GM Full-Size Trucks 1980-1987 Repair Guide

Wheel Cylinders

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4 and 5

  1. Jack up your truck and support it with jackstands.
  2.  
  3. Remove the wheel and tire.
  4.  
  5. Back off the brake adjustment and remove the drum.
  6.  
  7. Disconnect and plug the brake line.
  8.  
  9. Remove the brake shoe pull-back springs.
  10.  

If desired, the brake shoes and components may be removed for easier access.



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Fig. Fig. 1: If the wheel cylinder on your truck is attached with bolts, use a box wrench or ratchet to loosen them



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Fig. Fig. 2: With the retainers removed and the brake line disconnected, remove the wheel cylinder from the backing plate

  1. Remove the screws securing the wheel cylinder to the backing plate. Later models have their wheel cylinders retained by a round retainer. To release the locking tabs, insert two awls (see illustration) into the access slots to bend the tabs back. Install the new retainer over the wheel cylinder abutment using a 1 1 /8 in., 12-point socket and socket extension.
  2.  



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Fig. Fig. 3: Later wheel cylinder are held in place by a retainer



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Fig. Fig. 4: Bend back the tabs on the retainer using two awls



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Fig. Fig. 5: Install the new retainer over the wheel cylinder using 1 1/8 inch twelve point socket and extension

  1. Disengage the wheel cylinder pushrods from the brake shoes and remove the wheel cylinder.
  2.  
  3. To install, place the wheel cylinder into position and torque the retaining bolts to 180 inch lbs., install the pushrods and install the inlet tube and torque to 120-280 inch lbs. Bleed the brake system.
  4.  

OVERHAUL



See Figures 6, 7, 8, 9, 10 and 11

As in the case with master cylinders, overhaul kits for wheel cylinders are readily available. When rebuilding and installing wheel cylinders, avoid getting any contaminants into the system. Always install clean, new high-quality brake fluid. If dirty or improper fluid has been used, it will be necessary to drain the entire system, flush the system with proper brake fluid, replace all rubber components, refill, and bleed the system.



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Fig. Fig. 6: Exploded view of wheel cylinder



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Fig. Fig. 7: Remove the cylinder links

  1. Remove the cylinder links, then remove the rubber boots from the cylinder ends with pliers. Discard the boots.
  2.  
  3. Remove and discard the pistons and cups.
  4.  
  5. Wash the cylinder and metal parts in denatured alcohol or clean brake fluid.
  6.  



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Fig. Fig. 8: Grasp and pull or carefully pry the rubber boots from the ends of the cylinder


CAUTION
Never use a mineral-based solvent such as gasoline, kerosene, or paint thinner for cleaning purposes. These solvents will swell rubber components and quickly deteriorate them.

  1. Allow the parts to air dry or use compressed air. Do not use rags for cleaning since lint will remain in the cylinder bore.
  2.  



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Fig. Fig. 9: If dry, filtered compressed air is available, use it to blow out the wheel cylinder body and passages



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Fig. Fig. 10: Inspect the cylinder body for scratches or damage

  1. Inspect the piston and replace it if it shows scratches.
  2.  
  3. Lubricate the cylinder bore and counterbore with clean brake fluid.
  4.  



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Fig. Fig. 11: Exploded view of the wheel cylinder components

  1. Install the rubber cups (flat side out) and then the pistons (flat side in).
  2.  
  3. Insert new boots into the counterbores by hand. Do not lubricate the boots.
  4.  

 
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