Differential Rebuild - Rear

Complete disassembly, inspection, and rebuild of the rear differential assembly including carrier bearings, pinion bearings, ring and pinion gears, and all seals on the 1970 AMC Rebel Machine.

Warnings

Tools required

Parts

• Differential rebuild kit (includes bearings, seals, shims) × 1 — Use OEM specification for AMC Dana 44 or AMC 15
• Ring and pinion gear set × 1 — Match original gear ratio or desired replacement
• Pinion seal × 1 — Included in rebuild kit
• Differential side bearings × 2 — Included in rebuild kit
• Pinion bearings (front and rear) × 2 — Included in rebuild kit
• Carrier bearing shims × 1 — Assorted thickness pack
• Pinion depth shims × 1 — Assorted thickness pack
• Ring gear bolts × 10 — Use OEM specification
• Differential cover gasket × 1 — Use OEM specification
• Axle seals × 2 — Use OEM specification
• Gear oil additive (limited slip, if equipped) × 1 — Use OEM specification
• Thread locker (red, high strength) × 1 — Loctite 271 or equivalent
• RTV silicone sealant × 1 — Use as directed

Fluids

• SAE 80W-90 GL-5 gear oil — 3 qt

Preparation

1. Raise vehicle and support securely on jack stands at the frame rails
2. Remove rear wheels
3. Chock front wheels and ensure parking brake is released
4. Mark driveshaft-to-pinion flange orientation for proper reassembly phasing
5. Place drain pan under differential
6. Clean exterior of differential housing thoroughly to prevent contamination during disassembly
7. Photograph or mark carrier cap orientation and bearing adjuster positions for reference

Procedure

1. 1

   Remove driveshaft and axle shafts
   Remove driveshaft U-bolts or flange bolts at pinion yoke and secure driveshaft out of the way. Remove differential cover bolts and drain gear oil completely. Remove axle shaft retaining bolts or C-clips (depending on axle type). Carefully slide both axle shafts out of housing and set aside.
2. 2

   Mark and measure initial setup
   Before disassembly, use dial indicator to measure and record ring gear backlash at four points 90 degrees apart. Record pinion bearing preload using inch-pound torque wrench on pinion nut (rotational torque). Mark carrier bearing caps with punch marks matching housing for proper reinstallation orientation. Measure and record carrier bearing adjuster positions by counting exposed threads.
3. 3

   Remove carrier bearing caps and differential assembly
   Remove carrier bearing cap bolts. If equipped, back off carrier bearing adjusters evenly. Carefully pry differential carrier assembly out of housing using pry bars on both sides simultaneously. Remove carrier with ring gear attached and place on clean workbench. Remove carrier bearing adjusters and shims, keeping left and right sides separated and labeled.
4. 4

   Remove pinion assembly
   Using pinion holding tool, remove pinion nut while counting exact rotational torque required. Remove pinion flange using appropriate puller. Tap pinion shaft rearward and remove from housing along with pinion depth shim, rear bearing cone, and collapsible spacer. Remove front pinion bearing cone from pinion shaft. Press or tap out front and rear pinion bearing races from housing. Remove and discard pinion seal.
5. 5

   Disassemble differential carrier
   Mark ring gear to carrier orientation. Remove ring gear bolts (may require heat if thread locker was used). Tap ring gear off carrier with brass drift. Drive out differential pinion shaft retaining pin. Remove pinion shaft, spider gears, and side gears. Keep all components organized. Press or pull carrier bearings from carrier housing using bearing separator and press.
6. 6

   Clean and inspect all components
   Thoroughly clean all components with solvent and dry with compressed air. Inspect ring gear and pinion for scoring, pitting, or excessive wear on tooth surfaces. Check all bearing races and cones for pitting, spalling, or discoloration. Inspect carrier and housing for cracks or damage. Inspect axle splines for wear. Replace any damaged components. Measure ring gear runout if reusing old gear (maximum 0.005 inch runout).
7. 7

   Install new pinion bearing races
   Press new front and rear pinion bearing races into housing using appropriate bearing race installation tools. Ensure races are fully seated and square in housing bores. Check seating by attempting to insert feeler gauge between race and housing shoulder - no gap should exist.
8. 8

