Replace the ring and pinion gears in the rear differential of a 2016-2024 Hyundai Tucson 2.5L I4 AWD, including disassembly, gear installation, bearing preload adjustment, and backlash measurement.

Warnings

Tools required

Parts

• Ring and pinion gear set (must match ratio) × 1 — Use OEM specification or quality aftermarket
• Pinion bearing kit (inner and outer bearings, races, seal) × 1 — Use OEM specification
• Carrier bearing set (if applicable) × 1 — Use OEM specification
• Pinion seal × 1 — Use OEM specification
• Ring gear bolts × 1 — Use OEM specification
• Pinion nut × 1 — Use OEM specification
• Differential cover gasket or RTV silicone × 1 — Use OEM gasket or Hyundai-approved RTV
• Crush sleeve or solid spacer (depending on design) × 1 — Use OEM specification
• Shim kit for pinion depth and bearing preload × 1 — Use OEM specification

Fluids

• 75W-90 GL-5 Gear Oil — 2.5 qt

Preparation

1. Raise vehicle on lift or secure on jack stands at manufacturer-specified lift points
2. Remove rear wheels and set aside
3. Place drain pan under rear differential
4. Mark driveshaft and differential companion flange orientation for reassembly alignment
5. Support rear differential housing with transmission jack if removing from vehicle
6. Disconnect rear driveshaft from differential and secure out of the way
7. If removing differential: disconnect axle shafts, breather hose, and mounting bolts
8. Clean exterior of differential housing thoroughly to prevent contamination during disassembly
9. Prepare clean workspace with all specialized tools and new parts readily accessible

Procedure

1. 1

   Drain differential and remove cover
   Remove differential cover drain plug if equipped, or loosen cover bolts in crisscross pattern to drain fluid into pan. Once drained, remove all cover bolts and carefully pry cover away from housing. Clean all old gasket material from both cover and housing mating surfaces with gasket scraper. Inspect drained fluid for metal particles indicating existing gear damage.
2. 2

   Mark and measure existing setup
   Before disassembly, use dial indicator to measure and record ring gear backlash at 4 points around the gear (should be 0.13-0.18mm). Mark bearing cap orientation with punch marks. Measure and record pinion bearing preload by removing pinion nut and measuring rotational torque with inch-pound torque wrench (typically 10-15 inch-pounds for used bearings). Take photos of gear contact pattern if available. Record any visible shim thicknesses.
3. 3

   Remove differential carrier assembly
   Remove carrier bearing cap bolts and mark caps for correct reinstallation orientation. Use pry bars to carefully extract the differential carrier assembly with ring gear attached from the housing. Set carrier assembly in padded vise or holding fixture. Keep carrier bearings and shims organized by side (left/right) if reusing.
4. 4

   Remove pinion gear assembly
   Hold pinion flange with holding tool and remove pinion nut (may require significant force - typically 200+ ft-lbs to remove). Mark pinion flange orientation to pinion shaft. Use puller to remove companion flange. Carefully tap pinion shaft out from front of housing, catching rear pinion bearing and crush sleeve as they exit. Remove pinion seal with seal puller. Drive out front and rear pinion bearing races from housing using brass drift.
5. 5

   Remove old ring gear from carrier
   If reusing carrier, mark one ring gear tooth and corresponding carrier position. Remove ring gear bolts (typically left-hand thread). If bolts are tight, apply penetrating oil and use impact wrench. Once bolts are removed, tap ring gear off carrier with dead blow hammer. Clean carrier mounting surface thoroughly. Press off carrier bearings using bearing puller if replacing.
6. 6

   Install new pinion races and determine pinion depth
   Drive new pinion bearing races into housing using race driver, ensuring they are fully seated. Install pinion depth setting gauge tool per manufacturer instructions. The pinion gear has an etched number (like +2 or -3) indicating variance from nominal in hundredths of millimeter. Use this number with gauge tool and micrometer to determine correct shim thickness for pinion depth. 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 failure. Take multiple measurements to verify accuracy.
7. 7

   Assemble and install pinion gear
   Install selected pinion depth shim on pinion shaft. Press rear pinion bearing onto shaft using hydraulic press and bearing installation tool. Insert pinion assembly into housing from rear. Install front pinion bearing race, bearing, new crush sleeve (or solid spacer with shims per service manual), and new pinion seal. Install companion flange and new pinion nut. Gradually tighten pinion nut while measuring bearing preload with inch-pound torque wrench. Target preload is typically 15-25 inch-pounds for new bearings. Do not overtighten as crush sleeve cannot be reused if collapsed too much.
   ⚠Pinion bearing preload must be set precisely. Too loose causes noise and wear; too tight causes bearing failure. If using crush sleeve, it can only be crushed once - replacing if target preload is exceeded.
8. 8

