Wheel Cylinder

Replace a leaking or worn rear wheel brake cylinder on a 1972 Ford F-100 with 302ci V8, including brake bleeding and system verification.

Warnings

Tools required

Parts

• Rear wheel cylinder × 1 — Use OEM specification for 10" or 11" rear drum application
• Brake shoe return springs (if damaged) × 1 — Use OEM specification
• Brake shoe hold-down springs and pins (if damaged) × 1 — Use OEM specification
• Brake hardware kit (optional) × 1 — Use OEM specification

Fluids

• DOT 3 brake fluid — 0.75 qt

Preparation

1. Park vehicle on level surface and place wheel chocks in front of front wheels.
2. Loosen lug nuts on the wheel where cylinder will be replaced while vehicle is on ground.
3. Raise rear of vehicle and support securely on jack stands rated for vehicle weight under frame rails.
4. Remove wheel completely.
5. Locate brake fluid master cylinder and verify fluid level before starting work.
6. Have new wheel cylinder, brake fluid, and all tools within reach before disassembly.

Procedure

1. 1

   Remove brake drum
   Remove the brake drum retaining clips (if present) by prying off with flathead screwdriver. Pull drum straight off hub. If drum is stuck, back off brake adjuster through adjustment slot in backing plate using flathead screwdriver to retract shoes, or tap drum edge lightly with rubber mallet to break rust seal. Mark drum orientation if planning to reuse.
2. 2

   Inspect and photograph brake assembly
   Spray brake assembly thoroughly with brake cleaner and wipe away excess dust with rags. Take a photograph or make note of brake spring positions and shoe orientation for reassembly reference. Inspect brake shoes for contamination from leaking wheel cylinder fluid - if shoes are oil-soaked, they must be replaced.
3. 3

   Remove brake shoe return springs
   Using brake spring pliers or brake tool, remove the two upper brake shoe return springs connecting the tops of the primary and secondary shoes. These are the large curved springs above the wheel cylinder. Remove lower return spring if present on this axle configuration.
4. 4

   Remove brake shoe hold-down hardware
   Remove the hold-down spring retainers from both brake shoes. Press down on hold-down retainer while rotating it 90 degrees to align slot with pin head, then release spring pressure and remove retainer and spring. The pin remains in the backing plate. Repeat for second shoe. Set hardware aside for reuse unless damaged.
5. 5

   Disconnect brake shoes from wheel cylinder and adjuster
   Lift brake shoes away from wheel cylinder pistons at top and disconnect from the star-wheel adjuster mechanism at bottom. Note position of adjuster star wheel and orientation. Remove adjuster assembly by spreading shoes slightly. Remove brake shoes completely from backing plate.
6. 6

   Disconnect brake line from wheel cylinder
   Place catch pan under backing plate. Using 3/8" flare nut wrench, carefully loosen brake line fitting at rear of wheel cylinder. Turn counterclockwise 3 to 4 turns until fluid begins to drip, then complete removal. Immediately plug line end with rubber cap or wrap with plastic to prevent excessive fluid loss and contamination. Verified detail (The 9mm equivalent is offered as an alternate for an American-made 1972 truck that uses SAE inverted flare fittings; the metric callout is anachronistic and misleading. Brake line fittings on this era Ford are SAE (typically 3/8" or 7/16" for the fitting, though the AI's 11/32" size itself is questionable and should be verified against the actual line nut).): Using the appropriately-sized SAE flare nut (line) wrench, carefully loosen brake line fitting at rear of wheel cylinder.
7. 7

   Remove wheel cylinder mounting bolts
   From rear of backing plate, remove the two wheel cylinder mounting bolts using 9.0 lb-ft (12.0 Nm). These bolts pass through backing plate from rear. Remove wheel cylinder from backing plate front side. Verified detail (This is the AI's best-guess torque for the wheel cylinder mounting bolts and is unverified against Ford factory documentation for the 1972 F-100. Needs direct spec confirmation.): 9.0 lb-ft (12.0 Nm)
8. 8

