Removal and Installation of Rear Brake Pads

REMOVAL

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

* If the brake pads are to be reused, they must be marked during removal. Do not swap the pads between positions. This may cause uneven braking. Only install genuine BMW pads or pads approved by BMW. All rear pads must always be replaced at the same time, even if one of them has not reached the wear limit.

2. Disconnect the brake pad wear sensor plug on the right caliper by hand (arrow in the accompanying illustration). Do not pull on the cable.

3. Remove both plastic caps (1) from the mounting screws and remove the two screws using a hex key.

4. Remove the clip (3) using a screwdriver.

5. Pull the caliper back and off.
6. Remove the outer pads.

7. The inner pad is retained by the spring (6) in the brake piston. Remove the pad.

Installation

* Do not press the brake pedal when the brake pads are removed, otherwise the piston may be forced out of the housing.

INSTALLATION

1. Check the brake pad wear sensor. If the insulation of the contact plate is worn, the cable insulation is damaged, or the plastic element is worn, replace the sensor.
2. Clean the pad guide surface in the caliper housing opening with a soft metal brush or a cloth moistened with alcohol. Do not use solvents containing mineral oils or tools with sharp edges. If the pads are to be reused, clean them as well.

3. Before installing the pads, check the brake disc for scoring by running your fingers over it. If scoring is present, the disc must be replaced. Clean the brake disc if it has a grey or blue discoloration before installing new brake pads.
4. Measure the disc thickness. Refer to Brake Disc Thickness Measurement.

5. Check the protective cap (2) on the piston. If damaged, replace it, as dirt entering the cylinder may cause loss of caliper sealing. To do this, the caliper must be removed and disassembled (dealer service only).

6. Press the piston back using a special tool. A wooden block (for example, a hammer handle) may also be used for this purpose. Take particular care that the piston does not tilt and that the protective cap is not damaged.

* When the piston is pressed, brake fluid is forced from the cylinder back into the reservoir. Monitor this and, if necessary, suction out the fluid.

7. Use a plastic bottle to suction out the fluid. Do not use a bottle that held drinking liquid. Brake fluid is poisonous. Never suction it out with your mouth through a hose. After replacing the brake pads, do not allow the brake fluid level in the reservoir to exceed the MAX mark, as the fluid expands when heated. Fluid overflowing from the system runs down the master cylinder, damaging the paint and causing corrosion.

* If the brake pads are heavily worn, check the piston for free movement. To do this, insert a wooden block into the caliper and have an assistant press the brake pedal. The piston should move out and in easily. Be careful not to push the piston out completely. If the piston moves with difficulty, the caliper requires repair.

8. To prevent disc brake squeal, lubricate the parts listed below with special paste. The following pastes may be used: Plastilube, Tunap VC 582/S, Chevron SRJ/2, Liqui Moly LM-36 or LM-508-ASC.
a) The contact surface of the piston against the brake pad.

b) Clean the contact surface (3) of the caliper and apply a thin layer of paste to the areas shaded in the accompanying illustration.

c) Clean the caliper bracket at the guide pins and apply a thin layer of special paste to the areas shaded in the accompanying illustration.

* Paste must never get onto the protective cap, the brake pad or the brake disc. If paste gets onto these surfaces, wipe it off immediately with alcohol or replace the protective cap.
Do not lubricate the backing plate of the brake pad.

9. Insert the brake pad with the spring into the piston.

10. Insert the outer brake pad (9) into the caliper and install the caliper over the brake disc. Make sure the brake pads are clean.

11. Visually inspect the two caliper mounting bolts. If necessary, clean the threads of dirt, and chase the threads in the caliper with a tap. Replace bolts with damaged threads or signs of rust. Tighten the bolts with a 7 mm socket wrench to a torque of 30 N·m.

* Clean the bolts only; do not lubricate them.

12. Install the caps on the bolts.
13. Connect the wear sensor plug connector on the left side of the vehicle. The wire must pass through the loop of the bleed screw cap.

14. Install the bracket onto the caliper.
15. Install and secure the front wheels. Do not lubricate the wheel mounting bolts with oil. Install the wheels so that the marks made during removal line up. Lower the vehicle onto the wheels and tighten the mounting bolts in a crisscross pattern to a torque of 100 N·m.

* Press the brake pedal firmly several times until resistance is felt. This pushes the brake pads against the disc and brings them to their working position.

16. Check the brake fluid level in the reservoir. If necessary, top up to the MAX mark.
Caution, check the following for security:
a) Are the brake hoses secured?
b) Is the brake hose secured in its bracket?
c) Is the bleed screw tightened?
d) Is there sufficient brake fluid in the reservoir?
e) With the engine running, check the system for leaks. To do this, press the brake pedal with a force of 200 - 300 N (20 - 30 kgf) and hold it for 10 s. The pedal force must not decrease while holding.
f) Check all connections for leaks.
24. New brake pads must bed in. To do this, brake the vehicle several times from 80 km/h to 40 km/h with light pedal pressure. Allow the brakes to cool between applications.

* Do not brake hard during the first 200 km of driving.

* Dispose of brake pads properly. Do not dispose of them with household waste.