drivetrain

Front Differential

for 2021 Hyundai Tucson 2.5L I4 · AWD

Difficulty

Advanced

Time

4.0 h

Tools

Steps

This procedure covers removal and replacement of the front differential assembly on a 2016-2024 Hyundai Tucson with 2.5L I4 AWD, including driveshaft disconnection, axle separation, and fluid refill.

Warnings

⚠️Vehicle must be securely supported on jack stands rated for the vehicle weight. Never work under a vehicle supported only by a floor jack.

⚠The front differential may contain residual hot gear oil if vehicle was recently operated. Allow adequate cooling time before draining.

⚠Axle nuts are torqued to 250 Nm (184 lb-ft) and will require significant force to loosen. Ensure the vehicle is stable and wheels are properly chocked.

ℹ️Some models use staked axle nuts that must be replaced. Others use cotter pins. Inspect your vehicle's configuration before beginning work.

Tools required

Floor jack and jack standsEssential

Torque wrench (20-300 Nm range)Essential

Socket set (10mm-32mm)Essential

Breaker barEssential

Pry bar

Oil drain pan (3+ quart capacity)Essential

Gear oil pump or fluid transfer bottleEssential

Dead blow hammer

Wire brush

Gasket scraper

6-point axle nut socket (32mm)Essential

Wheel chocksEssential

Parts

Front differential assembly × 1 — Use OEM specification
Differential cover gasket × 1 — Use OEM specification
Axle nut (if staked type) × 2 — Use OEM specification
Differential drain plug washer × 1 — Use OEM specification
Differential fill plug O-ring × 1 — Use OEM specification

Fluids

75W-90 GL-5 Gear Oil — 1.5 qt

Preparation

Park vehicle on level surface and engage parking brake
Place wheel chocks behind rear wheels
Loosen front wheel lug nuts while vehicle is on ground (do not remove)
Raise front of vehicle and support securely on jack stands at manufacturer-designated lift points
Remove both front wheels completely
If equipped, remove front skid plate or under-engine cover
Place drain pan under front differential assembly

