The brake discs on M3 models are directional and differ from side to side, with the left side disc part number ending in an odd number and the right side disc part number ending in an even number. Begin by blocking the front wheels and loosening the rear wheel bolts by 1.4 turns. Raise and support the rear of the vehicle, then remove the rear wheels without loosening or disconnecting the
Brake Caliper fluid hose; support the caliper assembly with mechanic's wire to prevent damage. Remove the brake caliper and the brake caliper bracket. Use a 6mm hex socket to remove the special, shouldered recessed hex fastener, applying penetrating lubricant if it is corroded. To remove a seized brake disc, loosen the retaining bolt about 3 turns, spray lubricant around the disc-to-hub seam, and install two wheel bolts approximately 10 turns, then rap sharply on the disc's flat surface without contacting the machined area. For installation, check the disc and replace if necessary, ensuring any protective coatings are removed from a new disc. Clean the hub and brake disc surfaces, applying a light coat of anti-seizing compound before installing the disc and tightening the retaining fastener to 12 ft.lbs. (16 Nm). Adjust the parking brake as needed, then reinstall the wheels, hand tightening the lug bolts. Lower the vehicle until the tires contact the surface and torque the lug bolts in a crisscross pattern to 66-81 ft.lbs. (90-110 Nm). Finally, burnish the discs by making 5 full stops from 30 mph (50 km/h), allowing the brakes to cool, followed by 5 additional stops from the same speed to ensure full braking efficiency. The rear brake disc inspection follows the same procedures as the front brake disc.