Replace the rear wheel cylinder on a 2021-2024 Ford F-150 with 3.5L EcoBoost engine, including brake system bleeding and verification.

Warnings

Tools required

Parts

• Rear wheel cylinder × 1 — Use OEM specification or quality aftermarket
• Brake hardware kit (if replacing springs/clips) × 1 — Rear drum brake hardware kit
• Brake shoe set (recommended if contaminated with brake fluid) × 1 — Rear brake shoe set

Fluids

• Motorcraft DOT 4 LV Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks in front of front wheels
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle with floor jack and support on jack stands at frame rails
5. Remove rear wheel completely
6. Have a helper available for brake bleeding procedure or use a pressure bleeding system

Procedure

1. 1

   Remove brake drum
   Remove the brake drum from the hub assembly. If drum is stuck due to rust or brake shoe wear, use a rubber mallet to tap around the outer edge. If still stuck, thread two M8 bolts into the drum puller holes and tighten evenly to force drum off hub. Clean backing plate with brake cleaner once drum is removed.
2. 2

   Inspect and document brake assembly
   Take a photo of the brake assembly for reference during reassembly. Inspect brake shoes for fluid contamination, wear, and condition. Check all springs and hardware for damage. If brake shoes are contaminated with brake fluid from the leaking wheel cylinder, they must be replaced.
   ℹ️Brake shoes contaminated with fluid will have reduced braking performance and must be replaced.
3. 3

   Remove brake shoes and hardware
   Using brake spring removal tool, carefully remove the upper and lower return springs. Remove the hold-down springs and pins from both brake shoes. Disconnect the parking brake cable from the parking brake lever. Remove both brake shoes as an assembly, noting the position of the adjuster mechanism and parking brake strut.
4. 4

   Disconnect brake line from wheel cylinder
   Place a catch pan under the wheel cylinder. Using a line wrench, carefully loosen and disconnect the brake line fitting from the rear of the wheel cylinder. Immediately plug the brake line with a rubber cap or plug to minimize fluid loss and prevent contamination. Allow wheel cylinder to drain into catch pan.
   ⚠Use a line wrench (flare nut wrench) to prevent rounding off the brake line fitting.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
5. 5

   Remove wheel cylinder mounting bolts
   Remove the two wheel cylinder mounting bolts from the backing plate using appropriate socket. Carefully pull the wheel cylinder away from the backing plate. Inspect the mounting surface on the backing plate and clean any rust or debris with a wire brush.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
6. 6

   Prepare and install new wheel cylinder
   Remove the new wheel cylinder from packaging. Verify it matches the old cylinder and includes proper mounting hardware. Apply a thin coat of brake-compatible anti-seize to the mounting bolt threads. Position new wheel cylinder on backing plate, aligning mounting holes. Install and torque mounting bolts to specification.
   Torque spec

   Mounting Bolts31 Nm (23 lb-ft)
7. 7

   Connect brake line to new wheel cylinder
   Remove the plug from the brake line. Inspect the brake line flare for damage or deformation. Thread the brake line fitting into the wheel cylinder by hand to ensure proper engagement and prevent cross-threading. Using a line wrench, torque the fitting to specification.
   ⚠Start the fitting by hand and ensure it threads smoothly. Cross-threading will damage the wheel cylinder and require replacement.
   Torque spec

   Line Fittings23 Nm (17 lb-ft)
8. 8

   Reinstall brake shoes and hardware
   If installing new brake shoes, transfer the parking brake lever to the new shoe. Lubricate the six brake shoe contact points on the backing plate with high-temperature brake grease (do not contaminate friction surfaces). Reconnect parking brake cable to lever. Install brake shoes with adjuster mechanism and strut in proper positions per reference photo. Install hold-down pins and springs, then upper and lower return springs using brake spring tool.
9. 9

   Adjust brake shoes and install drum
   Rotate the brake adjuster star wheel to expand the shoes until they nearly contact the drum diameter. Clean the brake drum mating surface on the hub. Install the brake drum, ensuring it seats properly on the hub. The drum should drag slightly when rotated. Back off adjuster 3-4 clicks until drum rotates freely with minimal drag.
10. 10

    Bleed the brake system
    Fill the master cylinder reservoir with fresh DOT 4 LV brake fluid to the MAX line. 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 helper pump brake pedal 3-4 times and hold. Open bleeder screw to release fluid and air, then close before helper releases pedal. Repeat until fluid flows clear without air bubbles. Torque bleeder screw to specification. Check and top off master cylinder after bleeding.
    ⚠Never allow the master cylinder reservoir to run dry during bleeding or air will enter the system.
    ℹ️You may need to bleed additional wheels in the proper sequence (furthest from master cylinder first: right rear, left rear, right front, left front) for complete air removal.
    Torque spec

    Bleeder Screw10 Nm (7 lb-ft)
11. 11

    Reinstall wheel and lower vehicle
    Install wheel onto hub and start all lug nuts by hand. Using a star pattern, snug lug nuts with hand tools but do not fully torque. Lower vehicle until tire just contacts ground to prevent wheel rotation. Torque wheel lug nuts to specification in a star pattern. Completely lower vehicle and remove jack stands.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Verify brake pedal feels firm with no sponginess after bleeding
2. Check master cylinder fluid level and top off to MAX line with DOT 4 LV fluid
3. Pump brake pedal several times to seat brake shoes against drum
4. Test parking brake engagement and adjust cable if necessary
5. Properly dispose of old brake fluid and contaminated parts per local regulations

Verification

• Start engine and pump brake pedal - it should be firm and hold steady pressure
• Check for any brake fluid leaks at wheel cylinder, brake line connection, and bleeder screw
• Test drive in safe area at low speed to verify proper brake operation
• Perform several moderate brake applications to seat brake shoes properly
• Re-check brake fluid level after test drive and top off if needed
• Verify no brake warning lights are illuminated on instrument cluster
• Check parking brake holds vehicle on incline

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