This procedure covers the removal and replacement of the rear trailing arm on a 2015-2020 Ford F-150 RWD with the 3.5L EcoBoost engine.

Warnings

Tools required

Parts

• Rear trailing arm × 1 — Use OEM specification
• Trailing arm mounting bolts (if corroded) × 2 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Chock front wheels securely
3. Loosen rear wheel lug nuts while vehicle is on ground
4. Raise rear of vehicle and support with jack stands under frame rails
5. Remove rear wheel on side being serviced
6. Spray all trailing arm mounting bolts with penetrating oil and allow to soak for 10-15 minutes

Procedure

1. 1

   Support rear axle
   Position a floor jack under the rear axle housing near the trailing arm being replaced. Raise jack just enough to take the load off the suspension, but do not lift the axle. This prevents the suspension from dropping when the trailing arm is disconnected.
2. 2

   Remove front trailing arm bolt
   Locate the front mounting bolt where the trailing arm attaches to the frame. Use a socket and breaker bar to remove the bolt and nut. The bolt passes through the trailing arm bushing and frame bracket. Note the orientation of the bolt for reinstallation.
3. 3

   Remove rear trailing arm bolt
   Locate the rear mounting bolt where the trailing arm attaches to the rear axle housing. Remove the bolt and nut using a socket and breaker bar. You may need to slightly adjust the floor jack height to relieve tension on the bolt.
4. 4

   Remove trailing arm
   With both bolts removed, pull the trailing arm away from the frame and axle mounts. If the arm is stuck due to corrosion, use a pry bar to carefully separate it from the mounting points. Inspect the removed arm for damage, cracks, or worn bushings.
5. 5

   Prepare mounting locations
   Clean the mounting surfaces on both the frame bracket and axle housing using a wire brush. Remove any rust, debris, or corrosion. Inspect the mounting holes for damage or elongation. Check that mounting hardware threads are clean and serviceable.
6. 6

   Install new trailing arm
   Position the new trailing arm between the frame mount and axle mount. Insert the front bolt through the frame bracket and trailing arm bushing first, threading the nut on by hand. Then insert the rear bolt through the axle mount and trailing arm bushing, threading that nut on by hand. Do not tighten bolts at this stage.
7. 7

   Align and snug bolts
   Ensure the trailing arm is properly seated in both mounts and the bolts are centered in their mounting holes. Snug both bolts by hand or with a ratchet, but do not torque them yet. The bushings must be torqued with the suspension at ride height to prevent binding.
8. 8

   Reinstall wheel and lower vehicle
   Install the rear wheel and thread lug nuts on by hand. Lower the vehicle until the full weight is on the wheels, but keep the jack stands in place for safety. The suspension must be at normal ride height before final torquing.
9. 9

   Torque trailing arm bolts
   With vehicle weight on the suspension, torque both the front and rear trailing arm mounting bolts to specification. These are critical fasteners that must be torqued at ride height to prevent premature bushing failure.
   Torque spec

   Control Arm Bolts165 Nm (122 lb-ft)
10. 10

    Final wheel installation
    Raise the vehicle slightly to remove jack stands. Lower vehicle completely to the ground. Torque wheel lug nuts in a star pattern to specification.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)

Reassembly

1. Ensure both trailing arm bolts were torqued with vehicle weight on suspension
2. Verify wheel lug nuts are properly torqued after first 50 miles of driving
3. If both trailing arms were replaced, repeat procedure for opposite side

Verification

• Test drive vehicle at low speed and verify no unusual noises from rear suspension
• Check for proper tracking and alignment - vehicle should not pull to one side
• Visually inspect trailing arm bolts are tight and properly seated
• Listen for any clunking or rattling over bumps which could indicate loose hardware
• Consider having a professional wheel alignment performed if vehicle pulls or tire wear is uneven

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