Keep careful notes of the test. Here, Chuck Gibson has written notes on his hand and I'm t
After we've made the car neutral in handling, we need to make a couple of hard runs and note the tire temperatures. A car that is balanced as to the dynamics related to how the front and rear suspensions are working with or against each other will show the balance in the tire temperatures. The LF tire will be near the same temperature and working as hard as the LR tire in a balanced setup.
If the LF tire is the coolest tire on the car (by far the most common condition) then you should make changes to the setup to help heat that tire up and therefore make it work harder. With the popular Big Bar and Soft Spring (BBSS) setups, the opposite is usually true. The LR tire might be the coolest tire on the car and we need to make changes to cause the left-side tires to be the same.
Tire wear can tell us a similar story when racing on dirt. Dirt teams rarely take tire temperatures. They do feel the tires for temperature, so we know they feel it's important. But tire wear can also tell us how hard a tire is working.
Here are a few changes that help us move toward a more balanced state:
To reduce the tendency for the rear to out-roll the front (cooler LF tire)
1. Decrease the LR spring rate or increase the right rear spring rate.
2. Raise the Panhard bar.
3. Soften the RF spring rate on lower-banked tracks.
4. Stiffen the LF spring rate.
5. Move the moment center to the left.
Talk to the driver after each run and ask specific questions. Have him run the lap in word
To reduce the tendency for the front to out-roll the rear (as is often the case when teams try the BBSS setups)
1. Reduce the RR spring rate.
2. Raise the LR spring rate.
3. Lower the rear moment center/Panhard or J-bar.
4. Increase the size of the front sway bar (2.0-inch diameter might be a bit much--try a 1.375- or 1.500-inch diameter bar if you've been using a smaller bar).
5. Stiffen the front spring rates.
With each change, you'll need to also change the crossweight percent in order to maintain the neutral handling. The crossweight will have to increase in the first examples because as the LF tire begins to have more grip and work harder, the car will turn better and we'll need to tighten it up using a higher percent of crossweight.
In the second set of examples where the front out rolls the rear, the crossweight will need to be reduced as the rear tires develop more grip.
If your team has always used Ackermann to help the car to turn in conjunction with a tight and unbalanced setup (the LF tire runs cooler than the LR tire), then as you make changes to load the LF tire, the Ackermann will have to be reduced and/or eliminated.
A tire that is not working much (less vertical load on it) will gain traction by using Ackermann. If we load that tire, it'll really take off in the steered direction and work against the RF tire. The end result will be a severe push as the two front tires will be trying to go in different directions and both give up their grip on the track.
In our test, we were able to view the data after each run. We looked at the shock travels,
Finding the dynamic balance for the car is not the end of our goal, but is the very foundation of a good setup. It's the first and most important step in the overall setup for the purpose of getting ready to race. Small changes to the setup can now be felt by the driver as never before and we can further fine tune the setup for improved entry and exit performance.
Entry problems are almost always caused by rear alignment issues or incorrect shock rates, mostly in the RF and LR corners of the car. Make absolutely sure that the rearend is aligned properly and square to the centerline of the car. Don't take this subject lightly because you'll struggle long and hard to overcome a poorly aligned rearend to no avail. No setup change can effectively overcome an alignment problem.