the high spring rate of the bumps caused an anti-roll effect similar to large sway bars. We no longer needed the two inch sway bars and those were reduced to less than 1.5 inches in diameter.

Teams soon learned that they didn’t need the super stiff RR spring and large spring split either. The RR spring rates came down to around 250 to 300 ppi, the actual rate dependent on the panhard bar height. All was better, but not perfect.

The truth was the bump stop setups were very hard to manage and perfect. I talked to a well-seasoned crew chief recently who had tuned his bump stop setup and went from bad to good with just a 1/32” packer adjustment. That is way too much on the knife edge as far as I am concerned.

Then out came the bump springs. These provided a more consistent spring rate over the bump stops where with those, the spring rate was variable and increased tremendously in a very short amount of compression Bump stops traveling under a half inch go from less than 100 ppi to over 2,000 in that distance. Bump springs are much more consistent and tunable.

During all of this, the shock guru’s were having a field day. To make the soft spring and bump setups work, you needed high rebound shocks that would work with the high spring rate of the bumps. These were miss-named “tie-down” shocks. This was a misnomer because their original intent was not to tie down, but to control.

Here we go again, if 200 pounds of nose (rate before movement of the shock) were good, then 400 or 600 would be better. And if 600 pounds of force at 3 inches per second of shock speed were good, then 1200 pounds might be better.

The teams running bumps soon learned that there are limits to everything and found a happy medium for RR spring rates, sway bar sizes and shock rebound rates. But then the teams running Non-Bump setups thought it would be a good idea for them to run “tie-down” shocks on their “soft conventional” setups. They wanted the low front attitudes that we enjoyed on the bump cars, but didn’t have the proper equipment to run them.

That never stopped anyone from doing the wrong thing, and they did. Now the front shocks with the high rebound rates over came the ride springs and jacked down. That is to say, as the shock compresses, there isn’t nearly enough spring force to push it back up any time soon. So, the front ends go lower and lower.

If it needs to rebound, it cannot. The tire loses load and then grip. The car pushes badly and the setup balance is ruined. All because these teams try to do something the car was not designed to do.

The point is this, live within the confines of the design you are racing with. Don’t do crazy things that aren’t meant to be. In those classes where you must run more conventional setups without bumps, work with what you have. Match the springs up with shocks made with normal rebound rates.

You can run a little larger rebound rates and sway bars without ill effects, but don’t go overboard either. The fastest non-bump setups are nothing special, trust me. They are just balanced with the four spring rates and sway bar rate that work in combination with the right panhard bar height, and cross weight. When you get those working together, the four tires will work as hard as possible and you’ll be fast for a long time. It’s not magic, or is it?

If you have comments or questions about this or anything racing related, send them to my email address: chassisrd@aol.com or mail can be sent to Circle Track, Senior Tech Editor, 1733 Alton Parkway, Suite 100, Irvine, CA.

Anti_Squat

Hi Bob –

I read with interest your “Advanced Anti-Squat Techniques” article in the 2.17 issue of CT. Can this technique be used to advantage turning both left and right? I’m building a street rod and want to set it up to run parking lot autocross (Goodguys) and some road race track time.

I’m planning on using a four bar rear end setup in a Satchell Link arrangement (parallel top bars and diverging inclined bottom bars). This arrangement fits better between the X-members of my frame and I’m thinking I won’t need an extra bar to stabilize the rearend laterally. I understand this arrangement is suppose to provide considerable anti-squat with roll understeer and a low roll center.

Your article states the lower bars of the three bar system are not considered an adjustable item for AS. Would the Satchell Link minimize the rear steer characteristics you mentioned? Could changing the angle of the bottom bars be utilized to adjust the amount/location of the AS like relocating the front frame mount of the top third bar detailed in the article?

On the reverse side, during deceleration how long of a Swing Arm will be required to minimize traction loss and prevent brake hop? Can a good +/- AS balance be achieved? My front suspension will be a double A-frame layout with R&P steering. Any suggestions and guidelines you can provide will be greatly appreciated. Keep up the good work,

Jeff Beuter

Jeff,

Your design will have a low roll center and should control lateral movement. My thoughts on the lower control arms is this, the angles are critical to control rear steer. As the car rolls, those bars, in combination with the top bars, can create rear steer depending on the angles of the bars.

