That last one is one to watch. If your driver has practiced at a speed that is somewhat slower than race speeds, not only will the setup feel different between the different speeds, the tire sizes will change differently. To see true pressure/temperature gains, simulate race speeds-in other words, get after it in practice. If you have noticed, the top drivers never pussy-foot around the track.

2. A Hung Suspension Spring
This is very simple and straight forward. When you jack up the car, the spring has an opportunity to hang in the lower control arm, in the case of a big spring car, or hang in the shock with a coilover car. This can happen in any type of race car from a Stock class Bomber to a sophisticated Formula car and even in the Cup series.

If this happens, it will change your weight distribution dramatically. There are several ways to help prevent this from happening. First and foremost is to limit the suspension travel in droop from where the wheel is at ride height.

If you have installed a chain or cable between the frame and lower control arm, when you jack up the car, the spring won't have the chance to hang on the seat. Some teams use ring spacers between the spring and the seat on a coilover. These can shift and end up between the seat and the spring causing a substantial difference in ride height at that corner

With a big spring design, the spring can rotate to where the open end of the coil spring will not be at the proper place within the lower control arm spring pocket. This will affect ride height and the weight distribution causing the handling to go south on you.

3. Bad Locker Springs (And Other Rearend Maladies)
I have seen many teams chase their setups all season long when the real problem had more to do with maintenance. With a Detroit Locker-type of differential, the springs that do the job of locking both axles up upon acceleration can and do get weak as time goes on.

Excess heat in the rearend will accelerate the process of these springs going "bad." When they do lose their tension, the axle that the bad spring is supposed to lock up will not. This leaves you with a car that drives off one rear tire and exit performance will definitely suffer.

Specialty rear differentials sometimes use aluminum gearsets to help distribute the forces between the rear wheels. These need to be inspected and possibly replaced as often as necessary to insure that there will not be a failure. Consult the manufacturer to obtain a proper maintenance schedule for your product.

The solution might be to use a rearend cooler if you race for more than 35 or 40 laps. Break apart the rearend and check the tension on the springs often to prevent a failure. The manufacturer can tell you the designed rate of these springs and how often to replace them.

4.Ignition Wire Problems
On initial installation, many teams will wire the ignition so that the leads from the box to the distributor will be crossed. On some models of ignition boxes and distributors, similar color wires are not intended to be mated. This is not a racing problem because you will never get the motor to fire properly anyway.

Follow the instructions on both the distributor and ignition box so that the proper wires will be joined. Additional problems may arise from the way you connect the wires. Always use heavy-duty quality connections to reduce the chance they will break from all of the vibration that race cars produce. Solder the connections and use heat shrink on all joints. A little time and effort spent here can save a loss of ignition down the track.

5. Belt Alignment Problems-Pulleys
How many times have you seen or heard of a team experiencing loss of oil pressure or cooling due to a broken or thrown engine belt. Most of these occurrences can be traced right back to a misalignment in the pulley system. The belts always seem to come off during the race and not in practice when it could be easily fixed. Why is that?