Turbo 400 Question

[72k20Farmtruck]

Does anyone here know if there is a difference in turbo 400 valvebodies over the years? I rebuilt a 75 transmission and used a valvebody from an 82 and now I don’t have reverse. Drives forward very nicely, hard to tell if I have low gear too, it compression braked from 3-2 but didn’t seem like it was going 2-1. Thanks!!

[NoNeck]

GM went to metric in the TH400 around 1979-80. I'm not sure if the valve bodies were different but maybe someone will chime in.

Good luck,
POP

[painterljp]

We had a problem with ours also. We had ours rebuilt by a friend of mine. Worked fine for about 50 miles then didn't have either first or second. Went into reverse very softly. We tried to change valve body found there was a ball missing. We ended up pulling it back out and found 2nd gear band was slipping and burnt. We had it rebuilt again by a different person seems to drive ok now but haven't drove the truck 20 miles since we put it back in. Going to get it out today and drive it and see what happens now. We changed the governor also before pulling it back out. Hopefully it doesn't happen again. Will keep you posted. Subscribed to find out your problem. Wouldn't shift til weird rpm. Also. Can't figure it out either. Hopefully someone will chime in that knows more about transmissions. First time it had a shift kit valve body in it. Now it just has a stock one from who knows what year. Will keep you posted.

[72k20Farmtruck]

Originally Posted by painterljp

We had a problem with ours also. We had ours rebuilt by a friend of mine. Worked fine for about 50 miles then didn't have either first or second. Went into reverse very softly. We tried to change valve body found there was a ball missing. We ended up pulling it back out and found 2nd gear band was slipping and burnt. We had it rebuilt again by a different person seems to drive ok now but haven't drove the truck 20 miles since we put it back in. Going to get it out today and drive it and see what happens now. We changed the governor also before pulling it back out. Hopefully it doesn't happen again. Will keep you posted. Subscribed to find out your problem. Wouldn't shift til weird rpm. Also. Can't figure it out either. Hopefully someone will chime in that knows more about transmissions. First time it had a shift kit valve body in it. Now it just has a stock one from who knows what year. Will keep you posted.

That’s exactly the route i went too, had problems previously with a shift kit vb so i went back to a stock one, before i went to the stock one i had reverse, now i dont. Pulled the pan today and realized i hadn’t tightened the large servo!! Must’ve gotten distracted because bolts were hand tightened and that was it hahaha. I slapped another vb in there too just in case. It got late so I’ll put the pan on and give it a shot tomorrow morning. I’ll post the results.

[72k20Farmtruck]

Originally Posted by NoNeck

GM went to metric in the TH400 around 1979-80. I'm not sure if the valve bodies were different but maybe someone will chime in.

Good luck,
POP

Thanks for the tip! Definitely changed out that 82 vb for an older one.