TH400 weak links

[UncleBob]

When building a turbo 400 tranny for dealing with 800-1000HP, what modifications/parts are crucial?

I'm not much of a tranny guy, I'm trying to get an idea of what level is realistic.....is this a situation where I'd be better off building a powerglide for good longevity? I'd rather not use a powerglide if I can avoid it.

[MrPbody]

Bob,

The usual modifications include an aftermarket "heavy duty" sprag (one-way clutch), 6-clutch drum (forward drum) and a good shift kit. We recommend TransGo for TH400. If it's a race car, a "reverse" valve body is called for (reverses the shift pattern for the forward gears). A trans-brake is another option. What kind of racing will it see?

In a lighter car, PowerGlide has an "edge". In a heavier car (over 2,600 lbs.), TH400 with a bit taller rear gear is called for.

Jim

[UncleBob]

Originally Posted by MrPbody

Bob,

The usual modifications include an aftermarket "heavy duty" sprag (one-way clutch), 6-clutch drum (forward drum) and a good shift kit. We recommend TransGo for TH400. If it's a race car, a "reverse" valve body is called for (reverses the shift pattern for the forward gears). A trans-brake is another option. What kind of racing will it see?

In a lighter car, PowerGlide has an "edge". In a heavier car (over 2,600 lbs.), TH400 with a bit taller rear gear is called for.

Jim

it would be street/drag racing car, and it would be heavier than 2600#, more like 3200. But it will be a turbo'd engine, so taller gearing is quite OK.

Its as always a question of how much is street and how much is strip. but thats purely performance, I'm just trying to find out if the TH400 could handle the abuse

[MrPbody]

Bob,

You'll get other opinions, but mine is that TH400 is absolutely the best 3-speed automatic ever made by anyone. It's every bit as tough as C-6 or 727, and has a more "sophisticated" power flow and shift process. It's the MOST popular (3-speed) in drag racing for many reasons.

If your budget can stand it, companies like TCI and ATI build 400s guarenteed to stand up to 1,500-plus horsepower. Just how big a "turbo'd" are you building?

Jim

[UncleBob]

Originally Posted by MrPbody

Just how big a "turbo'd" are you building?

Jim

as big as I can for as little money as possible

But I don't want to do the revolving-door on trannies either.

How much do the insane-HP-capable prepped 400's go for? I assume they aren't cheap....

[MrPbody]

Bob,
I can't say for sure. Upwards of $2,000, I would guess. I would contact TCI first. They have the high-end covered.

Jim