Prior to removing the tranny and replacing the clutch on my '80 Spitfire
(about two months ago) the overdrive unit seemed to work perfectly.
Until last night, I thought I had a slipping clutch -- which I'm now
convinced to be the overdrive. While removed, the only thing I did to
the tranny and overdrive was to drain the fluid (no idea what was in
it), clean the filters and top it off with the specified 85-90 GL/4 gear
oil.
I've spoken to a reported guru of gearbox/od units who tells me he never
puts 90 wt. gear oil in them -- too slippery and can cause the unit to
slip when in direct drive. Says he has always put straight motor oil in
-- 50 wt. His suggestion to me is to drain the unit and fill it with
regular automatic transmission fluid, run it for a few miles and drain
again -- the A.T.F. to help clean out the 90 wt. gear oil. Then to fill
the unit with straight 50 wt. motor oil. He offered this suggestion
prior to my sending the thing to him for a rebuild, so I believe he has
my best interest at heart.
Would like to know if any other listers have had this type of problem
and/or comments regarding the above. In other words, what do you guys
have in your gearbox?
Best regards,
Ed Hamilton
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