It might be wise for you to mock up the suspension using tack welds to mount the links. Then bump the wheels to see if there is any fore/aft movement of the wheel. If so, the proper side-view angle of the links to prevent rear steer might be detrimental to anti-squat.

That is why the three link systems work so well. You can angle the upper middle link to create the AS while running angles in the trailing links that won’t create much rear steer. Maybe you should re-think your rear suspension and use a three link. Most of the late model types of road racing cars have used that system for a long time.

Anti_Squat 2

Hi Bob,

Your article on anti-squat has me wondering, what is your opinion of reducing AS to allow more of the torque load to be absorbed by the rear springs and shocks?  I’m considering replacing a torque absorbing third link with a solid link and running less AS on a pavement modified to achieve the same effect.  Any thoughts?

Rich

Rich,

What you are doing is allowing the car to squat, which can be very useful.  If you run more angle in the left trailing arm (front higher than the rear), the squat motion will kick the left rear wheel back on acceleration creating rear steer to the left. This tightens the rear of the car and points the driving force left of centerline.

You get a combination of rear tire angle of attack which provides more traction while using the trust of the motor to drive the rear end left when it really wants to go right. This combination is very effective for cars with smaller and/or harder tires to be able to use more throttle off the corners. I see no real advantage to zero rear squat anyhow.

Back To Racing

Hello,

My name is Dustin Bates and I’m from Southwest Florida. I have been reading your articles for as long as I can remember. I’ll try to keep this as short as possible. In 2008 we got out of late model racing due to the economy tanking and at that point in time everyone seemed to be shifting over to the Anderson Elite style big spring cars from BBSS coil over cars and we followed suit. We had just built a big spring car but never got to race it.

Fast forward to now and my dad and I want to get back into late model racing. We only plan on running the newly opened 417 Southern Speedway, Desoto, and Showtime. So since exploring the late model scene again I am seeing there’s a couple guys running Anderson Elite style big spring cars, but everyone seems to have shifted back to big bar soft spring coil cars, or what’s new to us, bump stop cars. So here’s my question, if you were in our shoes which route would you go?

We do not have a car yet, so we have the option of going in any of the ways. Initially we were planning on having Dave Pletcher build us a new big spring late model designed a lot like Dickies big spring cars. But after exploring what everyone else is running these days chassis wise we are left wondering if a big spring car can still be a competitive car with all of today’s new BBSS and bumpstop cars.

If it’s not too much to ask can you maybe give us a little insight into what would be our best option. We of course want a fast competitive car but one that stays consistent throughout the race time wise. Thanks in advance,

Dustin Bates

Dustin,

You could do very well with a big spring late model car. It is very adaptable to running soft springs and bump stops, or springs which I highly recommend. The shock being mounted separate from the spring helps you work with the bumps. Be sure to get the screw jack shock height adjustment for the upper shock mount.

The newest late models coming out of Wisconsin are mounting separate bump shafts outside the coil-over assembly just for that reason and they are easier to work with when the spring is not in the way.

With the spring and shock separate, you can work with the shock much easier than you could with a coil over. The car doesn’t care which it is, coil over or big spring. And the bump springs are far more consistent than the bump stops. Dick and I tested bump springs on his Elite late model and were very fast on some of the tracks you mentioned.

No one successful uses big sway bars anymore, especially when using bump springs. So the term, Big Bar does not apply now days. There are many spring companies offering bump springs today and there are more rates available than ever before.

Left Rear Axle Weight

Hi Bob,

I had just finished reading some information where some dirt late model teams are adding weight to the LR axle tube, some going as far as building the tube out of tungsten, when my latest issue of Circle Track arrived.

