Improper assembly or accidents can lead to warping of shock absorbers and later to serious component damage. ZF Aftermarket describes what to pay attention to during inspection and installation.
Warping can severely reduce the service life of shock absorbers. ZF Aftermarket explains the causes as well as the effects on the chassis component technology and suggests preventative solutions.
Defective shock absorber due to bent piston rod after accident
ZF Aftermarket names two main reasons for shock absorber distortion: Firstly, even minor accidents may lead to the shock absorbers' mounting points being displaced so that they are no longer flush. Frequently, the piston rod is also bent in the process. Secondly, lack of care during installation is a frequent cause. When the axle is still suspended, the shock absorbers must not be tightened firmly – the reason: Once the vehicle stands on the ground again, the mounting points are not properly aligned anymore either. The serious impact on the inner workings of the shock absorber is identical in both cases.
Piston rod chromium plating worn through due to distortion
Due to the distortions, one side of the chromium plating on the piston rod surface presses against the guide and sealing unit with each stroke – and is ultimately worn through. This results in strong wear on the seals and piston rod guide, mostly ending in a loss of oil and, thus, performance of the shock absorber.
Too high tightening torque leads to pin joint tearing out
To prevent the described distortions and defects, workshops should abide by one simple rule: As a basic principle, shock absorbers may only be tightened once the vehicle stands on its wheels – or when the wheels are pressed upwards with tools such as hydraulic jacks. Also, the specified tightening torque must be observed.
Last but not least, shock absorbers installed under tension or a fastening nut tightened too firmly may lead to the pin joint tearing out. To prevent material overexpansion due to excessive tightening torques, it must be observed that, as a rule, no impact wrenches must be used when performing this work.
If these ZF Aftermarket tips are observed, shock absorbers will function safely and reliably in the long term. This is relaxing for workshop customers too.
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