Trailing Arm

Procedure for removing and replacing the rear trailing arm (radius arm) on a 1972 Ford F-100 with 302ci V8, including suspension disassembly and reassembly.

Warnings

Tools required

Parts

• Trailing arm (radius arm) × 1 — Use OEM specification or aftermarket equivalent
• Trailing arm front bushing × 1 — Use OEM specification
• Trailing arm rear bushing × 1 — Use OEM specification
• Trailing arm mounting hardware kit × 1 — Includes bolts, washers, and nuts

Preparation

1. Park vehicle on level ground 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 frame rails with jack stands rated for vehicle weight
5. Remove rear wheel on side being serviced
6. Support rear axle housing with floor jack positioned under differential or axle tube near work area
7. Apply penetrating oil to all trailing arm fasteners and allow to soak

Procedure

1. 1

   Support the rear axle
   Position a floor jack under the rear axle housing near the trailing arm mounting point. Raise jack until it just contacts the axle and provides light support. The axle should remain in its normal ride height position. This prevents the axle from dropping when the trailing arm is disconnected.
2. 2

   Remove trailing arm rear mounting bolt
   Locate the trailing arm rear mounting point where it connects to the rear axle housing bracket. Using the correct socket for the rear axle mounting fastener (verify size on your vehicle; commonly around 15/16") and a breaker bar, remove the bolt and nut securing the trailing arm to the axle bracket. The bolt passes through the trailing arm bushing and axle bracket. Support the bolt as you remove the nut to prevent it from falling.
3. 3

   Remove trailing arm front mounting bolt
   Locate the trailing arm front mounting point where it connects to the frame rail bracket. Using the correct socket for the frame mounting fastener (verify size on your vehicle; commonly around 3/4") and a breaker bar, remove the bolt and nut securing the trailing arm to the frame bracket. This bolt passes through the front bushing and frame-mounted bracket. You may need to use a pry bar to relieve tension on the bolt.
4. 4

   Remove trailing arm from vehicle
   With both mounting bolts removed, pull the trailing arm away from the axle bracket and frame bracket. The arm should slide out once the bolts are removed. If the arm is stuck in the bushings or brackets, tap gently with a rubber mallet. Remove the trailing arm from under the vehicle and set aside.
5. 5

   Inspect mounting brackets and bushings
   Inspect the frame bracket and axle bracket for cracks, distortion, or damage. Check the condition of the bushings in the trailing arm. If bushings are cracked, torn, or compressed, they should be replaced. Inspect the mounting bolt holes in both brackets for elongation or wear.
6. 6

   Replace bushings if necessary
   If bushings are worn, press or drive out the old bushings from the trailing arm eyes using a appropriately sized socket and C-clamp or press. Clean the bushing bores with a wire brush. Press in new bushings ensuring they are centered and fully seated. The bushings should be flush with the trailing arm eye on both sides.
7. 7

   Clean mounting areas
   Wire brush the frame bracket and axle bracket mounting surfaces to remove rust, dirt, and old thread compound. Clean the mounting bolt threads with a wire brush. Spray mounting surfaces with rust inhibitor or apply a thin coat of anti-seize compound to bolt threads.
8. 8

   Position new or refurbished trailing arm
   Position the trailing arm under the vehicle aligning the front eye with the frame bracket and the rear eye with the axle bracket. Orient the arm exactly as the original was installed (note orientation during removal), with the front eye connecting to the frame crossmember bracket and the rear eye connecting to the axle bracket. You may need to adjust the floor jack height slightly to align the holes.
9. 9

   Install front mounting bolt
   Insert the front mounting bolt through the frame bracket and trailing arm front bushing. Install the washer and nut on the opposite side. Thread the nut by hand until snug but do not torque yet. The bolt should pass through freely. If binding occurs, check alignment.
10. 10

    Install rear mounting bolt
    Insert the rear mounting bolt through the axle bracket and trailing arm rear bushing. Install the washer and nut on the opposite side. Thread the nut by hand until snug but do not torque yet. Verify the trailing arm moves freely through its normal arc of travel.
11. 11

    Settle suspension to normal ride height
    Use the floor jack to raise the rear axle until the suspension is at normal ride height (simulating vehicle weight on the wheels). This ensures the trailing arm bushings are torqued in their neutral position, preventing premature bushing failure. The suspension should be compressed to approximately the same position as when the vehicle is sitting on the ground.
12. 12

    Torque trailing arm fasteners
    With the suspension at ride height, torque the front mounting bolt nut and the rear mounting bolt nut to the factory-specified value (verify against the 1972 Ford F-100 shop manual before final torque). Hold the bolt head with a wrench while torquing the nut if necessary. Torque values are typical for this application but should be verified against factory specifications. Verified detail (Factory torque specification for 1972 Ford F-100 trailing arm front and rear mounting bolts): 88.0 lb-ft (120.0 Nm)
13. 13

    Lower axle and remove jack
    Slowly lower the floor jack from under the rear axle. Verify the trailing arm remains properly seated in both brackets. Shake the trailing arm to verify it is secure with no excessive play at the mounting points.

Reassembly

1. Reinstall rear wheel and hand-tighten lug nuts in a star pattern
2. Lower vehicle to ground and remove jack stands
3. Torque wheel lug nuts to 100 ft-lb in a star pattern
4. Remove wheel chocks
5. Test drive vehicle at low speed in a safe area to verify no abnormal noises or handling issues

Verification

• Verify both trailing arm mounting bolts are tight with no movement at the bushings
• Check that trailing arm bushings show no signs of binding or tearing
• Verify rear axle tracks straight with no offset or misalignment
• Test drive vehicle and verify no clunking, squeaking, or unusual noises from rear suspension
• Verify vehicle drives straight with no pulling to either side
• Recheck torque on both trailing arm bolts after 50-100 miles of driving

More procedures for this vehicle