Wheel Cylinder

Replace the rear wheel cylinder(s) on a 1970 AMC Rebel Machine to restore proper drum brake hydraulic function and stopping power.

Warnings

Tools required

Parts

• Rear wheel cylinder × 2 — Use OEM specification for 10-inch drums
• Brake hardware spring kit × 1 — Rear drum brake hardware kit
• Brake fluid DOT 3 × 1 — Use OEM specification

Fluids

• DOT 3 brake fluid — 1 qt

Preparation

1. Park vehicle on level surface and chock front wheels securely
2. Loosen rear wheel lug nuts while vehicle is on ground
3. Raise rear of vehicle and support on jack stands placed under rear axle housing
4. Remove rear wheels completely
5. Locate and open master cylinder reservoir cap to prevent vacuum lock during disassembly
6. Place drain pan under work area to catch brake fluid

Procedure

1. 1

   Remove brake drum
   Remove the brake drum retaining clips if present. Pull drum straight off the axle hub. If drum is stuck, tap gently with rubber mallet around the outer edge. Do not pry between drum and backing plate as this can damage sealing surfaces.
2. 2

   Inspect brake system
   Examine the wheel cylinder for fluid leaks, corrosion, or damaged bleeder screw. Check brake shoes for contamination, lining thickness, and even wear. Note the position and orientation of all brake springs and hardware before disassembly.
3. 3

   Remove brake shoe return springs
   Using brake spring pliers, carefully remove the upper and lower brake shoe return springs. These are under significant tension. Remove the shoe hold-down springs and pins by pressing and rotating 90 degrees.
   ⚠Brake return springs are under high tension and can cause injury if released improperly. Keep face and hands clear of spring path.
4. 4

   Disconnect brake shoes from wheel cylinder
   Spread the top of the brake shoes apart slightly and unhook them from the wheel cylinder pistons. Remove the brake shoes as an assembly, noting the position of the self-adjuster mechanism, spring, and cable.
5. 5

   Disconnect brake line from wheel cylinder
   Using a flare nut wrench, carefully loosen and remove the brake line fitting from the rear of the wheel cylinder. Immediately plug the brake line with a rubber cap or bolt to minimize fluid loss and prevent contamination.
   ⚠Use only a flare nut wrench to prevent rounding the soft brass fitting. Standard wrenches will damage the fitting.
6. 6

   Remove wheel cylinder mounting bolts
   Remove the two bolts securing the wheel cylinder to the backing plate from behind. The wheel cylinder will now be free. On some configurations, access may require reaching behind the backing plate through the axle flange opening.
7. 7

   Clean mounting surface
   Spray backing plate and wheel cylinder mounting area with brake cleaner. Use a wire brush to remove any rust, old gasket material, or debris from the mounting surface. Ensure the surface is clean and flat for proper sealing.
8. 8

   Install new wheel cylinder
   Position the new wheel cylinder onto the backing plate, aligning the mounting holes. Insert and hand-tighten the mounting bolts from behind the backing plate. Tighten bolts snugly in a cross pattern to ensure even seating against the backing plate.
9. 9

   Reconnect brake line
   Thread the brake line fitting into the new wheel cylinder by hand first to ensure proper thread engagement. Tighten with flare nut wrench until snug, being careful not to over-torque the brass fitting. Connection should be tight but not forced.
10. 10

    Reinstall brake shoes and hardware
    Lubricate shoe contact points on backing plate with high-temperature brake grease. Reinstall brake shoes, ensuring self-adjuster mechanism is properly positioned. Hook shoes onto wheel cylinder pistons. Install hold-down pins and springs, then return springs in reverse order of removal.
11. 11

    Adjust and verify brake assembly
    Verify all springs and hardware are properly installed and positioned. Manually actuate the self-adjuster mechanism to pre-adjust the shoes. Check that shoes move freely and return properly. Ensure no interference with backing plate or axle components.
12. 12

    Reinstall brake drum and wheel
    Clean inside of brake drum with brake cleaner. Slide drum over shoes and onto hub. Install wheel and hand-tighten lug nuts in star pattern. Repeat entire procedure for opposite side wheel cylinder. Lower vehicle and torque lug nuts to specification in star pattern.
13. 13

    Bleed brake system
    Fill master cylinder reservoir to proper level with fresh DOT 3 brake fluid. Bleed both rear wheel cylinders starting with the wheel furthest from master cylinder. Have assistant pump brake pedal three times and hold, then open bleeder screw until fluid stops flowing. Close bleeder before pedal reaches floor. Repeat until fluid runs clear without air bubbles. Maintain reservoir level throughout bleeding process.

Reassembly

1. Ensure master cylinder reservoir is filled to proper level with DOT 3 brake fluid
2. Torque wheel lug nuts to 75-80 ft-lbs in star pattern with wheels on ground
3. Pump brake pedal several times to seat brake shoes against drums before moving vehicle

Verification

• Check for brake fluid leaks at all wheel cylinder connections and bleeder screws
• Verify firm brake pedal with no sponginess after several pumps
• Test brakes at low speed to ensure even braking with no pull to either side
• Verify parking brake operates correctly and holds vehicle on incline
• Re-check master cylinder fluid level after test drive and top off if necessary
• Inspect drums for proper rotation without dragging or unusual noise

More procedures for this vehicle