34 21 200 Removing and installing or replacing brake pads on both rear disc brakes
Special tools required:
Necessary preliminary tasks:
- Remove wheels
- Remove BRAKE PAD WEAR SENSOR
Observe SAFETY INSTRUCTIONS on raising the vehicle.
Remove plastic plugs (1).
Right side:
Disconnect plug connection for brake pads wear sensor.
Release guide screws (2) with special tool 34 1 080.
Installation:
Only clean guide screws; do not grease.
Check threads.
Replace all guide screws which are not in perfect condition.
Tightening torque 34 21 5AZ .
Lift out retaining spring (3).
Withdraw brake caliper backwards.
Turn piston fully back with special tool 34 1 050.
- Pay attention to brake fluid level in expansion tank; brake fluid that spills over will damage paintwork.
Remove outer brake pad.
Inner brake pad is located with its spring in the piston.
If the brake pads are worn on one side, they must not be mixed up!
Observe MINIMUM THICKNESS OF BRAKE PADS .
Clean brake pads.
Do not apply grease to brake pad backplate.
Check minimum brake disc thickness:
- Position special tool 34 1 280 at three measuring points in area (1) and measure.
- Compare measurement result and lowest value with SETPOINT VALUE .
New brake pads may only be installed if the brake disc thickness is greater than or equal to the MINIMUM BRAKE DISC THICKNESS (MIN TH) (not incl. M vehicles).
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 (MIN TH).
The minimum brake disc thickness is configured in such a way that it lasts the life of a further set of brake pads (does not apply to M vehicles and perforated brake discs).
Check dust sleeve (1) for damage and replace if necessary.
Clean contact face (2) of brake piston and apply a thin coating of anti-squeak compound.
Clean mounting faces (1) and (2) of brake pads hammer heads/brake caliper housing and coat with anti-squeak compound.
Clean contact face (3) of brake caliper and apply a thin coating of anti-squeak compound.
Clean brake caliper mounting bracket at hammer head guides and apply a thin coating of anti-squeak compound.
- Fully depress brake pedal several times so that brake pads contact brake discs.
- When installing new brake pads at front and rear axles, brake fluid level must be brought up to "MAX" marking.
- Read and comply with notes on BREAKING IN NEW BRAKE DISCS / BRAKE PADS .
- If necessary, when replacing pads, reset CBS display in accordance with MAINTENANCE REMINDER LIGHT RESET PROCEDURES .
The fault memory entry must be deleted. The vacuum pressure sensor only has to be replaced if the fault is entered repeatedly.