Chassis roll moves the upper ball joints to the right, changing the front cambers so that
4. Rear Steer
Some rear suspension systems can be adjusted for rear steer. If the adjustments are such that the rear end is made to move so that the right rear wheel is farther to the rear than the left rear wheel, we have rear steer to the right. This makes the car very loose and we need to adjust the suspension components so that it will not steer in this manner.
If the car is a dirt Late Model and the track is very dry and slick, this type of rear steer can actually help the car keep grip with the rear tires. This is a special case, and in almost every other situation, we try not to steer the rear of the car to the right, be it dirt or asphalt.
1. Improper Shock Rates
The left rear shock may be too soft in rebound or the right front shock may be too stiff in compression which will tend to load the right front and left rear tires on initial entry under hard braking. These two corners make up the crossweight, and anytime we increase the crossweight percent, we tighten the car. To fix this, increase the rebound in the left rear shock and/or soften the compression in the right front shock.
2. Spring Rates
The spring rates in the car may contribute to a tight car on entry. If the front springs are split so that the right front spring is higher than the left front spring, then an effect similar to the shock notes above takes place. The stiffer right front spring causes the crossweight percentage to go up as we enter and brake into the corner. Reduce the spring split across the front to reduce the effect of increased crossweight percent on entry braking.
Chassis dive pulls both top ball joints in towards the centerline of the car and changes t
3. Brake Bias Imbalance
Again, make sure your brake bias is tuned correctly. If too much of the bias is on the front brakes, the car will push under heavy braking. If you lightly brake into the corner, it should get better. That is one way to tell if the front has excess bias.
4. Lack of Anti-Dive
If the car is diving excessively under heavy braking, the right front wheel will lose camber quickly and the tire will lose traction. Anti-dive properties can help the situation. Although the camber change is quick and the wheel returns to normal camber settings a short time later, once a push starts, it is hard to stop it without slowing way down.
We want to eliminate the camber change by designing anti-dive into our front suspension. If we angle (from a side view) the upper control arm shaft that is mounted to the chassis so that the front is higher than the rear, we will have introduced some amount of anti-dive into the front suspension. We can also create more anti-dive by raising the rear chassis mount of the lower control arm.
5. Right Front Camber
Change -The right front wheel will always experience movement as the car enters and rolls into the turns. If the front geometry is not designed correctly, then as the car dives and rolls, the right front camber relative to the racing surface will change and the tire will lose grip. In testing over a five-year period, it was discovered that most tires want no change in camber relative to the race track surface as the car dives and rolls. We cannot read this type of camber change merely from bumping the wheel because the effect of chassis roll on camber change is missing.
The next segment of the track we will explore in Part Two is the exit portion. Many racers agree that the problems that occur here can be the most detrimental to performance in the actual race. In practice, we never have to make a pass in "anger." Problems with exiting under power can be OK when we are by ourselves, but in the race, when we need for the car to turn well or to have good bite off as we drive under a car, that push or "loose off" condition rears its ugly head and prevents us from moving up through the field.
Next time, we will examine ways to fix exit woes.