In "TR7 and TR8 5-Speed Gearbox Overhaul" in the Vintage Triumph Register
#51, p. 995, the (uncredited) author, apparently writing for a monthly
British publication, wrote:
By the way, these gearboxes do not run on standard gearbox
oil. At one time it was recommended that you use TQX
automatic transmission fluid in them, but a better alternative
is Catrol [sic] SMX which is a special light gear oil.
As much as I like to trust anything that is published, I would like to
hear the opinions of others on the selection of gearbox oil. I am
reticent to believe someone whose name is not given and who cannot
spell Castrol.
I have some experience with the issue to share. My TR7 was built with
ATF in the gearbox. The first mechanic that saw my car saw that that
oil was not the specified one and swapped in the oil in the written
recommendations, which I think was Hypoid 70W80. The second gear
synchro would not work when cold in this condition. I had a second
problem with the transmission in that it leaked through the control
shaft hole, and the leaking oil coated the rubber-coated transmission
mount, dissolving the rubber. I did an experiment and found that the
ATF dissolved the rubber about twice as fast as did normal (80W90)
transmission fluid. Anyway, I now run a 50/50 mix of the Hypoid and
ATF fluids in the gearbox. A second mechanic told me that there was
the production change to recommend ATF that is mentioned above.
Does anyone have any comments on this issue?
--Joe Gorin joeg@sr.hp.com '80 TR7 convertible (5-speed)
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