Axle Seal - Rear

This procedure covers the removal and replacement of the rear axle seals on a 1966 Chevrolet Corvette with independent rear suspension, including differential fluid draining and refilling.

Warnings

Tools required

Parts

• Rear axle shaft seal × 2 — Use OEM specification
• Differential cover gasket × 1 — Use OEM specification

Fluids

• 75W-90 GL-5 Gear Oil — 2 qt

Preparation

1. Park vehicle on level ground and engage parking brake.
2. Chock the front wheels securely.
3. Raise the rear of the vehicle and support on jack stands positioned under the frame rails, not the suspension components.
4. Remove both rear wheels to improve access to the halfshaft area.
5. Allow the differential to cool if the vehicle has been recently driven.

Procedure

1. 1

   Drain differential fluid
   Position the drain pan under the differential. Remove the differential cover/carrier bolts working in a crisscross pattern (verify exact bolt count against factory service manual). Carefully pry the cover away from the housing using a pry bar at the designated pry points. Allow all fluid to drain completely into the pan. Inspect drained fluid for metal shavings or debris that might indicate internal wear.
2. 2

   Remove differential cover and inspect
   Once fluid has fully drained, remove the differential cover completely. Clean the mating surface on the differential housing with a wire brush and brake cleaner, removing all old gasket material. Inspect the ring and pinion gears visually for obvious damage or excessive wear.
3. 3

   Remove halfshaft U-bolt straps
   Locate the universal joint connecting each halfshaft to the differential output stub shaft. Remove the 2 U-bolts securing each U-joint strap (4 bolts total per side). Support the halfshaft to prevent it from dropping and damaging the U-joint.
4. 4

   Separate halfshaft from differential
   Carefully pull the halfshaft away from the differential stub shaft, separating the U-joint. Secure the halfshaft out of the way using wire or a bungee cord to prevent strain on the outboard U-joint or suspension components. Repeat for the opposite side.
5. 5

   Remove axle shaft seals
   Using the axle seal puller or seal removal tool, carefully extract the old seal from each side of the differential housing. The seal sits in the differential housing bore where the output stub shaft exits the carrier. Take care not to damage the bore surface or the stub shaft surface during removal. Note the depth and orientation of the original seal installation.
6. 6

   Clean and inspect sealing surfaces
   Thoroughly clean the seal bore in the differential housing and the stub shaft sealing surface using brake cleaner and shop rags. Inspect the stub shaft for scoring, grooves, or damage that could cause the new seal to leak. Check the seal bore for nicks or burrs. Minor imperfections can be smoothed with fine emery cloth.
7. 7

   Install new axle shaft seals
   Lightly coat the outer edge of the new seal with gear oil. Position the seal squarely in the bore with the seal lip facing inward toward the differential. Using the seal driver or appropriately sized socket, tap the seal evenly into place until it seats at the same depth as the original seal. Ensure the seal is fully seated and not cocked in the bore. Repeat for the opposite side.
8. 8

   Reinstall differential cover with new gasket
   Position the new differential cover gasket on the housing, ensuring all bolt holes align. If using RTV instead of a gasket, apply a continuous 1/8 inch bead to the cover mating surface. Install the differential cover and thread in all cover bolts finger tight (verify exact bolt count against factory service manual). Tighten the bolts in a crisscross pattern to ensure even gasket compression. Final torque specification must be verified against the factory service manual before tightening; do not rely on an estimated value.
9. 9

   Reconnect halfshafts to differential
   Align the halfshaft U-joint with the differential stub shaft U-joint. Install the U-joint strap and 2 U-bolts per side. Tighten the U-bolt nuts securely. Torque specification must be verified against the factory service manual before tightening; do not rely on an estimated value. Repeat for the opposite side.
10. 10

    Refill differential with gear oil
    Using a fluid pump or funnel with hose, refill the differential through the fill plug opening with GL-5 gear oil of the factory-specified viscosity and capacity (verify exact fill plug location, capacity, and viscosity against the factory service manual). Fill until oil reaches the bottom of the fill plug hole. Install and tighten the fill plug securely.
11. 11

    Reinstall wheels and lower vehicle
    Reinstall both rear wheels and tighten lug nuts in a star pattern. Lower the vehicle from the jack stands and perform final lug nut torque to the factory-specified value (verify against the factory service manual) with the vehicle on the ground.

Reassembly

1. Ensure all U-bolt nuts are properly torqued and safety wired if originally equipped.
2. Double-check that the differential fill plug is installed and tight.
3. Verify no fluid leaks are present at the differential cover or axle seals before returning vehicle to service.

Verification

• Start the engine and allow it to idle. Shift through all gears to circulate fluid through the differential.
• Inspect around both axle seals and the differential cover for any signs of leakage.
• Take the vehicle for a short test drive, making several turns in both directions to load the differential.
• Re-inspect all seal areas and the differential cover after the test drive for any signs of seepage.
• Check differential fluid level after test drive and top off if necessary.

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