Removing and Installing/Replacing Both Rear Brake Discs

34 21 320 - Removing and installing or replacing both rear brake discs (S85)





Special tools required:
- 34 1 280 34 1 280 Sliding Caliper





Necessary preliminary tasks:
- Remove wheels Removing or Installing Front or Rear Wheel
- If necessary, remove and clean brake pads Removing and Installing/Replacing Brake Pads on Both Rear Disc Brakes
After completing work:

- Adjust parking brake Adjustments.
- Read and comply with notes on braking in new brake discs / brake pads Procedures.





Check minimum brake disc thickness:

- Position special tool 34 1 280 34 1 280 Sliding Caliper at three measuring points in area (1) and measure.
- Compare measurement result and lowest value with setpoint value [1][2]34 21 Rear Brake.





Important!
In the case of M vehicles and perforated brake discs, new brake pads may only be installed if the brake disc thickness is greater than the minimum brake disc thickness [1][2]34 21 Rear Brake (MIN TH).

Brake discs may only be replaced in pairs (on each axle).

If the brake discs are replaced, you must also fit new brake pads.

The brake discs of M models are tied to the direction of travel:

The uneven part number denotes the left brake disc, the even part number the right brake disc!





Release screws (1), remove brake caliper and tie up.

Note:
Brake hose remains connected.

Installation Note:
Tightening torque 34 21 3AZ 34 21 Rear Brake.





Release screws (1) and remove brake disc (2).

Important!
To release brake disc: Do not under any circumstances strike friction ring with a hammer or similar! If necessary, carefully tap on base of brake disc chamber with a rubber mallet.

Installation Note:
Make sure contact surfaces between wheel hub and brake disc are absolutely clean.

Replace screws.

Tightening torque 34 21 1AZ 34 21 Rear Brake.

NOTE:
- If brakes pads have been replaced during procedure, reset CBS display in accordance with factory specification, please refer to: Vehicle/ Instrument Panel/ Gauges and Warning Indicators/ Maintenance Required Lamp Indicator/ Service and Repair Service and Repair