th400 build

[462 Chevelle]

im in the process of rebuilding my th400 and i have no idea what im doing i plan on going into it and changing all the parts in the kit and putting it back together how i took it apart. any tips on when i put it back together. i have everything in the case out except the piece that has the hidden valve body bolt. the pan is still on and its set up to finish draining overnight. tomorrow i plan on completely dissasembling it and putting it in the parts washer a few hours. and buttoning it up with all the new parts i have. and having the converter flushed. trans did not blow up or anything just acting funny and whining real loud. im changing the front pump, clutches, steels, new band, all orings gaskets and seals and putting the shift kit in. kolene steels, red alto clutches and kevlar band is what is in the kit and b and m shift kit.

[sean Buick 76]

Do you have a good manual?

[462 Chevelle]

i have a bunch of old chilton manuels. but to answer your question, no. im just winging it. gotta learn somehow. i got a buddy of mine thats built 5 or 6 for race cars in the past few years who is going to help me if i get in a bind.

[sean Buick 76]

Cool, man! Not much to loose!

[462 Chevelle]

right. ive tore about 5 of them apart and i have a few laying around so im pretty familiar with how it comes apart but any part i touch i have absolutely no idea what its called. i know what clutches steels and the band are... but thats about it. if i mess it up... ill try it again.

[BRUCE ROE]

I learned by following the factory manual, pretty complete. Be patient, and
don't force anything that doesn't seem to fit. There are a few tools, and a
few tricks, that make the job much easier. A rebuild kit won't have everything
you need, like torrington bearings and thrust washers. I recommend using the
old steel clutch plates if undamaged, or at least reuse the wavey plates. If you
don't, it will shift rougher than originally. I buy rebuild kits with no steels (I
have PLENTY of extras) and save a lot of money. See some of my home made
tools on PHOTOBUCKET, sub albums SWITCH PITCH TRANSMISSIONS, and BUILD
A SWITCH PITCH TRANSMISSION. Non switch pitch are almost the same.
good luck, Bruce Roe


http://s93.photobucket.com/albums/l71/bcroe/(that is a lower case "L"71, not an upper case "i"71) click on a Sub-Album click on a picture to enlarge + explanation, or click on "view as a slide show"

[satch]

i have a bunch of old chilton manuels. but to answer your question, no. im just winging it. gotta learn somehow. i got a buddy of mine thats built 5 or 6 for race cars in the past few years who is going to help me if i get in a bind.

You should get a good book with step by step instructions (I used Ron Sessions book). I rebuilt my TH350 that way and it worked great. Some things that I gleaned from rebuilding (which should apply to the TH400): the rebuild kits don't include all the bushings. I had to buy a separate bushing kit and I replaced all the worn bushings with new bushings and wider bushing where I could (a good manual will tell you minimum ID's so you can measure for wear). When replacing the clutches and steels, you need to measure the stack clearances with a feeler gauge so you might have to get various different clutch pressure plates (not in the rebuild kit) to be right where you want to be. If it's too tight, you'll get extra friction, heat and wear, if it's too lose, it'll affect shift speed. When you're putting it back together, you can air check the clutch assemblies with compressed air. This will activate a clutch stack so you know the piston is sealing properly. Lastly, the best thing I did after struggling with the tranny was to finally build a wood box with a hole in it so I could work on the transmission in an vertical position, makes dropping in all the parts easy (and also measuring endplay easier).

[GS44667]

Make sure to use lint free rags when working on automatics...

[462 Chevelle]

what kind and where does trans assembly lube go??

[462 Chevelle]

when the sprag came out all the bearings that were in it fell out. is it supposed to do that? would a 80s model th400 that was originally behind a diesel truck have some tough hard parts in it i should rob? i also have a trans out of a big pontiac. and a spare trans out of an electra all th400s

[462 Chevelle]

the one way clutch was smoked to all hell. so were the clutches in the piece that is built in the input shaft(not sure what its called) i have everything put in but the pump and the valve body, i should have it done by tomorrow night. i hope it works ok! once i figured out the order it goes its easy i had to take it apart 3 times. once i had all the way to the pump together and i had an extra snap ring. it was the one you put in before you put in the rear chunk piece with the planetaries and all the other pieces and the output shaft. but anyways...

