Spotting defective shock absorbers


Post created: 17 June 2021

Shock absorbers play a vital role in ensuring the safety of your vehicle. The main function of a shock absorber is to dampen the spring oscillations, and keep the tyres in contact with the road. The only point of contact between a vehicle and the road are four pieces of rubber, each the size of a postcard, and with the bumps and potholes on our current road surfaces, correct contact with the road surface is even more important.

When your vehicle’s shock absorbers are worn, this can cause stress and premature failure on many other parts and can further cause:

  • 10% increase in braking distance
  • 15% greater chance of aquaplaning
  • 25% reduction in tyre life
  • Reduced cornering ability
  • Poor ride comfort
  • Increased fuel consumption

Due to the dangers that worn shocks can cause to you and your vehicle, AutoZone has provided a summary below of the tell-tale signs of defective shock absorbers.

Jammed damper

When your damper is not fluid and smooth in operation, it will most likely be due to bent or damaged internal piston rods (perhaps caused by a previous accident) trapped debris may also be the direct cause of sticky operation (this may also be the result of incorrect installation of the shocks). This scenario will cause the inner piston rod to be restricted within its movement resulting in the entire inner mechanism being unguided. This results in a sticky inner damper

Stem mount broken off

If your vehicle’s stem mount has broken off, this could be as a result of incorrect installation; securing nuts were over torqued or an impact wrench was possibly utilized when installing the shocks. This scenario would cause the material to over stretch resulting in a material yield/stress failure and the mount end breaking off.

Our AutoZone experts suggest that, to avoid the mount from breaking off, you should never use impact wrenches for assembly of your shocks.

Rod eye cracked or completely broken off

Rod eyes cracking or breaking off completely are a result of many irregular fitting scenarios, these include the following:

  • The end stop for the spring path is defective or missing (e.g. due to a previous repair from an accident). The damper must perform the end stop’s function of the shock geometry which will result in excessive strain.
  • Incorrect adjustment of the air spring level.
  • Excessive strain caused by continuous, arduous and harsh operation on poor roads
  • Shocks installed with trapped stresses.

The above will result in a defective rod eye which will restrict or completely prevent the damper from performing at its full potential. This will result in the vehicle handling poorly and transmitting the feeling of the vehicle wandering slightly and emanate a continuous loud knocking noise whilst driving.

To prevent the above mentioned scenarios, our AutoZone experts suggest never using impact wrenches during assembly of your vehicle’s shocks. It is also recommended that you test your vehicle’s shocks every 20 000km. If you are unsure, you can always give our technical department a call on 086 112 2111 or email us at Or simply visit your nearest AutoZone store to check out our range of shocks from various brands like FEMO, Monroe and Gabriel.