Chicagoland MG Club: Tech Tips

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Spridget Rear Axle
Oil Leak

by Norm Kerr - Ann Arbor, MI

  • plugged breather (plastic "mushroom" located at the top of the axle housing, RH of the differential). Pull off the top "cap" and then unscrew the "stem" to clean.
  • bad wheel bearing (causing seal to not touch properly)
  • worn out seal (or dried by age, especially on a car not run for years)
  • worn housing (if you can feel a groove, have a machine shop install speedy sleeves to restore the sealing surface)
        ==> photos before/after
  • torn or re-used gasket (trim the inner diameter of the new gasket so it doesn't touch the O ring. Max gasket thickness 0.010", any thicker will result in a loose wheel bearing. Some leave the gasket off and use a Permatex type sealer instead.)

    Make sure the leak is actually from the axle seal. Rear brake cylinders develop leaks (look for fluid around the dust seals), and are cheap to replace ($20). If the liquid is on the cylinder and under its dust seals, it is leaking. If it is around the hub (not easy for the brake fluid to get there), then the axle seal is leaking. If there is liquid all over everything, then both are probably leaking.

    When replacing the bearing, use a 207-FF (double sealed bearing, which then acts as a supplemental seal against axle oil leak). You can purchase from any foreign auto parts store (also used in Subaru's). If using a sealed bearing, be sure to lube the original axle seal real well before installing the hub to the axle, because it won't be getting any of the oil it normally sees.

    Hub seal dimensions OD 2.5, ID 1.75, seal lap 0.375".

    If you have a persistent leak between the axle and its mating surface on the hub, your axle may be bent, or you've swapped them R x L (RH is longer and will jam against the diff pin, preventing seal). The original O ring is 0.115", though a larger dimension could be tried if struggling with leaks.

    Hub nut torque (not shown in the manuals): 40 ~ 45 ft-lb. No need for much torque, as this only needs to hold the bearing race securely against the axle housing, and rotation is prevented by the lock tab.
    LH hub nut has reverse thread (same reason as the RH wire wheel nut, but opposite side of the car, because of the rotation direction effect)

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