BMW Coupes and Sedans 1970-1988 Repair Guide

Brake Disc (Rotor)

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REMOVAL & INSTALLATION



1600, 2000, 2002, 2500, 2800, Bavaria, 3000 and 3.0 Models

See Figure 1

  1. Raise the vehicle and support safely on jackstands.
  2.  
  3. Remove the wheel and tire assembly.
  4.  
  5. Remove the two bolts which retain the caliper to the spindle and slide the caliper off the disc. Wire the caliper up out of the way so that the flexible brake hose is not strained or kinked.
  6.  
  7. Remove the grease cap from the hub. Remove the cotter pin, castellated nut, and washer retaining the disc and hub assembly to the spindle. Put off the wheel and hub assembly together with the wheel bearings and grease seal.
  8.  



Click image to see an enlarged view

Fig. Fig. 1: Rotor and wheel bearing assembly

  1. Remove the Allen head bolt(s) which retain the disc to the hub and lift off the disc.
  2.  

If the disc is rusted or otherwise fused to the hub, loosely bolt the wheel and tire back to the hub. then, grasp the disc firmly and twist the disc back and forth, while pulling up on the disc simultaneously. This should jerk the disc loose from the hub. A little penetrating fluid on the lug nut studs will help also.

  1. Check the disc for scoring or excessive corrosion. Minimum disc thickness is:

    1600, 2000 and 2002 models-0.35 inches (9mm)
     
    2500, 2800 and Bavaria models-0.45 inches (11.7mm)
     
    3.0 models-0.81 inches (21mm)
     

  2.  
  3. If in the refinishing operation, the disc is cut to less than the minimum thickness, the disc must be replaced.
  4.  

The thickness of the disc must not vary more than 0.0078 inches (0.2mm) measured at 8 points on the contact surface with a micrometer.

To install:
  1. It is good practice to remove, clean, repack and install the wheel bearings into the hub as outlined in this section.
  2.  

To install:
  1. Install the disc onto the hub. Tighten the Allen bolts to 43 ft. lbs. (56 Nm).
  2.  
  3. Install the disc and hub assembly onto the spindle. Adjust the wheel bearings as outlined in this section. Once the wheel bearings are properly adjusted, check disc run-out with a dual gauge. Maximum permissible run-out is 0.0078 inches (0.2mm).
  4.  
  5. Install the caliper, tightening the retaining bolts to 58 ft. lbs. (75 Nm).
  6.  
  7. Install the wheel and tire assembly. Lower the car and perform a road test.
  8.  

3, 5, 6 and 7 Series

See Figures 2, 3 and 4

  1. Raise the vehicle and safely support on jackstands.
  2.  
  3. Remove the lug bolts and remove the front wheel.
  4.  
  5. Remove the caliper mounting bolts, and tie the caliper up out of the way (brake line still connected) using a piece of wire.
  6.  
  7. Remove the bolts which secure the caliper bracket to the steering knuckle.
  8.  
  9. Use an Allen wrench to remove the bolt retaining the disc to the hub. Then, remove the disc.
  10.  

These discs are balanced. Be careful not to disturb the weights.

  1. To inspect the disc, reposition it on the hub, install the retaining bolt, and tighten to 36-42 inch lbs. (47-54 Nm). On 733i models, tighten to 23-24 ft. lbs. (30-31 Nm).
  2.  

To install:


Click image to see an enlarged view

Fig. Fig. 2: With the caliper safely wired aside, remove the bracket securing the caliper to the knuckle



Click image to see an enlarged view

Fig. Fig. 3: Remove the Allen bolt from the rotor face



Click image to see an enlarged view

Fig. Fig. 4: Lift the rotor off the hub assembly

  1. Adjust the wheel bearings as described below.
  2.  
  3. Use a dial indicator mounted at a point on the front suspension to measure the total runout of the disc. Maximum runout is 0.0078 inches (0.2mm) on all models except 733i. On 733i models, the allowable amount is 0.0058 inches (0.15mm). Use a micrometer and measure the total variation in the thickness of the disc at 8 evenly spaced points around the disc. If tolerances are greater than this, the disc must be machined.
  4.  
  5. Install the wheel and lower the vehicle.
  6.  

 
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