Wheel Cylinder

Remove and replace the rear wheel cylinder on a 1966 Chevrolet Corvette to restore proper brake function and eliminate fluid leaks.

Warnings

Tools required

Parts

• Rear wheel cylinder × 1 — Use OEM specification or Wagner/Raybestos equivalent
• Brake shoe hold-down springs and pins (if damaged) × 1 — Use OEM specification
• Brake hardware kit (optional) × 1 — Use OEM specification

Fluids

• DOT 4 Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and place wheel chocks in front of front wheels.
2. Loosen lug nuts on the wheel where cylinder replacement is needed while vehicle is still on ground.
3. Raise vehicle with floor jack at appropriate rear jacking point.
4. Support vehicle securely on jack stands placed under frame rails.
5. Remove wheel completely.
6. Place drain pan under work area to catch brake fluid.

Procedure

1. 1

   Remove brake drum
   Remove the two drum retaining screws if present. Pull brake drum straight off the axle hub. If drum is stuck due to rust or brake shoe wear, back off the brake adjustment by accessing the adjuster slot on the backing plate and rotating the adjuster star wheel downward with a flathead screwdriver. If drum remains stuck, use a brake drum puller or tap gently around the perimeter with a rubber mallet.
2. 2

   Inspect and photograph brake assembly
   Before disassembly, photograph the brake shoe arrangement and spring positions for reference during reassembly. Inspect brake shoes for contamination, lining thickness, and uneven wear. Check for fluid leakage around the wheel cylinder dust boots indicating cylinder failure.
3. 3

   Remove brake shoe return springs
   Using brake spring pliers or standard pliers, carefully remove the upper and lower brake shoe return springs. Note the position and orientation of each spring. Remove the adjuster spring and adjuster lever assembly.
4. 4

   Remove brake shoe hold-down hardware
   Remove the brake shoe hold-down springs and pins from both shoes. Press down on the hold-down spring cup while rotating it 90 degrees to release it from the slotted head of the hold-down pin, which is retained from behind the backing plate. Remove both shoes as an assembly, disconnecting the adjuster mechanism.
5. 5

   Disconnect brake line from wheel cylinder
   Using a brake line wrench, carefully loosen and remove the brake line fitting from the rear of the wheel cylinder. Be prepared for brake fluid to drip. Immediately plug or cap the brake line to prevent fluid loss and contamination entry. Clean the brake line fitting threads with brake cleaner.
6. 6

   Remove wheel cylinder mounting bolts
   Remove the two wheel cylinder mounting bolts from the backing plate using the appropriate SAE wrench or socket (verify size against factory specification). The bolts are accessed from the rear of the backing plate. Remove the wheel cylinder from the backing plate.
7. 7

   Clean backing plate and cylinder mounting area
   Spray backing plate thoroughly with brake cleaner, wiping away all residue with shop rags. Use a wire brush to clean the wheel cylinder mounting surface on the backing plate, removing all rust and old gasket material. Clean the brake line fitting threads.
8. 8

   Install new wheel cylinder
   Position the new wheel cylinder onto the backing plate, aligning the mounting holes and brake line port. Install the two mounting bolts and tighten securely. Thread the brake line fitting into the new wheel cylinder by hand first to ensure proper alignment, then tighten with a brake line wrench until snug. Do not overtighten the brake line fitting.
9. 9

   Reinstall brake shoes and hardware
   Referring to your earlier photographs, reinstall the brake shoes with hold-down pins and springs. Connect the adjuster mechanism between the shoes. Install the lower return spring first, then the upper return spring. Reinstall the adjuster spring and lever assembly. Ensure all components are properly seated and the shoes move freely when the adjuster is rotated.
10. 10

    Adjust brake shoes preliminary setting
    Rotate the brake adjuster star wheel upward until the shoes drag slightly against the inside of the drum when the drum is test-fitted. Then back off the adjuster 8-10 clicks until the drum rotates freely with only slight drag. This provides the initial adjustment for proper brake operation.
11. 11

    Reinstall brake drum and wheel
    Clean the drum interior and hub surface with brake cleaner. Install the brake drum over the shoes and onto the hub. If equipped, install the two drum retaining screws. Mount the wheel and hand-tighten the lug nuts in a star pattern.
12. 12

    Bleed brake system
    Fill the master cylinder reservoir with fresh DOT 3 brake fluid (factory specification; DOT 4 is an acceptable upgrade for this glycol-based system). Starting with the wheel cylinder just replaced, attach clear tubing to the bleeder screw and submerge the other end in a container with clean brake fluid. Have an assistant pump the brake pedal 3-4 times and hold pressure. Open the bleeder screw 1/2 turn and allow fluid and air to escape until flow stops. Close bleeder before assistant releases pedal. Repeat until no air bubbles appear in the discharge. Bleed all four wheels starting with the wheel cylinder farthest from the master cylinder and working toward the nearest, typically in the order: right rear, left rear, right front, left front. Keep master cylinder full throughout bleeding process.
13. 13

    Lower vehicle and perform final wheel torque
    Lower vehicle from jack stands to ground. Torque lug nuts to factory specification in a star pattern. Remove jack stands and lower vehicle completely.

Reassembly

1. Ensure all brake hardware is properly installed and return springs are correctly positioned.
2. Verify brake line fitting is tight and shows no signs of leakage.
3. Double-check that master cylinder is filled to proper level with DOT 4 brake fluid.
4. Confirm wheel lug nuts are torqued to specification after vehicle is on ground.

Verification

• Start engine and pump brake pedal several times. Pedal should feel firm and not sink to floor.
• Check for brake fluid leaks at wheel cylinder and brake line connection.
• Test drive vehicle in safe area at low speed, verifying brakes apply evenly without pulling to one side.
• After test drive, recheck brake adjustment and fluid level. Adjust shoes if necessary for optimal pedal height.
• Inspect wheel cylinder area again after test drive for any signs of leakage.

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