This procedure covers replacement of the limited slip clutch pack in the rear differential of a 2021-2024 Ford F-150 with 3.5L EcoBoost engine and RWD configuration.

Warnings

Tools required

Parts

• Limited slip clutch pack kit × 1 — Ford OEM or equivalent with correct disc count
• Differential cover gasket × 1 — Use OEM specification
• Friction modifier additive × 1 — Ford XL-3 or equivalent for limited slip
• RTV silicone gasket maker (if gasket not used) × 1 — Motorcraft TA-31 or equivalent

Fluids

• Motorcraft 75W-140 Synthetic Gear Oil — 2.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Chock front wheels securely
3. Raise rear of vehicle and support on jack stands at frame contact points
4. Remove both rear wheels
5. Mark driveshaft and differential yoke alignment with paint marker for reinstallation reference
6. Place drain pan under differential
7. Allow differential to cool to ambient temperature if vehicle was recently operated

Procedure

1. 1

   Remove driveshaft
   Remove the four driveshaft bolts at the differential yoke. Support the driveshaft and lower it clear of the differential. Use wire or string to secure the driveshaft to the chassis to prevent strain on the transfer case output.
   Torque spec

   Driveshaft Bolts85 Nm (63 lb-ft)
2. 2

   Drain differential fluid
   Remove all differential cover bolts gradually, loosening in a crisscross pattern. Carefully pry the cover away from the housing at the bottom edge first to allow controlled drainage into the drain pan. Remove cover completely and set aside. Inspect drained fluid for metal particles indicating wear or damage.
   ⚠Fluid will drain quickly once cover is loosened. Position drain pan to catch full volume.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
3. 3

   Clean housing and inspect components
   Use shop rags to clean residual fluid from inside the differential housing. Inspect ring and pinion gears for wear, scoring, or damage. Check carrier bearings for roughness or play. If any damage is found, the complete differential may require overhaul beyond clutch pack replacement.
4. 4

   Remove differential pinion shaft
   Locate the pinion shaft lock bolt on the rear of the differential carrier (visible through the differential cover opening). Remove the lock bolt completely. Carefully drive the pinion shaft out toward the ring gear side using a brass punch and hammer. The shaft should slide out freely once the lock bolt is removed.
   ⚠Do not lose the pinion shaft lock bolt. Mark orientation of pinion shaft for reassembly.
5. 5

   Remove spider gears and side gears
   Rotate the differential carrier to align the spider gears with the access opening. Remove both spider gears and their thrust washers. Push the axle shafts inward slightly and remove both side gears with their thrust washers. Keep all components organized and note their orientation for proper reassembly.
6. 6

   Remove old clutch pack
   Remove the existing clutch pack from both sides of the carrier. The pack consists of alternating friction discs and steel plates. Count the discs and plates as you remove them, noting their order and orientation. Inspect discs for glazing, cracking, or excessive wear. Measure disc thickness and compare to new parts to assess wear.
   ℹ️Keep track of shim thickness and location if shims are present. These control clutch pack preload.
7. 7

   Clean carrier and prepare for assembly
   Thoroughly clean all clutch pack contact surfaces in the differential carrier using shop rags and solvent if needed. Remove any glazing or debris from the splines. Inspect the carrier housing for cracks or damage. Ensure all oil passages are clear and unobstructed.
8. 8

   Install new clutch pack
   Soak new friction discs in 75W-140 gear oil for at least 15 minutes before installation. Install the new clutch pack following the exact sequence specified in the kit instructions, typically alternating steel plates and friction discs. Start with the correct component against the carrier housing (usually a steel plate). Ensure all discs and plates seat fully on their respective splines. Install any shims or preload adjusters as specified.
   ⚠Clutch pack sequence and orientation is critical. Refer to kit instructions for exact assembly order.
   ℹ️Friction discs must be thoroughly soaked in gear oil before installation to prevent initial dry operation.
9. 9

   Measure and adjust clutch pack clearance
   Using a dial indicator or feeler gauges, measure the clutch pack end clearance. Place the dial indicator on the end plate and zero it. Lift the clutch pack and record the total movement. Typical clearance is 0.020-0.040 inches, but verify against kit specifications. Adjust clearance by changing shim thickness if needed. This clearance controls limited slip engagement characteristics.
   ⚠Incorrect clearance will cause improper limited slip operation. Too tight causes binding, too loose reduces locking action.
10. 10

    Reinstall side gears and spider gears
    Coat all thrust washers with gear oil. Install the side gears with their thrust washers in the same orientation as removed. Install the spider gears and their thrust washers, ensuring they mesh properly with the side gears. Rotate the carrier to verify smooth operation and proper meshing.
11. 11

    Reinstall pinion shaft and lock bolt
    Align the spider gears and slide the pinion shaft back through the carrier in the same orientation as removed. The shaft should pass through both spider gears. Rotate the assembly to align the lock bolt hole. Install and tighten the pinion shaft lock bolt. Verify the pinion shaft is fully seated and cannot rotate.
    ⚠Pinion shaft lock bolt must be tight. A loose lock bolt will allow the shaft to migrate and cause catastrophic failure.
12. 12

    Clean and prepare cover mating surfaces
    Thoroughly clean the differential housing mating surface and cover using a plastic scraper to remove all old gasket material or RTV. Ensure surfaces are completely clean and dry. Do not use metal scrapers that could gouge the aluminum surfaces. Wipe surfaces with solvent and lint-free rags.
13. 13

    Install differential cover
    Install new gasket on differential housing, or apply a continuous 3-4mm bead of RTV silicone if using gasket maker (allow RTV to skin over for 5-10 minutes before installation). Position cover carefully and install all bolts finger-tight. Tighten bolts in a crisscross pattern to specified torque in three progressive steps: 33%, 66%, then 100% of final torque.
    ℹ️If using RTV, wait 1 hour before filling with fluid to allow proper curing.
    Torque spec

    Differential Cover Bolts35 Nm (26 lb-ft)
14. 14

    Fill differential with gear oil
    Remove the differential fill plug (located on front or side of housing). Using a fluid pump, fill the differential with Motorcraft 75W-140 synthetic gear oil until it reaches the bottom of the fill hole. Add the appropriate amount of friction modifier additive as specified on the product (typically 4 oz for Ford limited slip differentials). Reinstall fill plug and tighten securely.
    ⚠Limited slip differentials require friction modifier additive. Failure to add will cause chattering during turns.
15. 15

    Reinstall driveshaft
    Align driveshaft to differential yoke using alignment marks made during disassembly. Install all four driveshaft bolts and tighten to specification in a crisscross pattern. Verify driveshaft rotates freely without binding.
    Torque spec

    Driveshaft Bolts85 Nm (63 lb-ft)

Reassembly

1. Reinstall both rear wheels and torque lug nuts in star pattern to specification
2. Lower vehicle from jack stands to ground
3. Remove wheel chocks
4. Start engine and verify no leaks from differential cover
5. Test drive vehicle through several figure-8 turns in both directions to distribute friction modifier and verify proper limited slip operation

Verification

• Check for fluid leaks around differential cover after test drive
• Verify smooth operation with no chattering, clicking, or grinding noises from rear axle
• Confirm limited slip function by performing controlled single-wheel spin test (one rear wheel should not spin freely without resistance)
• Monitor differential temperature after test drive - excessive heat indicates improper clutch pack clearance or installation
• Recheck differential fluid level after 50-100 miles of driving and top off if needed

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