While the crew went to work refueling during a break in a long-distance race, this Modifie
Start with the RF tire. The middle of the tire surface is cooler than the outside edges. This means more pressure needs to be added. The LF middle temperature is higher than the outsides, so pressure must be reduced. The left-rear (LR) tire shows the middle again higher than the outsides, another case for pressure reduction. The right-rear (RR) tire temperatures rise as we go from the outside to the inside. The middle should be 213 degrees if the pressure is correct. This tire bears watching, but needs no pressure changes for now.
With those changes, the car is sent out for the next session. This is where the results of the change become known. The RF tire, although not even in temperature across the face, has an even difference from the outside to the inside. The LF tire is also fairly even in difference across the tire. The LR tire shows fairly even temperatures with the inside (meaning the edge toward the inside of the racetrack), showing a slightly higher temperature than the outside. The RR tire shows the same tendency as the LR tire, with slightly higher inside temperatures.
The LF tire is hotter on the outside edge (away from the inside of the track), so there is a need to increase the positive camber. Again, about a 11/416-inch movement of the upper control arm shaft to push the top of the tire away from the centerline is a good adjustment.
Those changes are made and the car is sent out for another run. Chart 3 shows the results of session 5. The camber changes have produced nice tire temperatures at the front of the car. The RF tire is nearly even across the face, and the LF tire is also very good. With those changes, the setup can be analyzed by looking at the average temperatures of the four tires.
If you can, buy a large dial tire pressure gauge so you can read whole pounds and incremen
The temperatures from session 5 would normally indicate a loose car, but knowing that the LF tire is not working hard enough, we might guess that the car is tight-loose. This is a condition in which the car is really tight, but not skating the front tires, and the driver compensates by steering harder in the middle. The added steering input causes the front of the car to quickly gain traction, and as it begins to overcome the rear traction level, the driver gets back into the throttle and the rear tires break loose.
The tire temperatures might lead us to believe that the car is loose, and the driver will confirm that because all he can feel is the car going loose on exit. The real indicator is in the degree of steering input. The crew and the driver can see that the input to the steering wheel is more than should be needed to execute the turn. A setup change is needed to reduce or eliminate the tight condition.
The setup changes that might be made include raising the Panhard bar, increasing the RR spring rate, reducing the LR spring rate, softening the RF spring rate, and stiffening the LF spring rate. All of these changes will help the chassis to be more balanced and make the LF tire work harder.
Another quick look at the tire temperatures shows that all four tires are a bit hotter on the inside (again, related to the track, not the individual tire) edges. By reducing pressure in all of the tires by 1 pound, the temperatures may even out further. We will assume that we made the correct changes to the setup and tire pressures as we look at session 6.
Used properly, a simple tread depth gauge, such as this Longacre unit, can tell exactly ho
If setup changes were tried before tire pressure and camber problems were fixed, the whole process might not have worked as well. We might still be chasing the handling balance or throwing crutches at the car to make it neutral in handling, but not balanced.
These numbers can be achieved in the real racing world. Teams have gone through this process and achieved the same results. Some racers might say they have never been able to get the left-side tires equal in temperatures, but then again, many teams have never had a truly balanced setup.
Now that we know the method to find that sought after balance, we can begin to make adjustments to make our cars better.