This procedure covers the replacement of rear leaf spring U-bolt kits on a 2011-2014 Ford F-150 4WD, including removal of old U-bolts, inspection of components, and installation with proper torque specifications.

Warnings

Tools required

Parts

• Leaf spring U-bolt kit (includes U-bolts, nuts, and backing plate) × 1 — Use OEM specification or equivalent

Preparation

1. Park vehicle on level, solid surface and engage parking brake
2. Place wheel chocks in front of both front wheels
3. Spray penetrating oil on all U-bolt nuts and allow to soak for at least 15 minutes
4. Loosen rear wheel lug nuts while vehicle is on ground, but do not remove

Procedure

1. 1

   Raise and support vehicle
   Lift the rear of the vehicle using a floor jack at the rear axle differential. Raise until rear wheels are off the ground. Place jack stands under the frame rails on both sides, ensuring they are positioned on solid frame contact points. Lower the vehicle onto jack stands. Leave the floor jack under the axle with slight upward pressure to support the axle assembly, but not enough to compress the leaf springs.
2. 2

   Remove rear wheels
   Finish removing the loosened lug nuts and remove both rear wheels. This provides better access to the U-bolt assembly and allows inspection of brake components.
3. 3

   Support axle independently
   Position the floor jack directly under the axle tube near the U-bolt location being serviced. Apply just enough upward pressure to prevent the axle from dropping when the U-bolts are removed, but do not lift the axle away from the leaf spring. The spring should maintain light contact with the axle.
4. 4

   Remove U-bolt nuts
   Using a 3/4 inch socket and ratchet, remove the four nuts securing the U-bolts (two per U-bolt). Work in a crisscross pattern, loosening each nut gradually rather than removing one completely before starting the next. This prevents binding. If nuts are severely corroded, apply additional penetrating oil and use a breaker bar for extra leverage.
   ⚠Do not allow nuts to drop into suspension components. Keep track of all hardware for proper disposal.
5. 5

   Remove U-bolts and backing plate
   Once all nuts are removed, extract the U-bolts by pulling them downward out of the mounting plate. Remove the backing plate (also called spring plate or axle seat) from between the axle and leaf spring. Inspect the plate for cracks, excessive wear, or deformation. The plate should be replaced if damaged.
6. 6

   Inspect components
   With U-bolts removed, inspect the leaf spring top surface for wear patterns, cracks, or broken leaves. Check the axle spring perch for corrosion, damage, or wear. Inspect the center bolt that holds the spring pack together; if the head is damaged or the spring leaves are shifting, the entire spring may need replacement. Clean both the axle perch and spring contact surfaces with a wire brush to remove rust and debris.
7. 7

   Position new backing plate
   Place the new backing plate from the U-bolt kit onto the top of the leaf spring, ensuring it is centered over the axle. The plate should fit the contour of the spring. Verify the axle is seated properly in the spring center with the axle spring perch aligned. Adjust the floor jack height if necessary to achieve proper alignment.
8. 8

   Install new U-bolts
   Insert the new U-bolts up through the holes in the mounting plate and backing plate, ensuring they pass on either side of the axle tube. Thread the new nuts onto the U-bolt ends by hand until they contact the mounting plate. Verify all components are properly aligned before proceeding. Apply a light coating of anti-seize compound to the threads if desired, but avoid getting any on the torque surface of the nuts.
9. 9

   Torque U-bolt nuts to specification
   Using a torque wrench, tighten the U-bolt nuts in a crisscross pattern to the manufacturer's specification. Ford typically specifies 76-98 lb-ft for F-150 rear U-bolts, but verify with your specific U-bolt kit instructions as torque values may vary based on U-bolt diameter and thread pitch. Tighten in three stages: first to 25 lb-ft, then 50 lb-ft, then final specification. This ensures even clamping force and proper seating of all components.
   ℹ️U-bolt torque specifications are not provided in the verified database. Consult the replacement U-bolt kit instructions or Ford service manual for proper torque value, typically 76-98 lb-ft for this application.
10. 10

    Repeat for opposite side
    If replacing U-bolts on both sides of the axle, reposition the floor jack under the opposite side axle tube and repeat steps 4 through 9 for the second U-bolt assembly. Maintain vehicle support on jack stands throughout this process.
11. 11

    Reinstall wheels
    Place the rear wheels back onto the hubs, threading lug nuts by hand to start. Use a torque wrench to tighten lug nuts to specification in a star pattern.
    Torque spec

    Wheel Lug Nuts156 Nm (115 lb-ft)
12. 12

    Lower vehicle and perform final torque check
    Carefully raise the vehicle slightly off the jack stands using the floor jack, remove the jack stands, and lower the vehicle completely to the ground. With the full vehicle weight on the suspension, perform a final torque check on all U-bolt nuts using the same crisscross pattern. This is critical as the leaf spring will settle under load and may require slight additional tightening to maintain proper torque.
    ℹ️Some settling is normal. Plan to re-check U-bolt torque after 50-100 miles of driving.

Reassembly

1. Ensure all U-bolt nuts are torqued to specification with vehicle weight on suspension
2. Verify wheel lug nuts are properly torqued in star pattern
3. Remove wheel chocks and verify parking brake releases properly

Verification

• Visually inspect U-bolt installation to confirm backing plate is seated flush and U-bolts are properly positioned around axle tube
• Check that there is no gap between the leaf spring and axle, and no gap between backing plate and spring top surface
• Test drive vehicle at low speed and listen for any unusual noises from rear suspension, such as clunking or rattling that would indicate loose components
• After 50-100 miles of driving, re-torque U-bolt nuts to specification as leaf springs will settle under normal load
• Inspect for any signs of axle movement or U-bolt loosening during the first few hundred miles

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