Removal
Warning: The operation of lifting and installing the vehicle on stands is associated with danger! Therefore, before carrying out the operation, read Section Jacking and towing.
1. Mark the direction of rotation of the tire with an arrow. Loosen the wheel mounting bolts. Raise and place the car on stands.
Warning: The process of removing the calipers of different models may differ. Always replace the mounting bolts of the corresponding caliper with new ones, as they are self-locking. In addition, it is necessary to pay attention to the fact that the mounting bolts of the corresponding brake disc have a set tightening torque.
2. Rear brake: Disconnect the parking brake cable from the caliper, refer to Section Removal and installation rear wheel brake pads.
Warning: In general, the caliper can be removed without removing the brake pads.
3. Unscrew the caliper mounting bolts and tie the caliper to the suspension with wire.
Caution: Do not disconnect the brake hose, otherwise the air in the brake system will have to be removed using a special device after installation.
4. If the caliper needs to be completely removed:
- At the front caliper, disconnect the brake line where it connects to the hose;
- At the rear caliper, first disconnect the brake line from the brake hose and then, if necessary, disconnect the hose at the caliper.
Warning: Brake fluid will leak out when the brake system is opened. Place a bottle intended exclusively for brake fluid under the leaking fluid. You can also siphon the fluid out of the reservoir beforehand.
5. Remove the brake disc.
Caution: If the brake disc is to be used again, do not remove it from the hub by force (hammer blows). To do this, use a rust solvent.
Installation
To achieve uniform braking on both sides, it is necessary to have brake discs with the same surface quality. Therefore, it is necessary to replace both brake discs of one axle or grind them to the same size.
The service station can check the disks for axial runout. The maximum runout should not exceed 0.05 mm, and the maximum difference in disk thickness should not be more than 0.01 mm.
1. Measure the thickness of the brake disc, refer to the relevant Section.
2. If there is rust on the brake disc flange and wheel hub, it must be removed.
3. Clean the surface of the new brake disc from the protective coating with thinner.
4. Reinstall the caliper. Use new self-locking bolts as specified. Make sure that the brake hose is not twisted. Observe the specified tightening torque for the respective caliper, refer to Specifications.
5. Rear brake: Connect the parking brake cable to the caliper and adjust the parking brake, refer to Section Adjusting the parking brake.
Caution: If the brake hose has been removed, secure it and bleed the system with a special tool (work of the service station).
6. Observing the direction of rotation, install the wheel. Lower the car onto the wheels, and only then tighten the mounting bolts crosswise to the torque 120Nm.
Caution: While standing, press the brake pedal several times until you feel resistance.
7. Check the fluid level in the reservoir and add fluid if necessary.
Attention, please perform a reliability check:
- Are the brake hoses secured?
- Is the brake hose secured in the holder?
- Are the air bleed nipples tightened?
- Is there enough brake fluid?
- With the engine running, check for leaks. To do this, press the brake pedal with a force of 200–300 N (20–30 kg) for 10 s. The pedal should not weaken. Check all connections for leaks.
Carefully allow the new brake pads to break in. To do this, brake the car several times from 80 to 40 km/h, lightly pressing the pedal. Allow the brake to cool between braking.
(This publication is borrowed from the resource «AUDImanual»)