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i just got a th400 rebuilt over 6years ago and never ran ....

down4thakrown

down4thakrown

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i just picked up a th400 tranny with a 205 slipyoke. for 450$ but the tranny was never run and rebuilt bout 6 years ago. it still has the date written on it. and looks clean. but the input and out put shafts has alot of surface rust. and looks like it sat out side. from what i can see the inside is some what clean. has a little dirt/dust. i really dont want to have it gone through. is there a way to bench flush it? i was thinkin of just shootin alot of carb cleaner in it and wd40 for the seals? then flush it when i install it. when i put it in gear i cant move it by hand and in neutral its really tuff to move by hand. im thinkin its just cause its dry and never had any fluid in it.:dunno: whats the brotherhood say?
 
definitely don't put any wd-40 or carb clean in it, the frictions are very sensitive to contamination and many types of solvent could ruin them if it gets into the clutch packs on startup.

I would clean the shafts off with cleaner and or steel wool after taping the gaps shut so you dont get anything inside the trans.

I would also pull the pan and see if its still clean in there or if any water or debris got in it.

At that point I would decide if it's worth installing or if it needs more disassembly.
 
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Hard to say,really,if you would be able to toss it in as-is and run it,and get away with it.....we sold many automatics at the junkyard that sat for years,and most of them worked fine,the few that didn't may have been junk when the car came in before my boss owned the yard,or they may have gone sour from sitting--no way to tell.............................................................I have a few trannies that worked great when I pulled them out--but have sat a long time,but out of the weather,I'd take the gamble and use them if I had too--worst case scenario I'd have to yank one back out and have it rebuilt..chances are they would work OK...I'd change the fluid and filter and cross my fingers..I've seen later model trannies bought at salvage yards that had rust on the valve bodies when the pan was dropped to install a new filter,and they still worked good...
 
Pay special attention to the holes in the input shaft and make sure no critter has created a home, same thing for the cooler fittings and case vent. Also, check the output shaft where the governor gear rides to be sure there is no corrosion as this will eat a gear up fast.
 
thers no corrosion on the shaft but theres is some surface rust. is that gear and shaft hard to change. i thinki i see a little allen set screw on ther. if i were to unscrew that could i get that plastic gear and shaft out?looks like nuthing made a home in the input shaft. but i cant get it to turn by hand no matter what gear i have it in. and the seal looks very dirty.
 
The large shaft sticking out of the pump is the stator shaft and will be stationary, the smaller shaft protruding from it's center is the input shaft and should turn freely. If it does not then this trans will require disassembly and a bit more work.
 
that sux cuz i cant get that inside shaft to spin. atleast with my hand. i dont wana try pliers or anything like that. isnt there gear reduction kits for the th400?
 
The thing about auto trannies is that they really don't do anything until the pump builds pressure. So as far as turning things by hand, all gear selections will be about the same except for Park, because of the pawl. It might be hard getting the input shaft to turn by hand, but I know there is a tool made to fit those splines. The only other thing I know of to fit the splines is inside the torque converter. Again, the converter is a hydraulic unit that really has no coupling from the case to the output until it really gets spinning. So you can't test that by hand either.

I would pull the pan first and look for signs of contamination by anything but ATF. It also shouldn't be too much trouble to pull the pump, have a look inside the unit and make sure the pump isn't frozen. You might also call around and check for shops with a tranny dyno. I don't know the cost for this, but it can save you the effort of an install and pull.
 
ive never pulled the pump. is that 8-10 bolts in the bellhouseing? well i called one tranny shop and they wanted to charge me a complete rebuild. but ill try the dyno performance shop tomarrow.
 
I'd be more worried about condensation that built up inside the case and may have rusted the valve body and internal spools,etc,than clutches....after seeing how many trannies we sold at the salvage yard that looked like junk inside and out,yet still worked OK,I'd say stick it in and hope for the best....why rebuild it again if it might have nothing wrong with it??...
 
agreed. Put it in and test it out. Worst case scenerio is it needs a rebuild and you wasted a little time and labor throwing it in there and taking it back out.
 
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