Limited Slip Clutch Pack

This procedure covers the replacement of the clutch pack in the limited slip differential of a 1970 AMC Rebel Machine, requiring removal of the differential carrier from the rear axle housing.

Warnings

Tools required

Parts

• Limited slip clutch pack kit × 1 — Use OEM specification for AMC Twin-Grip differential
• Differential cover gasket × 1 — Use OEM specification
• Differential carrier shims × 1 — Assortment for backlash adjustment
• Differential side bearing preload shims × 1 — Use existing or obtain assortment
• RTV silicone gasket maker × 1 — High-temperature rated
• Gear oil additive (limited slip) × 1 — Use specification for clutch-type limited slip

Fluids

• SAE 80W-90 GL-5 gear oil — 4 qt

Preparation

1. Park vehicle on level surface and place wheel chocks in front of front wheels
2. Raise rear of vehicle and support securely on jack stands placed under frame rails
3. Remove both rear wheels to allow axle shaft movement if needed
4. Clean exterior of differential housing and cover thoroughly with wire brush
5. Place drain pan beneath differential cover

Procedure

1. 1

   Drain differential and remove cover
   Remove all differential cover bolts and carefully break seal with putty knife. Allow gear oil to drain completely into drain pan. Remove cover and old gasket material. Clean both cover and housing mating surfaces thoroughly with wire brush and solvent.
2. 2

   Mark carrier bearing caps and check preload
   Using a permanent marker or punch, mark the carrier bearing caps and housing to ensure correct reinstallation position. These caps are matched and must return to original positions. Measure and record bearing preload by checking rotational torque of pinion gear using inch-pound torque wrench.
3. 3

   Remove carrier bearing caps
   Remove carrier bearing cap bolts from both sides of the housing. Keep caps with their respective bolts and shims. Note thickness and position of any shims found behind bearing caps for reference during reassembly.
4. 4

   Spread housing and remove carrier assembly
   Install differential spreader tool on axle housing. Mount dial indicator to measure spread. Carefully spread housing NO MORE than 0.015 inches while monitoring dial indicator. With housing spread, carefully pry carrier assembly upward and out of housing. Remove spreader tool immediately after carrier is removed to prevent housing distortion.
5. 5

   Remove ring gear from carrier
   Mount carrier assembly in a vise using soft jaws to protect surfaces. Remove all ring gear bolts (typically left-hand thread). Tap ring gear lightly with soft-face hammer to separate from carrier case. Mark ring gear and carrier for proper orientation during reassembly.
6. 6

   Disassemble differential case
   Drive out differential cross pin retaining roll pin using appropriate punch. Remove cross pin (also called spider pin). Rotate side gears and remove pinion gears, side gears, and thrust washers through carrier opening. Keep left and right side components separate and labeled.
7. 7

   Remove old clutch packs
   Extract all clutch discs and plates from both sides of the differential case. Typical AMC Twin-Grip configuration uses alternating steel plates and friction discs. Count and record the number and arrangement of clutches from each side. Clean all clutch cavities thoroughly and inspect for scoring or damage.
8. 8

   Install new clutch packs
   Install new clutch pack components in same arrangement as original. Typically begins with a steel plate, then alternates friction disc and steel plate. Ensure plates are installed flat and not cocked. Soak friction discs in limited slip additive for 15 minutes before installation per manufacturer instructions. Verify clutch stack height matches original measurements.
9. 9

   Reassemble differential internals
   Install side gears with thrust washers into carrier case over clutch packs. Install pinion gears and thrust washers onto cross pin, then install cross pin through case and gears. Ensure all gears mesh properly and rotate freely. Install cross pin retaining roll pin and peen in place to prevent migration.
10. 10

    Install ring gear to carrier
    Align ring gear to carrier using previous alignment marks. Install all ring gear bolts (left-hand thread) and tighten in star pattern. Without factory torque specifications, use standard practice of 70-85 ft-lbs for these bolts, tightening progressively in multiple passes.
11. 11

    Install carrier assembly into housing
    Install differential spreader tool and spread housing to 0.015 inches maximum as measured with dial indicator. Carefully lower carrier assembly into housing, ensuring bearing cups seat properly. Install original shims in their marked positions. Remove spreader tool and install bearing caps in their original positions according to previous marks.
12. 12

    Adjust backlash and bearing preload
    Install bearing cap bolts finger tight. Check ring gear to pinion backlash using dial indicator mounted against ring gear tooth. Backlash should be 0.005-0.009 inches. Adjust by moving shims from one side to the other (keeping total shim thickness constant to maintain bearing preload). Add equal shims to both sides to increase preload without changing backlash. Typical preload adds 0.005-0.010 inches beyond zero endplay.
13. 13

    Check gear tooth contact pattern
    Apply gear marking compound to several ring gear teeth. Rotate pinion through several revolutions in both directions while applying resistance. Check tooth contact pattern. Pattern should be centered on tooth face. Adjust pinion depth or backlash as needed to achieve proper contact. Without factory specifications, use standard pattern recognition for spiral bevel gears.
14. 14

    Final tightening and pattern verification
    Torque bearing cap bolts to 35-45 ft-lbs in progressive steps. Recheck backlash after torquing. Verify rotational drag is appropriate for limited slip differential (should show resistance compared to open differential). Recheck gear pattern after final torquing and adjust if necessary.
15. 15

    Install differential cover and refill
    Clean cover and housing mating surfaces. Install new gasket with thin bead of RTV on both sides, or use RTV alone per preference. Install cover bolts and torque in star pattern to 20-25 ft-lbs. Fill differential with SAE 80W-90 GL-5 gear oil mixed with limited slip additive per additive manufacturer instructions. Fill to bottom of fill plug hole. Install fill plug. Reinstall wheels and lower vehicle.

Reassembly

1. Torque differential cover bolts in star pattern to prevent warping and leaks
2. Always use limited slip additive appropriate for clutch-type differentials
3. Verify all drain and fill plugs are tight before lowering vehicle
4. Check for leaks after initial test drive and retorque cover bolts if necessary

Verification

• Test drive vehicle and verify limited slip function by performing slow, tight turns - should feel slight chattering or binding indicating clutches are engaging
• Check for gear oil leaks around differential cover after test drive
• Listen for abnormal noises such as whining, grinding, or clunking which would indicate improper backlash or bearing preload
• Verify smooth operation with no vibration during acceleration
• In low-traction conditions, both rear wheels should receive power indicating proper limited slip operation

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