GM Chevy Mid-Size Cars 1964-1988 Repair Guide

Wheel Cylinders

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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! When cleaning brake surfaces, use a commercially available brake cleaning fluid.

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7 and 8

  1. Raise and support the front of the vehicle safely using jackstands.
  2.  
  3. Remove the wheel and the brake drum for access to the wheel cylinder assembly.
  4.  

In most cases, the wheel cylinders may be removed from the backing plate without completely removing the brake shoes and related components. Some of the upper springs must usually be removed in order to allow the shoes to spread and provide the necessary clearance for wheel cylinder removal.

  1. Clean away all dirt, crud and foreign material from around wheel cylinder. It is important that dirt be kept away from the brake line when the cylinder is disconnected.
  2.  
  3. Disconnect the inlet tube line from the back of the wheel cylinder. Immediately plug or cap the line to prevent system contamination or excessive fluid loss.
  4.  



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Fig. Fig. 1: Exploded view of the round retainer type wheel cylinder



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Fig. Fig. 2: Two awls may be used to bend the retainer stubs, releasing the wheel cylinder

Wheel cylinders are retained to the rear of the brake backing plate by two types of fasteners. One type uses a round retainer with locking clips while the other simply uses two bolts threaded into the wheel cylinder body.

  1. To remove the round retainer type cylinders, insert two awls or pins into the access slots between the wheel cylinder pilot and the retainer locking tabs. Bend both tabs away simultaneously. The wheel cylinder can be removed, as the retainer is released.
  2.  
  3. To remove the bolted wheel cylinders, loosen and remove the bolts from the back side of the backing plate, then remove the wheel cylinder assembly.
  4.  



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Fig. Fig. 3: Exploded view of the bolted wheel cylinder mounting

To install:
  1. For round retainer type wheel cylinders, position the cylinder and hold it in place with a wooden block between the cylinder and the axle flange. Install the new retainer clip, using a 1 1 / 8 in. 12-point socket and socket extension. The socket is used to assure that the retainer seats evenly.
  2.  
  3. For bolt type wheel cylinders, position the cylinder and secure using the retaining bolts.
  4.  
  5. Remove the cap or plug, then connect and secure the inlet line.
  6.  
  7. Assemble the remaining brake components which were removed, then install the tire and wheel assembly.
  8.  
  9. Bleed the wheel cylinder, then remove the jackstands and carefully lower the vehicle.
  10.  



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Fig. Fig. 4: Use a line wrench to loosen the inlet pipe fitting from the rear of the wheel cylinder



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Fig. Fig. 5: If equipped, use 2 awls to free the round retainer from the cylinder



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Fig. Fig. 6: Remove the necessary springs, then carefully spread the brake shoes for access



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Fig. Fig. 7: A small prytool may be used to assist in freeing the wheel cylinder



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Fig. Fig. 8: Upon installation, a socket and extension should be used to seat the round retainer

OVERHAUL



See Figures 9, 10, 11, 12, 13, 14, 15 and 16

Wheel cylinder overhaul kits may be available, but often at little or no savings over a reconditioned wheel cylinder. It often makes sense with these components to substitute a new or reconditioned part instead of attempting an overhaul.

If no replacement is available, or you would prefer to overhaul your wheel cylinders, the following procedure may be used. 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.

The wheel cylinder may be equipped with links (often found on the bolted retainer type) or with pistons. The pistons may be identified by the round, flat ends with which they are equipped. Links found on wheel cylinders are often much thinner that the pistons and are equipped with a larger, notched end.

  1. Remove the wheel cylinder from the vehicle.
  2.  
  3. For link type cylinders, remove the cylinder links, then remove the rubber boots from the cylinder ends with pliers. Discard the boots. Link type cylinders are equipped with inner pistons and cups.
  4.  
  5. For piston equipped cylinders, first remove and discard the old rubber boots, then withdraw the pistons. Piston cylinders are equipped with seals and a spring assembly all located behind the pistons in the cylinder bore.
  6.  
  7. Remove and discard remaining inner components (pistons, seals, cups and spring(s), as equipped). Compressed air may be useful in removing these components. If no compressed air is available, be VERY careful not to score the wheel cylinder bore when removing parts from it.
  8.  
  9. Wash the cylinder and metal parts in denatured alcohol or clean brake fluid.
  10.  


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.  
  3. Inspect the piston and replace it if it shows scratches.
  4.  
  5. Lubricate the cylinder bore and counterbore with clean brake fluid.
  6.  
  7. If equipped, position the spring assembly.
  8.  
  9. Install the rubber cups (flat side out) and/or inner then the pistons (flat side in), as applicable.
  10.  
  11. Insert the new boots into the counterbores by hand. Do not lubricate the boots.
  12.  
  13. For link equipped cylinders, install the links.
  14.  
  15. Install the wheel cylinder to the vehicle.
  16.  



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Fig. Fig. 9: Exploded view of a piston type wheel cylinder assembly



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Fig. Fig. 10: If necessary, loosen and remove the bleeder screw from the wheel cylinder



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Fig. Fig. 11: For piston type cylinders, first pry free old boot



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Fig. Fig. 12: Once removed, the boot should be discarded



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Fig. Fig. 13: Remove the piston from the cylinder bore



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Fig. Fig. 14: With the bleeder screw installed, a small amount of compressed air may be used to free the inner components



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Fig. Fig. 15: Remove the spring assembly from the cylinder bore



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Fig. Fig. 16: Exploded view of the spring and end components from a piston cylinder (there is an additional seal, piston and boot on the other end)

 
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