>From opnmail2.corp.hp.com!GORIN_JOE/HP5300_A0 Fri Jun 18 11:11:26 1993
>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.
The change to ATF was done by Jaguar-Rover-Triumph and was announced in a f
formal technical bulletin (I have a copy of it at home). The real problem
with using regular gearbox hypoid oil is that when cold (especially really c
cold), the small plastic impellers which are internal to the Rover gearbox
may tend to break because of the thickness of the hypoid and the speed
the impellers turn. Many folks have switched to using a General Motors
gearbox fluid with excellent results.
>
>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
As mentioned above, the written (workshop manual) recommendations were
supercedded by the technical memo from the factory.
>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.
Standard Disclaimer- Any opinions, etc. are mine and NOT my employer's.
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Bill Sohl (K2UNK) BELLCORE (Bell Communications Research, Inc.)
Morristown, NJ email via UUCP bcr!cc!whs70
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