I found some GM Synchromesh Transmission Oil at my local auto parts store
and I'm about to see how that works in my non-overdrive 1969. My gearbox
shifts pretty stiffly until it's well warmed up, so I thought I'd try a
change of lube to see what happens. The oil is rated at SAE 75 and GL3, and
supposedly has just the right lubricity for synchros to work well. I'll
report back once I've tried it. As far as the correct lube goes for Laycock
overdrives, I think they're pretty tolerant of different viscosities. I
used to use non-detergent SAE 30 engine oil in my Austin-Healeys and the O/D
seemed to work just fine with that, while in a type "J" unit in a Volvo I
used 80/90 gear oil. I believe that the higher viscosity oil encourages
more positive engagements and probably longer life of the cone clutch in
the O/D. Also, it was commonly believed that you shouldn't use high
detergent engine oil in a Laycock overdrive. Gear oil has much fewer
additives so is fine.
With regard to overdrives vs. 5-speed conversions, I would probably stick to
the ol' Laycock unit if my beast had one. The TR gearbox has a few weak
areas, but is pretty easy to rebuild and the Laycock O/D can be rebuilt by
anyone with reasonable mechanical skills, a good workbench, good set of
tools, patience and a good manual. (I've done two of them - one pretty well
screwed up!) But as my old faithful 1969 is overdrive-less, I'm considering
going the 5-speed conversion route. I like to drive long distances, and the
ability to get the revs down at speed would be welcome. But, before I am
ready to write a big check to buy a kit, does anyone actually know anyone
who's running a 5-speed conversion TR6? I'm curious to get some feedback as
to how it feels, shifts, etc. Also, last summer at the TRF Summer Party, I
met Nick from NAR, inc. who said that they were developing a kit (or
importing a kit, I can't remember) for a 5-speed TR conversion using a
Nissan transmission. He said that the gearbox was widely available and the
kit was going to reasonably priced. He said to check their web site, but so
far no news about a kit from them.
Regards,
Rex Townsend
Bainbridge Island, Washington (State)
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