Complete disassembly, inspection, and rebuild of the rear differential assembly including bearing replacement, gear setup, and backlash adjustment for the AAM 11.5 inch rear axle.

Warnings

Tools required

Parts

• Differential rebuild kit (bearings, seals, shims) × 1 — Use OEM specification
• Ring and pinion gear set × 1 — Match existing gear ratio
• Pinion seal × 1 — Use OEM specification
• Axle shaft seals × 2 — Use OEM specification
• Differential cover gasket or RTV sealant × 1 — Mopar RTV or equivalent
• Ring gear bolts × 10 — Use OEM specification
• Pinion nut × 1 — Use OEM specification
• Drain plug washer × 1 — Use OEM specification
• Shop towels and brake cleaner × 1 — Generic

Fluids

• Mopar 75W-140 Synthetic Gear Lubricant — 2.5 qt

Preparation

1. Park vehicle on level surface and chock front wheels securely
2. Raise rear of vehicle and support on jack stands at frame rails
3. Remove both rear wheels and set aside
4. Mark driveshaft-to-pinion flange orientation with paint marker for reinstallation alignment
5. Place large drain pan under differential
6. Have all special tools and new parts ready before beginning disassembly
7. Verify replacement ring and pinion match existing gear ratio (check axle code tag)

Procedure

1. 1

   Drain differential and remove cover
   Remove drain plug using appropriate socket and drain all gear oil into catch pan. Once drained, remove all differential cover bolts in a cross pattern. Carefully pry cover off using a flat pry bar at designated pry points. Clean mating surfaces thoroughly with brake cleaner and scraper, removing all old gasket material or RTV.
   Torque spec

   Drain Plug55 Nm (41 lb-ft)
2. 2

   Remove driveshaft and axle shafts
   Remove four u-joint strap bolts at pinion flange and carefully lower driveshaft, supporting it to avoid damaging u-joint. If equipped with CV style rear driveshaft, remove CV bolts at differential flange. Remove axle shaft retaining bolts from inside differential housing. Using slide hammer or careful prying, extract both axle shafts from housing. Keep shafts in order if reusing.
   Torque spec

   Driveshaft U-Joint Straps20 Nm (15 lb-ft)

   CV Bolts82 Nm (61 lb-ft)
3. 3

   Mark and measure preload values
   Before disassembly, use inch-pound torque wrench on pinion nut to measure and record pinion rotating torque (should be 15-25 in-lbs for used bearings). Paint mark relationship between pinion gear and carrier for reference. Use dial indicator to measure and record ring gear backlash at four points around ring gear (should be 0.006-0.010 inches). Document all measurements.
   ℹ️These baseline measurements are critical for achieving proper setup during reassembly.
4. 4

   Remove differential carrier assembly
   Remove carrier bearing cap bolts (mark caps left/right for reinstallation). Install case spreader tool on housing and carefully spread case just enough to remove carrier (maximum 0.015 inches spread). Use pry bars to carefully lift carrier assembly out of housing. Remove case spreader immediately after carrier is out. Place carrier assembly on clean workbench.
   ⚠️Do not over-spread housing beyond 0.015 inches or permanent case damage will occur.
5. 5

   Remove ring gear from carrier
   If ring gear is riveted, use rotary cutter or grinder to remove rivet heads, then drive out rivets with punch. If bolted, remove ring gear bolts in cross pattern. Use soft-faced hammer to tap ring gear off carrier. Mark ring gear orientation to carrier if reusing. Clean all surfaces thoroughly.
   ⚠Ring gear is heavy and may fall once fasteners are removed. Support it during removal.
6. 6

   Disassemble and measure carrier
   Drive out differential pinion shaft roll pin. Remove pinion shaft, side gears, pinion gears, and thrust washers. Keep all components organized and labeled. Inspect all parts for wear, pitting, or damage. Using bearing puller, remove carrier bearings from carrier assembly. Measure and record bearing preload shim thickness for reference.
   ℹ️Even if reusing carrier components, replace all bearings as part of differential rebuild.
7. 7

   Remove pinion gear assembly
   Hold pinion flange with holder tool and remove pinion nut. Use puller to remove flange from pinion shaft. Tap pinion shaft out from front of housing (will come out rear). Remove pinion seal. Carefully drive out front and rear pinion bearing races from housing. Remove collapsible spacer, front bearing, rear bearing, and shims from pinion. Measure and record all shim thicknesses.
   ℹ️Pinion nut is one-time use only. Always replace with new nut during reassembly.
8. 8