   Clean and prepare backing plate
   Clean wheel cylinder mounting area on backing plate thoroughly with brake cleaner and wire brush. Remove all rust, old brake fluid residue, and debris from mounting bolt holes and brake line port area. Ensure backing plate surface is clean and dry for new cylinder seal.
9. 9

   Install new wheel cylinder
   Position new wheel cylinder against backing plate, aligning mounting bolt holes and brake line port. Insert mounting bolts from rear of backing plate and thread in by hand. Tighten mounting bolts evenly and securely. Verify cylinder is seated flush against backing plate and pistons move freely by hand.
10. 10

    Reconnect brake line
    Remove plug from brake line. Thread brake line fitting into wheel cylinder by hand first to ensure proper thread engagement and prevent cross-threading. Once hand-tight, use flare nut wrench to snug fitting securely. Do not overtighten as steel fittings can strip or cross-thread easily - firm snug is sufficient.
11. 11

    Reinstall brake shoes and hardware
    Reinstall adjuster mechanism between shoes in proper orientation with star wheel accessible through backing plate adjustment hole. Position brake shoes on backing plate, engaging with wheel cylinder pistons at top and adjuster at bottom. Install hold-down pins through backing plate and shoes, then secure with springs and cups. Install all return springs in original positions using brake spring pliers. Verify shoes move freely and center properly.
12. 12

    Adjust brake shoes initial clearance
    Through adjustment slot in backing plate, turn adjuster star wheel with screwdriver to expand shoes until they drag slightly when drum is test-fitted. Back off star wheel 8 to 10 clicks until drum rotates freely with very slight drag. This provides initial adjustment for bleeding process.
13. 13

    Reinstall brake drum and wheel
    Clean drum inner surface with brake cleaner. Slide drum over shoes and onto hub in original orientation. Install drum retaining clips if equipped. Install wheel and thread lug nuts by hand. Lower vehicle until tire contacts ground but weight is still on jack stands. Tighten lug nuts in star pattern to 103.0 lb-ft (140.0 Nm).
14. 14

    Bleed wheel cylinder
    Locate bleeder valve on top or rear of wheel cylinder. Place box end wrench on bleeder valve and attach clear hose, submerging other end in clean brake fluid in container. Have assistant pump brake pedal 3 to 4 times and hold pressure. Open bleeder valve 1/2 turn while pedal is held - fluid and air will discharge. Close bleeder before pedal reaches floor. Repeat process until fluid flows clear with no air bubbles. Close bleeder valve securely. Do not allow master cylinder to run dry during bleeding.
15. 15

    Check master cylinder and system pressure
    Add fresh DOT 3 brake fluid to master cylinder to proper level. With vehicle still supported on jack stands and wheel installed, pump brake pedal firmly 10 to 15 times. Pedal should build firm pressure and hold. If pedal remains soft, repeat bleeding procedure at affected wheel. Check for leaks at wheel cylinder body, mounting bolts, and brake line connection.

Reassembly

1. Lower vehicle completely to ground and torque lug nuts to final specification in star pattern.
2. Perform final brake pedal test - pedal should be firm within upper half of travel.
3. Top off master cylinder with fresh DOT 3 brake fluid to MAX line.
4. If both rear wheel cylinders were replaced, bleed opposite side following same procedure.
5. Dispose of old brake fluid and contaminated brake shoes according to local regulations.

Verification

• Check for fluid leaks at wheel cylinder body, mounting area, and brake line fitting with vehicle weight on wheels.
• Pump brake pedal repeatedly - pedal should achieve firm pressure within 2 to 3 pumps and hold steady when pressed continuously for 30 seconds.
• Test drive vehicle in safe area at low speed - brakes should apply evenly without pulling to either side.
• After test drive, recheck brake fluid level and inspect wheel cylinder for leaks.
• Verify proper brake shoe adjustment by checking that drum rotates freely with only slight drag when wheel is spun by hand.
• After 50 to 100 miles of driving, recheck brake adjustment and fluid level, readjusting shoes if necessary.

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