Ackermann is one setting that...
Ackermann is one setting that can ruin an otherwise great setup. In this day and age, we no longer need Ackermann to help turn the car. Reduce your Ackermann to near zero.
Every race car needs a certain amount of tire stagger. The rear tire sizes must be different in order to compensate for the turn radius so that both rear wheel RPM will be equal. Excess stagger should never be used as a crutch to help make the car turn if it is tight.
4. Balance and Crossweight - A loose or tight car can also be caused by a tight or loose setup. Either of these two can be caused by an unbalanced setup, or by running the wrong amount of crossweight percentage. Tire temperatures can tell a lot about the setup and where we need to look to fix the setup balance problem.
In the case of an unbalanced setup causing a tight condition, the rear of the car wants to roll more so than the front. There are several things we can do to help balance the car. We can raise the panhard bar to raise the rear moment center which will cause the rear suspension to want to roll less. We can reduce the rear spring split if we are using a softer right rear spring by stiffening the RR spring and/or reduce the LR spring rate.
To reduce rear steer, find...
To reduce rear steer, find the trailing arm angles that will serve to locate the rear end with chassis movement so that there is very little rear steer. Even with the dirt teams, rear steer is being re-evaluated.
At the front end, we can do a few things to cause the front to roll more to try to match the rear roll angle. If we have a much stiffer RF spring, we can soften the RF spring, stiffen the LF spring or run a stiffer LF spring than the RF spring on flatter tracks. The stiff LF spring setup does not work well on tracks banked over 10 degrees. Changing to a smaller sway bar will also increase the front roll angle. With the BBSS setups, reduced roll angle is the overall goal, but teams have been changing to smaller bars of under 1 1/2 inches recently.
With the BBSS setups, the front may want to out roll the rear, causing excess load to be put on the right rear tire through the turns. This happens when the crew knows there needs to be a spring split in the rear by installing a stiffer RR spring than the LR spring, but goes overboard and uses much too stiff a RR spring. When the LR tire is the coolest on the car, the rear spring split may be too much.
5. Tight/Loose Syndrome - A car can appear to be loose when in fact it is tight. This condition is very hard to detect from a driver's perspective. The feel is that the car is loose right at mid-turn and off the corner. What sometimes happens is that the car is tight and the driver turns the steering wheel far enough to get the car to turn.
Balance in chassis setup involves...
Balance in chassis setup involves the relationship of the front suspension to the rear suspension in a dynamic sense. These two systems influence each other because they are attached by the chassis. So, we need to make sure they are happy with each other in their actions. Getting along applies to our setups too.
Because the front tires generate more traction with a greater angle of attack, the driver is actually putting more traction into the front end. The once tight condition now switches to loose as the front gains grip from excess steering angle. This happens very quickly and the rear end snaps loose as the throttle is applied. All the driver knows is that the car is loose. To correct this, we have to fix the tight condition to cure the loose condition. This malady is more common than most racers know.
6. Shocks - For a car to be fast, the driver must have a good feel for what the car is doing. A soft ride that feels sloppy does nothing to give a driver confidence in knowing what the car will do next.
Many racers think that increased compression in the shocks should help this problem, but too often that has an opposite effect. The car may indeed need more compression in the shocks, but the rebound should always be higher than the compression to control excess body sway and roll. In most cases, just increasing the rebound resistance will solve the problem.
Again, with the Big Bar and Soft Spring setups, excess movement of the suspension can be a problem. Higher rebound rates are essential for controlling suspension movement. Many of the tech support persons who work for short-track shock companies have worked out shock valving solutions for those who want to experiment with the BBSS setups.