[BRUCE ROE]

when the sprag came out all the bearings that were in it fell out. is it supposed to do that? would a 80s model th400 that was originally behind a diesel truck have some tough hard parts in it i should rob? i also have a trans out of a big pontiac. and a spare trans out of an electra all th400s

In my PHOTOBUCKET there is a LOT of discussion of using the best parts over the years
of production. That includes the INTERMEDIATE CLUTCH (factory manual name) , not sure that is the
sprag you mentioned. Bruce Roe

[462 Chevelle]

the piece im calling the sprag is the piece that makes it hard to stab the piece with the output shaft attached and the piece with the planetary gears on it, they attach together to make that heavy assed piece i took in and out 12 times before i realized that the very bottom washer has to be sitting in the trans before you stab the huge piece... does that make sense? then there is another 'sprag' up towards the front of the trans. but it didnt give me any trouble. my fingertips are killing me from stabbing the thingy im calling a one way clutch because it only turns one way.

[D-Con]

Most decent trans men will be so happy to relive the good old days when transmissions were easy that they won't charge much to assemble for you. Of course if you're just feeling adventurous, well have fun! I don't mind assembling and reassembling the trans too bad, it's the R&R I can't stand!

[462 Chevelle]

the local trans guy wanted 600 to put it together if i did the r and r and bought all the parts. i have buddy that has a th400 built to handle 1200 hp with a jw bell on it he only wanted 950 for. i decided to get a kit and do it myself even thouhg i just realized i didnt check the clearances on the clutch plates... guess i get to take it apart again tomorrow. i remember the very bottom set of clutches being tighter to align to fit the one way clutch dealy in there. could someone help me id these parts, ive been googling for a minute but cant find any good pics or descriptions. i feel like an idiot calling them dealys and pieces.

---------- Post added at 10:40 PM ---------- Previous post was at 10:37 PM ----------

http://www.eatmyshifts.com/TH400_BlowUp.htm
just when i start asking questions lol

[462 Chevelle]

got the trans in the car earlier and the stupid whine is still there. it has a good known pump in it from a trans i pulled myself. the pump i had used a yellow spring in it and the pump i put in the trans had a blue spring in it.. trans works great in reverse but when you put it in drive low or 2 it will barely pull itself. any ideas on what to do next? i put a shift kit in while it was out and i removed the accumulater spring. and removed 3 checkballs and drilled 2 orifices. did i miss something? i didnt air test the clutch packs because i dont know how.

[462 Chevelle]

pressures are as follows.
75 in park 150 in reverse 75 in drive 150 in low. anyone please? im swapping converters tomorrow to see if it makes a difference. but i really am doing all this blindly, my pressures are good so it has to be a mechanical problem? to much clutch pack clearance or bad converter but it seems to work fine in revers just not forward. it will go a few mph then just slip like hell. and tranny screams to all hell in reverse and low but not in park or nuetral,

---------- Post added at 10:44 PM ---------- Previous post was at 10:22 PM ----------

could the sprag in the torque converter be causing this? anyone have any ideas. im at a loss.

[satch]

I only have experience with my TH350 so maybe someone with TH400 experience can help you better. But here's what I know from doing my TH350, hope it helps you,

On the sprag, if the rollers fall out too easy, then the springs between the rollers are worn and the sprag should be replaced. The springs push the rollers up the ramp in the cage which keeps it from going in one direction. You did say it was working though and could only rotate in one direction so it sounds like the sprag is ok.

On air checking, the TH350 has different passages than a TH400 so I can't tell you which specific passage to put the air on but basically what air checking does is it simulates the fluid pressure by using the compressed air. So you put compressed air into the specific passage (i.e., hole) going to the piston which then applies the clutch. Which hole you put it on depends on which of the clutch stack you are testing. If you get a good diagram of the bottom (the brain looking part, you have to take the valve body off to test) of the tranny which points out which holes are for which clutches, then that's where you apply the compressed air. When you apply the compressed air, you will hear a noise as the piston moves and compresses the clutch plates. And when you release the air, you will hear a noise as the springs in the clutch assembly pushes the piston back. If you don't hear it move or if it moves but you hear alot of air escaping then the seal is bad. I used a rubber tip on an air gun. You have to use the rubber tip to get a good seal, I messed around for awhile and then finally bought the tip for $3. I know when I installed my seals, you have to make sure the 'V' shape on the seal is pointing in the correct direction (i.e., which ever way the fluid is going to push on the seal so it will tend to open that 'V' under pressure and seal tight.) I used lots of vaseline on the seal and a feeler gauge to run around the perimeter to get the piston to seat properly. Make sure you don't cut the seal with the feeler gauge or cut the seal by forcing the piston in.

The other air check I did was when I had the pump out and the clutch stack sitting on it vertically. You apply air to the correct passage on the perimeter of the pump body. You will see the clutch move up when you apply air and come down when you remove the air. If you don't have a diagram telling you which hole to apply air to, you could figure this hole out yourself, because there's only several holes on the perimeter of the pump and you could try them all until you found the one that moves the clutch stack. BTW, I used about 40lbs air pressure.


