How to test shocks

There are many ways to test for worn shock absorbers. Below are 3 examples.

Visual Inspection

Leaking oil
Broken/corroded mountings
Failure of mounting bushes
Damaged body
Corroded/ damaged piston rod
Abnormal tyre wear

Bounce Test

This test is easier if a colleague can help you.

Whilst the vehicle is at rest, look at the gap between the tyre and wheel arch.
Push hard on a corner of the vehicle and make the vehicle bounce.
Stop pushing when the vehicle is at its lowest point.
Then watch the gap between the tyre and wheel arch.

With a perfectly functioning shock absorber, the vehicle should bounce up beyond its rest point, then immediately return to its rest point and stop.

If the vehicle continues to bounce below the rest point and then settles, the shock absorber would appear to be performing weakly.

If the vehicle continues to bounce beyond this time, then the shock absorber is having minimal damping effect.

Suspension Test Machine

This tests both the effectiveness of the shock absorbers, and the entire suspension system - including springs. It is not possible to specifically identify shock absorber wear as opposed to other related components such as springs.

Any of these 3 tests are inconclusive on their own and they should therefore be combined.