   Clean and inspect all components
   Thoroughly clean housing, carrier, and all reusable components in parts washer. Inspect ring gear and pinion for wear patterns, chipping, or excessive wear. Check housing for cracks, especially around bearing bores. Inspect carrier for cracks or damage. Replace any worn or damaged components. Clean and inspect all bearing bores in housing.
   ⚠Any cracks in housing or carrier require component replacement. Do not attempt to weld or repair.
9. 9

   Install new pinion bearing races and set pinion depth
   Press new front and rear pinion bearing races into housing using race installer tool. Using pinion depth setting gauge tool set, determine correct shim thickness for new pinion gear (account for pinion variance number stamped on pinion). Install determined shims on pinion shaft, then press on rear pinion bearing. Install collapsible spacer (do not compress yet), front bearing, and seal. This is a trial setup only.
   ℹ️Pinion depth is the most critical measurement in differential setup. Take time to verify measurements multiple times.
10. 10

    Set pinion bearing preload
    Install pinion flange and new pinion nut. Gradually tighten pinion nut while checking rotating torque with inch-pound torque wrench. Target preload is 25-35 in-lbs for new bearings. Once correct preload is achieved, remove pinion assembly and install new pinion seal properly. Reinstall pinion with flange and tighten nut to achieve same preload value. Verify pinion depth with dial indicator.
    ⚠If pinion nut is over-tightened and preload is too high, entire collapsible spacer and nut must be replaced. Cannot be loosened and re-used.
11. 11

    Install ring gear on carrier
    Heat new ring gear in oven to 200°F or use heat gun to expand slightly. Align ring gear to carrier in correct orientation (check alignment marks or gear rotation direction). Install new ring gear bolts with thread locker. Tighten bolts in star pattern to specification in three stages (1/3, 2/3, then full torque). Allow to cool completely before handling.
    ⚠Ring gear must be installed in correct orientation or gear pattern will be incorrect and cause noise.
12. 12

    Assemble carrier internals
    Install thrust washers, pinion gears, and side gears into carrier. Lubricate all components with gear oil during assembly. Install pinion shaft through carrier and gears. Verify gears rotate smoothly. Install new roll pin through carrier and pinion shaft. Press new carrier bearings onto carrier hubs using press or bearing installer.
    ℹ️Ensure roll pin is fully seated and does not protrude into gear mesh area.
13. 13

    Install carrier and set backlash
    Install carrier bearing shims (start with original thickness). Use case spreader to spread housing slightly. Install carrier assembly into housing. Install bearing caps in correct orientation (left/right as marked). Tighten bearing cap bolts to specification. Remove case spreader. Mount dial indicator on housing with plunger on ring gear tooth. Rock ring gear back and forth while holding pinion and measure backlash. Adjust shims side-to-side to achieve 0.006-0.010 inches backlash with 0.003-0.005 inches total bearing preload.
    ℹ️Moving shims from one side to other changes backlash. Equal thickness shims on both sides controls bearing preload.
14. 14

    Check gear pattern and finalize setup
    Apply gear marking compound to 8-10 teeth on ring gear. Rotate pinion in both directions under light load. Check contact pattern on ring gear teeth. Pattern should be centered on tooth face. If pattern is incorrect, adjust pinion depth or backlash as needed. Repeat pattern check until optimal pattern is achieved. Document final shim configuration.
    ⚠Improper gear pattern will cause noise and premature wear. Pattern must be correct before final assembly.
15. 15

    Final assembly and fill
    Clean all gear marking compound from components. Install new axle shaft seals using seal installer. Install axle shafts and secure with retaining bolts. Apply RTV sealant to differential cover or install new gasket. Install cover and tighten bolts in cross pattern. Install drain plug with new washer. Remove fill plug and fill with specified gear oil until it begins to run out of fill hole. Install fill plug. Install driveshaft aligned to original marks.
    Torque spec

    Cover Bolts46 Nm (34 lb-ft)

    Drain Plug55 Nm (41 lb-ft)

    Fill Plug55 Nm (41 lb-ft)

Reassembly

1. Verify all fasteners are torqued to specification using star pattern where applicable
2. Ensure no tools or parts were left inside differential housing
3. Check that driveshaft phasing is correct and u-joint straps are properly seated
4. Install wheels and torque lug nuts in star pattern to specification
5. Double-check that fill plug and drain plug are secure

Verification

• Lower vehicle and test drive at low speed (under 25 mph) for first 15 minutes, checking for unusual noise or vibration
• After test drive, recheck differential for leaks at cover, pinion seal, and axle seals
• Check fluid level at fill plug - should be at bottom of fill hole threads
• Drive vehicle through multiple acceleration, deceleration, and turning cycles to seat gears
• After 50-100 miles, recheck fluid level and inspect for leaks
• Listen for whining, howling, or clunking noises that could indicate improper setup
• Consider changing gear oil after initial 500-mile break-in period to remove metal particles from gear seating

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