Differential Rebuild - Rear

Complete disassembly, inspection, and rebuild of the rear electric drive unit differential assembly on a 2023 Rivian EDV 500, including bearing and seal replacement.

Warnings

Tools required

Parts

• Rear differential bearing kit × 1 — Use OEM specification
• Ring and pinion shim kit × 1 — Use OEM specification
• Differential cover gasket × 1 — Use OEM specification
• Pinion seal × 1 — Use OEM specification
• Side bearing seals × 2 — Use OEM specification
• Ring gear bolts × 1 — Use OEM specification
• Differential case bolts × 1 — Use OEM specification
• RTV silicone sealant (EV-safe) × 1 — Use OEM specification

Fluids

• 75W-90 GL-5 Gear Oil — 2.5 qt

Preparation

1. Connect Rivian diagnostic software and document any existing fault codes
2. Perform high voltage lockout/tagout procedure per Rivian service manual
3. Remove HV service disconnect and store in secure location with appropriate warning tags
4. Raise vehicle on lift and support securely on jack stands rated for EV weight
5. Remove rear wheels and store safely
6. Place vehicle in service mode to disable traction control and parking brake
7. Disconnect 12V battery negative terminal
8. Allow rear drive unit to cool to ambient temperature if vehicle was recently driven
9. Clean exterior of rear drive unit thoroughly to prevent contamination during disassembly

Procedure

1. 1

   Remove rear drive unit from vehicle
   Support rear drive unit with transmission jack. Disconnect all electrical connectors from drive unit, labeling each for reinstallation. Remove coolant lines from motor housing and cap openings. Remove drive axles from both sides and support with wire. Remove drive unit mounting bolts and carefully lower unit from vehicle. Transport to clean workbench.
2. 2

   Drain differential fluid and separate motor housing
   Position drive unit with differential cover facing up. Remove differential cover drain plug and drain all gear oil into appropriate container. Remove differential cover bolts in cross pattern and remove cover. Inspect fluid for metal particles or contamination. Disconnect motor housing bolts and separate electric motor assembly from differential housing, taking care not to damage stator windings.
3. 3

   Remove differential assembly
   Mark bearing caps for reinstallation position and orientation. Remove bearing cap bolts and carefully lift off caps. Install differential spreader tool and spread housing just enough to remove differential assembly (do not exceed 0.010 inch spread). Remove differential assembly with side bearings attached. Remove and mark side bearing shims for reference during reassembly.
4. 4

   Disassemble and inspect ring gear
   Mark ring gear position relative to differential case. Remove ring gear bolts (these are one-time-use and must be replaced). Carefully separate ring gear from differential case using soft drift punches. Inspect ring gear teeth for wear, pitting, scoring, or cracking. Measure ring gear runout with dial indicator - replace if runout exceeds 0.003 inches.
5. 5

   Remove and measure pinion assembly
   Mark pinion nut position for preload reference. Hold pinion flange and remove pinion nut. Remove pinion flange using appropriate puller. Carefully tap pinion shaft out of housing from ring gear side. Remove pinion bearings, shims, and spacers, keeping all components organized. Measure and record original shim thicknesses and bearing preload values for reference.
6. 6

   Clean and inspect all components
   Thoroughly clean all differential components with appropriate solvent. Inspect all gear teeth using magnification for wear patterns, scoring, or cracks. Check all bearing races for pitting, spalling, or discoloration. Inspect differential case and housing for cracks or damage. Measure all gear and bearing surfaces with micrometer - replace any components outside OEM specifications.
7. 7

   Remove and install bearing races
   Using bearing race puller, remove all bearing races from differential housing and pinion. Clean all bearing bores thoroughly. Using hydraulic press and appropriate drivers, install new bearing races ensuring they are fully seated and square. Verify race seating by measuring depth at multiple points around circumference.
8. 8

   Determine pinion depth shim thickness
   Install pinion depth gauge tool set per manufacturer instructions. Measure pinion depth and compare to specifications. Calculate required shim thickness based on measurements and pinion gear depth variance marking (etched on pinion head). Install calculated shim on pinion shaft. This is critical for proper gear contact pattern.
9. 9

   Assemble and set pinion bearing preload
   Install rear pinion bearing on shaft. Install pinion assembly into housing with shims and front bearing. Install collapsible spacer, front bearing, and pinion flange. Install new pinion nut and gradually tighten while checking rotating torque with inch-pound torque wrench. Target preload is 15-20 inch-pounds for new bearings. Replace collapsible spacer and repeat if preload is exceeded.
10. 10

    Install ring gear and differential assembly
    Install ring gear on differential case in original position. Install new ring gear bolts with thread locker and tighten in star pattern. Verify ring gear runout is within specification. Install new side bearings on differential case using bearing installer. Heat bearings to 200°F for easier installation.
11. 11

    Set backlash and bearing preload
    Install differential assembly into housing with spreader tool. Install side bearing shims starting with original thickness. Install bearing caps in marked positions and torque bolts. Measure backlash at four points around ring gear - target is 0.005-0.008 inches. Adjust shim thickness to achieve proper backlash: add shim to ring gear side to decrease backlash, add to opposite side to increase. Verify side bearing preload is correct.
12. 12

    Check gear contact pattern
    Apply gear marking compound to several ring gear teeth. Rotate pinion through several revolutions in both directions under light resistance. Inspect tooth contact pattern - should be centered on tooth face for drive and coast sides. Adjust pinion depth shims if pattern is too high or low on tooth. Adjust backlash if pattern is too far toward toe or heel. Repeat until pattern is correct.
13. 13

    Final assembly of differential
    Once gear pattern is verified correct, perform final assembly. Install new differential cover gasket or apply RTV sealant in continuous bead. Install differential cover and torque bolts in cross pattern. Install new pinion seal using seal driver. Reinstall motor housing to differential housing with new gasket, ensuring proper alignment of coolant passages.
14. 14

    Reinstall drive unit and fill with fluid
    Lift rear drive unit into position using transmission jack. Install all mounting bolts and torque to specification. Reconnect drive axles to differential output flanges. Reconnect all electrical connectors per labeling. Reconnect coolant lines and torque fittings. Fill differential with 2.0 quarts of 75W-90 GL-5 gear oil through fill plug. Install fill plug and torque to specification.
15. 15

    System verification and calibration
    Reinstall rear wheels and torque lug nuts to specification. Reconnect 12V battery. Reinstall HV service disconnect and remove lockout/tagout devices. Connect Rivian diagnostic software and clear any fault codes. Perform drive unit relearn procedure per Rivian specifications. Verify proper operation by running vehicle on lift through all drive modes while monitoring for abnormal noise or vibration.

Reassembly

1. Ensure all bearing preload and backlash measurements are documented and within specification before final assembly
2. Use only new fasteners for critical components including ring gear bolts and pinion nut
3. Apply appropriate thread locker to all differential bolts per OEM specifications
4. Verify gear contact pattern is correct before final closure to prevent premature failure
5. Follow proper torque sequence on all multi-bolt components to prevent warping

Verification

• Connect diagnostic software and verify no fault codes are present after relearn procedure
• Test drive vehicle at various speeds and verify no abnormal noise from rear differential
• Check for fluid leaks around differential cover, pinion seal, and axle seals after test drive
• Verify proper torque transfer in all drive modes including forward, reverse, and regenerative braking
• Recheck differential fluid level after 50 miles of driving and top off if necessary
• Monitor for any temperature warnings or performance issues during first 500 miles of operation

Related trouble codes on this vehicle

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