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

Brake Rotor

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REMOVAL & INSTALLATION



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.
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  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.
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  5. Remove the internal hex bolt from the hub and pull the rotor off the hub.
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  7. Check the rotor and replace as necessary. Install the rotor and caliper. Install the wheels. Adjust the parking brake.
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  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.
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INSPECTION



  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.
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  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).
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  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).
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  7. Replace or machine the rotors on both sides if found defective.
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