C6 failure diagnosis, any AT mechs in here?

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IacoccaWasFord - 19 Oct 2006 18:52 GMT

'68 C6 behind a truck 390 failed when it "slammed" into reverse with
choke on. Initially loud "clattering" noise from trans, then nothing.
Now, I get drive in 2 and 3 only, no 1 and R, but I can feel the
low-reverse clutch engaging when selected. It's due for a rebuild
anyway. "Slamming" into reverse had been a problem for awhile, cured
it once by "unsticking" the boost valve spool, but it came back.
Control pressure was OK.

Looking at the schemo, I figured the only thing that could cause drive
in 2 and 3 and no lo-rev would be a broken low-reverse one way clutch
inner race. I've never heard of this before, but it would've had to
break all five attaching bolts to the case; either that, or the inner
race hub itself disintegrated. It was below freezing when this
happened, and steel gets more brittle as temperature decreases.

Anyone ever see this before?? Every trans shop guy I've spoken to
never has. If it's just a matter of five broken bolts, I'm betting
large that I can replace the inner race, put a master kit in it and be
good to go. Opinions?

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phaeton - 20 Oct 2006 17:32 GMT

> '68 C6 behind a truck 390 failed when it "slammed" into reverse with

> Anyone ever see this before?? Every trans shop guy I've spoken to
> never has. If it's just a matter of five broken bolts, I'm betting
> large that I can replace the inner race, put a master kit in it and be
> good to go. Opinions?

I haven't opened a C6 in awhile, but that sounds correct to me. I have
seen one sprag clutch that was in itty bitty pieces (although I think
that was a GM transmission like a turbo 400).

Long as the metal hasn't destroyed any of the hydraulics you should be
fine with a new clutch and a master kit. (might as well throw a shift
improver kit while you're at it, too)

-phaeton

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