Turbo 400 help

83trekker · October 30, 2014

I know this isn't the place for a turbo 400 but there is so many GM knowledgeable people on here I thought I would take a chance. I have a turbo 400 mated to a np205 tcase in my 83 Toyota trekker 4x4. The case had a crack in it and always leaked, so I got a another case for it. I took my 400 and took it apart but I didn't take any of it apart just pulled the guts as complete as possible.

I then put all the guts into my new case, everything fit perfect and spun when turning the shaft. No weird noises, all the balls put back in the right place in the valve body and valve body torque down. So I installed it in my truck and started it up. And it has no gears at all.

I took off the linkage and manually changed the gears with my hand and nothing at all. There is no weird sounds or anything. Its full of fluid , now Its prob over full now cause I through more in it just to make sure and its pretty high on the dipstick. So what could I have done wrong where it wont engage into any gears all? Its spinning because the tcase when I change into all gears grinded a little bit. I really don't want to pull the tranny out again if possible!! Any ideas I really appreciate it!!!!!

Should note that as far as I know this tranny is all stock, and I took every part from my cracked tranny and put it into the new case and it worked great until I touched it lol. The converter looks to be fully engaged as when I bolted it to the fly wheel there was the same space as when I took it out..

00Silverado4x4 · October 30, 2014

Moving to Transmission section.

ifixedit · October 30, 2014

I recently did a B&M shift kit install on the turbo 350 in my 77 Camaro. I realize there are considerable differences between the two, but as I recall it was fairly easy to get the separator plates, gaskets and so on installed incorrectly which would result in the trans not wanting to shift or go into gear. Before you yank the tranny out I'd drop the pan and make sure you installed the separator plates and gaskets in the correct order. I also believe if you need an illustration of this you can get the original instructions in PDF form with pictures off the B&M site that shows detail of how things go back together. I also see they talk about the possibility of incorrectly installed governor tubes. Maybe you throw a shift kit in it while you're at it?

Here it is and might provide a clue or two,. http://www.bmracing.com/bmnew/pdf/9500019.pdf

Hope this helps to some extent anyways.

83trekker · October 30, 2014

Well I put the gasket that was for the valve body, then the separator plate then the gasket for the cover on and made sure they were in order and im almost positive I torqued down all those bolts on the valve body. I guess im gonna have to drop the pan to check stuff out. Wish I had a drain plug on the pan.

ifixedit · October 30, 2014

I guess im gonna have to drop the pan to check stuff out. Wish I had a drain plug on the pan.

Same here, it's a pain in the a**. Get the big drain pan out, keep it handy, loosen the bolts on one end of the pan, remove them on the other end and lower one end the pan slowly to allow it to drain. Hopefully you can at least re-use the new trans fluid you just put in it. I keep some of those painters funnels with the screens in them handy and put one in the funnel to filter out any possible dirt and debris when I pour the fluid back in, but only if the fluid is new, not worth it on anything used.

Edit: Maybe you've already done this but when I installed the shift kit in my TH350, when I first put it in drive it sat and did nothing and I started thinking "uh, oh, what did I screw up?" I shifted it in and out of gear a few times and finally just left it in Drive while the engine idled, it probably took at least 15 seconds of waiting and then it finally went into gear and has workded fine since. If it's anything like mine was, after you have removed the valve body and all the fluid has drained out of the passages, it probably isn't going to go into gear right away. Have you put it in Drive and allowed it some time (maybe 10-20 seconds) to pick up the fluid? If you rev up the engine a little that may get things working as well, just keep your foot on the brake. ;-) Other than that it looks like on the TH400 you want to look at the govenor tubes for a non shift situation, that or a seal somewhere else was missed or is leaking.

83trekker · October 31, 2014

Forgot to attach the pin off of the rooster comb to the valve, all good now!

ifixedit · October 31, 2014

Excellent! Glad to hear you figured it out! Now for that B&M shift kit.

Spurshot · November 20, 2014

A TH4000 is a good trans. I had one behind a 400 then a 327, both hopped up pretty good, in my 79 El Camino. It was a pretty easy conversion, just shift linkage and driveshaft yoke change.