Car keeps bouncing after bumps
The car floats or wallows over undulations instead of settling once.
Direct causeShock absorbers no longer damping the springs.
Physical realityThe spring carries the weight; the shock decides what the spring does next. Once the damping is gone the spring keeps oscillating, and while it does, the tyre spends part of its time lightly loaded or off the road entirely. A tyre carrying no load cannot brake and cannot steer.
Safety riskMedium to high, and the most underrated fault on this list. Worn dampers lengthen braking distances measurably and let the back of the car step out over a mid-corner bump.
Required fixInspect for oil loss and check the springs and top mounts at the same time. Shocks are replaced in axle pairs, never singly.
What usually causes it
- Worn or leaking shock absorbers — the usual cause. An oil film down the body means the seal has gone and the damping with it.
- Failed top mounts — often a knock on turning as well as poor control, because the strut is no longer located properly at the top.
- Sagging or broken springs — the ride height drops on one corner and the geometry goes with it.
- Worn bushes — let the whole assembly move, so the damper cannot work against a fixed point.
About the bounce test
Pushing down hard on one corner and letting go — more than one rebound suggests the damper is worn. It is worth doing, but know its limit: it only catches shocks that are badly gone. A damper can be well past useful and still settle in one bounce, which is why a visual inspection for oil loss matters more than the test.
Diagnostic verification criteria
How a workshop separates these causes rather than replacing parts in sequence.
- Primary indicator: Wet streaking down the shock body. That is a failed seal, and a shock that has lost its oil has lost its damping regardless of how the car feels.
- Tolerance limit: Shocks are replaced in axle pairs. A new damper beside a worn one gives that axle uneven damping left to right, which handles worse than leaving both worn ones in place.
- Secondary failure risk: Worn dampers cup the tyres and accelerate bush and mount wear, so the longer it is left the more of the corner is replaced with it.
RM Steering and Suspension replaces shocks, struts and mounts in Brackenfell, Cape Town, in axle pairs and with the cause checked first.
Request a suspension inspection