This procedure replaces the front strut mounts (upper strut bearing assemblies) on a 2015-2020 Ford F-150 with the 3.5L EcoBoost V6 engine, requiring strut removal from the vehicle.

Warnings

Tools required

Parts

• Front strut mount assembly (left) × 1 — Motorcraft CK-4B503 or equivalent
• Front strut mount assembly (right) × 1 — Motorcraft CK-4B504 or equivalent
• Strut-to-knuckle bolt set × 2 — Use OEM specification if replacement needed

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Place wheel chocks behind rear wheels
3. Loosen front wheel lug nuts 1/4 turn while vehicle is still on ground
4. Raise front of vehicle with floor jack at designated lift points on frame
5. Support vehicle on jack stands rated for vehicle weight, placed at frame rails behind front suspension
6. Remove both front wheels completely
7. Spray penetrating oil on strut tower nuts, strut-to-knuckle bolts, and sway bar link nuts
8. Open hood and prop securely

Procedure

1. 1

   Access strut tower mounting nuts
   Locate the strut tower under the hood. On the driver side, you may need to move aside wiring harnesses or other components for clear access. On the passenger side, remove the air intake duct if necessary for better access. Identify the three 15mm nuts securing the strut mount to the strut tower. Do NOT remove these nuts yet.
2. 2

   Disconnect sway bar link (if necessary)
   If the sway bar link interferes with strut removal, disconnect it from the lower control arm or strut bracket. Hold the sway bar link shaft with a 6mm Allen key to prevent rotation, then remove the nut with a 14mm wrench or socket. Support the link so it doesn't hang on the sway bar.
   Torque spec

   Sway Bar Link70 Nm (52 lb-ft)
3. 3

   Remove strut-to-knuckle bolts
   Locate the two large bolts connecting the strut to the steering knuckle at the bottom of the strut assembly. These are 18mm bolts oriented horizontally. Support the strut assembly from below or have an assistant hold it. Remove both bolts completely. You may need to use a pry bar to separate the strut from the knuckle once bolts are removed. The knuckle will now be free to move; be careful not to overextend CV axle or brake hose.
   ⚠Do not allow the knuckle/hub assembly to hang freely by the brake hose or CV axle. Support it with wire or a jack stand if needed.
   Torque spec

   Strut-to-Knuckle Bolts140 Nm (104 lb-ft)
4. 4

   Remove strut tower nuts and extract strut
   Return to the engine bay. While supporting the strut assembly from below (or having an assistant hold it from below), remove the three 15mm nuts from the top of the strut tower. Once all three nuts are removed, carefully lower the strut assembly down and out through the wheel well. Maneuver past the brake hose and CV axle. Place the strut assembly on a stable workbench.
   ⚠The strut assembly weighs 30-40 lbs and will drop when the last nut is removed. Maintain firm control during removal.
   Torque spec

   Strut Tower Nuts50 Nm (37 lb-ft)
5. 5

   Install spring compressors
   With the strut on the workbench, install the spring compressor tools on opposite sides of the coil spring (180 degrees apart). Follow the spring compressor manufacturer's instructions exactly. Ensure the compressor hooks are fully engaged on the coil spring and are seated in the coil valleys, not on the peaks. Alternate tightening each compressor gradually and evenly (a few turns at a time) to maintain even spring compression.
   ⚠️This is the most dangerous step. Improperly installed spring compressors can slip, causing violent spring release. Verify compressor engagement before applying significant tension. Keep your face and body clear of the spring path.
6. 6

   Compress spring and remove strut shaft nut
   Continue compressing the spring gradually and evenly until you can see visible gap between the upper spring seat and the spring, and the spring is no longer pushing on the strut mount. You should be able to wiggle the upper mount slightly. The center shaft nut at the top of the strut is typically 18mm or 21mm. Use a box wrench to hold the strut shaft from rotating (there will be flats on the shaft) while removing the top nut with a socket. Remove the nut, washer, and upper strut mount assembly.
   ⚠️If the spring is not sufficiently compressed, the mount will be under tension and the shaft nut will be difficult to remove. Do NOT force it. Compress the spring more until the mount is free-floating.
7. 7

