Leaf Spring

This procedure covers the removal and replacement of a rear leaf spring on a 1972 Ford F-100 with 302ci V8 engine, including U-bolt removal, spring shackle disassembly, and reinstallation.

Warnings

Tools required

Parts

• Rear leaf spring (driver or passenger side) × 1 — Use OEM specification
• U-bolt kit (4 U-bolts per side) × 1 — Use OEM specification
• Spring shackle bushings (front and rear) × 1 — Use OEM specification
• Spring shackle bolts and nuts × 1 — Use OEM specification

Preparation

1. Park vehicle on level, solid ground and engage parking brake
2. Chock the front wheels on both sides
3. Spray all U-bolt nuts, spring shackle bolts, and mounting hardware with penetrating oil if hardware appears corroded
4. Loosen (but do not remove) the wheel lug nuts on the side being serviced
5. Raise the rear of the vehicle using a floor jack at the frame rail
6. Place jack stands under the frame rails on both sides, ensuring vehicle is stable
7. Remove the rear wheel on the side being serviced
8. Position a floor jack under the rear axle housing near the wheel being serviced to support the axle weight

Procedure

1. 1

   Support and lower the rear axle
   With the floor jack positioned under the axle housing, raise the jack just enough to contact the axle and take up the weight. Slowly lower the jack to allow the leaf spring to extend and relieve tension, but do not let the axle hang on the shock absorbers. Lower approximately 3-4 inches from ride height to create clearance between the spring and frame.
2. 2

   Remove shock absorber lower mount
   Locate the lower shock absorber mounting bolt on the axle bracket. Using a 9/16 inch socket, remove the lower shock bolt and nut. Swing the shock absorber up and out of the way. This prevents damage to the shock during spring removal.
3. 3

   Remove U-bolt nuts and washers
   Locate the 4 U-bolt nuts securing the spring to the axle housing (2 U-bolts straddling the axle, 4 nuts total). Using a 9/16 inch socket, remove all 4 nuts and flat washers. Set hardware aside for comparison with new parts. Verified detail (Incorrect count - should be 2 U-bolts with 4 nuts total per side (not '2 U-bolts per side'). Each U-bolt creates 2 threaded ends, so 2 U-bolts = 4 nuts on one side of the truck.): Locate the 4 U-bolt nuts securing the spring to the axle housing (2 U-bolts with 4 nuts total).
4. 4

   Remove U-bolts and spring plate
   Remove the 2 U-bolts from the axle spring perch. Remove the spring plate (saddle) that sits between the U-bolts and the leaf spring. Inspect the spring plate for cracking or damage.
5. 5

   Remove rear spring shackle
   Locate the rear spring shackle connecting the rear spring eye to the frame bracket. Using a 3/4 inch socket, remove the upper shackle bolt connecting the shackle to the frame bracket. Then remove the lower shackle bolt connecting the shackle to the spring eye. Remove the shackle assembly. Note the orientation of bushings and sleeves for reassembly.
6. 6

   Remove front spring mounting bolt
   Locate the front spring eye bolt that passes through the frame bracket. Using a 3/4 inch socket and wrench, remove the nut from the front spring bolt. Using a pry bar or hammer, drive the bolt out of the spring eye and frame bracket. The bolt may be seized in the bushing and require significant force.
7. 7

   Remove leaf spring assembly
   With both ends disconnected, carefully lower and remove the leaf spring assembly from the vehicle. The spring will be heavy and awkward to handle. Inspect the frame brackets and axle spring perch for damage or excessive rust.
8. 8

   Inspect and prepare new spring
   Compare the old spring to the new spring to verify correct length and number of leaves. If reusing spring shackles, inspect bushings for cracking, compression, or deterioration. Replace bushings if worn. Wire brush the axle spring perch and frame mounting brackets to remove rust and debris.
9. 9

   Install front spring eye
   Position the new leaf spring with the front eye aligned with the frame bracket. Insert the front spring eye bolt through the frame bracket and spring bushing. Install the nut on the bolt but do not fully tighten yet. Leave the nut loose enough for the spring to pivot.
10. 10

    Install rear spring shackle
    Position the rear spring shackle to the rear spring eye and install the lower shackle bolt with nut. Then align the upper shackle with the frame bracket and install the upper shackle bolt with nut. Do not fully tighten either bolt yet. Leave hardware loose enough for suspension movement.
11. 11

    Position spring on axle perch
    Using the floor jack, carefully raise the axle housing until the spring center bolt aligns with the locating hole in the axle spring perch. Verify the spring is centered on the perch with equal overhang on both sides.
12. 12

    Install spring plate and U-bolts
    Place the spring plate over the leaf spring and axle. Install the 2 new U-bolts from the kit, ensuring they pass through the spring plate and axle spring perch. Install flat washers and nuts on all 4 threaded ends (2 per U-bolt). Hand-tighten the nuts in a criss-cross pattern to draw the assembly together evenly.
13. 13

    Torque U-bolt nuts
    Using a torque wrench and 9/16 inch socket, tighten the U-bolt nuts in a criss-cross pattern to 75 ft-lbs. Make multiple passes, increasing torque gradually (25 ft-lbs, 50 ft-lbs, then 75 ft-lbs) to seat the spring plate evenly.
14. 14

    Raise axle to ride height
    Using the floor jack, raise the rear axle until the suspension is at normal ride height (wheels would be on the ground). This loads the suspension and positions the spring bushings correctly before final tightening.
15. 15

    Torque spring eye and shackle bolts
    With the suspension at ride height, torque the front spring eye bolt nut to 100 ft-lbs using a 3/4 inch socket. Torque both rear shackle bolts (upper and lower) to 65 ft-lbs. These must be torqued at ride height to prevent bushing bind.
16. 16

    Reinstall shock absorber
    Swing the shock absorber back into position and align the lower mount with the axle bracket. Install the lower shock bolt and nut. Torque the lower shock bolt to 52.0 lb-ft (70.0 Nm) using a 9/16 inch socket.

Reassembly

1. Reinstall the wheel and hand-tighten lug nuts in a star pattern
2. Raise the vehicle slightly, remove jack stands, and carefully lower the vehicle to the ground
3. Torque wheel lug nuts to 100 ft-lbs in a star pattern
4. After 50-100 miles of driving, re-torque all U-bolt nuts to 75 ft-lbs to account for spring settling

Verification

• Visually inspect that the spring is centered on the axle perch with equal overhang
• Verify all U-bolt nuts, spring eye bolts, and shackle bolts are properly torqued
• Check that the vehicle sits level side-to-side at normal ride height
• Test drive the vehicle at low speed and verify no unusual noises or handling issues
• Inspect for any fluid leaks from the shock absorber after reinstallation

More procedures for this vehicle