Leaf Spring U-Bolt Kit

Replace the rear leaf spring u-bolts and mounting hardware to restore proper axle-to-spring clamping force and suspension integrity.

Warnings

Tools required

Parts

• Leaf spring u-bolt kit (includes u-bolts, nuts, and spring plate) × 1 — Use OEM specification or equivalent heavy-duty aftermarket
• Spring plate cushion (if deteriorated) × 1 — Use OEM specification

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Chock front wheels securely
3. Spray penetrating oil on all u-bolt nuts and allow to soak for 15-30 minutes
4. Loosen (but do not remove) rear wheel lug nuts while vehicle is on ground

Procedure

1. 1

   Raise and support vehicle
   Using a floor jack, raise the rear of the vehicle by the frame rails. Place jack stands under the frame rails on both sides, ensuring they are positioned securely on solid frame sections. Lower vehicle onto jack stands. Remove rear wheels completely.
2. 2

   Support rear axle assembly
   Position a floor jack or axle stand under the center of the rear differential housing. Raise jack until it just contacts the differential, providing support but not lifting the axle. This will control axle position when u-bolts are removed. Verify brake lines, vent hoses, and ABS wiring have adequate slack for axle to lower approximately 2-3 inches.
   ⚠️The axle must be supported before removing u-bolts. Failure to support the axle can result in sudden drop, component damage, or serious injury.
3. 3

   Remove shock absorber lower mount (if necessary)
   If the shock absorber lower mount interferes with u-bolt access, remove the lower shock mounting bolt on the side being serviced. Support the shock to prevent it from hanging on the upper mount.
4. 4

   Remove u-bolt nuts
   Using a breaker bar and socket, remove the four u-bolt nuts from one side of the axle. Remove the u-bolt spring plate (the metal plate that sits between the nuts and the axle perch). Carefully extract both u-bolts from the spring pack and axle assembly. Inspect the spring plate cushion for deterioration, cracking, or compression damage.
5. 5

   Clean mounting surfaces
   Use a wire brush to thoroughly clean the top of the spring pack where the axle perch sits, the axle perch bottom surface, and the spring plate contact area. Remove all rust, dirt, and old rubber debris. This ensures proper seating and torque transfer.
6. 6

   Install new spring plate cushion
   If replacing the spring plate cushion, position the new cushion on top of the leaf spring pack, centered under where the axle perch will sit. Ensure the cushion is properly oriented with any locating features aligned.
7. 7

   Position axle and install new u-bolts
   Using the floor jack, carefully raise or lower the axle assembly until the axle perch is centered on the spring pack and cushion. Insert the new u-bolts through the spring pack from the bottom, ensuring they pass on either side of the axle perch. The u-bolt legs should extend evenly above the spring pack.
8. 8

   Install spring plate and nuts
   Place the new spring plate over the u-bolt threads, ensuring it sits flat against the top of the spring pack. Thread all four u-bolt nuts onto the u-bolt threads by hand until finger-tight. Verify the spring plate is seated evenly and the axle perch is properly centered on the spring.
9. 9

   Torque u-bolt nuts in sequence
   Torque the u-bolt nuts in a criss-cross pattern (front-left, rear-right, front-right, rear-left) in three stages: first to 50 lb-ft, then to 100 lb-ft, and finally to the manufacturer's specification (verify against the kit instructions and service manual; commonly in the range of 140-160 lb-ft for the larger-diameter u-bolts used on Ram 2500). Consult the u-bolt kit instructions for exact torque specification as it varies by u-bolt diameter and thread pitch. Re-check all four nuts after final torque to ensure even clamping.
   ⚠U-bolt torque specification varies by bolt size and application. Always follow the kit manufacturer's torque specification, as over-torquing can damage springs and under-torquing can allow axle movement.
10. 10

    Repeat for opposite side
    Repeat steps 4 through 9 for the u-bolts on the opposite side of the axle. Maintain axle support with the floor jack throughout the process.
11. 11

    Reinstall shock absorbers
    If shock absorber lower mounts were removed, reinstall the lower shock mounting bolts and torque to specification (typically 60-70 lb-ft, consult service manual for exact specification).
12. 12

    Reinstall wheels and lower vehicle
    Reinstall rear wheels and thread lug nuts by hand. Carefully raise vehicle off jack stands using floor jack, then remove jack stands. Lower vehicle to ground. Torque wheel lug nuts to specification in a star pattern.
    Torque spec

    Wheel Lug Nuts183 Nm (135 lb-ft)

Reassembly

1. After 50-100 miles of driving, re-torque all u-bolt nuts to specification to compensate for spring pack settling
2. Inspect u-bolt torque again after 500 miles and at regular intervals during routine maintenance

Verification

• Verify all u-bolt nuts are torqued to specification and show no signs of looseness
• Check that the axle assembly sits centered on the leaf springs with no lateral shift
• Confirm adequate clearance between axle, spring pack, and frame components throughout suspension travel
• Test drive vehicle and verify no clunking, banging, or unusual handling behavior from the rear suspension
• Inspect for any fluid leaks from differential or brake components that may have been disturbed during the procedure

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