heres a look at the inside of my transmission in case anyone has a th400 a wants to see inside...

with the torque converter off you see the pump. you need a slide hammer to take the pump off (or a BFscrewdriver) and patience. next:

in removing the govenor use a twist motion to free the gear. in using a valve body improver kit you will replace the two springs in the gov. nxt:

then you flip your trans over and take off the pan/pick-up filter/ and spacer tube.(deep pans have longer tube) the red/orange wire you see is to the detent selinoid. this energizes a back up light (yippie) obviously the arm on the sproket looking thing is the gear selector. the valve body bolts are torqued to 11 inch pounds (like 5 ft.lbs) barely snug. then your valve bdy plate and gaskets. lastly a view of the vlve bdy channels (at this time note wether you have a (6) ball or (7) ball set up and thier location for rebuild.)
nxt:

this is the accumulator piston the spring and PLASTIC cup. this cup is the weak point of a th400. they always snap...mine here is snapped i replaced w/ an aluminum one. the second part of the accum. piston is this pin spring and backing plate. now onto the reverse servo. accum. is the small port, reverse servo is the big port.

okay, first pic above is the revere servo in a rebuild you replace the seals on the inner piston and outer "hub" and a improver kit gives you a beefier spring. and a homebrew accumulator improvement would be to REMOVE the spring in the accumulator and not use one. a new metal gasket for a rebuild (the octagon looking mtl gasket. now lets stand the trans on end a dive into the guts...pump off and a rebuild is a new seal (lube new one w/ trans gel) i'll cover rebuilding the pump later. now your looking at the clutch

now the forward clutch is removed to reveal the direct clutch and after that you can remove the manual second band note pin hold and reinstall a new band the same manner. once the man. 2nd is out you come to your first case ring:

remove the case snap ring but notice first its clocking position. 8 o'clock. then remove all your plates and steels they alternate but vary from 6 ball and 7 ball /350's and 400's some have a wavy plate as well (again various modeling) just remove and install the same but with NEW. nxt:

srry wrong pic, but now we remove the geartrain...but first remove the geartrain bracing bolt found on the outside in the middle of where the valve body was. remove the bolt and gears will come out.

the center hole on the side of the geartrain is the brace bolt hole i was talking about.the orange and blue plastic seals are to be replaced with new and now we get into the snap rings and sun gears and a whole big wampin mess. im quitting on this for to-nite and will pick back up tomarrow... and this tear down is applicable for a TH350 as well. and is what would have to happen if you had output shaft discrepencys between transmission and transfer case. (i had to swap out my shaft for a 32 spline for my np241 case) individual components are best left to a shop to rebuild. some i did and some i had a shop do, due to the pressure of springs inside it. l8tr.

this is a good addition to the builders corner i want to do a th350 swap into my tj when i blow up the tf999 again but a th400 would be good also. keep up with the info and pics

for the pics above....after you remove the center support assembly, you come to thereaction carrier assembly. in the reaction crr assem, you see the "chain" thats the low roller clutch. once thats out you can remove the fretting ring, and rear reaction drum spacer. then remove needle bearings, sun gear shaft bushings, sun gear shaft assy. (hollow steel with splines at each end) there is a snap ring at the rear ring gear on the train that comes off then you can spin out the sun gear (thats the sprocket in the middle of the other gears) once that is accomplished the reaction drum input assy. will come off the output carrier assembly

now more pics:

above series of pics is reaction drum input carrier assy taken out. then geartrain turned ovr and fretting ring taken out to continue break down. then remove thrust washer

first pic above is sun gear taken out along with the sun gear shaft assy.(hollow tube w/ splines at each end ) and all the other forementioned stuff. take out the needle bearings to the rear internal ring gear.

top pic is ring gear and shaft, and bottom pic is lastly the output shaft. in the case all you have left is a bronze/steel thrust washers. things to remember: sun gear faces flat side up chamfer down. clocking positions of case fretting rings. directional facing of revers band. direct clutch you want a shop to rebuild for you (its a pain) and that is nessasary to build better than stock with heavier clutches and steels. ohh and i made a mistake earlier when i said i swapped to a 32 spline output shaft. it had a 32 spline shaft, and i had to swap to a 27 spline like a th350 to fit up with my transfer case.

the last three pics is everything the th400 consists of. the th350 is the same in components but may be accomplished with some variances. i put in a master rebuild kit/valve body improver kit/shift improver kit/run with no accumulator piston spring for instant activation/race clutches and steels/high friction bands.<--these break down faster but are still rated for 100k miles. but as a whole the "clutching" power and torque capasity far outshine a 1ook versus 150k rating.

im gonna end up using the turbo 350 in my tj i have a stock 4.0l and every bit of hp is important. it takes 62hp to run a stock th400 and 36hp to run a th350 and just for the rock buggy guys out there a powerglide only uses 15hp i would love to use a powerglide i found all the stuff to build it stronger but cant find the stuff to convert to 4wd

you might wanna look into a 700r4<-it will need a brain though

and thanks for the input horse stats...i had no idea. i knew the th400 was the heaviest to turn, but 62 horse is greedy! all in all this trans (although power hungry) will stand up to whatever i can throw at it. i looked into a th350 as well, and i may build one as a spare (they would use the same output shaft now that i converted) but i think (could be wrong) the gearing is lower on the 400, and its a brute. i also have a 2nd 400 case in case i crack mine.

the forward gears for a th400 are 2.48, 1.48, 1.0 and the th350 forward gears are 2.52, 1.52, 1.0. i can see the uses of a th700r4 but im a little weary ive blown up 4 of them in 2wd vehicals, 3 were in trucks and one was in a firebird. i stick with 3sd autos now

im going to put a thread up on a bunch of transmissions for reference

well after solving a heat issue in my motor (turned out to bo the heater core) i've flogged this trans for about ten months now and and i'll never regret my choice. (i may build a big block to power it though) i will be installing a manual valve body into it possibly over this winter. love winter projects.

Very nice thread