Chevy 400 turbo rebuild

Iceman83 · Jul 29, 2012

Last ride I went on I burnt the pump up in my transmission. Reason being transmission fluid running back into my transfercase and draining my transmission dry. I'm running a 400 turbo 205 set up. My question is what seal has gone bad to allow this and what kind of upgrades should I do to the transmission while I'm having it rebuilt. I'm definately having a reverse valve body put in but any one got any other suggestions? Thanks ahead of tim ;D

skipnrocks · Jul 29, 2012

your output seal on the tranny would have to be bad to loose fluid out the back... unless you had some serious wear on the input shaft for the tcase..

greenlion · Jul 30, 2012

Do 34 element sprag and upgraded clutches along with the valvebody while it's out.

smurfy90 · Jul 30, 2012

greenlion said:
Do 34 element sprag and upgraded clutches along with the valvebody while it's out.

get to work. :flipoff1:

Billcow · Jul 30, 2012

My trans has no place for a seal. I also run a klune-v in front of a 205 and the klune adapter has a larger cavity than the 205 adapter so when going up a long hill i fill up the cavity where the speed-o is and the adapter cavity and it will start to run hot so i run an extra qt. to help offset this prob. TCI has a reverse shift manual shift with compression braking valve body that is good and it is hard to beat parts, fluid and converters from PTC.

If the fluid went into the 205 then that front seal is bad

Iceman83 · Jul 30, 2012

Thanks for all the input everyone . That helps out a lot. Just one more question best I can tell there is no seal on the transmission output or in the collar between the transfer case and transmission there's only a seal on the transfercase input shaft it looks good but I'm gonna replace it anyway hopefully that fixes it.

doctordick · Jul 30, 2012

There's a passage in the rear of the case to allow fluid to get to the speedo gear and a drainback passsage. I think most of the fluid comes back up the drainback hole when on a steep incline. There's no seal on the output shaft, it rides in a bushing and the only seal is in the tailshaft housing in 2wd config. If I were a real slick machinist, I'd make a ring to go in the back on the trans housing that would accept a seal on the output shaft. Then I'd sell 'em for a lot of money because everybody that runs a GM automatic has that problem.