th400: all the same?

[uda]

was wondering if all th400 are the same or did they come a bit beefier depending on what they came behind..... Example: Is a th400 behind a 4bt stronger than a th400 that came behind a 454? Or other applications?

Have one from a '81 chevy crew cab 4x4.Just want to know............

BASIC QUESTION................Are all th400 created equally?

[tacoma73]

"stronger"? No. 4bt, and 6.2 400's have different converters.

The 4bt should have a TH475, which you could argue is stronger, they have straight cut gears.... but the torque range on a 4bt isn't THAT impressive.

[lumpdog]

Well, if yours is a 4x4 case, then you have the strong version of the case. Internals should be the bigger clutch packs and such since it was in a truck. I have seen some behind a 4.3 that had fewer clutches, but those are few and far between.

[Grumpy_old_fart]

earlier (pre70) caddy th400s had the 6 clutch forward drum, and the 32 element sprag would slide right on it.

6 bolt pumps are different than 8 bolt pumps, one is narrower than the other *(the pump gear itself is narrower). the narrower pumps are more desirable for high rpm applications, because they dont pump TOO much fluid, which is a waste of hp at high rpm.

later cases required a snap ring in the case to keep things in order, too. Earlier cases didnt all need that snap ring.

as for heavy duty cases, I wouldnt worry about heavy duty and th400 being used in the same sentence.... theyre pretty heavy duty no matter what case you get.

You can upgrade to 4l80e planets to get some more strength, but they arent the straight cut like a 475 are. Unless youre towing 30k lbs, you wont need the straight cut gears.

edit: forgot the switch pitch stuff, too.

you can find 65-69 buick or olds th400s with a switch pitch converter that will allow you to have a stall that is induced by a switch.. kinda neat, but not meant for huge hp.

Theres probably a bunch of stuff i am missing....

[tacoma73]

Forgot about the weird BOP stuff.

For anyone thinking that the TH475 stuff is a good idea for a rebuild or something, know that the parts alone are like $900... and you end up with a way overbuilt, noisier transmission for that.

I'm going to take this opportunity to remind everyone to keep their transmissions cool. Run a cooler!

Originally Posted by Grumpy_old_fart

earlier (pre70) caddy th400s had the 6 clutch forward drum, and the 32 element sprag would slide right on it.

6 bolt pumps are different than 8 bolt pumps, one is narrower than the other *(the pump gear itself is narrower). the narrower pumps are more desirable for high rpm applications, because they dont pump TOO much fluid, which is a waste of hp at high rpm.

later cases required a snap ring in the case to keep things in order, too. Earlier cases didnt all need that snap ring.

as for heavy duty cases, I wouldnt worry about heavy duty and th400 being used in the same sentence.... theyre pretty heavy duty no matter what case you get.

You can upgrade to 4l80e planets to get some more strength, but they arent the straight cut like a 475 are. Unless youre towing 30k lbs, you wont need the straight cut gears.

edit: forgot the switch pitch stuff, too.

you can find 65-69 buick or olds th400s with a switch pitch converter that will allow you to have a stall that is induced by a switch.. kinda neat, but not meant for huge hp.

Theres probably a bunch of stuff i am missing....

[Grumpy_old_fart]

Originally Posted by tacoma73

Forgot about the weird BOP stuff.

For anyone thinking that the TH475 stuff is a good idea for a rebuild or something, know that the parts alone are like $900... and you end up with a way overbuilt, noisier transmission for that.

I'm going to take this opportunity to remind everyone to keep their transmissions cool. Run a cooler!

on the cooling note... caddy transmissions came with a 3/8 line fitting for the cooler lines.

[uda]

Thanks alot guys.I think I'm gonna keep the tranny and axles out of it and part the rest out.....
Anyone have an idea on what a 454 is worth? I believe it has a bit low compression in 2 cylinders.

[onetonbb74]

There are 10 different output shafts for the th400.