Lower Control Arm - Rear

This procedure covers the removal and replacement of the rear lower control arm on a 1972 Ford F-100 with leaf spring rear suspension.

Warnings

Tools required

Parts

• Rear lower control arm (radius arm) × 1 — Use OEM specification
• Control arm front bushing × 1 — Use OEM specification
• Control arm rear bushing × 1 — Use OEM specification
• Control arm mounting bolts (if corroded) × 2 — Use OEM specification

Preparation

1. Park vehicle on level, solid ground and set parking brake firmly
2. Place wheel chocks on both sides of front wheels
3. Loosen rear wheel lug nuts (side being serviced) while vehicle is on ground
4. Apply penetrating oil to all control arm mounting hardware and allow to soak

Procedure

1. 1

   Raise and support vehicle
   Raise the rear of the vehicle using a floor jack positioned under the center of the rear axle housing (differential) or on the axle tube near the spring seat. Lift until the tire clears the ground by 3-4 inches. Place a jack stand under the frame rail behind the rear wheel well. Lower the vehicle onto the jack stand while keeping the jack in position under the axle to control axle movement.
2. 2

   Remove rear wheel
   Remove the lug nuts completely and remove the rear wheel and tire assembly. Set aside in a safe location. Verified detail (A 1972 F-100 (half-ton) typically uses a 5-lug wheel, not 8-lug. 8-lug is characteristic of F-250/F-350 (3/4 and 1-ton). Lug count needs verification.): Remove the 5 lug nuts completely and remove the rear wheel and tire assembly.
3. 3

   Identify control arm mounting points
   Locate the rear lower control arm (radius arm). The front mount attaches to a bracket on the frame rail approximately 24 inches forward of the axle. The rear mount attaches to a bracket on the rear axle housing. Inspect both mounting points for corrosion and damage.
4. 4

   Support rear axle
   Position a second floor jack under the rear axle housing on the side being serviced, near the coil spring seat / axle tube. Raise jack until it just contacts the axle with slight upward pressure. This prevents the axle from shifting when the control arm is removed.
5. 5

   Remove rear control arm mounting bolt
   Locate the rear mounting bolt that connects the control arm to the axle housing bracket. Using a 3/4" socket and breaker bar on the bolt head and a 3/4" wrench on the nut, loosen and remove the bolt. The bolt passes through the control arm bushing and axle bracket. Remove the bolt completely and retain the washer and nut if reusing.
6. 6

   Remove front control arm mounting bolt
   Locate the front mounting bolt that connects the control arm to the frame rail bracket. Using a 3/4" socket and breaker bar on the bolt head and a 3/4" wrench on the nut, loosen and remove the bolt. The bolt passes through the control arm bushing and frame bracket. You may need to use a pry bar to apply slight pressure to the control arm to relieve binding. Remove the bolt completely and retain hardware if reusing.
7. 7

   Remove control arm
   With both mounting bolts removed, pull the control arm away from the mounting brackets. The arm should come free easily. If the bushings are seized in the brackets, use a pry bar to carefully work the arm loose. Inspect the removed arm for cracks, bending, or damage.
8. 8

   Inspect and clean mounting brackets
   Inspect the frame rail bracket and axle housing bracket for cracks, elongated bolt holes, or damage. Use a wire brush to clean rust and debris from the bracket surfaces and bolt holes. If brackets are damaged, they must be repaired or replaced before installing the new control arm.
9. 9

   Install bushings in new control arm
   If the new control arm does not have bushings pre-installed, press or drive the front and rear bushings into the control arm eyes. Ensure bushings are seated fully and oriented correctly with any grease fittings accessible. Apply a light coating of soap solution to bushing outer surfaces to ease installation into brackets.
10. 10

    Position new control arm
    Position the new control arm into place with the front end at the frame bracket and the rear end at the axle bracket. Align the control arm bushing holes with the bracket holes. You may need to use the floor jack under the axle to raise or lower the axle slightly to align the holes.
11. 11

    Install front mounting bolt
    Insert the front mounting bolt through the frame bracket and control arm bushing from the inboard side. Install the washer and nut on the outboard side. Thread the nut on by hand until snug but do not fully tighten yet. The vehicle weight must be on the suspension before final torquing.
12. 12

    Install rear mounting bolt
    Insert the rear mounting bolt through the axle bracket and control arm bushing. Install the washer and nut. Thread the nut on by hand until snug but do not fully tighten yet. Ensure the control arm moves freely without binding.
13. 13

    Reinstall wheel and lower vehicle
    Reinstall the rear wheel and tire assembly. Thread all 5 lug nuts on by hand, then tighten in a star pattern until snug. Remove the jack stand from under the frame rail. Carefully lower the vehicle using the floor jack until the full weight is on the suspension and the tire is firmly on the ground. Remove wheel chocks.
14. 14

    Torque control arm mounting bolts
    With the vehicle weight on the suspension, torque the front and rear control arm (trailing arm) mounting bolts to the factory specification from the 1972 F-100 shop manual (VERIFY — do not rely on estimated values). Torque the wheel lug nuts to the factory specification (approximately 85-115 ft-lbs for a 5-lug F-100 — VERIFY) in a star pattern. Verified detail (Factory torque specification for 1972 Ford F-100 wheel lug nuts): 103.0 lb-ft (140.0 Nm)
    ⚠Control arm mounting bolts must be torqued with vehicle weight on the suspension to prevent bushing bind and premature wear.

Reassembly

1. Control arm mounting bolts must be torqued to specification with vehicle at normal ride height
2. Verify all hardware is tightened and no tools are left under vehicle
3. Test drive vehicle at low speed and listen for unusual noises from rear suspension

Verification

• Visually inspect both control arm mounting bolts to confirm they are fully installed and torqued
• Grasp the control arm and attempt to move it by hand - there should be no excessive play at the mounting points
• Drive vehicle forward and backward slowly while turning to verify normal suspension operation and no clunking noises
• Check that the rear axle alignment appears correct and the vehicle tracks straight

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