Dampers Part 3: Bump and Rebound

If you have adjustable dampers on your car, it’s crucial to understand what is actually changing when you turn that knob to tune your suspension.

Damper valving is more complicated than just “stiff” or “soft.” This simplified view is counterproductive when setting up an adjustable coilover.

For example, many increase the damping on their coilovers to reduce bottoming out. This does not work if you’re only adjusting rebound. It’s making things worse.

Bump damping (aka compression) is the force the damper generates in reaction to the wheel moving upwards. That’s when you hit a bump and when the car is rolling, pitching up, or diving.

Rebound damping is the force the damper generates resisting extension. So after hitting a bump or a really sweet jump. Rebound force acts against the springs to hold the wheel up. Extension also occurs in roll, pitch, and dive.

One wheel may be compressing while another is extending. Think about what each wheel is doing for every phase of a corner and how that relates to the damper.

Under braking, the front is compressing (bump) while the rear is extending (rebound).

On corner entry, the outside dampers compress and the inner wheels extend.
The rear compresses and the front extends as you exit the corner and accelerate down the straight.

Tuning for each of these phases is for another article. But remember that adjusting for one phase of a corner may alter performance elsewhere.