   Install ring gear on carrier
   Heat new ring gear in oven to approximately 200°F (95°C) or use heat gun to expand the ring gear bore. Clean carrier ring gear mounting surface with brake cleaner. Align ring gear holes with carrier and install while warm. Install new ring gear bolts with medium-strength thread locker, tightening in star pattern to pull gear evenly onto carrier. Torque bolts per service manual specification (typically 80-100 ft-lbs). Allow assembly to cool to room temperature.
9. 9

   Install carrier bearings and measure runout
   Press new carrier bearings onto carrier housing using hydraulic press and proper bearing installation tool. Support ring gear to prevent damage during pressing operation. Once bearings are installed, mount dial indicator to housing and measure ring gear runout at the back face near the ring gear teeth. Runout should not exceed 0.05mm (0.002 inch). If excessive, check for debris under ring gear or carrier damage.
10. 10

    Install carrier assembly and set backlash
    Install carrier assembly with bearings into housing. Install bearing caps in original orientation (matching punch marks). Start with shims approximately 0.1mm thicker than original on each side. Install and finger-tighten cap bolts. Mount dial indicator to measure backlash at ring gear teeth. Adjust shim thickness side-to-side to achieve 0.13-0.18mm backlash while maintaining proper carrier bearing preload (typically 5-10 inch-pounds additional preload beyond bearing drag). Moving shims from one side to the other changes backlash without affecting preload significantly.
    ℹ️Backlash adjustment requires patience and multiple shim changes. Keep detailed notes of shim combinations tested. Carrier bearing preload is set by total shim thickness; backlash is adjusted by moving shims side to side.
11. 11

    Check gear contact pattern
    Apply thin coat of gear marking compound to 8-10 ring gear teeth in three locations around the ring. Rotate pinion through several revolutions in both directions while applying light resistance to the carrier. Examine the contact pattern on the gear teeth. The pattern should be centered on the tooth face, slightly toward the toe, and cover 50-60% of tooth length. Adjust pinion depth (shims) 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 longevity. Reference a gear pattern interpretation guide. Pattern adjustment may require removing pinion and changing depth shims.
12. 12

    Finalize bearing cap installation
    Once backlash and contact pattern are correct, remove bearing caps one final time and apply medium-strength thread locker to cap bolt threads. Reinstall caps in correct orientation and torque bolts per service manual specification (typically 55-65 ft-lbs). Recheck backlash after final torquing to confirm it remained in specification. Check that carrier rotates smoothly without binding.
13. 13

    Reinstall differential cover and fill
    Install new gasket or apply continuous bead of RTV silicone to differential cover mating surface. Install cover and torque bolts in crisscross pattern to specification. If removed from vehicle, reinstall differential assembly into vehicle using transmission jack, torque mounting bolts, reconnect axle shafts and breather. Fill differential with 2.0 quarts of 75W-90 GL-5 gear oil through fill plug until oil reaches bottom of fill hole. Install and torque fill plug.
    Torque spec

    Differential Cover Bolts35 Nm (26 lb-ft)

    Mounting Bolts27 Nm (20 lb-ft)
14. 14

    Reinstall driveshaft and wheels
    Align driveshaft to companion flange using marks made during disassembly. Install driveshaft bolts or U-joint straps and torque evenly to specification. Reinstall rear wheels and torque lug nuts in star pattern to specification. Lower vehicle to ground.
    Torque spec

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

    Wheel Lug Nuts140 Nm (103 lb-ft)
15. 15

    Break-in and final verification
    Start engine and allow to idle. Shift transmission through all gears to circulate fluid. Test drive vehicle at moderate speeds (under 50 mph) for first 15-20 miles, making frequent direction changes and light acceleration/deceleration to allow gears to wear in properly. Listen for any abnormal whining, grinding, or howling noises. Check differential for leaks after test drive. Recheck fluid level and top off if necessary. Avoid heavy acceleration or towing for first 500 miles of break-in period.
    ⚠New ring and pinion gears require proper break-in procedure. Excessive load or speed during break-in period can cause premature gear failure.

Reassembly

1. Ensure all bearing preload and backlash specifications are within factory tolerances before final assembly
2. Use all new crush sleeves, seals, and gaskets - never reuse these components
3. Apply thread locker to all critical fasteners as specified
4. Verify gear contact pattern is correct before final cover installation
5. Torque all fasteners in proper sequence and to exact specifications
6. Use only the specified 75W-90 GL-5 gear oil - limited slip additives only if differential has limited slip clutches

Verification

• Confirm backlash is between 0.13-0.18mm at multiple points around ring gear
• Verify pinion bearing preload is within specification (typically 15-25 inch-pounds for new bearings)
• Check that gear contact pattern is centered on tooth face with proper coverage
• Ensure differential rotates smoothly without binding or excessive noise
• Test drive vehicle and listen for abnormal gear noise (whine, howl, or grinding)
• Check for differential leaks at cover, pinion seal, and axle seals after test drive
• Verify proper fluid level at fill plug after test drive
• Confirm no vibration or unusual driveline behavior during acceleration and deceleration

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