Limited Slip Clutch Pack

Replace the clutch pack and friction discs in the Ford 9-inch limited slip differential rear axle to restore proper traction performance.

Warnings

Tools required

Parts

• Limited slip clutch pack kit (includes friction discs and steel plates) × 1 — Ford 9-inch Traction-Lok clutch pack kit
• Differential cover gasket × 1 — Ford 9-inch 10-bolt cover gasket
• Pinion shaft lock bolt × 1 — Use OEM specification
• Differential case bearing shims (assorted) × 1 — Use existing unless damaged
• RTV silicone gasket maker (high-temp) × 1 — Permatex Ultra Black or equivalent

Fluids

• 80W-90 GL-5 rear differential oil — 3.5 qt
• Limited slip additive — 0.25 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Chock front wheels to prevent rolling
3. Raise rear of vehicle and support on jack stands under frame rails
4. Allow differential to cool completely if recently driven
5. Mark driveshaft and pinion yoke alignment with paint marker for reinstallation reference
6. Have all tools and parts ready before beginning disassembly

Procedure

1. 1

   Remove differential cover and drain fluid
   Position drain pan under differential. Remove the axle shafts (or disconnect as needed), then remove the driveshaft. On the Ford 9-inch removable-carrier axle, remove the 10 nuts securing the third member (carrier) to the axle housing and withdraw the entire carrier assembly from the front of the housing to access the differential. Clean the housing and carrier mating surfaces thoroughly with brake cleaner.
2. 2

   Remove pinion shaft lock bolt and shaft
   Locate the pinion shaft lock bolt on the differential case (accessible through the carrier opening). Remove the lock bolt completely. Carefully drive the pinion shaft out from the opposite side using a brass punch and hammer. The shaft should slide out freely once the lock bolt is removed. Set shaft and bolt aside.
3. 3

   Remove axle C-clips and spider gears
   The Ford 9-inch uses flange-retained (bolt-in) axle shafts, not C-clips. Remove the retainer nuts/bolts at each backing plate and withdraw the axle shafts from the housing before removing the third member. Once the carrier is out, the spider (pinion) gears and side gears can be removed after driving out the pinion shaft. Keep gears organized and note their orientation for reassembly.
4. 4

   Remove ring gear bolts and mark bearing caps
   Remove the ring gear bolts from the differential case using appropriate socket. NOTE: verify thread direction — many Ford 9-inch ring gear bolts are left-hand thread. Confirm count and thread direction before removal. Use paint marker to clearly mark both differential bearing caps and their corresponding positions on the carrier (driver side/passenger side and orientation). This ensures proper reassembly alignment. Remove bearing cap bolts. Verified detail (This step conflates two separate operations. Ring gear bolts should not be removed for clutch pack service—they attach the ring gear to the case. Only bearing cap bolts need removal. This creates confusion about which bolts to actually remove.): Use paint marker to clearly mark both differential bearing caps and their corresponding positions on the carrier (driver side/passenger side and orientation). This ensures proper reassembly alignment. Remove bearing cap bolts.
5. 5

   Remove differential case assembly
   Carefully pry bearing caps loose and remove them. Note the shim pack thickness behind each bearing cap and keep shims organized by side. Lift the differential case assembly with ring gear attached straight up and out of the carrier. Place assembly on clean workbench with ring gear facing up.
6. 6

   Disassemble limited slip clutch pack
   Place differential case in a vise with soft jaws (or protect with wood blocks). Remove the S-shaped preload spring from the top of the case. Note the clutch pack arrangement: there are 4 friction discs (bronze/tan color) and 4 steel plates alternating in the stack. Remove all friction discs and steel plates, keeping them in order. Inspect all components for wear, scoring, or damage.
7. 7

   Clean differential case
   Thoroughly clean the inside of the differential case using brake cleaner and shop towels. Remove all old clutch material residue and metal particles. Clean the clutch pack surfaces on both sides of the case. Inspect case for cracks or damage. Dry completely with compressed air or clean towels.
8. 8

   Install new clutch pack
   Begin with a steel plate on the bottom (against the case surface), then alternate friction disc, steel plate, friction disc, continuing the pattern. Install all 4 steel plates and 4 friction discs according to the new clutch pack kit instructions. Ensure friction discs are properly seated in the case splines. Install the new S-shaped preload spring on top of the clutch stack, ensuring it seats in the machined grooves.
9. 9

