High-Banked Setups
For a setup that uses higher-rated springs in the front and rear for a higher-banked race track, we might use a pair of 6.5/4.5 shocks on the front and a pair of 5.5/3.5 shocks on the rear. That is because the higher rating in the springs promotes rebound and therefore we increased the rebound resistance. The higher spring rates also resist compression and so we can reduce compression resistance in the shocks.
For a shock installation such as this coilover design, the shock/spring combination will move at a slower speed than the wheel. If the speed of the movement of the wheel were 5 inches per second, then, due to the motion ratio and the shock installation angle of the shock/spring, the shock speed would be only 3.82 inches per second.
When the banking of the race track is very high, say 18 degrees or more, we need split valving, but we would go up on both the rebound and compression rather than up on rebound and down on compression. The reason is that the turn speeds are much higher on the very high-banked tracks and the shocks will move much faster in both the transitional areas of entry and exit, and also as the car goes over bumps and dips in the race track. Without the higher level of control, the suspension might bottom out with obvious negative results.
A more realistic layout for a very high-banked track might be a pair of 6.5/5.5 shocks on the front and a pair of 5.5/4.5 shocks on the rear. We have increased the resistance for both rebound and compression as well as introduced split-valving to a degree.
On many big-spring stock-clip stock cars, the speed of the wheel, the shock and the spring are all different. If the wheel were moving at a speed of 5 inches per second, the shock would be moving at 3.82 inches per second and the spring would move at 2.65 inches per second. If the shock were mounted farther from the ball joint, then it would need to be designed with a higher rate of resistance for both rebound and compression.
Low-Banked Race Tracks
For low-banked race tracks, we would need to spring the car much softer to slow down all of the movements in order to help maintain traction. One of the basic ingredients needed to maintain grip at low-banked tracks that have less grip is to soften the whole setup, including spring rates and shock rates. As we soften the springs, we will also soften the front shocks to say 5/4 valving and the rear shocks to a pair of 4/3 shocks. This is the general way shocks can be matched to the stiffness of the spring setup.
One exception is when we go beyond the normal softening of the springs into what has become known as the "soft spring - big sway bar" setups that have become popular in short track asphalt racing. These setups often use super soft springs in the front and, to help control dive on entry, the teams must increase compression resistance to overcome the tendency for the car to bottom out as we brake and turn left on entry into the corners. Here is where we might go back to the true 50/50 shocks. The debate is still on as to whether there is a need for the SS-BS setups and it has definitely been realized that those setups do not work in all situations.