Automotive Shock Absorber Lifespan

To rapidly dampen vibrations between the frame and the body and to improve ride smoothness and comfort, automotive suspension systems are typically equipped with shock absorbers. Currently, double-acting tubular shock absorbers are widely used in vehicles.

Shock absorbers are components subject to wear and tear during vehicle operation. Their performance directly affects vehicle 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 with your hand; if it is not warm, it indicates there is no internal resistance and the shock absorber is not functioning. Add an appropriate amount of lubricating oil and test again. If the housing becomes warm, the unit was simply low on oil and should be topped up; otherwise, 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 working properly.

3. If the vehicle vibrates violently during emergency braking while moving slowly, it indicates a problem with the shock absorbers.

4. Remove the shock absorber, hold it upright, and clamp the lower mounting eyelet in a vise. Pull and push the piston rod vigorously several times; there should be steady resistance. The resistance when pulling up (rebound stroke) should be greater than when pushing down (compression stroke). If the resistance is unstable or absent, the unit may lack oil or have damaged valve components; it should be repaired or the parts replaced.

Once a problem or failure is identified, first check for oil leaks or traces of old oil leakage.

If oil seals or gaskets are cracked or damaged, or if the reservoir cap nut is loose, the seals may have failed and should be replaced with new ones. If the oil leak persists, remove the shock absorber. If any binding or inconsistent resistance is felt, further inspect the clearance between the piston and the cylinder barrel, check the piston rod for bending, and examine the surfaces of the piston rod and cylinder barrel for scratches or scoring marks.

If there is no oil leakage, inspect the connecting pins, connecting rods, mounting holes, and rubber bushings for damage, broken welds, cracks, or detachment. If these components are in good condition, disassemble the shock absorber further to check the fit clearance between the piston and cylinder, inspect the cylinder for scoring, verify the integrity of valve seals and the fit between valve discs and seats, and check the extension spring for excessive softness or breakage. Repair or replace parts as necessary.

Additionally, shock absorbers may produce noise during operation. This is typically caused by collisions with leaf springs, the frame, or the axle; damaged or detached rubber pads; deformed dust covers; or insufficient fluid levels. Identify the specific cause and perform the necessary repairs.

After inspection and repair, the shock absorber should be tested on a dedicated test bench. When the stroke is 100 ± 1 mm, the resistance during both the extension and compression strokes must meet specified standards, indicating that the shock absorber is functioning correctly.