I was reading your article and looked at the page to the right and there was a well known company selling brackets to mount lead to left rear axle tubes. Seeing this I figured that it must really be being done and it sure goes against the theory that your un-sprung weight should be as light as possible. I think I can see where this could help the forward bite of the left rear tire but I would like to hear your take on this. Thanks for your great articles.

Fred Ehlert

Fred,

I, for one, have never said that un-sprung weight should be as light as possible. At the front, the un-sprung weight does not transfer because of the double A-arm system. So, making lighter spindles, etc. makes no sense. When you take that weight that used to be in the wheel assembly and move it to the frame, a percentage of it now transfers from left to right.

As for the rear end and weight transfer, yes some of the rear weight transfers in the rear end assembly, which includes the wheels and tires, from left to right in a left turn. But, the lower the Center of Gravity of the mass, the less weight transfer that occurs. Since the rear end assembly has a lower CG than the car in most cases, less load will transfer if you put it there.

So, more weight stays on the LR tire than before and I’m sure the teams who have tried this report more forward bite as a result. Next you’ll see heavier hubs, brake rotors, wheels and more on the left side of the rear ends.

All of this is much different than stacking lead bars off the extreme left rear corner of the car. All that does is create a leverage affect that sends the rear of the car towards the wall. Never do this with any race car. I’ve seen it tried and I’ve seen it fail.

The post Have Racers Gone to the Extreme? (Plus Q&A) appeared first on Hot Rod Network.

The use of stacked springs has become commonplace among many top Dirt Late Model teams. It wasn’t always that way. As far as I know, the first test using stacked springs in a dirt late model occurred in March of 1998 at Eldora Speedway. Coincidentally, I was there, and I was surprised.

We were there, I assumed, to test a new setup arrangement I had developed for the upcoming Dream race that seemed to work out very well. My friends at the test wanted to see how stacked springs would work, so we tried them too. Although the stacked spring concept as it was arranged then did not work well at the then high banked Eldora track, it would eventually gain traction for use at lower banked tracks.

The stacked spring concept began with desert racers in the Baja Pro Trucks as far as I can ascertain. I’m sure someone will correct me if I am wrong on that. Anyway, those trucks needed a compliant spring that gained rate, but it needed to be very long due to the high amounts of suspension travel. The same is true for the right front and left rear corners on many Dirt Late Models in today’s racing.

The use of stacked springs, first in the right front of the Dirt Late Models, allowed the car to run on a very soft spring rate on entry to the corners until a heavier rate was needed through mid-turn and then off the corners. Now, in today’s racing, the stacked spring concept is being used at the left rear also and sometimes in the right rear of those cars.

If you use stacked springs in your car, or you are thinking about switching to stacked springs, here are some important tips and technical information you will need to know. This mostly comes from professionals in the racing spring business I have talked to and who work directly with race teams. I admit that I knew very about the use of stacked springs before I researched and sought out the help of these individuals.

Definitions Of Stacked Springs – Basically there are two ways to run stacked springs. One is called Stacked springs because all you are doing is stacking two springs in series, with the same or different rates, to achieve a longer spring that is a softer rate than either of the springs used.

If you stack a 10 inch 400 ppi and a 6 inch 400 ppi spring, you get a combined rate of 200 ppi. You may not be able to find a 16 inch 200 ppi spring, so this provides more spring length to use. We’ll go over how to find that rate later on.

The other way to use stacked springs is to use the Dual Stage system. This system is also a stacked spring in that you use two springs on top of each other in series. The difference is that you also use a stop mechanism that eliminates the travel of one of the springs at some point of shock travel to where the car is then riding on only the one spring.

With the Dual system, you can run a softer spring on the top and a stiffer spring on the bottom. As the shock travels, the divider between the shocks moves up the shock body. At a predetermined (by you) point, the divider hits the stop and the top spring is no longer able to compress.

Since only the bottom spring is now the only one working, its rate is what the car runs on as long as the shock is compressed at least that far. So, for example, if we want to run a 450 ppi (pounds per inch) spring through the middle and off the turns, but require a much softer spring rate to enter the corner with, we can stack a 300 ppi spring on top of a 450 ppi spring.

