Glossary
Damper Settings Explained: Bump, Rebound, High and Low Speed
A damper converts suspension movement into heat and controls how quickly weight transfers, how the car settles after a bump and how the tyre tracks the road. Bump (compression) damping resists the wheel moving up into the body; rebound damping resists it extending. Low-speed damping (shaft speeds below about 50 mm/s) governs body motions from driver inputs, while high-speed damping handles bumps and kerbs.
| Symptom | Likely adjustment | Why |
|---|---|---|
| Understeer on turn-in | Reduce front low-speed bump or rear low-speed rebound | Lets the front load faster |
| Oversteer on turn-in | Increase front low-speed bump | Slows front load build-up |
| Oversteer on corner exit | Reduce rear low-speed rebound or increase rear low-speed bump | Keeps the rear tyres loaded as the car squats |
| Skating over bumps | Reduce high-speed bump | Lets the wheel absorb the hit |
| Car feels floaty, slow to settle | Increase low-speed rebound | Controls body oscillation |
Bump and rebound
Bump damping is active when the wheel moves towards the chassis: braking at the front, hitting a bump, the outside wheels in a corner. Rebound is active as the wheel extends: the inside wheels in a corner, the rear under braking, the front on corner exit. Because weight transfer compresses one end and extends the other, the compression setting at one end and rebound at the other work together.
Low speed versus high speed
Shaft speed, not car speed, defines the split. Driver inputs such as turn-in and throttle produce slow shaft speeds and are controlled by the low-speed bleed circuits. Bumps, kerbs and curbs produce fast shaft speeds, controlled by the shim stacks. Tuning low speed changes balance and feel; tuning high speed changes how the car copes with the surface.
A damper histogram from data logging, or the shock velocity analyser in Setup Genius, shows how much time each damper spends in each speed band and whether the car is over- or under-damped.
Frequently asked questions
Do dampers change how much the car rolls?
Not in steady state. Roll angle is set by springs and bars. Dampers change how quickly the car reaches that roll angle and how it behaves while getting there.
What is a damper click?
One detent on the adjuster. Clicks are not standard across brands: on one damper two clicks might change force 10%, on another 2%. Always record clicks per damper model.
Should I run more rebound than bump?
Traditionally yes, often 2:1 to 3:1 rebound to bump in force terms, because the spring assists bump and opposes rebound. Modern aero cars sometimes run much higher bump to hold platform.
Related
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