Locking Hub - Auto

This procedure covers the replacement of automatic locking hubs on a 1994-2007 Dodge Ram 2500 with the 5.9L Cummins diesel engine and 4WD.

Warnings

Tools required

Parts

• Automatic locking hub assembly (left) × 1 — Warn or OEM equivalent
• Automatic locking hub assembly (right) × 1 — Warn or OEM equivalent
• Hub cover screws (if not included with hubs) × 12 — Use OEM specification
• Axle nut cotter pin × 2 — Use OEM specification
• Front differential gasket or RTV sealant × 1 — Use if differential service performed

Fluids

• 75W-90 synthetic gear oil — 3.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Shift transfer case to 2WD (2H) position
3. Chock rear wheels securely
4. Loosen front wheel lug nuts while vehicle is on ground (do not remove)
5. Raise front of vehicle and support securely on jack stands at frame rails
6. Remove front wheels completely
7. Clean hub area and surrounding components with brake cleaner to remove dirt and debris

Procedure

1. 1

   Remove hub cover screws
   Locate the cover screws (typically 5 or 6, verify count) securing the locking hub cover to the hub body. Remove all screws and carefully pull the hub cover away from the hub assembly. Inspect the cover for damage and clean any debris from the mating surface.
2. 2

   Remove axle nut cotter pin
   Straighten and remove the cotter pin from the axle nut using pliers. If the cotter pin is damaged or difficult to remove, use a small punch to drive it out. Discard the old cotter pin; a new one must be used during reassembly.
3. 3

   Remove axle nut
   Using a breaker bar and appropriate socket, loosen and remove the axle nut. This spindle/bearing adjustment nut must be set to the manufacturer's bearing preload procedure (typically seat the bearings, then back off and set to specification), not a high fixed torque. Verify the correct spindle nut procedure and torque in the service manual before removal. Have an assistant apply the brakes or use a pry bar between wheel studs to prevent hub rotation if necessary.
   ⚠Use proper technique to avoid injury when applying force to break the axle nut loose
4. 4

   Remove locking hub assembly
   Pull the automatic locking hub assembly straight off the axle shaft and hub spindle. The assembly may be tight; use gentle back-and-forth rocking motion if needed. Inspect the axle shaft splines for wear or damage. Note the position of any shims or spacers behind the hub.
5. 5

   Inspect hub mounting surface and axle shaft
   Thoroughly clean the hub mounting surface on the spindle using a wire brush and brake cleaner. Inspect the axle shaft splines for damage, wear, or debris. Check the spindle bearing area for grease contamination or wear. If excessive wear is present, further service may be required.
   ℹ️Any fluid leaking from the axle shaft area indicates a failed axle seal requiring differential service
6. 6

   Prepare new locking hub
   Remove new automatic locking hub from packaging and verify it matches the original hub design. Ensure all internal components move freely and the hub cam mechanism operates smoothly. Apply a thin coating of clean wheel bearing grease to the axle shaft splines and engagement components.
7. 7

   Install new locking hub assembly
   Align the new hub assembly with the axle shaft splines and spindle. Ensure the hub cam is in the unlocked (2WD) position. Carefully slide the hub assembly onto the axle shaft, ensuring proper engagement of all splines. The hub should seat flush against the spindle mounting surface.
8. 8

   Install and torque axle nut
   Thread the axle nut onto the axle shaft by hand until snug. Use a torque wrench to tighten the axle nut to specification. The nut must be torqued with the hub stationary; have an assistant apply brakes or use a pry bar between wheel studs.
   ⚠Critical torque specification must be met for proper hub bearing preload and safety
9. 9

   Install new cotter pin
   Reinstall the retaining hardware per the spindle nut design (typically an inner adjusting nut, keyed lock washer, and outer lock nut), verifying the correct locking method for this axle. If the hole does not align with a nut slot, tighten the nut slightly (do not loosen) until alignment is achieved. Bend the cotter pin ends to secure the nut. Alternatively, if equipped with a staked nut design, stake the nut per manufacturer specifications.
10. 10

    Install hub cover
    Clean the hub cover mating surface and ensure the gasket or seal is properly positioned. Align the hub cover with the hub body and install all cover screws by hand. Tighten the screws in a criss-cross pattern to ensure even seating.
11. 11

    Repeat procedure for opposite side
    Perform steps 1 through 10 on the opposite front wheel to replace the second automatic locking hub. Both hubs must be replaced as a pair to ensure proper 4WD engagement and operation.
12. 12

    Reinstall wheels and lower vehicle
    Install front wheels and thread lug nuts by hand until snug. Lower vehicle until tires just contact the ground but weight is still on jack stands. Torque wheel lug nuts in a star pattern to specification. Fully lower vehicle and remove jack stands.
    ⚠Always use star pattern when torquing lug nuts to prevent wheel distortion

Reassembly

1. Ensure all fasteners are torqued to specification
2. Verify cotter pins are properly installed and bent to prevent axle nut loosening
3. Confirm hub covers are fully seated with no gaps
4. Double-check wheel lug nuts are torqued in star pattern

Verification

• Test drive vehicle in 2WD mode and verify no unusual noises or vibrations from front hubs
• Shift transfer case to 4WD High and drive forward 10-20 feet to engage automatic locking hubs
• Verify 4WD engagement by listening for hub engagement click and testing power delivery to front wheels
• Return to 2WD mode and drive forward; hubs should disengage after 10-20 feet of reverse travel
• Re-check wheel lug nut torque after 50-100 miles of driving
• Inspect hub area for any fluid leaks after test drive

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