BMW Coupes and Sedans 1970-1988 Repair Guide

Wheel Cylinders

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REMOVAL & INSTALLATION




CAUTION
Brake shoes and pads may contain asbestos, which has been determined to be a cancer causing agent. Never clean the brake surfaces with compressed air. Avoid inhaling any dust from any brake surface. When cleaning brake surfaces, use a commercially available brake cleaning fluid.

  1. Remove the brake drum as outlined in this section.
  2.  
  3. Loosen the brake shoes by rotating the adjustment screw on the backing plate. (Turn the left hand screw clockwise and the right hand screw counterclockwise.)
  4.  
  5. Disconnect and plug the brake line to the wheel cylinder. Remove the bleed screw and mounting hardware from behind the backing plate.
  6.  
  7. Push the wheel cylinder from side to side and remove.
  8.  
  9. Reverse the above procedure to install the wheel cylinder.
  10.  
  11. Install the brake shoes and adjust the drum brakes as outlined in this section.
  12.  
  13. Bleed the brake system using clean DOT 3 or 4 brake fluid.
  14.  

OVERHAUL



See Figure 1

  1. Remove the wheel cylinder as in this section.
  2.  
  3. Place the cylinder on a flat clean surface.
  4.  
  5. Remove the protective rubber end caps (5 ) from the wheel cylinder body (1) and withdraw the piston (4), sleeves (3), and compression spring (2).
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of drum brake wheel cylinder

  1. Clean all parts in clean brake fluid or methylated alcohol. Inspect the compression spring, pistons and cylinder bore. Replace the spring if it is distorted. Replace the pistons and cylinder if either is corroded or scored. Always use new rubber sleeves and protective end caps to assemble. Finally, check the condition of the grooves at the ends of the cylinder. If they are damaged, the cylinder body will need to be replaced.
  2.  
  3. Dip the cylinder bore, pistons, and the new seals in clean brake fluid or Ate cylinder paste.
  4.  
  5. Insert the piston and seal assemblies together with the compression spring into the bore.
  6.  
  7. Install the new rubber end caps on the cylinder, making sure that the lips on the end caps seat fully in the cylinder grooves.
  8.  
  9. Install the wheel cylinder to the backing plate.
  10.  
  11. Install the brake shoes as outlined earlier in this section.
  12.  
  13. Bleed the entire brake system using new DOT 3 or 4 brake fluid.
  14.  

 
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