Clutch — check (Audi 80 B4)

The first signs of wear on the clutch disc appear as clutch slippage. The fact that the clutch disc is slipping can be recognized when driving in high gear in «Full load». At the same time, the number of engine revolutions increases, but the speed of movement does not change. In order to finally make sure that the friction linings of the driven disk are worn out, use the following technique.

1. Apply the parking brake lever and start the engine.

2. Engage 3rd gear and «give» gas. If the handbrake is OK, the engine will stall. But if the engine continues to run, then it's time to change the clutch disc. If gear shifting is difficult when the engine is warm, or shifting is accompanied by a grinding noise, then a clutch defect that does not disengage correctly can be assumed. The gearbox, as a rule, turns out to be nothing to do with such cases. To back up your assumptions, use the following trick.

3. Start the engine.

4. Depress the clutch pedal, wait approximately 3 seconds, and then try to engage 1st or reverse gear. If shifting is difficult or a grinding noise is heard in the gearbox, then there is a clutch separation defect. Difficulty separating the clutch or «falling through» clutch pedals indicate the presence of air in the clutch hydraulic actuator. Removing air from the hydraulic actuator will not eliminate the indicated defect. It is necessary to find the cause and place of air leakage and eliminate them. First of all, it is necessary to inspect the master and slave cylinders and make sure that there are no traces of brake fluid on them. To check the clutch slave cylinder, it must first be cleaned.


5. Replace clutch cylinders if they are leaking.

6. Check the clutch hydraulic drive and remove air from it.

7. Repeat the test.

Attention! Although the clutch hydraulic system uses the brake fluid from the expansion tank, there is no effect on the brake system if it leaks from the clutch hydraulic actuator. The hydraulic clutch intake fitting is located high enough on the expansion tank, so that a sufficient amount of fluid remains for the brake system.

Clutch release master cylinder - removal and installation

8. Take as much fluid as possible from the expansion tank with brake fluid.

9. Remove an overlay under the panel of devices of space for legs of the driver's side.

10. Place a rag under the master cylinder and disconnect the supply hose. Residual liquid will flow onto the rag.

11. Disconnect the hose for supplying pressure to the working cylinder located in the engine compartment on the left side, next to the vacuum brake booster.

12. Turn away two bolts with an internal hexagon of fastening of the main cylinder.

13. Remove the lock washer from the cylinder pusher to the clutch pedal and remove the mounting bolt.

14. Remove the cylinder.

When installing a new master cylinder, its pusher must be set so that the clutch pedal is almost 10 mm higher than the brake pedal.

Attention! The return spring must ensure that the clutch pedal returns to its original position. The pedal itself in the rest position must not touch the bracket of the brake and clutch pedals.

15. Turn away for performance of adjustment a counternut on a pusher and turn a pusher around the axis to the right or to the left.

16. Tighten locknut.

18. Remove air from the hydraulic clutch.

Clutch slave cylinder - removal and installation

19. Install in front of the car on the gantry (see illustration).



20. Disconnect the hydraulic hose from the working cylinder.

Attention! Substitute a container to collect the fluid flowing from the hose.

21. Turn out bolts of fastening of the working cylinder and take the cylinder from a transmission, having given it back. If necessary, use a rust remover and pry bar.

22. Lubricate the new cylinder with a thin layer of grease, and its pusher with molybdenum paste.

23. Install the working cylinder in place so that the corresponding holes for the mounting bolts match.

24. Return the mounting bolts with a torque of 25 Nm.

25. Remove air from the hydraulic actuator.

Clutch hydraulic - bleeding

In the absence of a device for removing air from the hydraulic drive, which is used in workshops, bleeding the hydraulic drive is performed in the same way as bleeding the brake drive.


26. Turn off the union of prorolling of one of brake mechanisms of forward wheels, and also the union of the working cylinder of coupling about one and a half turns.

27. Connect both fittings with a hose.

28. Depress the brake pedal slowly several times so that the brake fluid flows from the brake mechanism through the clutch hydraulic actuator. Do not press the brake pedal hard. In this case, the hose may break.

29. Watch the level of brake fluid in the expansion tank. As soon as air bubbles stop flowing from the clutch hydraulic drive into the tank, wrap both fittings and remove the connecting hose.

30. Check the brake fluid level in the expansion tank.