Measuring the pad thickness on the rear wheel brakes:
- 1 - lining material;
- 2 - carrier plate made of metal.
The wear control of the pads on the rear disc brakes is carried out in the same way as on the front ones. The same wear limit of 7 mm applies here - measured together with the lining carrier plate, which corresponds to a thickness of the lining itself of about 2 mm.
Simultaneously with the overlays, the condition of the brake discs is checked. The amount of wear and the sequence of actions is the same as on the front disc brakes.
In addition to the rear axle trims, four new self-locking bolts are also used, which are usually included with the trims in the package.
Replacing rear disc brake pads
Although this work is easy to carry out, it becomes a problem if there is no special key 3272 from the Audi workshop. The description that follows assumes that the workshop will loan you a key or that you can make one from a borrowed pattern.
1. Unscrew both fixing bolts of the brake caliper housing, while in the opposite direction, press the guide pin on the hexagon.
2. Remove the brake caliper housing.
3. Remove the pads from the guides.
4. Install special wrench 3272 on the brake piston (picture below) and screw the piston all the way in by turning the spindle to the right and the knurled roller to the left.
5. Let at the same time your assistant does not lose sight of the level of brake fluid in the reservoir. If she threatens to pour out, then suck her with a syringe for injection.
6. Never depress the piston with force and without rotation. Otherwise, the adjusting mechanism in the brake piston will be destroyed.
7. Insert new pads.
8. Tighten the brake caliper housing with new self-locking bolts to 30 Nm.
9. Use only a narrow open end wrench to push the guide pin in the opposite direction. The wide wrench will jam and the tightening torque will be distorted.
10. Before the first meters of the trip, depress the brake pedal several times to establish normal pedal clearance.
Removing the rear brake caliper
Here with the overlay key (3) the lower fixing bolt of the brake caliper housing is unscrewed. The guide pin is pressed in the opposite direction with an open-end wrench (2). In contrast to the Lucas brakes on the front wheels, the top mount is also loosened here (1). When mounting, use new self-locking mounting bolts!
With housing removed (4) brake calipers of the rear wheel are visible: 1 - outer lining; 2 - inner lining; 3 - brake piston with inserted heat shield.
Here, with the brake caliper housing dismantled, the brake piston of the rear disc brake is screwed in with a special wrench 3272 from the Audi workshop.
1. If the brake caliper needs to be replaced, remove the brake hose.
2. Dismantle the brake caliper housing as for lining replacement. In doing so, be sure to follow the instructions above in the text!
3. Remove the handbrake cables.
4. Loosen both fixing bolts of the brake carrier still attached to the axle.
5. Before installation, clean the serrated surfaces under the head of the mounting bolts (knurled bolts).
6. Use only the provided knurled bolts, never regular bolts.
7. When installing, tighten the fixing bolts of the brake support to 65 Nm.
8. When installing the brake caliper housing, follow the instructions above.
9. Before the first trip, depress the brake pedal several times in order to establish the normal pedal clearance.
Replacement of cuffs of back brake pistons
To replace defective cuffs of the brake pistons of the rear calipers, the same procedure applies as for the front ones.
Replacing the rear brake disc
1. Remove the rear brake caliper assembly.
2. Remove the brake disc.
3. Clean the adjoining surface of the wheel hub or sand it and install a new brake disc.
4. Carry out a new basic adjustment.
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