The main noise of the shock absorber can be classified as the following failure modes:

1. The friction sound, which is usually between piston rod and oil seal, such as squeak.

2. The crash sound which has a great diversity, the loose of the shock absorber cylinder lead to the crack sound; the loose of the fastener cause the metal crack sound ;the failure of the rubber parts lead to the crack sound.

3. Valve sound, which are mainly pop sound, cuckoo sound, drums, and sharp whistle.

The evaluation steps of shock absorber abnormal sound 
1. The shock absorber should be mounted on a matching model.
2. Check whether all parts of the suspension are abnormal (including: damage, shedding, deformation, interference, nut loosening, displacement, etc.):
A) If there is damage, take appropriate measures to repair or replace.
B) If there is no damage, replace it with the new shock absorber (in the case of spare parts, both left and right shock absorber), the verification test should be do as previously recorded in the same road , the abnormal sound is not caused by the shock absorber, the crack sound disappear ,then replace the failure of the shock absorber and install in another car which has the quite same condition to verify the test, if the abnormal sound reappear, the shock absorber has abnormal sound; if the abnormal sound disappears, then this Shock absorber does not exist abnormal sound.

Confirm when driving should pay attention to the following matters:

A) ensure the front and rear tire pressure must be in the vehicle within the pressure range.

B) be careful not to overload, try to avoid testing under the bad road conditions.

C) if conditions permit, test should be in the standard test field.