1. Cylinder. 2. Working piston. 3. Piston rod. 4. Sealing piece with washer. 5. Dividing piston. 6. Shock absorber disc. a. Oil chamber, b. Gas chamber
Attention: For the considered models, gas shock absorbers can be used, both with separating pistons and without them. In gas shock absorbers with separating pistons between the gas and oil chambers, the piston rod is located at the top of the shock absorber, while in shock absorbers without separating pistons, it is located at the bottom of the shock absorber.
Knocking coming from the rear shock absorbers may be due to the following reasons:
Shock absorber top mount incorrectly installed.
The rubber cushion of the lower shock absorber mount has departed.
With a significant loss of oil, the separating piston may begin to hit the piston rod.
Disconnected working piston. Press the stem, release it and then press again. If a knock is heard during the transition from the compression cycle to the recoil cycle, the shock absorber must be replaced.
Hissing sound from the rear shock absorbers:
If the balance piston is not well sealed, gas can enter the oil chamber, forming foam there, which is indicated by hissing sounds when driving. This defect requires replacement of the shock absorber, even if it is still functioning normally.
Checking the shock absorbers removed from the machine (front and rear):
Remove shock absorbers.
Carefully inspect the stems for surface damage.
Check stems for bending. To do this, lay out the shock absorbers on a wooden surface in the order of their installation.
Insert the rods one by one. A bent stem will inevitably get stuck in the guide bushing.
Attention: A thin film of oil on the rod is of factory origin.
While holding the shock absorber in its working position, slightly stretch it and then compress it. A good shock absorber in both cycles gives a smooth, even ride without sticking.
If there are signs of oil leakage, the shock absorber must be replaced.
Checking the oil reserve:
To check the oil reserve, measure the gap (A) piston rod. With loss of oil, this gap increases for shock absorbers with dividing pistons, and decreases for shock absorbers without dividing pistons.
During this test, the temperature of the shock absorber should be approximately 20°C.
Attention: A thin film of oil on the rod is of factory origin and does not indicate an oil leak.
Pull out the stem and lay it upside down on a flat surface.
Shock absorber with equalizing piston: Press the piston rod so that the stop on the working piston reaches the dividing piston. Measure gap (A) and compare it with the given value.
Shock absorber without separating piston: compress the shock absorber so that a distinct resistance is felt, indicating that the piston has entered the oil cavity. While holding the shock absorber in this position, measure the gap (A) and compare it with the given value.
The figure shows two rear shock absorbers, the first of which (1), manufactured by Fichtel &Sachs, is marked with one or two transverse white lines. shock absorber (2) (produced by Boge) marked with an oblique white line.
Caution: A hissing sound that can be heard when the shock absorber is compressed. does not indicate any malfunction.
shock absorber | Gap "A" piston rod, mm | |
new | allowable max, value | |
With separating piston front and rear | 0±2 | 32 |
without separating piston front and rear | 20±2 | 0 |
Fichtel&Sachs | 105±2 | 82 |
water | 147±2 | 137 |
Attention: The shock absorber with separating piston must be replaced if the maximum allowable value is exceeded "A", and a shock absorber without a separating piston - if the gap value "A" does not reach the maximum allowed value.
Further checking of shock absorbers requires special equipment and can only be carried out at a service station.