Many racers say one of the most mysterious parts on the car is the shock, or motion damper. It is often heard that there is potential for performance gains by experimenting with different shocks.

Going fast is not simply a case of bolting on different shocks. While we do agree that performance gains are possible and performance loss often comes with running the wrong shock rates, the first order of business is to work out any basic chassis setup problems you might have before experimenting with shocks. With that in mind, let's look at what shocks do and don't do.

What Shocks Don't Do

1. Shocks do not support the car.

2. Shocks do not control weight transfer.

3. Shocks do not affect chassis balance at mid-turn.

4. Shocks are not a cure-all for basic handling problems.

What Shocks Do

1. Shocks control (limit speed of) motion of the chassis and suspension.

2. Shocks, with varying designs of resistance, allow more or less rapid movement of a suspension corner than opposing corners.

3. Shocks regulate the amount of time it takes for a corner of the car, while in transition, to assume a new ride height.

4. Shocks can be used to redistribute the amount of weight on the four corners of the car as the car is in transition on corner entry and exit.

How Shocks Work

Shocks resist motion by using a piston and valves that are mounted on the end of a shaft and that move through a fluid of thin oil. The fluid must pass through holes, valves, and slots in the piston as the shaft is stroked in and out. Resistance is created when the oil is forced through the openings on each cycle. Basically, all racing shocks are of two designs: twin tube and mono-tube and can be either gas pressurized or "low" pressure. The twin tube literally has two tubes: The inside tube is where the work is done and the outside tube is a reservoir that holds extra fluids.

Shocks are Spring Dampers

Shocks are installed in race cars, as in any car, to primarily control oscillations caused by the displacement of the springs, especially coil springs. If we place weight on an undamped spring, such as when they support the car, and then push and release on one corner of the car, the spring will compress and decompress in a series of diminishing oscillations over a relatively long period of time. There is no known advantage to this condition and many disadvantages, so we use dampers to control the movement of the springs.