Using the Stacked formula to find the combined rate, we use the Top Spring rate times the Bottom Spring rate divided by the Top Spring rate plus the Bottom Spring rate. To find the example rate, we multiply 450 times 300 = 135,000. Then we add the two spring rates to get 750. Dividing the two, 135,000 divided by 750, we get a 180 ppi combined stacked spring rate.

So, on entry, our car rolls in on a spring rate at the right front of 180 ppi. Once the shock travels to a predetermined compression, the top 300 ppi spring is eliminated and the car now runs on the bottom 450 ppi spring at the right front until the shock de-compresses and the spring divider is no longer contacting the stop.

Another Dual Rate System – I will throw this in at this point. There is another Dual Stage system being used by some teams. It involves using a bump spring, or bump stop, on the RF corner. Just like the Dual system I described above, the rate changes as the shock travels.

With the bump spring, or for that matter bump stop, the car is suspended by the normal ride spring until it travels a predetermined amount. Then the bottom of the shock body, plus any stackers, contacts the bump and the ride rate is now the combined rate of the ride spring plus the bump rate.

The drawback to trying to go this route on dirt is that most bump springs, and especially the bump stops, do not have much travel before they coil bind or compress to solid. Some teams will stack two bump springs to get more travel, but now that stack equals a much softer bump spring rate.

Two 500 ppi bump springs that are stacked will equal a spring rate of only 250 ppi. To get back to the 500 ppi rate of just one spring, you would need to stack two 1,000 ppi bump springs.

Which Do I Run? – The choice of which to run, Stacked or Dual, depends on which corner you will be working with. Generally, the Stacked system works best on the LR corner to provide a longer spring to help it stay loaded when the LR corner hikes coming off the corners.

The same Stacked system will not work very well on the RF because the soft rate would cause the RF corner to travel too far. And, it would not produce the higher rate needed to gain loading for the RF and LR corners coming off the corners. So, we use the Dual system on the RF.

The combinations for each, the Stacked and Dual systems, are many. You will need to determine what you want to accomplish and then decide on the spring rates that will get that done for you. For the LR corner, make sure you end up with a combined rate that will work with the RR spring rate to balance the car. Too stiff and the car will be too tight in and through the middle. Too soft and the car will be too loose in and through the middle.

Important Considerations – Here are a few important considerations and tips on how to put together your stacked systems. You cannot just install two stacked springs in your car on any corner and just go racing. There is some shop preparation that is required.

First off, a longer spring will tend to bow more than a shorter one, no matter how good your spring is. This may be a problem that can be solved. On most quality springs, the ends are 180 degrees opposite where the tips on each end are pointed. This tends to offset the bowing tendency.

If you stack springs, you will need to arrange the springs so that the bowing tendencies of the two springs offset one another, just like the design in individual springs. This takes time and experimentation. How do we do that? We eliminate bowing by rearranging the location of the two springs after compressing the system on a commercial coil-over spring compressor to find a position for the springs that has less bowing.

Adding bearings to the top and bottom of the assembly will also help prevent bowing of the springs. The two springs must be allowed to twist, or wind and unwind, as the shock travels. That is the way springs work all of the time.

What Else You Need To Make This Work – Most teams, if they are going to get the most out of the stacked spring systems, will hire a shop that has a coil spring force measuring rig, or they will buy their own rig, to help in the setup of the stacked spring system.

These rigs measure force at predetermined compression amounts of the shock/spring combination. This is not a hard concept to learn and understand if you follow along with the overall picture. To do that, we need to mentally separate force from spring rate, they are two entirely different things.

Force is the overall work that the spring is doing based on how far it is compressed. A 500 ppi spring that is compressed two inches has 1,000 pounds of force. It gains 500 pounds of force for every inch it is compressed. The designation, 500 ppi, means that for every inch of compression, the spring gains 500 pounds of force. That is why it is labeled 500 pounds per inch.

In order for us to maintain our ride heights we had using our old one spring system, we need to measure the shock length at ride height and record that number. This is true no matter which corner of the car we are working with. With the LR using the Stacked system we also need to know how far the shock will extended when the rear is hiked up so that we install a Stacked spring system that is long enough.