The valve body determines which circuit gets activated and which passage gets the fluid pressure. Since your measured pressures are ok, then maybe your seals on the clutch piston aren't seated properly or are pointing the wrong direction.

I took a lot of pics when I was doing this. If I can find them, I'll post them but, again, its for a TH350 not a TH400 so hopefully, someone with TH400 can give you some specific help.

[R4E5G5L]

Pulling for you Lonnie. I'm clueless beyond the valve body, that's why I've been following this build.

Good luck,

[462 Chevelle]

I should have the converter in, in a few hours, if it is te converter do you think coan will work with me on getting this converter fixed. Hass less than 20 passes on it

---------- Post added at 08:27 AM ---------- Previous post was at 08:23 AM ----------

The clutch seals your talking about. Are those the inner and outer ones that were on that aluminum plate thingy that has 3 springs on the backside of it with a snap ring. I know they're facing the right direction but I couldn't tell you if they're torn or not they were a major pain to get seated

[satch]

I should have the converter in, in a few hours, if it is te converter do you think coan will work with me on getting this converter fixed. Hass less than 20 passes on it

---------- Post added at 08:27 AM ---------- Previous post was at 08:23 AM ----------

The clutch seals your talking about. Are those the inner and outer ones that were on that aluminum plate thingy that has 3 springs on the backside of it with a snap ring. I know they're facing the right direction but I couldn't tell you if they're torn or not they were a major pain to get seated

That sounds like what I'm talking about, except on my TH350 I had way more return springs (like 16 around the perimeter). The outer seal is lip down away from the springs. They're probably in right because the lip facing the right direction is what makes them a pain to get the piston in. If they're torn, they'll fail the air check.

[fireball]

When you say "whine" do you mean slippage like a stick shift as the clutch is engaged? If so, then the forward clutch is not grabbing. The forward clutch is not used in reverse, so that could explain it. The forward clutch should AlWAYS be air checked as the piston may not be seated properly. It is done by using an air chuck with a rubber tip on an air hose. To find the feed passage, all you need do is apply air to the hole between the sealing rings on the pump so that the air now comes out the feed hole. Make sure you have the thrust washer and sealing rings on the pump and then slide the front clutch assembly into the pump. Apply air through the feed hole and the piston should move. There should be no air leaking past the piston seals. Some leakage (very minor) may leak from the pump sealing rings as you are using air and not fluid. Do NOT use more that 20 psi to air check clutches as you may damage the rubber seals.
You can also air check the direct and intermediate clutches this way. Assemble the center support with piston/seals/sealing rings and place it on the work bench. Seat the direct clutch on the center support and apply air to the center hole. The intermediate piston should move and no air should leak aroung the seals. Some air will escape from the bleed orifice in the center support. Next apply air to the left and right holes. If you left the center seal out of the dircect clutch you will need to block one hole (thumb works) to get the clutch to air check. If not, one hole will work and apply but the other will bleed air and you will need to block the other hole. Again no more that 20 psi should work.
Did you check the end clearance on the trans? If the forward clutch sits too far forward, the pump rings will not seal in the clutch and pressure will bleed off. There are selective washer both for the pump and for the hub end of the forward clutch. A thichker hub washer will allow you to use a thinner one on the pump and get the pump sealing rings further into the clutch drum. As to pressure, the 75 psi is ok, but IMHO a bit low. With the blue pump spring you want 2 regulator springs (my opinion). You can use 3/8" diameter flat washer as shim as long as they fit and are the same thickness as the 1 shim that is usually on the valve. Some setups do not use a shim, so you need to check.
Lastly, if the foward clutch has been slipping, the friction clutchs will likely be ruined. It won't take long for that to happen.
I could write a book on this (Ron Sessions already did, but he left all the shift modifications out. Likely cause the shift kit suppliers would have sued) but you can use the book you have.
Good Luck!!

[462 Chevelle]

i changed the converter and the whine is gone. before i pulled the converter i spun it on the trans and i could hear something clicking inside the converter. put the other converter in and no clicking. the crappy thing is as soon as i put it in drive one of my tranny lines just shot fluid out of it like crazy... still will barely pull in drive, reverse is fine. out comes the tranny to check the forward clutch. is that the one that has the input shaft attached?

---------- Post added at 05:32 PM ---------- Previous post was at 05:08 PM ----------

do you guys think coan will work with me to get this converter right?

[fireball]

Yes, the drum with the input shaft is the forward clutch drum.

[462 Chevelle]

is that the only set of clutches i should be looking at and what could be wrong with them? the clearance was around .060 when i put it together. thrust was .020 or .040 i cant really remember 100%. is there any way a check ball or something in the valve body could be screwing up? like 2 hydraulic circuits linked together or something?