Withdrawal
Mark the position of the rear wheels on the hubs so that the balanced wheels can then be set to the same positions. Loosen the wheel bolts with the vehicle on the ground. Support the car at the rear and remove the rear wheels.
If the brake pads are to be used further, they must be marked before removal. Replacing and rearranging the pads from the right to the left wheel is unacceptable. Replacement may result in uneven braking. Be sure to use only original or certified BMW brake pads. Replace all brake pads on the rear wheels at the same time, even if only one of them has reached the minimum thickness.
On the right caliper, unplug the pad wear sensor plug from the brake pad, but pull on the plug, not the wire.
Squeeze out the two plastic caps from the mounting bolts and unscrew the two mounting bolts with an Allen socket.
Wring out the bracket (3) with a screwdriver.
Pull the brake caliper back.
Take out the outer block.
The inner pad is secured by a spring in the caliper piston. Take out the block.
Installation
Attention: With the brake pads removed, do not press the brake pedal, otherwise the pistons will pop out of the housing.
Check the pad wear sensor. If the insulation of the contact plate is frayed, the wire insulation is damaged, or the plastic parts are worn, replace the sensor.
Use a soft metal brush to clean the guide planes or shoe slots in the housing channel, or wipe them with a rag soaked in alcohol. Do not use mineral solvents or sharp instruments. If the brake pads are reused, they must also be cleaned.
Before installing the pads, it is necessary to check the brake disc by touch in order to detect scratches and gouges. Badly scratched discs should be replaced. Brake discs painted gray or blue must be cleaned before installing new pads.
Measure the brake disc thickness.
Check the dust cover on the piston for damage. Damaged covers must be replaced immediately, as dirt that has got inside will lead to leaks in the caliper. The replacement caliper must be removed and disassembled. Press the piston into the cylinder using the special tool. You can use a hardwood block (hammer handle). When doing this, care must be taken not to distort the piston and not to damage the piston surface and the dust cap.
When the piston is pushed in, the brake fluid from the cylinder will be squeezed out into the fluid reservoir. It is necessary to monitor the level of liquid in the tank and, if necessary, remove it with a syringe or rubber bulb.
Caution: Brake fluid is poisonous and must never be sucked out by mouth through a hose. After replacing the pads, do not raise the fluid level above the MAX mark on the tank, as the fluid expands from temperature and may spill out of the tank, which will damage the paintwork and cause.
Attention: With a strong nose of the pads, you need to check the ease of the piston stroke. To do this, insert a block of wood into the caliper, and the assistant should slowly press the brake pedal. The piston should slide in and out easily. To check another caliper must be installed. It is necessary to ensure that the piston is not completely squeezed out. If the piston stroke is heavy, the caliper must be repaired in the workshop.
To prevent disc brakes from squeaking, apply a thin layer of special anti-noise paste to the following parts.
Clean the contact surface (3) brake caliper and, in the places shown in the figure, apply a thin layer of anti-noise paste.
Clear Holder (brace) in the places of the guides and, in the places shown in the figure, lubricate with a thin layer of anti-noise paste.
Caution: The paste must never get on the dust caps, the working surface of the brake pads or the brake disc. If this does happen, the paste must be wiped off immediately and the area cleaned with alcohol or the dust caps replaced.
Caution: Do not lubricate the back of the brake pads.
Insert the brake pad together with the spring into the caliper piston.
Inspect the two brake caliper mounting bolts, clean the threads if necessary. If necessary, clean the threads in the bracket (fastening) caliper with a tap. Replace bolts with damaged threads or corrosion. Tighten the bolts with a 7 mm hex wrench to 30 Nm.
Attention: Do not lubricate the bolts, they only need to be cleaned.
Put on the protective caps of the bolts.
On the right side of the vehicle, connect the wear sensor connector to the brake pad. The wire must fit into the recess in the cap for the bleed valve.
Slide the caliper onto the brake caliper.
Install the rear wheels in accordance with the marks made earlier. Do not lubricate wheel bolts. Lower the vehicle and tighten the wheel bolts crosswise to 100 Nm.
Caution: With the vehicle stationary, depress the brake pedal firmly several times until a strong resistance is felt. In this case, the pads will lie against the brake disc and take the appropriate position.
Check the brake fluid level in the reservoir and, if necessary, top up to the MAX mark.
Gently break in the new brake pads by braking the vehicle several times from 80 km/h to 40 km/h on a road with light traffic, applying light pressure to the pedal. Allow the brakes to cool slightly between braking.
Attention: Before a run of 200 km, sudden braking should be avoided.