Ring and Pinion

Complete removal and installation of the rear differential ring and pinion gears, including disassembly of the differential carrier, gear setup with proper backlash and pattern verification, and reassembly.

Warnings

Tools required

Parts

• Ring and pinion gear set × 1 — Use OEM specification or aftermarket equivalent with correct ratio
• Pinion bearing set (inner and outer) × 1 — Typically included with gear set or order separately
• Carrier bearing set × 1 — Order as matched set
• Pinion seal × 1 — Use OEM specification
• Differential cover gasket or RTV sealant × 1 — Mopar RTV or equivalent if no gasket used
• Crush sleeve (pinion preload spacer) × 1 — Use OEM specification, single-use item
• Ring gear bolts × 1 — Use OEM specification, replace with new
• Pinion nut × 1 — Use OEM specification, replace with new
• Gear marking compound × 1 — Yellow and red compound for pattern checking
• Shim kit (pinion depth and carrier shims) × 1 — Assorted thickness shim set for Dana or Chrysler differential

Fluids

• 75W-90 synthetic gear oil — 2.75 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Loosen rear wheel lug nuts while vehicle is on ground
3. Raise rear of vehicle and support securely on jack stands under chassis frame rails
4. Remove both rear wheels
5. Place drain pan under differential
6. Mark driveshaft and pinion flange orientation for reassembly alignment

Procedure

1. 1

   Drain differential and remove cover
   Remove the differential cover drain plug if equipped, or loosen the cover bolts gradually starting from the top to allow fluid to drain in a controlled manner. Once drained, remove all cover bolts and carefully remove the cover. Inspect drained fluid for metal particles or unusual debris that may indicate previous gear damage. Clean the cover and housing mating surfaces thoroughly with solvent.
2. 2

   Remove driveshaft
   Remove the 4 bolts securing the driveshaft universal joint flange to the pinion flange. Support the driveshaft/prop shaft and disconnect it at both flanged connections. On the Viper's rear transaxle layout the prop shaft runs from the engine to the rear-mounted transaxle; remove the flange bolts at the differential/transaxle input flange rather than pulling a slip yoke from an extension housing. Use safety wire or cable ties to secure the driveshaft out of the way, or remove it completely from the vehicle. Stuff a clean rag into the transmission extension housing to prevent fluid loss.
3. 3

   Remove axle shafts
   This vehicle uses an independent rear suspension. Disconnect the half-shafts from the differential output flanges (typically retained by bolts or circlips at the stub axle flange) rather than pulling C-clip axles from axle tubes. Support and set the half-shafts aside; there are no axle tubes on this IRS differential. Inspect axle shaft splines and seals for wear. Set axle shafts aside in a clean area.
4. 4

   Mark and remove carrier bearing caps
   Use a center punch or marker to clearly mark the carrier bearing caps and housing for correct reassembly orientation. Remove the bearing cap bolts (typically 4 bolts total, 2 per cap). Carefully remove both carrier bearing caps. Note any carrier shims located between the carrier bearings and the housing bores, and keep them organized by side for reference during reassembly.
5. 5

   Remove differential carrier assembly
   Carefully lift the differential carrier assembly (including ring gear, spider gears, and carrier bearings) out of the housing. The carrier bearings will remain pressed onto the carrier. Place the assembly on a clean workbench. Inspect the ring gear for wear patterns, chipped teeth, or abnormal contact patterns.
6. 6

   Remove pinion nut and flange
   Use a pinion holding tool or large vise to secure the pinion flange. Mark the pinion nut position relative to the pinion shaft threads to record the original depth (reference only, not for final reassembly). Remove the pinion nut using a breaker bar or impact wrench. Use a puller to remove the pinion flange from the pinion shaft. Remove and discard the old pinion seal.
7. 7

   Remove pinion gear and bearings
   Carefully tap the pinion shaft from the front of the housing to drive it rearward and out. The pinion gear will come out with the inner bearing, crush sleeve, and shims. The outer bearing race will remain in the housing. Remove and discard the crush sleeve. Press or drive out both pinion bearing races from the housing using a bearing race driver or appropriate drift. Clean the bearing race bores thoroughly.
8. 8

   Disassemble carrier and remove ring gear
   If not already done, press or pull the carrier bearings off the differential carrier using a bearing puller or press. Mark the ring gear orientation to the carrier. Remove the ring gear bolts (verify thread direction against the service manual; these are right-hand thread on most Dana/Chrysler applications). Tap the ring gear off the carrier using a soft-face hammer. Inspect the carrier for cracks or damage.
9. 9