   Determine pinion depth setting
   Install pinion depth gauge tool with proper adapters for this axle. Use nominal shim thickness as starting point based on markings on new pinion head (typically +/- variance from nominal). Install appropriate pinion depth shim on pinion shaft. This is critical for proper gear contact pattern and requires precision measurement. Reference pinion depth gauge instructions and verify against new gear set markings.
9. 9

   Assemble and install pinion
   Lightly lubricate new rear pinion bearing with gear oil and press onto pinion shaft. Install pinion depth shim on pinion. Insert pinion assembly into housing from rear. Install new front pinion bearing cone. Lightly oil new pinion seal and install into housing using seal driver. Install pinion flange, new collapsible spacer, washer, and new pinion nut. Gradually tighten pinion nut while checking rotating torque frequently with inch-pound torque wrench.
10. 10

    Set pinion bearing preload
    Tighten pinion nut incrementally, checking preload after each adjustment. Target preload is 15-25 inch-pounds for new bearings (10-15 inch-pounds for used bearings) measured as rotational torque. Once target preload is reached, do NOT back off nut - collapsible spacer cannot be reused if overtightened. If preload is excessive, entire pinion assembly must be disassembled and new collapsible spacer installed.
11. 11

    Assemble differential carrier
    Assemble spider gears and side gears into carrier with thrust washers. Install pinion shaft and verify free rotation. Install pinion shaft retaining pin and stake in place. Press new carrier bearings onto carrier housing. If reusing ring gear, clean all thread locker residue from bolts and gear. Apply red thread locker to ring gear bolts. Position ring gear on carrier (align marks if reusing) and install bolts finger tight, then tighten in star pattern incrementally.
12. 12

    Install carrier assembly and set backlash
    Install carrier bearing shims on both sides (use original shim thickness as starting point). Install bearing adjusters on both shims. Carefully install carrier assembly into housing. Install carrier bearing caps in proper orientation (match punch marks). Snug bearing cap bolts finger tight. Adjust carrier bearing adjusters to remove all side play while maintaining ability to rotate carrier. Tighten bearing cap bolts progressively. Using dial indicator on ring gear tooth, adjust backlash to 0.005-0.009 inch by moving shims from one side to other (moving shim from right to left increases backlash).
13. 13

    Check gear contact pattern
    Apply thin coat of gear marking compound to 8-10 teeth on ring gear. Rotate pinion through several revolutions in both directions while applying light resistance to ring gear. Examine tooth contact pattern on drive and coast sides. Pattern should be centered on tooth face with slight bias toward toe and below pitch line. Adjust pinion depth shims to move pattern up or down on tooth (adding shim moves pattern toward toe). Adjust backlash to move pattern in or out on tooth face. Repeat marking and adjustment until proper pattern is achieved.
14. 14

    Final torque and secure assembly
    Once contact pattern is correct, tighten all carrier bearing cap bolts to proper specification. Verify final backlash is within 0.005-0.009 inch specification at four points around ring gear. Check that carrier bearing preload is adequate - adjusters should be tight. Stake or wire-lock carrier bearing adjuster locks if equipped. Apply RTV to differential cover and install with new gasket. Install axle shafts with new seals and secure with retaining hardware.
15. 15

    Fill with gear oil and road test
    Fill differential through fill hole with proper quantity and specification of gear oil. Add limited slip additive if equipped with limited slip differential. Install fill plug. Reinstall driveshaft in original orientation. Install rear wheels and lower vehicle. Test drive vehicle, listening for abnormal gear whine or noise. Check for leaks after test drive. Recheck gear oil level after 50-100 miles and inspect for metal particles in oil indicating improper setup.

Reassembly

1. Ensure all bearing caps and adjusters are installed in their original positions
2. Verify pinion nut is properly torqued and staked if applicable
3. Double-check that ring gear bolts are tightened in proper sequence with thread locker
4. Ensure differential cover is sealed properly to prevent leaks
5. Verify driveshaft phasing is correct by aligning marks made during disassembly

Verification

• Check for gear oil leaks around pinion seal, axle seals, and differential cover after test drive
• Listen for abnormal gear whine, howling, or clunking during acceleration and deceleration
• Verify smooth operation with no binding or excessive play in drivetrain
• Confirm proper backlash remains within specification after initial break-in
• Inspect gear oil after 50-100 miles for metal particles or unusual odor indicating improper setup
• Verify no excessive heat buildup in differential housing during normal driving

More procedures for this vehicle