BMW Coupes and Sedans 1970-1988 Repair Guide

Brake Caliper

Print

Models equipped with anti-lock brakes require expensive and specialized equipment to bleed the brake system. If you do not own or have access to this equipment, it is best to have a properly equipped professional perform this procedure.

REMOVAL & INSTALLATION



See Figures 1 and 2



Click image to see an enlarged view

Fig. Fig. 1: Use two flare-end wrenched to loosen the brake line and brake hose connection



Click image to see an enlarged view

Fig. Fig. 2: Finish removing the brake hose and remove the caliper

  1. Raise and support the vehicle. Remove the rear wheels.
  2.  
  3. Disconnect the brake pad wear sensor from the harness.
  4.  
  5. If the caliper is to be replaced, draw off the brake fluid from the reservoir and fix the brake pedal in the depressed position. This will prevent brake fluid from draining out of the brake lines while the line is disconnected form the caliper.
  6.  
  7. Use flare-end wrenches to loosen the connection between the caliper brake hose and the brake line from the master cylinder.
  8.  
  9. Remove the caliper to knuckle mounting bolts and pull the caliper off.
  10.  
  11. Finish separating the hose and brake line.
  12.  
  13. Remove the caliper and place on a clean surface.
  14.  
  15. Check the condition of the brake hose. If cracked or excessively worn, replace with a new hose.
  16.  

To install:
  1. Install the caliper and torque the bolts to 89 ft. lbs. (123 Nm).
  2.  
  3. Connect the brake line to the caliper and torque to 10 ft. lbs. (14.2 Nm).
  4.  
  5. Connect the brake wear sensor wire to the harness. Check for a good connection as most problems with the sensor circuit are caused by faulty connections. Check that the wire is held by the loop in the dust cover and the connector is held at the clips.
  6.  
  7. Clip the brake line into the holder. Bleed the brake system.
  8.  
  9. Install the wheels and torque to 65-79 ft. lbs. (90-110 Nm).
  10.  
  11. Check the brake fluid level in the reservoir and add if needed.
  12.  

OVERHAUL



The overhaul procedure covers replacement of the seal, dust boot and guide sleeves. If the piston or bore is found to be pitted or corroded, replacement of the caliper is recommended. Use a original manufacturer overhaul kit. Use all the parts contained in the kit. Work in a clean, dust free area. Use only alcohol and non-lubricated compressed air to clean the caliper and parts.

1977-83 630CSi, 633CSi and 1977-86 733i Models

Models equipped with anti-lock brakes require expensive and specialized equipment to bleed the brake system. If you do not own or have access to this equipment, it is best to have a properly equipped professional perform this procedure.

  1. Remove the caliper as described in this section. Remove the brake pads.
  2.  
  3. Remove the clamp and rubber piston seal on both sides of multiple piston caliper assemblies.
  4.  
  5. Place a hardwood block in the caliper between the pistons.
  6.  
  7. Plug the brake line connecting hole and retain the piston on the connecting hole side with brake pliers or other suitable tool. Hold the piston opposite the brake line connecting hole with brake pliers or other suitable tool and apply compressed air to the connecting hole. Apply air pressure gradually until the piston pops out.
  8.  
  9. Lift out seals with a pick or other suitable tool.
  10.  

To assemble:
  1. Clean all parts in alcohol and dry with clean compressed air. Replace those calipers that have damaged bores and pistons with scored or pitted surfaces.
  2.  
  3. Reassemble in reverse order, using all new seals from an overhaul kit. Be careful not to cock pistons in the bores when reinstalling. Coat all parts with silicone lubricant.
  4.  
  5. Check the 20° position of the piston, and adjust if needed.
  6.  
  7. Install the calipers and pads, and bleed the system, as described above.
  8.  

1984-88 528e Models

Models equipped with anti-lock brakes require expensive and specialized equipment to bleed the brake system. If you do not own or have access to this equipment, it is best to have a properly equipped professional perform this procedure.

For caliper overhaul procedures, please refer to the "Front Disc Brake" section.

1984-88 3 Series; 533i, 535i 633i, 635i and 735i Models

See Figures 3,4,5 and 6

Models equipped with anti-lock brakes require expensive and specialized equipment to bleed the brake system. If you do not own or have access to this equipment, it is best to have a properly equipped professional perform this procedure.

  1. Remove the caliper and brake pads. Remove the plastic caps and the guide bolts or slide pins.
  2.  
  3. Clean the exterior before further disassembly.
  4.  
  5. Use a pick tool or other suitable tool to remove the collar around the dust cover surrounding the caliper piston.
  6.  
  7. Remove the dust cover from the caliper assembly.
  8.  
  9. Place a piece of wood in the caliper and use compressed air at the hose connection to extend the piston out of the caliper body. Remove the piston.
  10.  
  11. Use a plastic pick to remove the seal from the bore.
  12.  



Click image to see an enlarged view

Fig. Fig. 3: Remove the metal collar around the piston dust cover



Click image to see an enlarged view

Fig. Fig. 4: Use compressed air to force the piston out of the caliper bore



Click image to see an enlarged view

Fig. Fig. 5: Remove the piston from the bore. Do not force it out. If it is difficult to remove twist it back and forth



Click image to see an enlarged view

Fig. Fig. 6: Use a pick or other suitable tool to remove the seal from within the cylinder bore

To assemble:
  1. Clean the bore and piston with alcohol and dry with non-lubricated compressed air.
  2.  
  3. Lubricate the parts with brake assembly paste.
  4.  
  5. Install the new seal in the groove.
  6.  
  7. Install the dust boot on the piston and slide the piston into the bore. Seat the boot into the grooves.
  8.  
  9. Install new guide bushing sleeves at the slides.
  10.  
  11. Assemble the caliper and install.
  12.  

 
label.common.footer.alt.autozoneLogo