Removal and Installation of Rear Wheel Disc Brake Calipers

Rear wheel disc brake 1 – brake disc. Replace only as a set for the entire axle. Remove the brake caliper before removing the disc. 2 – cap. Always replace. 3 – 12-point nut, 175 N·m 4 – Phillips screw, 4 N·m 5 – wheel bolt, 120 N·m 6 – wheel hub with bearing 7 – bolt, 60 N·m 8 – dust shield 9 – stub axle carrier 10 – axle beam 11 – socket head screw, 8 N·m 12 – ABS wheel speed sensor. Before installation, clean the mounting hole and lubricate with AUDI–G000650 grease. 13 – brake hose 14 – banjo bolt, 35 N·m 15 – bolt, 65 N·m 16 – brake caliper. After repair, adjust the parking brake before applying the foot brake. 17 – brake pads. Replace only as a set for the entire axle

REMOVAL

CAUTION

If the brake pads are to be reinstalled, they must be marked before removal. Do not swap brake pads from inside to outside or vice versa, or from the left wheel to the right. Swapping pads may lead to uneven braking. Always replace all pads at the same time, even if only one has reached the wear limit.

PROCEDURE

1. Mark the position of the rear wheels relative to the hub with paint. This allows the balanced wheel to be installed in its original position. Loosen the wheel bolts while the vehicle is still on the ground. Raise the vehicle, support it on stands and remove the rear wheels.

2. Release the parking brake cable. Remove the clip – 1 – from the side. Press the lever on the caliper in the direction of the arrow and disconnect the brake cable – 3 –.

3. Remove the brake caliper bolts at the top and bottom. Hold the guide pin with a wrench while loosening. Remove the caliper body; the brake hose remains connected.

4. Remove the brake caliper and secure it with wire to the body. Make sure the brake hose is not stretched.

5. Remove the brake pads and retainers from the guide. INSTALLATION

CAUTION

Do not depress the brake pedal with the pads removed. Otherwise, the piston will be pushed out of the housing. In this case, remove the caliper assembly and reinstall it at a service station.

6. Clean the guide surfaces and pad seats in the carrier with a rag and alcohol. Do not use solvents containing mineral oils or tools with sharp edges.

CAUTION

Use only alcohol to clean the brake.

7. Before installing the pads, check the brake disc by feeling it with your fingers. If there are scores, replace the brake discs.

8. Measure the disc thickness. If the discs are worn, replace them. Refer to the Brake Disc Thickness Check sub-section.

9. Check the piston dust boot for cracks. If damaged, replace the boot immediately, since dirt entering the caliper quickly causes loss of sealing. The caliper must be disassembled for this work (workshop work).

10. Screw the piston in by turning it clockwise with special tool AUDI–3272, applying considerable force. The collar (arrow on the left) of the tool must rest against the caliper. If the piston moves stiffly, turn it with a 13 mm wrench on the flats (A) of the tool.

CAUTION

Do not turn the brake piston using the piston reset tool or a hammer handle, otherwise the parking brake mechanism may be damaged. The HAZET 4970/3 tool may also be used.

11. If the special tool is not available, make a suitable steel plate and insert it into both slots of the brake piston. Turn the piston with firm movements.

CAUTION

When the piston is turned, brake fluid is forced from the brake cylinder into the reservoir. Monitor the fluid level in the reservoir and remove excess fluid if necessary. Use a plastic bottle reserved only for this purpose to extract brake fluid. Do not use a drinking-fluid bottle! Brake fluid is poisonous. Never siphon it by mouth through a hose. Use a syringe for this purpose. After replacing the brake pads, the fluid level in the reservoir must not exceed the MAX mark on the reservoir, because brake fluid expands when heated. Leaking fluid runs down the brake cylinder, damaging the coating and causing corrosion.

12. Insert a new retainer into the guide.

13. Insert the brake pads into the guide. Remove the protective film from the backing plate of the new brake pads.

14. Install the brake caliper and tighten the new mounting bolts to 30 N·m.

CAUTION

The repair kit contains four self-locking bolts, which must be installed.

15. Press the lever – 2 – on the caliper in the direction of the arrow and connect the parking brake cable – 3 –. Install the clip – 1 – on the side of the support.

16. Adjust the parking brake. Refer to the Parking Brake Adjustment sub-section.

CAUTION

The brake pedal may be pressed only after the parking brake has been adjusted.

17. Install the rear wheels so that the marks made during removal align. Tighten the wheel bolts. Lower the vehicle onto the wheels and tighten the wheel bolts in a crosswise sequence to 120 N·m.

CAUTION

Depress the brake pedal several times firmly until a distinct resistance is felt. This seats the pads against the brake disc and positions them correctly.

18. Check the brake fluid level in the reservoir. If necessary, top up to the MAX mark.

CAUTION

Check the following for security:

– Are the brake hose connections securely tightened? – Is the brake hose secured in its bracket? – Are the bleed screws tightened? – Is there sufficient brake fluid in the reservoir? – With the engine running, check the system for leaks. Press the brake pedal with a force of 200 – 300 N (20 – 30 kg) for 10 s. The pedal must not move away. Check all connections for leaks.

19. Carefully bed in the new brake pads. Brake the vehicle several times from 80 to 40 km/h, applying the pedal lightly. Allow the brakes to cool between applications.

CAUTION

In some regions, brake pads must be disposed of as special waste. Local authorities must inform drivers of approved disposal locations.