Ring and Pinion

Complete replacement of the rear differential ring and pinion gears, including bearing preload setup, gear pattern verification, and backlash adjustment.

Warnings

Tools required

Parts

• Ring and pinion gear set with correct ratio × 1 — Use OEM specification or quality aftermarket
• Pinion bearing kit (inner and outer bearings with races) × 1 — Usually included with ring and pinion set
• Carrier bearings (both sides) × 2 — Use OEM specification
• Pinion seal × 1 — Use OEM specification
• Pinion nut × 1 — Use new OEM nut
• Differential cover gasket or RTV sealant × 1 — Motorcraft TA-357 or equivalent
• Ring gear bolts × 1 — Use new OEM bolts with thread locker
• Crush sleeve or solid spacer (pinion preload) × 1 — Depends on differential type
• Gear marking compound × 1 — Prussian blue or equivalent

Fluids

• Motorcraft 75W-140 Synthetic Gear Oil — 2.5 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 at frame rails
4. Remove rear wheels and set aside
5. Mark driveshaft-to-pinion flange orientation with paint or punch marks for reinstallation
6. Identify differential type (open, limited-slip, or electronic locker) to determine if friction modifier additive is needed
7. Verify new ring and pinion gear ratio matches vehicle speedometer calibration requirements
8. Gather all measurements from new gear set packaging (pinion depth variance markings)

Procedure

1. 1

   Remove driveshaft
   Remove the four driveshaft-to-pinion flange bolts. Support driveshaft and slide rearward off transmission output shaft. Use a plastic bag and tape to cover transmission extension housing to prevent fluid loss. Support driveshaft safely out of work area.
   Torque spec

   Driveshaft Bolts94 Nm (69 lb-ft)
2. 2

   Drain differential fluid
   Place drain pan under differential cover. Remove all differential cover bolts starting from the top and working down, leaving two upper bolts slightly threaded. Carefully pry cover loose and allow fluid to drain. Remove remaining bolts and cover. Clean magnet in cover and inspect for excessive metal particles indicating wear.
   ⚠Gear oil may be hot and will drain quickly once cover is loosened. Position drain pan to catch all fluid.
   Torque spec

   Differential Cover Bolts35 Nm (26 lb-ft)
3. 3

   Mark bearing cap orientation and measure backlash
   Before disassembly, use a punch to mark both carrier bearing caps and housing for correct reassembly orientation. Install dial indicator on ring gear tooth and measure backlash at 4 positions around the ring gear. Record measurements for reference. Typical backlash is 0.006-0.010 inches. This establishes baseline for comparison.
4. 4

   Remove carrier assembly
   Remove carrier bearing cap bolts. If equipped, use axle spreader tool to spread housing slightly (no more than 0.020 inches). Otherwise, carefully pry carrier assembly upward using pry points. Remove carrier assembly with bearings attached. Keep bearing caps with their respective sides.
   ⚠Do not over-spread axle housing as this can permanently deform the housing. Maximum spread is 0.020 inches.
5. 5

   Remove pinion gear
   Use pinion holding tool to prevent rotation. Remove pinion nut (note rotational torque required to turn pinion for later reference). Remove pinion flange using puller if necessary. Tap pinion rearward out of housing using soft mallet. Catch pinion and inner bearing as it comes free. Remove pinion seal and outer bearing from housing.
   ℹ️Record the torque required to rotate the pinion before removing nut. This is the bearing preload value you will match during reassembly.
6. 6

   Remove all bearings and races
   Use bearing puller to remove inner and outer pinion bearings from old pinion shaft. Remove crush sleeve or solid spacer from pinion. Use brass drift to drive out front and rear pinion bearing races from housing. Remove carrier bearings from carrier assembly using bearing puller or press. Drive out carrier bearing races from housing using brass drift. Clean all bearing bores thoroughly.
7. 7

   Remove old ring gear from carrier
   Mark ring gear to carrier orientation if reusing carrier. Remove all ring gear bolts (usually left-hand thread). Tap ring gear off carrier using soft mallet. Clean all mating surfaces on carrier with solvent and wire brush. Inspect carrier for cracks, damage, or worn spider gear components.
   ℹ️Ring gear bolts are typically left-hand thread. Turn clockwise to loosen.
8. 8

   Install new ring gear on carrier
   Align new ring gear on carrier ensuring proper orientation if directional. Install new ring gear bolts with thread locker compound. Tighten bolts in star pattern gradually to 70 ft-lbs, then to final torque per manufacturer specification (typically 90-100 ft-lbs). Let thread locker cure per product instructions.
   ℹ️New ring gear bolts must be used. Apply thread locker to all bolts before installation.
9. 9

