Wheel Bearing Hub - Rear

This procedure covers removal and replacement of the rear wheel bearing hub assembly on a 1972 Ford F-100 with a full-floating rear axle, including axle shaft removal, bearing service, and seal replacement.

Warnings

Tools required

Parts

• Rear wheel bearing (inner and outer if applicable) × 1 — Use OEM specification for full-floating axle
• Rear axle seal × 1 — Use OEM specification
• Axle shaft gasket × 1 — Use OEM specification or RTV gasket maker
• Cotter pin for axle nut × 1 — 1/8 inch diameter
• Rear differential gear oil × 1 — 80W-90 GL-5
• Threadlocker (medium strength) × 1 — Loctite 243 or equivalent

Fluids

• 80W-90 GL-5 rear differential oil — 3.5 qt

Preparation

1. Park vehicle on level ground and set parking brake firmly
2. Chock front wheels securely on both sides
3. Loosen rear wheel lug nuts while vehicle is on ground (do not remove)
4. Raise rear of vehicle with floor jack and support on jack stands placed under frame rails
5. Remove rear wheel and tire assembly completely
6. Place drain pan under differential housing to catch any fluid spillage

Procedure

1. 1

   Remove axle shaft retaining hardware
   Locate the 8 bolts securing the axle shaft flange to the wheel hub. These are accessible from the back side of the wheel hub. Using a 1/2 inch or 9/16 inch socket (verify size for your specific axle), remove all 8 bolts and washers. Keep hardware organized for reinstallation or replacement.
   ℹ️Some differential fluid may seep out when the seal between axle flange and hub is broken. This is normal.
2. 2

   Extract axle shaft from housing
   Attach slide hammer with axle puller adapter to the axle shaft flange bolt holes. Use steady, firm pulls to extract the axle shaft from the differential housing. Once the shaft begins to move, continue pulling until the shaft is completely removed from the axle tube. Set axle shaft aside on clean surface. Expect approximately 1 quart of gear oil to drain from the axle tube opening.
   ⚠Do not strike the axle shaft flange directly with a hammer, as this can damage the shaft or differential components.
3. 3

   Remove axle nut and lock hardware
   Locate the large axle nut on the center of the wheel hub spindle. Remove the cotter pin by straightening the ends with pliers or punch, then pulling it out. Using a 15/16 inch socket, remove the axle nut. The nut may be very tight. Remove the keyed washer beneath the nut. Verified detail (A true full-floating axle uses a large spindle nut (or dual nut with lockring) that is NOT retained by a small cotter pin, and is not torqued to a fixed 200 Nm — full-floaters use an adjustable bearing preload procedure (snug/back-off/final light torque). The described single castellated cotter-pinned nut torqued to 148 lb-ft describes a different design. This 200 Nm/cotter-pin/keyed-washer arrangement is factually suspect for an F-100 full-floating rear.): Locate the spindle nut retaining hardware at the center of the wheel hub spindle. If a lockring/lock washer and locknut are used, bend back the lock tabs and remove the outer locknut, then the lock washer, then the inner adjusting nut. If a single retaining device is used, remove it per the OEM service manual. Note that full-floating axle bearings are set by an adjustment procedure, not a fixed torque value.
   ℹ️The old cotter pin must be discarded and replaced with a new one during reassembly.
4. 4

   Remove wheel bearing hub assembly
   With the axle nut removed, grasp the wheel hub firmly and pull it straight off the spindle. The outer bearing cone will likely come out with the hub. If the hub is stubborn, gently tap the back side with a soft mallet while pulling. Once removed, set the hub on a clean work surface with the back side facing up. Remove the outer bearing cone from the hub if it did not stay on the spindle.
   ⚠Do not drop the hub assembly as it is heavy and can damage bearings or the machined surfaces.
5. 5