   Install new pinion bearings and determine pinion depth
   Press the new pinion bearing races into the housing until fully seated, ensuring they are square and bottomed. Install the new inner pinion bearing onto the pinion shaft using a press. Refer to the pinion depth specification etched on the pinion gear head (typically a plus or minus number in thousandths). Use the appropriate shims behind the inner bearing race to achieve the correct pinion depth. This is a trial-and-error process requiring a pinion depth gauge or careful measurement. Start with the shim thickness recommended by the gear set manufacturer.
10. 10

    Set pinion bearing preload
    Install the pinion gear into the housing with the inner bearing, selected shim pack, and new crush sleeve. Install the outer pinion bearing onto the pinion shaft. Install the pinion flange and new pinion nut. Tighten the pinion nut gradually while checking rotational torque with an inch-pound torque wrench. The crush sleeve will compress as the nut is tightened. Set pinion bearing preload to the manufacturer's specification for new bearings (verify exact in-lb value in the service manual before finalizing). Do not back off the nut to reduce preload; if you over-tighten, the crush sleeve must be replaced and the process restarted. Record the final torque value and nut position.
11. 11

    Install ring gear on carrier
    Heat the new ring gear in an oven to approximately 200°F to expand the bore slightly (if applicable for press-fit applications). Align the ring gear to the carrier in the original orientation. Install new ring gear bolts with thread locker. Tighten the bolts in a star pattern incrementally to the specified torque. Allow the ring gear to cool if heated.
12. 12

    Install carrier bearings and set backlash
    Press new carrier bearings onto the differential carrier. Install the carrier assembly into the housing. Install shims behind each carrier bearing (start with original shim thickness as reference). Install the carrier bearing caps in their original orientation. Tighten the cap bolts snugly but not to final torque. Use a dial indicator mounted against a ring gear tooth to measure backlash while rocking the ring gear back and forth. Adjust shim thickness on each side to achieve the manufacturer-specified backlash (verify exact value in the service manual, commonly in the 0.005-0.010 inch range). Adding shims on the ring gear side decreases backlash; adding shims on the opposite side increases backlash. Shims must provide zero endplay with correct backlash.
13. 13

    Check gear tooth contact pattern
    Apply yellow gear marking compound to several teeth on the ring gear drive side. Rotate the pinion through several complete revolutions in both directions with light resistance (use a strap wrench on the flange). Examine the contact pattern on the ring gear teeth. The pattern should be centered on the tooth face, slightly toward the toe (inner edge) on the drive side, and slightly toward the heel (outer edge) on the coast side. Adjust pinion depth shims if the pattern is too high or too low on the tooth. Adjust backlash if the pattern is too far toward the toe or heel. Repeat pattern checks until correct. Apply red compound for final verification.
14. 14

    Final torque and verify preload
    Once backlash and gear pattern are correct, torque the carrier bearing cap bolts to the specified value in a cross pattern. Recheck pinion bearing preload by measuring rotational torque with an inch-pound torque wrench on the pinion nut. Preload should still be within specification after final carrier cap torque. Recheck ring gear backlash to ensure it did not change during final torque. Make final adjustments if necessary.
15. 15

    Install pinion seal and final assembly
    Install the new pinion seal into the housing using a seal driver, ensuring it is square and seated to the correct depth. Lubricate the seal lip with gear oil. Reinstall the pinion flange, aligning it to the pinion shaft. Install a new pinion nut and torque to the previously recorded value that achieved correct preload (the crush sleeve is already set). Install the axle shafts and secure with C-clips or retaining hardware. Clean the differential cover and housing mating surfaces. Apply RTV sealant or install a new gasket. Install the differential cover and torque the bolts in a cross pattern.
16. 16

    Fill differential and reinstall driveshaft
    Fill the differential with the manufacturer-specified quantity of the correct synthetic gear oil (verify capacity and required grade/friction modifier for limited-slip in the service manual) through the fill hole until oil reaches the bottom of the fill hole. Install the fill plug. Align the driveshaft to the pinion flange using the marks made during disassembly. Install the 4 driveshaft flange bolts and torque to specification. Reinstall the rear wheels and torque lug nuts to specification. Lower the vehicle.

Reassembly

1. Torque all fasteners to specification using a cross or star pattern where applicable
2. Ensure all alignment marks made during disassembly are matched during reassembly
3. Double-check that pinion bearing preload and ring gear backlash remain within specification after final assembly
4. Verify no tools or rags are left inside the differential housing before installing the cover

Verification

• Test drive the vehicle at various speeds and listen for abnormal gear whine, howling, or clunking noises
• Check for differential leaks around the pinion seal and cover after the first test drive
• Verify smooth engagement during acceleration and deceleration with no binding or roughness
• After 50-100 miles of operation, recheck the differential fluid level and inspect for metal particles in the fluid
• Monitor differential temperature during initial break-in; excessive heat may indicate improper setup

More procedures for this vehicle