Shock Valving
The internal calibration of fluid passages and shim stacks in a shock absorber that controls compression and rebound rates.
Shock valving refers to the design and arrangement of internal hydraulic passages and flexible metal shims inside a shock absorber or strut. This valving controls the flow of hydraulic oil as the shock extends and compresses, determining the vehicle's ride stiffness and handling characteristics.
The valving is divided into compression damping (resisting the shock compressing when hitting a bump) and rebound damping (controlling the rate at which the shock extends back out to prevent bouncing). The shim stacks flex open under fluid pressure; thin shims open easily for low-speed chassis movements (cornering), while stiffer shims resist high-speed movements (potholes). Custom valving allows enthusiasts to tune their suspension for specific road or off-road conditions.
Symptoms of incorrect or worn shock valving include excessive body roll, nose-diving during braking, squatting during acceleration, or a bouncy, uncontrolled ride over bumps. If a shock starts leaking its hydraulic oil, the damping force drops, rendering the valving ineffective. Leaking or worn shocks cannot be re-valved (unless they are high-end rebuildable units) and must be replaced in pairs.