TH400 Rebuild Advice

[65 Fastback]

Hi all,

I need to rebuild my Turbo 400 to handle up to 600HP to suit a new motor

The trans seems stock. I have upgraded the torque converter only at this stage.

Before I approach some trans rebuilders I want to get an idea of the parts upgrades I need to strengthen it so I can get value for money.

I want to keep it manual/automatic setup. I plan to remove the trans myself and take to the shop.

Im just a bit confused with the terminology... corvette servos, direct drums, 34 element sprags, shift kits etc

Thanks for any advice

[70's luvr]

I'd put this in the drive-train section. Clinebarger and others would steer you in the right direction.

[davepl]

A stock TH400 will handle everything an LS6 Chevelle can throw at it, so you'd figure a stock rebuild would be plenty for most of our trucks!

Be very clear what you want for a drive experience. If you stick a Stage III shift kit in it you're going to hate it (or love it) every time it kicks you in the spleen on a 1->2 upshift for no good reason. For classic trucks I like them nice and stock, but if yours is a performance build, that's different.

Just don't make the mistake I just made and am now in the process of fixing: a drag race transmission in a classic pickup.

[65 Fastback]

Originally Posted by davepl

A stock TH400 will handle everything an LS6 Chevelle can throw at it, so you'd figure a stock rebuild would be plenty for most of our trucks!

Be very clear what you want for a drive experience. If you stick a Stage III shift kit in it you're going to hate it (or love it) every time it kicks you in the spleen on a 1->2 upshift for no good reason. For classic trucks I like them nice and stock, but if yours is a performance build, that's different.

Just don't make the mistake I just made and am now in the process of fixing: a drag race transmission in a classic pickup.

I just had the same conversation with a transmission shop. The owner warned me about overbuilding for the street. I did some "internet" research and thought I needed the following:

install 4L80 Direct drum w/34 element sprag
install TH400 rebuild kit
dual feed oil to the direct clutches
Increase separator holes & fit Trans-go Stage 2 Shift kit
Block the 2-3 accumulator


He said I would be nuts. and I wouldn't enjoy the ride, all I needed was the 34 element sprag and a standard rebuild.

[mmiddle]

Put TOP-SHELF parts in it and the upgraded sprag. TH400s are incredibly strong. If you what the best advice call B&M. Those guys will shoot straight with you on your needs. Plus they are the experts on 400s. Every one else learned from B&Ms R&D work in the 1970s.

[clinebarger]

Originally Posted by mmiddle

Put TOP-SHELF parts in it and the upgraded sprag. TH400s are incredibly strong. If you what the best advice call B&M. Those guys will shoot straight with you on your needs. Plus they are the experts on 400s. Every one else learned from B&Ms R&D work in the 1970s.

B&M builds crap, I have been trough several of their units.....Junk. Their Shift Kits are JUNK also....Their Converters....You guessed it!

They should stick to selling Shifters, Coolers, & Governor kits, NOTHING else!

[Ironangel]

Originally Posted by clinebarger

B&M builds crap, I have been trough several of their units.....Junk. Their Shift Kits are JUNK also....Their Converters....You guessed it!

They should stick to selling Shifters, Coolers, & Governor kits, NOTHING else!

Well there you have it! No pulled punches from CB! Guess what kind of stall converter I bought yesterday? Yup, you guessed it, a B&M Tork Master 2000! But hey, at $150 it was the cheapest converter on ebay, I didn't even know it was a B&M converter until it was delivered! It will go well with the questionable 350THM I just rebuilt...Oh well, I'll blow them both up at the next burnout contest...My good tranny turned in to a back up tranny today..."Live and learn"