At the LR, we compress the Stacked spring and shock in the Force rig and adjust the spring height so that the force at compressed ride height is the same. If we compress the shock to the ride height amount and we end up with too much force, we back off the adjuster until the force is the same. Then our ride height will not change when we install this Stacked system.

For the RF corner, we will be running a Dual system. For this, in addition to finding ride height force, we also need to know how far the shock compresses at mid-turn when running a single spring. This motion produces its own force that we need to duplicate in the Dual system.

At the RF, we do the same as we just did with the LR for the overall Dual system ride height. For the transition from the stacked rate to the single spring ride rate, we need to know the average shock travel at mid-turn. Then we use our Force rig to find that force number in pounds.

We usually want to hit that mid-turn force number at some point after the spring separator has contacted the stop that eliminates the softer spring and when the RF corner is riding on only the higher single spring rate. The total amount you end up compressing only the single spring is something you will have to experiment with.

This timing has a lot to do with how long into the corner you want to be on the softer, Dual spring rate, before transitioning to the single higher rate. That is why most consultants suggest on-track testing to tune the transition point.

Shocks To Use With Stacked Systems – The shock package you will need for your stacked system is a little different than what you might be use to for single spring applications. We need to understand what we are trying to accomplish and then think out our shock rates.

For the RF, we need the shock to control the force levels we are working with at mid-turn and off the corners. By control I mean rebound settings in the shock. Those forces will be already known if you run through what we discussed above. They will be higher than standard because one of the benefits of the stacked Dual system is that it travels farther and generates more force.

For the LR corner, we want the shock to extend more easily and therefore the rebound rates for that shock would be lower than normal. Also, when we exit the corners, there will be some extension initially, then some compression of the shock and spring, so we might consider increasing the compression setting to take advantage of that to create more loading of the LR tire for late exit traction.

Outlawing Stacked Springs – It has been discussed within come sanctions, and enforced in others, that stacked spring setups be disallowed. The reason stated is to save the racer money. Many of these very same sanctions allow bumps stops and bump springs. Let’s examine the argument.

Cost is relative to many things. We know springs last a very long time. So, any investment in springs for setting up stacked spring systems will be a one time, or long term investment. And it can be argued that the teams may have the springs needed for the stacked spring systems already lying around the shop, unused. Now the cost is only the hardware needed to go on the shock and those parts are relatively cheap.

If bump stops are allowed, we know they don’t hold up to the rigors of dirt racing and need to be replaced on a regular basis, so the cost of those systems, while relatively cheap in the beginning, becomes more expensive in the long run.

The force rig that should be used by the teams to setup the stacked spring systems can be rented, or shopped out to a consultant, much like we do with our shocks. If the team does invest in the force rig, it is basically a spring tester designed to rate the spring/shock combination. Many teams already have those, and if not, they need them.

Getting a car to handle better makes for better racing and it is safer. The reason it is safer is because the cars no longer need to force the front end to turn like before these systems came out. With less sideways action, there is less contact between the cars and less overall damage from contact.

I really don’t see what the big deal is. Modern super late models on dirt run custom built engines that cost upwards of $40,000 in some cases and a stacked spring system cost pales in comparison. The difference between the stacked system and a single system is around $300-400 for parts. One crash will eat up more parts that that. So, I’m not convinced there is any realized savings in outlawing stacked spring systems for dirt racing.

Conclusion – The use of stacked springs in either configuration can make your car faster and easier to drive. If you run stacked spring systems, or intend to convert to stacked systems, be sure to follow the simple rules we have presented. Also, consult with your spring supplier, shock supplier and those who manufacture the force rigs so that you can get the most out of your application.

Sources:

Eibach Springs
800-507-2338
www.eibach.com

Gale Force Suspension
251-583-9748
www.galeforcesuspension.com

Hyperco Springs
800-365-2645
www.hypercoils.com

Intercomp
800-328-3336
www.intercompracing.com

Longacre
800-423-3110
www.longacreracing.com

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