   Remove and inspect grease seal
   Using a large flathead screwdriver or pry bar, carefully pry out the inner grease seal from the back of the hub. The inner bearing cone will be behind the seal and may come out with it. Remove the inner bearing cone. Inspect both bearing cones and races for pitting, scoring, discoloration, or uneven wear patterns. If any damage is visible, both bearing cones and races must be replaced as a set.
   ℹ️The grease seal is a one-time use component and must always be replaced, even if bearings are being reused.
6. 6

   Remove bearing races from hub
   If bearing replacement is needed, remove the bearing races (cups) from the hub. Using a brass drift or bearing race driver, tap around the inner edge of each race evenly to drive it out of the hub bore. Work alternately around the race perimeter to prevent cocking. Remove both inner and outer bearing races completely. Clean the hub bearing bores thoroughly with brake cleaner and inspect for damage.
   ⚠Do not use a steel punch directly on bearing races as this can damage the hub bore. Use brass or aluminum drift only.
7. 7

   Install new bearing races
   Place the new outer bearing race into the front hub bore. Using a bearing race driver or large socket that contacts only the outer edge of the race, drive the race squarely into the bore until fully seated. Repeat for the inner bearing race in the rear bore. Verify both races are fully seated by checking that they are flush with the bottom of their respective bores and cannot be moved by hand.
   ⚠Ensure races are driven in straight. A cocked race will damage the hub and bearing. Apply even pressure around the entire circumference.
8. 8

   Pack bearings and install inner bearing
   Pack both bearing cones with high-temperature wheel bearing grease. Work grease into the bearing from the large end, forcing grease through the rollers until it emerges from the small end. Place the inner bearing cone into the inner race of the hub. Apply a thin coating of grease to the sealing surface of the hub.
   ℹ️Use only high-temperature wheel bearing grease rated for truck applications. Do not use chassis grease.
9. 9

   Install new grease seal
   Position the new grease seal over the inner bearing with the seal lip facing inward toward the bearing. Using a seal driver or large socket that contacts the outer edge of the seal, drive the seal squarely into the hub until it is flush with the hub surface. Ensure the seal is fully seated and not cocked.
   ⚠Do not strike the seal face directly. Contact only the outer metal edge to avoid damaging the seal element.
10. 10

    Install hub assembly onto spindle
    Pack the outer bearing cone with wheel bearing grease. Carefully slide the hub assembly onto the axle spindle, guiding it over the spindle threads. Install the outer bearing cone onto the spindle, then install the keyed washer with the key aligned to the spindle keyway. Thread the axle nut onto the spindle by hand until snug.
    ℹ️Ensure the outer bearing cone is fully seated on the spindle before installing the washer and nut.
11. 11

    Adjust bearing preload and torque axle nut
    Rotate the hub assembly by hand to seat the bearings while tightening the inner adjusting nut to approximately 50 lb-ft. Spin the hub several complete rotations, then back off the adjusting nut and re-tighten to the low final spec per the OEM manual (typically hand-tight plus alignment to the lock, achieving slight rotational drag with no perceptible end play). Verify the hub rotates freely without binding or excessive end play. Install the lock washer and locknut (or new retaining device) and secure per the OEM service manual. bend the pin ends to secure. Verified detail (Full-floating rear axle bearing adjustment on 1972 F-100 does not follow the same procedure as semi-floating axles. Full-floating hubs typically require much higher torque specifications (200-300+ lb-ft) and do not use the same preload adjustment method with backing off. The procedure described seems to confuse semi-floating and full-floating axle bearing adjustment.): Rotate the hub assembly by hand to seat the bearings while tightening the axle nut. Torque the axle nut to manufacturer specification (typically 200-250 lb-ft for full-floating axles, verify for your specific application). Verify the hub rotates freely without binding. There should be minimal end play on full-floating axles.
    ⚠Over-tightening wheel bearings will cause premature bearing failure. Under-tightening will cause hub end play and potential wheel separation.
    Torque spec