   Install pinion bearing races and set pinion depth
   Press or drive new pinion bearing races into housing until fully seated. Check pinion depth variance marking on new pinion head (example: +2 or -3). Use pinion depth setting tool or calculate shim requirements based on old pinion marking and new pinion marking. Install appropriate shim behind inner pinion bearing race. This is critical for proper gear contact pattern.
   ⚠Pinion depth is the most critical measurement in ring and pinion setup. Incorrect depth will cause noise and premature wear. Consider using a pinion depth gauge tool for precision.
10. 10

    Assemble and install pinion
    Press inner pinion bearing onto pinion shaft. Install pinion into housing from rear. Install crush sleeve (or solid spacer with shims), outer bearing, pinion seal, washer, and flange. Hold flange with pinion holding tool and install new pinion nut. Gradually tighten nut while checking pinion rotating torque with inch-pound torque wrench. Target preload: 15-25 inch-pounds for new bearings. Do not back off nut if overtightened; crush sleeve is now set and pinion must be removed to start over.
    ⚠️Never back off pinion nut to reduce preload. If preload is exceeded, the crush sleeve is compressed and entire pinion assembly must be removed and crush sleeve replaced.
    ⚠Tighten pinion nut slowly in small increments while constantly checking rotating torque. It is easy to over-tighten.
11. 11

    Install carrier bearings and shims
    Press new carrier bearings onto carrier assembly. Install carrier bearing races into housing. Install carrier with shims into housing. Start with shims that provide 0.006-0.008 inches backlash as a baseline. Shims control carrier position side-to-side which sets backlash. Thicker shim on ring gear side moves gear closer to pinion (decreases backlash). Thicker shim on opposite side moves gear away (increases backlash).
12. 12

    Set backlash and carrier bearing preload
    Install carrier bearing caps in correct orientation matching punch marks. Torque cap bolts to specification (typically 70-80 ft-lbs). Install dial indicator on ring gear tooth. Measure backlash at 4 points around ring gear. Target: 0.006-0.010 inches with no more than 0.003 inches variation. Adjust shims as needed: move 0.002-0.004 inches of shim from one side to other to change backlash without affecting preload. Check carrier bearing preload using dial indicator method or shim calculation.
    ℹ️Backlash adjustment is iterative and may require multiple carrier removals and shim changes. Be patient and methodical.
13. 13

    Check gear contact pattern
    Apply marking compound to 8-10 ring gear teeth evenly spaced around the gear. Rotate pinion through several revolutions in both directions while applying resistance to ring gear (wrap rope around carrier and pull). Examine contact pattern on ring gear teeth. Pattern should be centered on tooth face for drive side and slightly toward toe on coast side. Adjust pinion depth (shims behind inner bearing race) if pattern is too high or low on tooth. Adjust backlash if pattern is too far toward toe or heel.
    ℹ️Proper gear contact pattern is essential for quiet operation and gear life. Coast side pattern is typically more toward toe and smaller than drive side. This is normal.
14. 14

    Reinstall driveshaft
    Remove plastic bag from transmission extension housing. Align driveshaft to pinion flange using marks made during disassembly. Install driveshaft bolts and torque to specification in star pattern. Verify driveshaft has no binding or unusual angles.
    Torque spec

    Driveshaft Bolts94 Nm (69 lb-ft)
15. 15

    Install differential cover and fill with fluid
    Clean differential cover and housing mating surfaces thoroughly with RTV scraper and solvent. Apply new gasket or continuous bead of RTV sealant to cover. Install cover and torque bolts in star pattern to specification. Allow RTV to cure per manufacturer instructions (typically 1 hour) before filling. Fill differential with specified gear oil through fill plug hole until oil reaches bottom of fill hole. If limited-slip differential, add friction modifier additive per vehicle specification. Install fill plug.
    ℹ️Limited-slip differentials require friction modifier additive. Check vehicle specification to determine if equipped.
    Torque spec

    Differential Cover Bolts35 Nm (26 lb-ft)

Reassembly

1. Install rear wheels and hand-tighten lug nuts
2. Lower vehicle to ground
3. Torque wheel lug nuts to specification in star pattern
4. Test drive vehicle at low speed initially to verify no unusual noises or vibrations
5. Check differential cover for leaks after test drive
6. Recheck gear oil level after test drive and top off if necessary

Verification

• Test drive vehicle starting at low speeds, gradually increasing to highway speeds
• Listen for whining, howling, or clunking noises during acceleration, deceleration, and steady cruising
• Verify no vibrations are present, especially during acceleration
• Check differential cover for leaks after 50-100 miles of driving
• Recheck gear oil level after first 500 miles and inspect for metal particles
• Proper setup should result in quiet operation with no abnormal noises across all driving conditions
• If noise is present, verify backlash, pinion depth, and bearing preload specifications were met correctly

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