Procedure

1
Drain front differential fluid
Locate the drain plug on the bottom of the front differential housing. Using the appropriate socket, remove the drain plug and allow all gear oil to drain completely into the drain pan. Remove the fill plug on the side of the differential housing to aid drainage and ventilation. Inspect drained fluid for metal particles or contamination.
2
Remove axle nuts from both front hubs
If axle nut is staked, use a chisel to unstake the nut collar from the axle groove. If equipped with cotter pin, remove and discard the pin. Using a 32mm socket and breaker bar, loosen and remove both front axle nuts completely. These nuts are torqued to 250 Nm and will require significant force. Set nuts aside (replace if staked type).
3
Disconnect CV axles from differential
Locate the inner CV joint mounting bolts where each axle connects to the front differential output flanges. There are typically 6 bolts per side. Remove all CV joint mounting bolts from both driver and passenger side axles. Carefully pull the axle shafts away from the differential and support them with wire or rope to prevent strain on outer CV joints. Do not allow axles to hang freely.
Torque spec
CV Bolts61 Nm (45 lb-ft)
4
Disconnect front driveshaft from transfer case
Locate the front driveshaft connection at the transfer case output. Mark the orientation of the driveshaft yoke to the flange for reassembly alignment. Remove the U-joint strap bolts connecting the driveshaft to the transfer case. Carefully lower the front of the driveshaft and secure it out of the way. Cap or tape the transfer case output to prevent fluid loss and contamination.
ℹ️Marking driveshaft orientation maintains proper balance and prevents vibration issues during operation.
Torque spec
Driveshaft U-Joint Straps20 Nm (15 lb-ft)
5
Disconnect rear driveshaft from differential (if necessary)
If the front differential connects to a rear driveshaft section, locate the connection point at the rear of the differential. Mark alignment and remove the U-joint strap bolts. Support the driveshaft and lower it away from the differential. Secure the driveshaft to prevent it from falling or being damaged.
Torque spec
Driveshaft U-Joint Straps20 Nm (15 lb-ft)
6
Remove differential mounting bolts
Locate all differential mounting bolts connecting the differential housing to the subframe or crossmember. There are typically 3-5 mounting bolts depending on the mounting bracket configuration. Support the differential with a transmission jack or suitable support before removing bolts. Remove all mounting bolts while supporting the differential weight.
⚠The front differential assembly weighs approximately 40-50 lbs. Ensure adequate support is in place before removing final mounting bolts.
Torque spec
Mounting Bolts27 Nm (20 lb-ft)
7
Remove differential assembly from vehicle
With all mounting bolts removed and the differential properly supported, carefully lower the differential assembly from the vehicle. Maneuver the assembly past any obstructions including the subframe, control arms, and axle shafts. Place the differential on a clean work surface for inspection or disposal.
8
Prepare and install replacement differential
Clean all mounting surfaces on the subframe and crossmember where the differential mounts. Inspect mounting brackets for damage or wear. If reusing the differential cover, clean the mating surface and install a new gasket. Position the replacement or rebuilt differential assembly onto the transmission jack and raise it into position, aligning mounting holes with the subframe.
9
Install differential mounting bolts
Start all differential mounting bolts by hand to ensure proper thread engagement. Once all bolts are started, tighten them progressively in a cross pattern to ensure even seating of the differential against the mounting surface. Torque all mounting bolts to specification using a torque wrench.
Torque spec
Mounting Bolts27 Nm (20 lb-ft)
10
Reconnect driveshafts
Align the rear driveshaft (if applicable) with the marked position on the differential flange. Install U-joint strap bolts and tighten evenly to specification. Reconnect the front driveshaft to the transfer case output, aligning marks made during disassembly. Install U-joint strap bolts and tighten evenly to specification. Remove any caps or tape from the transfer case output.
Torque spec
Driveshaft U-Joint Straps20 Nm (15 lb-ft)
11
Reconnect CV axles to differential
Guide both CV axle inner joints back to their respective differential output flanges. Ensure splines are properly aligned and seated. Install all CV joint mounting bolts on both sides (6 bolts per side). Tighten bolts progressively in a star pattern, then torque to specification.
Torque spec
CV Bolts61 Nm (45 lb-ft)
12
Install axle nuts
Clean the axle shaft threads and hub mating surfaces. If using new staked-type axle nuts, install new nuts on both front axle shafts. If using cotter pin type, install original or new nuts. Hand-tighten nuts, then use a torque wrench and 32mm socket to torque both axle nuts to specification. For staked nuts, use a punch to stake the nut collar into the axle groove. For cotter pin type, install new cotter pins and bend tabs to secure.
ℹ️Axle nuts must be properly secured with either staking or new cotter pins. Do not reuse staked nuts or cotter pins.
Torque spec
Axle Nut250 Nm (184 lb-ft)
13
Fill differential with gear oil
Install a new O-ring on the fill plug. Using a gear oil pump or fluid transfer bottle, add 75W-90 GL-5 gear oil through the fill hole until oil begins to seep from the fill hole opening. This indicates proper fill level (approximately 1.5 quarts). Install the fill plug with new O-ring and tighten securely. Install the drain plug with new washer and tighten securely.
14
Reinstall wheels and lower vehicle
Reinstall both front wheels, starting all lug nuts by hand. Tighten lug nuts in a star pattern to snug (do not torque while on jack stands). Reinstall front skid plate or under-engine cover if equipped. Carefully lower vehicle to the ground. With vehicle on the ground and full weight on wheels, torque lug nuts to specification in a star pattern.
Torque spec
Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

Ensure all drain and fill plugs are properly tightened with new sealing washers or O-rings
Verify all driveshaft U-joint straps are torqued evenly to prevent vibration
Confirm axle nuts are properly secured with either staking or new cotter pins
Double-check that all CV joint bolts are torqued to specification on both sides

Verification

Start the engine and allow it to idle. Listen for any abnormal noises from the front differential area
Perform a visual inspection under the vehicle for any gear oil leaks around the differential cover, drain plug, fill plug, and axle seals
Test drive the vehicle at low speed in a safe area. Listen for grinding, whining, or clicking noises that could indicate improper installation
Engage all-wheel drive system (if switchable) and verify proper engagement without noise or vibration
After 50-100 miles of driving, recheck differential fluid level through the fill plug. Top off if necessary
Inspect for leaks again after initial test drive and verify all mounting bolts remain tight