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Technical Info
Page 3

How to Shock Tune Your Chassis

Study the current Bilstein set-up recommendations for your particular type of racing. These combinations are tested and proven successful, but due to many variables that come into play under racing conditions, it is to your advantage to have a basic understanding of how shock damping rates affect your lap times. Adjustments can then be made with reasoning and understanding.

Simply stated, shock absorbers convert the kinetic energy of the spring movements into heat. This heat is then dissipated into the air through the shock tube or body. In practical application, shock absorbers are necessary to maintain maximum tire patch contact to the track as the car corners and negotiates irregularities on the racing surface.

Spring rates determine how far your chassis rolls, pitches or squats. Shock rates determine the length of time it takes for each of these movements to occur.

Rebound damping controls the movement of that part of the car's sprung mass that is stored in a compressed spring. The rebound damping rate determines how long it takes for the compressed spring to return to static ride height. The larger the rebound figure, the more the shock resists the compressed spring's effort to rebound, and the longer it takes for the chassis to return to the static ride height.

Compression damping controls only the oscillation of the car's unsprung weight. Therefore, it is normal to use less compression damping than rebound damping. The exception occurs when we choose to slow the downward movement on a particular corner of the car to mimic the effect of a stiffer spring.

If your car is:

Loose (Oversteer) from 0 to 90
Increase compression rate on front.
Decrease rebound rate on rear, or only on the left rear.

Tight (Understeer) from 0 to 90
Decrease compression rate on front, or only right front
Increase rebound rate on rear, or only on the left rear.

Loose (Oversteer) from 90 to 0
Decrease rebound rate on front.
Decrease compression rate on rear, or only on right rear.

Tight (Understeer) from 90 to 0
Increase rebound rate on front.
Increase compression rate on rear, or only on right rear.

When analyzing corner entry, or deceleration handling, realize that the chassis is affected by:

Compression rate in front
Rebound rate in rear

When analyzing corner exit, or acceleration handling, realize that the chassis is affected by:

Rebound rate in front
Compression rate in rear

Bilstein shocks are famous for their superior performance on very rough asphalt or rutted dirt tracks. You may need to choose a shock with more compression damping than found on our set-up sheets under extreme rough track conditions. We have included this section in our catalog to broaden your understanding of the function of shock absorbers and to show you the effect they have on handling.

Keep in mind that there are many adjustments on your chassis other than shock absorbers. The oversteer / understeer balance may be affected by stagger, tire compound, wheel spacing, spring rates, sway bar, panhard and others. Shocks can be used to fine tune your chassis to gain that last few tenths of a second on the track.