The disc brake mechanism of the rear wheels is automatically adjusted. The piston of the wheel cylinder, as the brake linings wear out, leaves the cylinder, providing optimal pressing of the pads to the disc during braking. The incoming brake fluid prevents the formation of play between the pads and the brake drum during braking.
The situation is different with the mechanical parking brake. At some point, the parking brake actuator pusher will not reach the wheel cylinder piston, which is displaced as the brake linings wear. The gap adjustment device prevents this situation, which, as necessary, «lengthens» pusher. The main element of the adjusting device is a threaded mechanism, through which, as the brake linings wear out, the second part of the pusher is displaced, thereby maintaining the same gap between the brake shoes and the piston and not allowing the piston to move back. For this reason, when replacing worn brake linings with new ones, the wheel cylinder piston cannot simply be pressed back into its original position. It should only be unscrewed back.
Checking the condition of the brake pads of the disc mechanism of the rear wheels is carried out in the same way as for the front wheels. The residual thickness of the brake linings, excluding base plates, must not be less than 2 mm (see illustration 5.0).
At the same time as checking the brake pads, the condition of the brake discs is also checked. The sequence of actions in this case, as well as the permissible wear of the disc, are identical to the procedure for checking and wear of the brake discs of the front wheels
Brake linings of disk brakes of back wheels - replacement
To replace the rear disc brake pads, in addition to new pads, four self-locking bolts are required, which are usually included in the delivery. In general, this work does not present any particular difficulties, provided that the car owner has a special key 3131 at his disposal. The following procedure is indicated taking into account the fact that such a key was purchased or made independently according to the template.
1. Turn out both bolts of fastening of a floating bracket. At the same time, hold the guide pin on the hexagon against turning.
2. Remove floating bracket (caliper).
3. Remove the brake pads from the guides.
4. Install special wrench 3131 on the piston of the wheel cylinder and screw the piston back into the cylinder (see illustration).
6. Ask an assistant to monitor the level of brake fluid in the expansion tank. If, at the moment the piston of the wheel cylinder returns, the level of the brake fluid increases so much that it can pour out over the edge, then remove the fluids.
Attention! The rear wheel disc brake wheel cylinder piston is screwed in, not pressed in. Failure to comply with this requirement will destroy the mechanism for adjusting the clearance between the piston and the parking brake actuator pusher.
7. Reinstall the pads with new brake pads.
8. Fasten the floating bracket with new self-locking bolts with a torque of 35 Nm. When tightening the bracket bolt, hold the guide pin with a thin wrench from turning. If you use a wrench thick enough to keep the guide pin from turning, then the wrench will be clamped when tightened and the tightening torque will be set incorrectly.
9. Perform brake adjustment. To do this, place the rear of the car on the goats.
10. Release the parking brake.
11. Make sure the parking brake cables are not tight. To do this, move and release the parking brake lever alternately on the calipers of the left and right wheels until it stops. If at the same time the parking brake lever of the opposite caliper also moves to the stop and returns to its original position, then the parking brake cables are too tight.
12. Loosen them by turning the central tension adjustment nut.
13. Lower the car.
14. Depress the brake pedal without starting the engine about 40 times.
15. Install the car on the goats.
16. Make sure the rear wheels turn freely.
Caliper - removal and installation
17. Disconnect the brake hose from the caliper if the caliper will be removed for replacement.
The procedure for removing the caliper is the same as when replacing the brake pads.
18. Disconnect the parking brake cables.
19. Turn out both bolts of fastening of a brake board to a nave. When installing, tighten these bolts to 65 Nm.
The installation of the caliper is carried out in the same way as when installing after replacing the brake pads.
20. Perform brake adjustment.
Replacing the cuffs of the piston of the wheel cylinder of the brake mechanism of the rear wheels is identical to the replacement of the cuffs on the front wheels.
Rear wheel brake disc - replacement
21. Remove a support.
22. Remove the brake disc.
23. Clean the brake disc seat on the hub and install a new brake disc.
24. Perform brake adjustment.
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