Rear Differential

Complete removal and replacement of the rear differential assembly on a 1970 AMC Rebel Machine, including driveshaft disconnection, axle removal, and differential housing extraction.

Warnings

Tools required

Parts

• Rear differential assembly × 1 — AMC 10-bolt with 3.54 or 3.91 ratio
• Differential mounting bushings × 2 — Use OEM specification
• U-joint straps and bolts × 1 — Use OEM specification
• Differential gasket or RTV sealant × 1 — Use OEM specification
• Gear oil (limited slip additive if equipped) × 1 — GL-5 80W-90 or 85W-140

Fluids

• Gear oil GL-5 80W-90 or 85W-140 — 3 qt

Preparation

1. Park vehicle on level surface and engage parking brake firmly
2. Chock front wheels securely
3. Raise rear of vehicle and support frame rails with jack stands rated for vehicle weight
4. Raise front of vehicle and support on jack stands to provide clearance for differential removal from rear
5. Remove both rear wheels
6. Apply penetrating oil to all fasteners that will be removed and allow to soak for 15-20 minutes

Procedure

1. 1

   Mark and disconnect driveshaft
   Use marker or paint pen to mark the relationship between the driveshaft yoke and pinion flange for proper alignment during reassembly. Remove the four U-joint strap bolts at the rear differential pinion yoke. Support driveshaft and carefully slide it rearward to separate from pinion, then rotate shaft forward and wire it to exhaust or frame to keep it out of the way.
2. 2

   Drain differential fluid
   Position drain pan under differential cover. Remove all cover bolts except the top two, loosen these top bolts, then carefully pry cover loose at bottom to allow fluid to drain in controlled manner. Once drained, remove remaining bolts and cover. Inspect fluid for metal particles indicating internal damage.
3. 3

   Disconnect brake components
   Remove brake drums from both sides. Disconnect brake hydraulic line at T-fitting on differential housing or at flexible hose connection point. Cap or plug brake lines immediately to prevent fluid loss and contamination. Disconnect parking brake cables from backing plates or differential housing mounting points.
4. 4

   Support axle housing
   Position transmission jack or differential jack under center of differential housing. Raise jack slightly to take weight off mounting points. Ensure jack is centered and stable before proceeding.
5. 5

   Remove shock absorber lower mounts
   Remove lower shock absorber mounting bolts from both shock absorbers where they attach to the axle housing or mounting plates. Allow shocks to hang free from upper mounts.
6. 6

   Disconnect rear springs
   Remove U-bolts securing the axle housing to the rear leaf springs on both sides. There are typically two U-bolts per side with nuts on top of spring perch plates. Remove spring perch plates after U-bolts are removed.
7. 7

   Disconnect anti-sway bar if equipped
   If vehicle is equipped with rear anti-sway bar, disconnect end links from axle housing mounting points on both sides.
8. 8

   Remove axle shafts
   Remove axle shaft retaining nuts or bolts from backing plate studs (typically four per side). Using slide hammer or by pulling evenly while rotating, extract both axle shafts from differential housing. Keep axle shafts with their respective bearings and seals if reusing.
9. 9

   Lower and remove differential assembly
   Double-check that all connections are disconnected. Carefully lower differential assembly using transmission jack, guiding it clear of leaf springs and brake components. Have assistant help guide assembly as it is heavy and awkward. Roll assembly out from under vehicle on jack.
10. 10

    Inspect and prepare mounting points
    Clean all mounting surfaces on leaf spring perches and shock mounting points with wire brush and brake cleaner. Inspect leaf springs for damage, especially spring center pins. Inspect U-bolt threads and replace if damaged. Check condition of spring perch bushings on replacement differential.
11. 11

    Install replacement differential
    Position replacement differential on transmission jack and roll under vehicle. Carefully raise into position, aligning spring perches with leaf springs. Ensure differential housing is centered between frame rails and properly seated on springs. Install spring perch plates and U-bolts, tightening nuts in criss-cross pattern to prevent binding. Do not fully torque at this time.
12. 12

    Install axle shafts
    Clean axle shaft splines and apply thin coat of gear oil. Insert axle shafts into differential housing, ensuring splines engage properly with differential side gears. Rotate axle slightly if needed to align splines. Seat axle shaft bearing retainer against backing plate and install retaining nuts or bolts.
13. 13

    Reconnect shock absorbers and stabilizer
    Reconnect lower shock absorber mounts to axle housing on both sides. If equipped with rear anti-sway bar, reconnect end links to axle housing mounting points.
14. 14

    Reconnect brake components
    Reconnect brake hydraulic lines at differential housing or flexible hose connection. Ensure fittings are clean and not cross-threaded. Reconnect parking brake cables to backing plates or housing mounts. Install brake drums.
15. 15

    Reconnect driveshaft
    Lower driveshaft and align marks made during disassembly between driveshaft yoke and pinion flange. Install U-joint straps and bolts, ensuring straps are properly seated in yoke caps. Tighten strap bolts securely.

Reassembly

1. Torque all U-bolt nuts to specification once vehicle is lowered to ground with suspension at normal ride height
2. Fill differential with proper gear oil through fill plug opening until oil reaches bottom of fill hole (approximately 2.5-3 quarts)
3. If limited slip differential, add appropriate friction modifier additive per manufacturer specifications
4. Bleed brake system completely to remove all air from hydraulic lines
5. Install differential cover with new gasket or RTV sealant, tightening bolts in criss-cross pattern
6. Adjust parking brake cable tension as needed
7. Install rear wheels and torque lug nuts to specification

Verification

• Lower vehicle to ground and bounce rear suspension to settle components before final torquing of U-bolts
• Check for any fluid leaks at differential cover and pinion seal
• Test brake pedal firmness and verify no soft pedal condition exists
• Verify parking brake holds vehicle on incline
• Road test vehicle at low speed to verify proper differential operation and no unusual noises
• Check for vibration that might indicate driveshaft phasing issue; re-verify alignment marks if vibration present
• Recheck all fasteners for proper torque after initial 50 miles of driving
• Monitor differential fluid level after first few drives and top off if necessary

More procedures for this vehicle