How to Determine When to Replace Shock Absorbers

The name "shock absorber" might suggest that these components are primarily responsible for absorbing vehicle vibrations, but that is not actually the case. When a vehicle travels over uneven roads, the energy generated by the resulting vibrations is mainly absorbed by the springs. However, after absorbing the shock, the springs tend to oscillate (bounce back); the shock absorber is then used to dampen these spring-induced oscillations.

When shock absorbers fail, they can no longer absorb the energy from the spring's rebound. Consequently, the vehicle body continues to bounce or oscillate after hitting a bump, compromising both driving stability and comfort. Simply put, the primary function of a shock absorber is to suppress spring oscillation and quickly stabilize the vehicle body.

We often hear the term "damping," but what exactly does it mean? In simple terms, damping is a form of resistance acting on a moving object, and this resistance is usually proportional to the speed of movement. Consider a common door closer: when you open the door gently, the resistance generated by the internal hydraulic cylinder is minimal, making it easy to push the door open; however, if you push hard, the increased resistance makes it more difficult to move. The same principle applies to automotive shock absorbers: when the spring undergoes significant extension or compression, the shock absorber exerts greater resistance due to the damping effect.

Shock absorbers generate this damping effect because, when compressed or extended under load, the internal piston forces hydraulic fluid or high-pressure gas through small valve orifices. The fluid or gas encounters resistance as it passes through these valves, creating the damping force. The magnitude of this damping is determined by factors such as the size of the valve orifices and the viscosity of the hydraulic fluid. Shock absorbers with higher damping are generally described as "stiffer"; higher damping makes the unit harder to compress or extend, thereby reducing body sway and improving tire traction on uneven roads, though this often comes at the cost of ride comfort. Shock absorbers are components prone to wear during vehicle operation. Their performance directly affects ride stability and the lifespan of other mechanical parts; therefore, it is important to keep them in good working condition. The following methods can be used to check their performance:

1. Drive the vehicle for 10 km on a rough road and then stop. Touch the shock absorber housing; if it does not feel warm, there is no internal resistance, indicating the shock absorber is not functioning. Add an appropriate amount of lubricating oil and test again; if the housing heats up, the unit was simply low on oil and should be topped up. If it still does not heat up, the shock absorber has failed.

2. Press down firmly on the bumper and release it; if the vehicle bounces two or three times, the shock absorber is functioning correctly.

3. If the vehicle vibrates violently when braking sharply while driving slowly, it indicates a problem with the shock absorbers.

Additionally, if oil leakage or abnormal noise occurs during use, you should promptly visit a professional repair shop to diagnose the issue and carry out repairs.