GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Wheel Cylinder

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CAUTION
Brake shoes 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! The first step in brake repairs should be cleaning brake surfaces, using a commercially available brake cleaning fluid.



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Fig. Fig. 1 Rear wheel cylinder removal and installation



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Fig. Fig. 2 Exploded view of rear wheel cylinder

REMOVAL & INSTALLATION



  1. Raise and safely support the vehicle. Remove the rear drum assembly.
  2.  
  3. Remove the brake shoe and lining assembly.
  4.  
  5. Disconnect and plug the inlet line. Remove the mounting screws and lockwashers.
  6.  
  7. Remove the wheel cylinder assembly.
  8.  

To install:

  1. Install the wheel cylinder assembly.
  2.  
  3. Install the mounting screws and lockwashers.
  4.  
  5. Install the brake shoe and lining assembly.
  6.  
  7. Install the brake drum.
  8.  
  9. Bleed the brake system. Check the brake fluid level in the master cylinder frequently while bleeding the system.
  10.  
  11. Lower the vehicle.
  12.  

OVERHAUL



As is the case with master cylinders, overhaul kits are available for the wheel cylinders. And, as is the case with master cylinders, it is usually more profitable to simply buy new or rebuilt wheel cylinders rather rebuilding them. When rebuilding wheel cylinders, avoid getting any contaminants in the system. Always install new high quality brake fluid; the use of improper fluid will swell and deteriorate the rubber parts.

  1. Remove the wheel cylinders.
  2.  
  3. Remove the rubber boots from the cylinder ends. Discard the boots.
  4.  
  5. Remove and discard the pistons and cups.
  6.  
  7. Wash the cylinder and metal parts in denatured alcohol.
  8.  


CAUTION
Never use mineral-based solvents to clean the brake parts.

  1. Allow the parts to air dry and inspect the cylinder bore for corrosion or wear. Light corrosion can be cleaned up with crocus cloth; use finger pressure and rotate the cloth around the circumference of the bore. Do not move the cloth in and out. Any deep corrosion can be cleaned up with crocus cloth; use finger pressure and rotate cloth around circumference of the bore. Do not move the cloth in an out. Any deep corrosion or pitting or wear warrants replacement of the parts.
  2.  
  3. Rinse the parts and allow to dry. Do not dry with a rag, which will leave bits of line behind.
  4.  

To assemble:

  1. Lubricate the cylinder bore with clean brake fluid. Insert the spring assembly.
  2.  
  3. Install new cups. Do not lubricate prior to assembly.
  4.  
  5. Install the new pistons.
  6.  
  7. Press the new boots onto the cylinders by hand. Do not lubricate prior to assembly.
  8.  
  9. Install the wheel cylinders. Bleed the brakes after installation of the drum.
  10.  

 
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