Are Your Seals Leaking?

[jim-d-amelio]

The transmission and differential seals on TR’s, Sunbeam’s and MG’s always seem to
leak causing that wonderful coating on the bottom of your car. Well,
maybe it isn’t the seal leaking!

I had “finished” overhauling my differential and it was set aside for
the next project. It was hanging on jackstands nose down and I noticed
a small puddle of oil right under the flange. I had just replaced the
seal and polished the sealing surface on the flange so this was a
puzzle. The oil was leaking out from under the washer and nut. It was
torqued to over 85 ft/lb and I would have thought this would provide
quite a good seal. Wrong! Over the years and who knows how many ham
fisted backyard mechanics the mating surface between the flange and
washer was scored. Further, on looking closely, the splines in the
flange were actually squeezed above the mating surface. The nut and
washer had been thoroughly torqued down onto just the spline tips. Add
in the scoring and it was a LEAK. As I was also working on the
transmission, I checked the trans flange and it was in the same sorry
shape.

The only good fix is to chuck the flanges up in a lathe and resurface
the washer mating surface so the washer can actually act as a seal. I
further surfaced just the splines another couple of thousands below the
washer surface as the torque on the splines wants to squeeze out the
splines into the washer lifting it away from the surface, thus leaking
over time. By the way, no amount of gasket sealer will seal up this
joint and will only glue your nut to the flange. Tip courtesy of Tom Wiencek.

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