From: Chris Kantarjiev <cak@parc.xerox.com>
One other other thing is that the additives used in some
gear oil (and aftermarket stuff like Slick-50) are
incompatable with Laycock overdrives.
Hmm. John, how do you then explain that Triumph specifies gear oil for
their gearboxes, including Laycock overdrives?
Wel, you must have one 'a them new-fangled tiny triumphs...
With the TR2/3, the factory specified engine oil for the gearbox. I
gather that sometime in the early TR4 era this changed to gear oil,
though I've not looked at a factory TR4 manual in many years. Also, at
least one of the non-factory TR3 books specified gear oil - either a
mistake, or because the TR3 and -4 transmissions are identical except
for the syncro first gear so they decided it was OK, or perhaps there
was a factory update bulletin that I don't know about?
In any event gear oil in the '60s presumably had neither super-whizzo
lubricity additives nor little teflon balls added as a matter of
course. I assume that basic traditional gear oils are OK, given the
low-sulpher consideration you mention.
RedLine; their engineers seem to actually know what a
Laycock overdrive is, at least...).
This is new, although I haven't talked to them for a couple of years.
Are you actually using a RedLine product in a Laycock box?
No. I'm way high-tech; I've got Valvoline SAE30 engine oil in my
gearboxes, or SAE50 in the months when average temps are above 70 or
so. The rather tired overdrive in the '2 had some trouble holding
pressure on warm days before I dissected it. The one in the '3A,
rebuilt about 8 years ago, is fine.
I talked to the RedLine folks some time ago, probably two or three
years, about this. I called to ask specifically about overdrives, and
we got into a fun discussion about it. The engineer I ended up
chatting with knew what a Laycock overdrive was, but not the details
of operation. We wandered through what the clutches had to do, and
what materials they were made of, how relevant clutch-style limited
slip diffs were to this question, and so on. Being a slug, I never
followed up on it, but the conversation left me rather impressed with
RedLine.
-john
John Wroclawski
jtw@lcs.mit.edu
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