Thanks to all for the questions, suggestions, etc.
To Don, the trans is about as close to level as possible. We spent a lot of
time over the winter getting the drive train level and in line. In past
years, it was lower in the rear. Combine that with running the recommended
amount of fluid and the effect of acceleration and I think we were always
starving the front section.
To Mayf, this is an ST-1200, but you are right, they all function about the
same. The front sprag works the hardest as it is locked up at the first to
second shift and has to take the abuse of the rest of the run. The clutch
pack in the last section slips the longest as they are the last to engage in
the 4-5 shift. There was evidence of excessive heat in the last stage clutch
pack.
To Neil and Bryan re additives and fluids. this is the trickiest issue of
all since the clutch packs need to be able to lock up (which would support
ATF), but the rest of the business could benefit from a light synthetic
motor oil with an additive package. I'll talk to Lenco again about that, but
after the last sprag, they recommended 30W dino oil, but the recommendation
was half hearted. As in, "Well, I guess you could try." I kinda think we're
the guinea pigs here. I had also asked them about pumps and circulation and
they said some had tried them, but the added complexity didn't seem to help
much.
To Bryan and Dave, by running lots more ATF than they recommended and have
some end up in the catch can, it indicated to me that the trans makes lots
of heat (no surprise there). Also, the vent line is out of the top of the
first stage, so the first stage should have been pretty full to be able to
puke some fluid. Also, this sprag had damage, but wasn't burned to death as
has happened in previous years. While we could 'dry sump' the transmission,
it might be worse since there is no oiling system other than parts just
splashing around and study as much as we have, there is no practical way to
build a pressurized oiling system.
A sponsor that helped us a lot this year has an additive that reduces
friction a lot. The typical use is in motor oil, but it has been used
successfully in transmissions and gearboxes, although I can't say for sure
that includes automatics. We may soak the sprag in the additive prior to
assembly.
Also, the ATF we've always used is the Mobil 1 synthetic. Which would be
better to carry the heat away, Mobil 1 ATF or a light motor oil? Are the
ZDDP additives compatible with or useful with ATF?
Jim Webb
Chock Full o' Nuts
AA/PP A/PP B/PP C/PP D/PP ?/FL
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