BMW 318/325/M3/525/535/M5 1989-1993 Repair Information

Brake Rotor



See Figure 1

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Fig. Fig. 1: Remove the screw before attempting to remove the caliper

  1. Raise and support the vehicle. Remove the rear wheels.
  3. Remove the caliper without disconnecting the brake line. Hang the caliper with a piece of wire so no tension is put on the brake line.
  5. Remove the internal hex bolt from the hub and pull the rotor off the hub.
  7. Check the rotor and replace as necessary. Install the rotor and caliper. Install the wheels. Adjust the parking brake.
  9. Burnish the rotors by making 5 full stops from 30 mph (50 km/h), then allow the brakes to cool. Make 5 additional stops from 30 mph (50 km/h) and allow the brakes to cool again. This will burnish the rotors and allow full braking efficiency.


  1. Use a micrometer to measure the thickness of the rotor at 8 points around the circumference. The rotor measurements should not deviate more than 0.0008 inches (0.02mm) from largest to smallest.
  3. The minimum machining thickness is 0.330 in (8.4mm) except for the M5 which has a machining thickness of 0.725 inches (18.4mm). The minimum wear thickness is 0.315 inches (8.0mm) except the M5 which is 0.709 inches (18.0mm).
  5. Remove the caliper or retract the brake pads. Bolt the rotor to the hub. Install a dial indicator with the tip perpendicular to the friction surface of the rotor. With the wheel bearings in serviceable condition, the axial runout must not exceed 0.008 inches (0.2mm).
  7. Replace or machine the rotors on both sides if found defective.