Ring and Pinion

This procedure covers the removal, replacement, and installation of the ring and pinion gears in the rear differential of a 2007 Ram 3500 4WD with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Ring and pinion gear set (must match existing ratio or plan for speedometer recalibration) × 1 — Use OEM specification or quality aftermarket
• Pinion bearing kit (includes front and rear pinion bearings and races) × 1 — Use OEM specification
• Carrier bearing set (left and right) × 1 — Use OEM specification
• Pinion seal × 1 — Use OEM specification
• Differential cover gasket × 1 — Use OEM specification or RTV silicone
• Ring gear bolts × 10 — Use OEM specification
• Pinion nut × 1 — Use OEM specification, do not reuse
• Crush sleeve or solid spacer (depending on application) × 1 — Use OEM specification, do not reuse
• Differential shims (assortment for pinion depth and carrier preload) × 1 — Use OEM specification

Fluids

• 75W-90 synthetic gear oil — 5.5 qt

Preparation

1. Park vehicle on level surface and set parking brake firmly
2. Place wheel chocks in front of front wheels
3. Raise rear of vehicle and support with jack stands at frame rails
4. Remove rear wheels
5. Mark driveshaft-to-pinion flange orientation with paint or punch marks for proper reassembly alignment
6. Place drain pan under differential
7. Have clean workspace prepared for disassembly and measurement procedures

Procedure

1. 1

   Remove differential cover and drain fluid
   Remove all differential cover bolts and carefully pry cover loose. Allow gear oil to drain completely into drain pan. Clean the differential cover and inspect for metal debris that may indicate previous gear damage. Clean the gasket mating surface on the housing.
2. 2

   Remove driveshaft
   Remove the fasteners securing the rear driveshaft to the pinion flange (verify configuration — may be U-bolt straps or flange bolts on this application). Support the driveshaft and slide it rearward out of the transfer case or transmission. Plug the transfer case/transmission output to prevent fluid loss. Secure driveshaft out of work area.
3. 3

   Mark and measure existing setup
   Before disassembly, use a dial indicator to measure and record ring gear backlash at four points around the ring gear (should be between 0.004"-0.010" typically). Rotate the pinion and check for smooth operation. Mark the relationship between carrier caps and housing with a punch mark. Paint mark one ring gear tooth and corresponding pinion tooth for reference. Measure and record pinion rotating torque with an inch-pound torque wrench.
4. 4

   Remove carrier bearing caps and differential assembly
   Remove carrier bearing cap bolts. If necessary, use a differential spreader tool to carefully spread the housing (maximum 0.015" spread). Do not over-spread or housing damage will occur. Use pry bars to carefully work the carrier assembly up and out of the housing. Remove carrier and set on clean workbench. If spreader was used, release tension immediately after carrier removal.
5. 5

   Remove pinion nut and pinion gear
   Use pinion holding tool to prevent flange rotation. Remove pinion nut (note the torque required to loosen for reference). Mark the pinion flange position relative to the pinion shaft. Use a flange puller to remove the pinion flange. Carefully tap the pinion shaft rearward out of the housing using a soft mallet. Catch the pinion as it exits to prevent dropping. Remove the front pinion bearing, crush sleeve/spacer, and rear pinion bearing from the pinion shaft and housing. Remove the pinion seal from the housing.
6. 6

   Disassemble carrier and remove ring gear
   Remove the ring gear bolts (right-hand thread on the AAM 11.5 axle). Use a brass drift and hammer to tap the ring gear off the carrier if it does not come off by hand. Remove carrier bearings using a bearing puller or hydraulic press with appropriate adapters. Keep left and right bearings separated and labeled if reusing (though new bearings are recommended).
7. 7

   Remove and install pinion bearing races
   Drive the old pinion bearing races out of the housing using a brass drift and hammer, working around the race evenly. Clean the bearing bore thoroughly. Install new front and rear pinion bearing races using a race driver, ensuring they are fully seated against the housing shoulders. Verify complete seating by attempting to insert a feeler gauge between race and shoulder.
8. 8

   Determine pinion depth
   Use a pinion depth gauge tool to measure the required pinion depth. Compare the variance number etched on the pinion head (+ or - value) to determine the required shim thickness behind the rear pinion bearing. This is a critical measurement. Install the appropriate shim(s) in the pinion bore. Press the rear pinion bearing onto the pinion shaft using a hydraulic press with the correct bearing installation tool.
9. 9

