Radius Arm Bushing

This procedure replaces the radius arm bushings on the front suspension of a 1972 Ford F-100, which connect the radius arms to the frame and axle.

Warnings

Tools required

Parts

• Radius arm bushing kit (front and rear bushings per side) × 2 — Use OEM specification
• Radius arm to frame mounting hardware kit (if corroded) × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and set parking brake
2. Place wheel chocks behind rear wheels
3. Loosen front wheel lug nuts while vehicle is on ground
4. Apply penetrating oil to radius arm mounting bolts at frame and axle
5. Raise front of vehicle and support frame rails on jack stands rated for vehicle weight
6. Remove both front wheels
7. Position floor jack under front axle center to support axle weight

Procedure

1. 1

   Support front axle and assess suspension position
   Place floor jack under the front axle differential housing center. Raise jack until it just contacts the axle and supports its weight but does not lift the vehicle higher. The axle should be in a neutral position with minimal load on the radius arms. Mark the current ride height position for reference during reassembly.
2. 2

   Remove radius arm to frame front mounting bolt
   Locate the front radius arm mounting point at the frame rail. The radius arm front end is retained at the frame bracket by the bushing assembly and a large retaining nut on the radius arm stud. Using the correct large SAE socket (verify size against the Ford service manual, commonly around 1-1/8 in), remove the front mounting nut and washers. The stud passes through the frame bracket and the front bushing of the radius arm. If seized, apply additional penetrating oil and allow to soak, then use breaker bar for removal. Remove bolt completely and set aside hardware. Verified detail (1972 F-100 used SAE/Imperial fasteners, not metric. The radius arm to frame bolt is typically 3/4 inch (requiring 1-1/8 inch socket), not 21mm. Metric fasteners were not standard on Ford trucks until the 1980s.): Using a 1-1/8 inch socket on the nut and 1-1/8 inch wrench on the bolt head, remove the front mounting hardware.
   ⚠This bolt may be under slight tension, control the socket to prevent sudden release
3. 3

   Remove radius arm to axle rear mounting bolt
   Locate the rear radius arm mounting point at the front axle beam, approximately where the I-beam curves upward. Using the correct SAE socket and wrench (verify size against the Ford service manual), remove the through-bolt and nut that secure the radius arm to the axle bracket. This bolt passes through the rear bushing eye of the radius arm. Once loosened, support the radius arm with one hand as you remove the bolt completely to prevent it from dropping. Verified detail (1972 F-100 used SAE/Imperial fasteners, not metric. The radius arm to axle bolt is typically 5/8 inch or 3/4 inch (requiring 15/16 inch or 1-1/8 inch socket), not 19mm. Metric fasteners were not standard on Ford trucks until the 1980s.): Using a 15/16 inch socket and wrench, remove the through-bolt and nut that secure the radius arm to the axle bracket.
4. 4

   Remove radius arm from vehicle
   With both mounting bolts removed, carefully lower and remove the radius arm from the vehicle. The arm may be tight in the mounting brackets and require light tapping with a hammer or prying with a pry bar to free it. Once removed, place the radius arm on a workbench for bushing removal. Inspect the arm for cracks, bends, or severe corrosion that would require replacement.
5. 5

   Remove old front bushing from radius arm
   The front bushing is pressed into the forward eye of the radius arm. Using a bushing press kit with appropriate size adapters, or a hydraulic press with support plates, press the old bushing out of the arm. Position the arm so the bushing can be pushed out through the open side. Apply steady pressure until the bushing sleeve and rubber separate from the arm eye. If using a C-clamp method, use a socket slightly smaller than the bushing outer diameter to push against the bushing, and a socket or pipe with an inner diameter LARGER than the bushing outer diameter on the opposite side so the bushing can pass into it. Clean the bushing bore thoroughly with a wire brush after removal.
6. 6

   Remove old rear bushing from radius arm
   The rear bushing is pressed into the rear eye of the radius arm using the same method as the front. Press the old bushing out using the bushing press or C-clamp method. The rear bushing bore should be cleaned thoroughly with a wire brush, removing all old rubber residue, rust, and debris to ensure proper fit of the new bushing.
7. 7

   Install new front bushing
   Apply a light coating of dish soap or bushing installation lubricant (not grease) to the outer diameter of the new front bushing. Position the bushing at the front eye of the radius arm, ensuring proper orientation if the bushing has a directional design. Using the bushing press or C-clamp method, press the new bushing straight into the arm eye until it is fully seated and flush with both sides of the eye. The bushing inner sleeve should be centered in the bore. Verify the bushing is not cocked or misaligned.
8. 8

   Install new rear bushing
   Apply light lubrication to the outer diameter of the new rear bushing. Position and press the rear bushing into the rear eye of the radius arm using the same method as the front bushing. Ensure the bushing is pressed in straight and seats completely flush. The inner metal sleeve must be properly centered to allow the mounting bolt to pass through freely.
9. 9

   Reinstall radius arm to axle
   Position the radius arm back into the vehicle, aligning the rear bushing eye with the mounting bracket on the front axle. Insert the rear mounting bolt through the axle bracket and radius arm bushing. Thread the nut onto the bolt by hand but do not tighten yet. The suspension geometry requires all fasteners to be torqued with the vehicle at ride height.
10. 10

    Reinstall radius arm to frame
    Align the front bushing eye of the radius arm with the frame mounting bracket. Insert the front mounting bolt through the frame bracket and radius arm bushing. Thread the nut onto the bolt by hand. Do not tighten yet. Both mounting points should have bolts finger-tight at this stage.
11. 11

    Load suspension to ride height
    Using the floor jack positioned under the front axle, carefully raise the axle until the suspension compresses to approximate normal ride height position. Reference the mark made during disassembly. The suspension should be at or near the position it occupies when the vehicle is sitting on the ground with normal load. This ensures the radius arm bushings are torqued in their neutral operating position, preventing premature bushing failure.
12. 12

    Torque radius arm fasteners
    With the suspension loaded to ride height, torque the radius arm mounting bolts. Torque the front frame mounting bolt/nut and the rear axle mounting bolt/nut to the values specified in the Ford factory service manual for the 1972 F-100 twin I-beam front suspension (verify against OEM documentation before final tightening). After torquing, verify both fasteners are secure and properly seated. Lower the jack slightly to verify the suspension holds position correctly.
13. 13

    Repeat procedure for opposite side
    If replacing bushings on both sides, repeat steps 2 through 12 for the opposite radius arm. Maintain axle support with the floor jack throughout the process. Ensure both sides are torqued with the suspension at ride height for proper bushing alignment and longevity.

Reassembly

1. Reinstall front wheels and torque lug nuts to manufacturer specification
2. Lower vehicle completely to ground
3. Remove jack stands and floor jack
4. Re-torque wheel lug nuts in star pattern after vehicle is on ground
5. Test drive vehicle at low speed and verify no unusual noises or handling issues

Verification

• Verify both radius arm mounting bolts are tight and properly torqued
• Check that radius arms move smoothly through suspension travel without binding
• Inspect for any fluid leaks that may have been disturbed during work
• Perform test drive and verify improved handling and elimination of clunking noises over bumps
• After 50-100 miles, re-check torque on all radius arm mounting fasteners

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