Removal and installation the rear brake disc (BMW 5 Series E39)

Removal

Remove the rear brake caliper. Do not unscrew the brake hose, otherwise the assembly will be removed from the brake system it will be necessary to remove the air.



Using a homemade wire hook, hang the caliper from the body. Make sure the brake hose does not twist.

Unscrew the "arrow" mounting bolt using a 5 mm external Allen key.

Release the parking brake completely.

Remove the brake disc. If the brake disc cannot be removed, the brake pads of the parking brake system squeeze away from the brake drum.

Installation

To ensure uniform braking on both sides of the bridge, both brake discs must have identical surfaces in terms of wear pattern and unevenness depth. Therefore, both brake discs of the bridge must be replaced or ground.

In the workshop, brake discs can be welded for runout. The maximum measured runout value of the brake surface of the installed disc should not exceed 0.2 mm.

Measure the thickness of the disc.

Clean new brake discs from protective coating with nitro solvent.

Place the brake disc on the rear wheel hub and secure it with a hexagonal socket head cap screw. First, turn the brake disc so that the holes for the bolt in the disc and hub match.



Insert the caliper with the brake pads installed. The brake hose should not twist or stretch. Tighten the caliper mounting bolts.

Caution: If the brake hose has been removed, tighten the brake hose and bleed the brake system, see page 107.

Adjust the handbrake.

Tighten the rear wheels. Do not lubricate the wheel bolts. Position the wheels so that the marks applied by removing the uterus coincide. Lower the car, tighten the wheel bolts crosswise to 100 Nm.

Caution: Press the brake pedal hard several times until you feel strong resistance. At the same time, the brake pads are applied to the discs and take the position corresponding to the operating conditions.

Check the brake fluid level in the expansion tank and, if necessary, top up the level to the MAX mark.

Attention: Perform a safety compliance check:

• Tighten the brake hoses securely?
• Is the brake hose in the holder?
• Are the air bleed valves tightened?
• Is there enough fluid in the brake system?
• With the engine running, perform a leak test. To do this, apply a force of 200 to 300 N to the brake pedal for approximately 10 seconds (from 20 to 30 kg). Do not release the brake pedal. Check all connections for leaks.

New brake discs must be run in in three phases.

• Phase 1: Five hard braking applications at 50 km/h on an empty street.
• Phase 2: Allow the brakes to cool.
• Phase 3: Five new braking applications at 50 km/h.

[The original source of the article is on the website «BMWMan»]