I Give Up - Why an A-904 Rolls A Sprag?

doc540 said

Thanks for offering help.

The '61 A-904 is cable operated from the pushbuttons (no external linkage on the trans).

When in "D" and taking off (slowly) from a stop, instead of shifting from "1" to "2", is shifts back down into REVERSE and rolls the sprag.

Same result as if one was driving 20+mph and manually shifting to reverse. It frags it. :pale:

Click to expand...

I did that once a long time ago at 60, but it didn't roll the sprag.
The crankshaft reversed direction instantly but the cam didn't. :D

It looks like you got the advice you needed.
I asked what I did to clarify what the symptoms were, and it HAS to be the valve body (OR possibly sealing rings left out on the rebuild) 2nd gear oil circuit crossing over to the reverse band servo somehow with the drivetrain still trying to drive the other direction, but I sure can't see how that could happen.
Also the more I think about it the more I have a hard time believing a valve body could do that at all with no driver input.

Air checking is the way to go, but I also understand that it's hard to tell someone that supposedly knows what they are doing how to do it. :D

BTW, a cable is still a linkage that can move causing problems. :D