   Assemble and install pinion assembly
   Install the pinion with rear bearing into the housing. Install the front pinion bearing onto the pinion shaft. Install new crush sleeve (or solid spacer with shims if used). Install the pinion flange, aligning reference marks. Install new pinion nut. Using the pinion holding tool, gradually tighten the pinion nut while checking pinion bearing preload with an inch-pound torque wrench. Target preload for new bearings is typically 20-40 in-lbs rotating torque. Tighten in small increments and check frequently. If crush sleeve is used, it cannot be loosened without replacement. If target preload is exceeded, the crush sleeve and nut must be replaced and the process repeated.
10. 10

    Install ring gear on carrier
    Clean the carrier and new ring gear mating surfaces thoroughly. Heat the ring gear in an oven or with a heat gun to approximately 200°F to ease installation. Align the ring gear onto the carrier and tap into place with a soft mallet. Install new ring gear bolts with thread locking compound (right-hand thread on the AAM 11.5). Tighten ring gear bolts in a star pattern in three stages to achieve proper final torque (consult factory service manual for specific torque value, verify exact spec for this AAM 11.5 axle).
11. 11

    Install carrier bearings and shims
    Press new carrier bearings onto the carrier hubs using a hydraulic press and appropriate bearing installation tool. Start with the shim thickness calculated or measured from the original setup. Install bearing and shim packs on both sides of the carrier. The shims control backlash and carrier bearing preload.
12. 12

    Install carrier assembly and set backlash
    Carefully install the carrier assembly into the axle housing, ensuring bearings seat properly in their races. If using a spreader tool, spread housing slightly (maximum 0.015"). Install carrier bearing caps in their original orientation (reference your punch marks). Install cap bolts finger tight. Release spreader if used. Check ring gear backlash with a dial indicator at four points around the ring gear. Backlash should be 0.004"-0.010" with 0.006"-0.008" preferred. Adjust by moving shims from one side to the other (adding shim to right side increases backlash; adding to left side decreases backlash). Ensure total shim thickness remains constant to maintain bearing preload. Once backlash is correct, torque carrier bearing cap bolts to specification (consult factory service manual, typically 100-125 ft-lbs).
13. 13

    Check gear contact pattern
    Apply gear marking compound to 4-6 teeth on the ring gear. Rotate the pinion in both directions under light load (use a pry bar against the ring gear for resistance). Examine the contact pattern on the ring gear teeth. The pattern should be centered on the tooth face, slightly favoring the toe and below the centerline. If the pattern is incorrect, adjustments to pinion depth (shims behind rear pinion bearing) or backlash may be required. This is an iterative process requiring experience. Consult a gear pattern chart for interpretation.
14. 14

    Install pinion seal
    Clean the pinion seal bore in the housing. Install the new pinion seal using a seal driver, ensuring it is square and seated to the proper depth. Lubricate the seal lip with gear oil before installing the pinion flange.
15. 15

    Final assembly and fill differential
    Clean all gear marking compound from the gears using brake cleaner and a brush. Install differential cover with new gasket or RTV silicone sealant (follow gasket manufacturer instructions for cure time if using RTV). Tighten cover bolts in a star pattern. Fill the differential with approximately 3.5-4.0 quarts of 75W-90 synthetic gear oil (verify exact capacity for the AAM 11.5 axle in the factory service manual; add friction modifier if equipped with limited-slip) through the fill plug until oil reaches the bottom of the fill hole. Install fill plug. Reinstall driveshaft, aligning reference marks made during disassembly. Install rear wheels and lower vehicle.

Reassembly

1. Ensure all fasteners are tightened to proper specifications
2. Verify driveshaft alignment marks were matched during reinstallation
3. Double-check that differential is filled to proper level with correct fluid
4. If gear ratio was changed, arrange for speedometer recalibration and potential PCM reprogramming

Verification

• Test drive vehicle at low speed and listen for unusual gear noise or vibration
• Check for gear oil leaks at differential cover and pinion seal
• After 50-100 miles of driving, recheck differential fluid level and inspect for leaks
• Gear noise during initial break-in is normal; excessive whining, howling, or clunking indicates improper setup
• Monitor differential temperature during first several drives; excessive heat indicates bearing preload or contact pattern issues
• After 500 miles, consider changing differential fluid to remove break-in debris

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