- A) slow return of the body to its original position when driving on rough roads;
- b) increasing body vibrations when the wheels collide with adjacent road irregularities;
- V) bouncing wheels even on a flat road surface;
- G) difficult stop (uncontrollability) car when braking (it may be due to other reasons);
- d) instability and skidding of the car when cornering;
- e) increased tire wear, accompanied by tread wear;
- and) knocks and creaks while driving. Noises can often also be caused by other causes, such as loose chassis bolts and nuts, a faulty hub bearing or CV joint. Therefore, before changing the shock absorber, it must be checked on the stand.
The performance of the shock absorber can also be checked manually.
However, a more accurate check is possible only when using special equipment, for example, a dyno, where the check is performed without dismantling the shock absorber, or on a special machine
Manual shock absorber performance test
1. Remove shock absorber.
2. Pull out the shock absorber rod, holding the removed shock absorber in the mounting position, and then press it back into the housing. The shock absorber rod must move equally smoothly and without jerks along the entire length of the stroke (see illustration).
3. Inspect the surface of the shock absorber rod for damage, and that there is no bending of the rod or jamming of the rod in the guide sleeve.
4. Check up a condition and landing of sealing rubber stoppers of the shock-absorber. The plugs must be firmly seated in the mounting holes, not cracked or damaged. Damaged rubber plugs can cause knocking noises while driving.
In gas-filled shock absorbers under gas pressure, the rod must itself return to its original position.
If this does not happen, then this does not mean that the shock absorber must be replaced. Its action, if there is no significant leakage of damping fluid, is equivalent to the function of a conventional shock absorber.
Vibration damping can also occur in the absence of pressure in the shock absorber. However, it will not be possible to avoid noise or knocking during the operation of the shock absorber.
During normal functioning of the shock absorber, small traces of the flow of damping fluid are not a reason to replace the shock absorber.
The damper is considered serviceable if the traces of damping fluid flow are within the range between the upper stem sealing ring and the lower spring cup, provided that the stain from the damping fluid has a matte tint or is covered with a dry layer of dust.
The flow of liquid in a small amount even has a positive effect, since the sealing ring is lubricated, which increases its service life. In case of significant oil leakage from the shock absorber, it must be replaced.
Shock Absorber Disposal
Before disposing of a defective shock absorber, the oil must be drained from them. After the oil has been removed, the shock absorber can be disposed of as normal scrap metal.
Attention! The pressure in the new shock absorber reaches 25 bar. Therefore, when opening the shock absorber, certain precautions must be observed, as well as protective goggles must be worn.
Draining the oil from the shock absorber can be done in two ways: by drilling a hole in it or by making a cut in the side wall.
Hole drilling
5. Clamp the dismantled shock absorber in a vise, placing it in a vertical position, rod down.
6. Drill a hole in the shock absorber housing at point A with a 5 mm drill. The hole should be about 20mm from the bottom of the shock absorber (see illustration).
7. Rear suspension shock absorber. Drill at point B another hole with a diameter of 5 mm, stepping back from the top of the shock absorber by about 30 mm. Distance «b» = 30mm (see illustration 5.6).
Attention!. With gas-filled shock absorbers, gas begins to escape after drilling the first wall of the shock absorber. Cover the hole with a rag while the gas escapes, and then continue to drill a hole on the wall of the inner sleeve.
8. Drain the oil from the shock by holding it over a container to collect the oil. At the same time, move the shock absorber rod up and down.
9. Completely drain the oil from the shock absorber. Drained oil must be disposed of at special points, and the shock absorber must be scrapped.