   Disassemble and inspect components
   Remove the upper mount assembly, bearing plate, spring upper seat, and any isolators or bumpers. Keep track of the order and orientation of all components. Inspect the spring for cracks or damage. Inspect the strut body for leaks (minor seepage is normal; dripping oil indicates failure). Mark the orientation of the spring on the strut body before removal if you plan to reuse the spring.
8. 8

   Install new strut mount
   Clean the strut shaft threads with a wire brush. Install components in reverse order: spring lower seat on strut body (if removed), spring (ensure proper orientation - end coils sit in formed pockets of spring seats), upper spring seat with correct orientation, bearing plate, and new strut mount assembly. Ensure all components are properly aligned. The mount typically has a notch or mark that should align with a specific orientation for proper installation.
   ⚠The upper mount has specific front-to-rear orientation. Incorrect installation will affect alignment and handling. Refer to manufacturer markings on the mount.
9. 9

   Reinstall strut shaft nut
   Thread the shaft nut onto the strut shaft by hand. Hold the shaft with a wrench on the flats and tighten the nut. Tighten firmly (typically 55-75 Nm / 40-55 lb-ft, though this value is not in your torque database - use factory specification if available or tighten securely). Ensure all components are properly seated and the mount sits flush.
10. 10

    Release spring compressors
    Very gradually and evenly release tension on both spring compressors, alternating between them (a few turns at a time on each). As you release tension, verify that the spring seats properly in the upper and lower spring seats. Once the spring is fully seated and bearing all load, completely remove the spring compressor tools.
    ⚠Release compressor tension slowly and evenly. Listen for any unusual sounds indicating improper seating. If anything seems wrong, stop and re-compress to investigate.
11. 11

    Reinstall strut assembly in vehicle
    Maneuver the strut assembly back up through the wheel well, carefully routing past the brake hose and CV axle. Align the three studs on top of the strut mount with the holes in the strut tower. Install all three 15mm nuts on the strut tower studs and tighten by hand. Support the bottom of the strut to maintain alignment.
    Torque spec

    Strut Tower Nuts50 Nm (37 lb-ft)
12. 12

    Connect strut to steering knuckle
    Align the steering knuckle with the strut bracket at the bottom of the strut. You may need to use a pry bar or jack to position the knuckle properly. Install both strut-to-knuckle bolts and hand-tighten. Verify proper alignment before final torquing.
    Torque spec

    Strut-to-Knuckle Bolts140 Nm (104 lb-ft)
13. 13

    Reconnect sway bar link
    If the sway bar link was disconnected, reconnect it to the lower control arm or strut bracket. Hold the link shaft with the 6mm Allen key and install the nut. Torque to specification.
    Torque spec

    Sway Bar Link70 Nm (52 lb-ft)
14. 14

    Torque all fasteners
    Using a torque wrench, torque the three strut tower nuts to 50 Nm (37 lb-ft) in a star pattern. Torque both strut-to-knuckle bolts to 140 Nm (104 lb-ft). If sway bar link was disconnected, verify it is torqued to 55 Nm (41 lb-ft).
    Torque spec

    Strut Tower Nuts50 Nm (37 lb-ft)

    Strut-to-Knuckle Bolts140 Nm (104 lb-ft)

    Sway Bar Link70 Nm (52 lb-ft)
15. 15

    Reinstall wheels and lower vehicle
    Install the front wheel and thread all lug nuts by hand to prevent cross-threading. Snug lug nuts in a star pattern but do not fully torque yet. Repeat for second side if performing both. Raise vehicle slightly with floor jack to remove jack stands. Lower vehicle completely to the ground. Torque wheel lug nuts to specification in a star pattern.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)

Reassembly

1. If both sides were performed, verify both strut mounts are installed with correct orientation
2. Verify no tools or parts were left in the engine bay or wheel wells
3. Check that all fasteners have been torqued to specification
4. Double-check that wheel lug nuts are properly torqued

Verification

• Start vehicle and turn steering wheel lock-to-lock while stationary. Listen for any clicking, popping, or binding from the strut mounts. All sounds should be normal
• Test drive at low speed in a safe area. Check for unusual noises over bumps, proper steering return to center, and normal handling
• After 50-100 miles, re-torque wheel lug nuts to specification and verify no looseness in strut mounting
• CRITICAL: Have a professional wheel alignment performed immediately. New strut mounts affect camber and may affect caster. Driving with improper alignment causes tire wear and affects handling and safety
• After alignment, perform final test drive to verify proper handling and no abnormal noises

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