   Reinstall differential case assembly
   On the Ford 9-inch, install the carrier and set bearing preload and backlash using the threaded side adjuster nuts (not shim packs). Tighten adjusters to establish correct backlash and bearing preload per spec. Carefully lower the differential case assembly into the carrier, aligning both bearings with their bores. Install bearing caps in their original positions according to the marks made during disassembly. Install cap bolts finger-tight.
10. 10

    Set bearing preload
    Torque bearing cap bolts to the Ford-specified value (verify against 9-inch service spec) in a cross pattern. NOTE: the Ford 9-inch sets carrier bearing preload via threaded adjuster nuts, not shims — adjust the side adjuster nuts to set preload and backlash. Install dial indicator on carrier housing with plunger against ring gear tooth. Using a pry bar, check ring gear backlash (should be 0.005-0.009 inch). Measure bearing preload by rotating pinion yoke with inch-pound torque wrench (rolling resistance should be 15-30 in-lb with new bearings, 10-15 in-lb with used bearings). Adjust shims as necessary to achieve correct preload. Verified detail (70 ft-lb may be too high for Ford 9-inch bearing cap bolts. Typical specification is closer to 40-50 ft-lb for these 7/16-inch bolts. 70 ft-lb risks stripping threads or warping the caps.): Torque bearing cap bolts to 40-50 ft-lb in a cross pattern.
11. 11

    Reinstall spider gears and axle components
    Install side gears into differential case. Install spider gears onto the pinion shaft locations, ensuring proper mesh with side gears. Slide pinion shaft through the case and spider gears, aligning the lock bolt hole. Install and torque the pinion shaft lock bolt to the Ford-specified value (verify against Traction-Lok service spec; typically ~15-20 ft-lb). Reinstall the flange-retained axle shafts into the housing and torque the retainer nuts/bolts at each backing plate to spec. Verify shafts are fully seated and retainers are secure. Verified detail (25 ft-lb appears too high for the Ford 9-inch pinion shaft lock bolt, which is typically a 5/16-inch bolt. Standard specification is 15-20 ft-lb to avoid stripping the differential case threads.): Install and torque the pinion shaft lock bolt to 15-20 ft-lb.
12. 12

    Prepare and install differential cover
    Clean differential cover mating surface thoroughly with brake cleaner. Apply a continuous 1/8-inch bead of RTV silicone to the cover flange (or use new gasket if preferred). Allow RTV to set for 5 minutes before installation. Position cover on housing and install all 10 bolts finger-tight. Torque bolts to 15-20 ft-lb in a star pattern, working from center outward. Verified detail (The Ford 9-inch has no rear cover. Sealing is done at the third-member-to-housing flange with a gasket. Cover torque of 25 ft-lb also seems high for a stamped cover, but this cover doesn't exist on a 9-inch regardless.): Clean the third-member-to-housing mating surfaces thoroughly with brake cleaner. Install a new carrier gasket (or thin RTV bead) on the housing flange. Reinstall the third member/carrier into the housing and install the retaining nuts. Torque the carrier retaining nuts to Ford spec in a cross pattern.
13. 13

    Refill differential with gear oil
    Remove the differential fill plug. Using a fluid pump, fill with approximately 2 to 2.5 quarts of 80W-90 GL-5 gear oil (verify exact 9-inch capacity), then add the appropriate amount of Ford friction-modifier/limited slip additive. Continue filling until oil reaches the bottom of the fill plug hole. Install fill plug and torque to Ford spec. Wipe excess oil from housing.
14. 14

    Lower vehicle and test operation
    Remove jack stands and carefully lower vehicle to ground. Start engine and allow to reach operating temperature. Test drive vehicle in a safe area, making gradual turns in both directions to verify limited slip operation. Listen for abnormal noises such as chattering, whining, or clunking. Re-check differential fill level after test drive and top off if necessary.

Reassembly

1. Allow RTV silicone to cure for 1 hour minimum before filling with oil, 24 hours for full cure
2. Verify axle C-clips are properly seated by attempting to pull axle shafts outward - they should not move more than 1/8 inch
3. Check for gear oil leaks around cover after first test drive
4. Limited slip function may take 50-100 miles of driving to fully break in the new clutch pack

Verification

• Test limited slip function by safely spinning one rear wheel with transmission in neutral and opposite wheel chocked - wheel should turn with moderate resistance, not freely
• No gear oil leaks visible around differential cover or pinion seal
• No abnormal noises during turns or acceleration
• Both rear wheels should drive together under moderate acceleration on dry pavement
• Differential should exhibit smooth operation with no chattering during low-speed turns after break-in period

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