Gary Nafziger wrote:
> I neglected to mention in my last post that I do have
> overdrive! Sorry about that. I assume the tranny and od
> share the same oil, but I cannot use GL-4?
Gary,
I just received a newsletter from the "Triumph Register of
Southern California" yesterday, in which their technical
expert, Ken Gillanders, who has been racing Triumphs for
longer than I've been out of diapers, has his regular
technical column. In this issue, the topic was
transmission lubricants.
To summarize his article, he describes some problems
he has encountered after two years of experimentation with
synthetic transmission lubricants. The first of these was
that the synthetic is *so* slippery, that there is a
tendency of the car to pop out of third gear when braking
*hard* downhill. (Remember, these are racing TRs.) What
he found to be happening is that the weight of the shifter
shaft, fork, and 3/4 synchro is sufficient to overcome the
resistance holding it in gear when the sudden deceleration
of the car pulls on it. He was able to duplicate this
behavior with the tranny out of the car by holding the
transmission with the input shaft pointing down, dropping it
from about shoulder height, and catching it just before it
hit the ground. (I'm not quite sure how he did this without
breaking his back!) Anyway, this may actually be a sign of
how good the synthetics are, unless you regularly stop your
Triumphs *very* hard.
The second problem was of more concern. He found that on
short, twisting courses with heavy use of first gear, it
became increasingly difficult to get into first. After
about 20-30 engagements, it could no longer be done at all.
Upon disassembly, they found that the synthetic oil was
too slick to allow the heavier gears to be "slowed down"
by the synchros when shifting, thereby grinding off the
pointed teeth until they were flat. I speculate that if
one shifts more slowly this problem may be avoided.
He didn't encounter either of the above problems with
80W90 gear oils.
His conclusion was to return to 80W90 GL4 gear oil in
non-overdrive gearboxes, and 20-50 engine oil in the
OD-equipped units. (He suggested Valvoline Racing 20W50
for OD gearboxes.)
He didn't explain in that article the reason for the
20-50 engine oil rather than 80W90 gear oil for OD gearboxes,
but Ken Gillanders is a very-well respected Triumph guru, who
isn't just an "old-timer" who refuses to try new things. Many
of his tech articles are on experiments performed with modern,
uprated components, hardware, etc., where he often switches
to the new technology in favor of the way Triumph did it.
I speculate that he really gave the synthetics a fair chance,
and decided against them.
For a car that isn't raced, your conclusions may be
different, that is, your mileage may vary!
--ken
VTR WWW Maintainer -- http://www.vtr.org
--
Kenneth B. Streeter | EMAIL: streeter@sanders.com
Sanders, PTP2-A001 |
PO Box 868 | Voice: (603) 885-9604
Nashua, NH 03061 | Fax: (603) 885-0631
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