We’re going to continue where we left off in our analysis of your handling woes. If you missed it, we’ve already addressed the problem of an ill-handling machine entering the turn. Now we’ll try to help you find your problem by focusing on the symptoms through the middle of the turn, keeping in mind that some handling problems have multiple sources.
It’s important to remind you that before you undertake this analysis, you need to make sure your team has already completed the tasks of proper alignment of the rear end, checked and set the correct toe in the front wheels, checked and eliminated bump steer and checked and reduced the Ackermann to a minimum.
We’ll also assume that your team has evaluated their front geometry and re-designed it as necessary for a more efficient front end dynamic. If not, please go back and read our numerous articles on those subjects. If so, and any one of these were out of whack, then maybe those were some of the problem. If everything checked out, then let’s continue.
Tight or Loose Middle
If your problem is tight or loose through the entry and middle, then the fixes listed here could solve both entry and mid-turn handling. Chances are the problems we focused on for entry problems would not necessarily cause mid-turn handling problems. Here is what does and does not.
Some shock experts would like to think that they can correct any handling problem with changes to shock rates and that is just not true. The middle segment is what we call steady state where the car has settled in to the turn radius and there is very little, if any, movement of the shocks or springs.
If there is no movement of the shocks, then there can be no influence by the shocks on the chassis dynamics that influence the load distribution. Of course, it is possible that extreme entry problems caused by shocks can linger and affect the mid-turn. Regardless, any residual influence that might be caused by turn entry problems should have been corrected by now because we solved the entry problem first.
The most obvious reasons for being tight or loose through the middle segment of the turn involves the basics of tight or loose, or so most crew chiefs think. In some cases, this is not all there is to it. There are two things at play, handling balance and dynamic, or chassis balance.
Handling balance is when the driver says I am pushing (tight) or free (loose). The team could conceivably make a simple adjustment to the cross weight percent to make the car temporarily neutral in handling. But that might not solve the underlying problem.
If our setup is loose, meaning the front has more grip than the rear, it is true that we can make the car neutral by adding cross weight. But the loose problem might be that the front has more grip because it is more efficient due to the setup in the car, not as a result of weight distribution.
The tell-tale sign that the car is dynamically balanced and has the correct setup is when the tire temperatures are very close to even front to rear on each side. A dynamically balanced chassis shows near equal tire temperatures for the left side tires, and for the right side tires, front to rear, not side to side. This means that the loads on the tires are ideal.
If your tire temps are good and the car is still not neutral in handling, then you can go ahead and make changes to the weight distribution (cross weight or bite) to make the car neutral for handling balance.
There is a fixed cross weight that works for each car that is determined by a combination of the front to rear percent and the un-sprung weight values. Each car has a load transfer at the front and rear and a predetermined amount of load needs to be on each tire at static ride height in order for the tires to be correctly loaded at mid-turn.
The secret to proper setup is to balance the setup so that each end is in sync with the other end of the car and this makes the load transfer predictable. After all, it is the distribution of loads on the four tires through the turns that will determine how good the setup is and how well your car will perform.
So, how do we balance the setup? If the front is more efficient (has more grip), we need to help the rear suspension to gain grip. We can do that by lowering the rear moment center by lowering the panhard bar if so equipped. We can also reduce the RR spring rate, or stiffen the LR spring rate.
If the rear has more grip than the front and the tire temperatures show a cooler LF tire than the LR tire, then we need to raise the rear moment center by raising the panhard bar. Or, we can soften the LR spring and/or stiffen the RR spring. Both of these changes will reduce the rear roll to more equally match the front roll.
In addition to those changes, we can also increase the rear spring base to reduce the rear roll by moving the springs out. This works for dirt cars where the top of the coil-overs, usually the RR, can be adjusted for width. On a dry slick track, the top mount would be moved in towards centerline for more roll and on tacky tracks it should be moved out to produce less roll.
After you find the balance, the car might not be neutral in handling at that point. This is when you can make changes to the weight distribution, cross weight or bite, to make the car neutral in handling.
Sources:
AFCO Racing
www.afcoracing.com
800-632-2320
Allstar Performance
www.allstarperformance.com
269-463-8000
Coleman Racing
www.colemanracng.com
800-221-1851
Day Motorsports
www.daymotorsports.com
800-543-6238
Design Engineering Inc DEI
www.designengineering.com
800-264-9472
DMI / Bulldog Rear Ends
www.diversifiedracing.com
717-397-5347
DRP Performance Products
www.drpperformance.com
888-399-6074
Frankland Racing
www.franklandracing.com
888-873-2736
Hawk Brakes
www.hawkperformance.com
330-722-4295
Intercomp Racing
www.intercompracing.com
800-328-3336
Integra Shocks and Springs
www.integrashocksandsprings.com
800-472-3464
Longacre Racing Products
www.longacreracing.com
800-423-3110
Landrum Performance Springs
www.landrumspring.com
(574) 353-1674
Performance Friction Brakes
www.performancefriction.com
800-521-8874
QA1
www.qa1.net
800-721-7761
Quick Performance
www.quickperformance.com
515-232-0126
RE Suspension
704-664-2277
www.resuspension.com
Wilwood Motorsports
www.wilwood.com
805-388-1188
The post Solving Your Handling Problems: Mid Turn appeared first on Hot Rod Network.