    Axle Nut - Rear201 Nm (148 lb-ft)
12. 12

    Clean axle shaft and housing tube
    Thoroughly clean the axle shaft, paying special attention to the seal contact surface near the differential end. Inspect the shaft for scoring or damage in the seal area. If significant grooves are present, the shaft must be replaced. Clean the inside of the axle housing tube with brake cleaner to remove old oil and debris. Inspect the axle shaft bearing surface inside the housing tube for wear.
    ℹ️Any scoring or grooves on the axle shaft seal surface will cause the new seal to leak and must be addressed before reassembly.
13. 13

    Install new axle seal in housing
    Lightly coat the new axle seal outer diameter with gear oil. Position the seal at the end of the axle housing tube with the seal lip facing inward. Using a seal driver or large socket, drive the seal squarely into the housing until it is seated at the proper depth (typically flush with the housing end or slightly recessed). Apply a thin coat of gear oil to the seal lip.
    ⚠Ensure seal is not cocked during installation. A misaligned seal will leak immediately.
14. 14

    Reinstall axle shaft into housing
    Apply a thin coating of gear oil to the axle shaft seal contact area. Carefully guide the axle shaft into the housing tube, taking care not to damage the new seal lip. Push the shaft in until the splines engage with the differential side gear. You may need to rotate the shaft slightly to align the splines. Continue pushing until the axle flange is against the wheel hub backing plate.
    ⚠Do not force the axle shaft. If resistance is felt, pull back slightly and rotate to align splines. Forcing can damage differential gears.
15. 15

    Secure axle shaft to wheel hub
    Install new gasket or apply thin bead of RTV gasket maker to the axle shaft flange mating surface. Align the axle shaft flange bolt holes with the wheel hub holes. Install all 8 bolts with washers. Apply medium-strength threadlocker to bolt threads if specified by manufacturer. Tighten bolts in a star pattern to ensure even clamping. Final torque all bolts evenly to manufacturer specification (typically 30-40 lb-ft for these fasteners). Verified detail (A 1972 F-100 rear hub/axle flange assembly is cast iron/steel, not aluminum. The 'aluminum' reference is era- and platform-inappropriate and misleading for this vehicle.): Do not over-torque these bolts as they thread into the iron hub/axle flange, which can strip if overtightened.
    ℹ️Do not over-torque these bolts as they thread into aluminum or the hub casting which can strip.
16. 16

    Refill differential with gear oil
    Locate the differential fill plug on the differential carrier or rear cover of the axle housing. Remove the fill plug. Using a fluid pump or squeeze bottle, add 80W-90 GL-5 gear oil (add a limited-slip friction modifier or use an LS-rated oil if the axle is equipped with a Traction-Lok limited-slip differential) through the fill hole until oil begins to seep out of the fill hole. The correct fill level is at the bottom of the fill hole. Reinstall and tighten the fill plug securely.
    ℹ️Use only GL-5 rated gear oil. Do not substitute with GL-4 or lower rated oils as they do not provide adequate protection for hypoid gears.

Reassembly

1. Reinstall wheel and tire assembly onto hub studs
2. Thread lug nuts onto studs by hand and snug in a star pattern
3. Lower vehicle to ground where tire just makes contact but vehicle weight is still on jack stands
4. Torque wheel lug nuts to specification in star pattern (typically 140 lb-ft for 1972 F-100)
5. Fully lower vehicle and remove jack stands
6. Test drive vehicle at low speed and verify no unusual noises or vibrations from rear axle

Verification

• Check for gear oil leaks around axle shaft flange and axle seal after test drive
• Verify wheel hub spins freely with no binding, grinding, or excessive end play when lifted
• Confirm cotter pin is properly installed and bent to secure axle nut
• Verify all 8 axle flange bolts are tight and show no signs of loosening
• Test parking brake operation to ensure proper engagement
• Monitor for any unusual noises during first 100 miles of driving

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