Need help with TH350 or TH400 parts.

[kc2006]

Hi all, I'm going to be building a TH350 or a TH400 and i need it to be able to take 500-600 ft lbs torque and 450-600hp. I found a good shop in town to rebuild the tranny, but i don't know an extreme amount about trannies. I was wondering what parts am i going to need to get to make the tranny strong enough for the power? I plan on getting a B&M Master Racing Overhaul kit, a shift kit, a B&M holeshot torque converter (3000stall). What other things should i get? Thanks in advance!

 

[jakeshoe]

Ok,
Since none fo the gurus have answered, here goes.
Depends on the trans you intend to use, Th350 or Th400, and the application.

Th350: Street/Strip
Go to www.bulkpart.com and get a kit w red or blue frictions. I usually just use regular steels.
Buy a brass screen filter,
get a red lined band,
A Transgo valve body reprogramming kit Stage 1&2 for manual /auto or stage 3 for full manual.
Buy a new intermediate sprag (roller clutch) and the hardened race.
Also wise to use a new low/reverse roller clutch.
If doing yourself buy a complete bushing and washer kit too, helps to have extra.
Double up the bushings on the sun gear on each end, redrill fluid holes and deburr.
You can use 4L60-E late model low reverse steels in the Th350 for less drag, not absolutely necessary but good to do.
Machine the direct drum piston down to accept an additional friction and steel, about .160" but check clearances with 4 clutches, then machine as necessary.
I leave the cushioning plate out on the direct.
In the forward I use a cushioning plate as well as the intermediates.
Be sure pump is in good shape.
I would probably use a different converter, one of these guys should be able to guide you on that.
Set endplay on the tight side, i usually aim for .010-.015" or so.
That's all I can think of on the TH350 off the top of my head, just be sure all the bushings are good.

TH400:
Same deal on the kit,
get a 4L80-E intermediate band, it is wider. I get the red lined ones.
Get a direct drum from a 1965-1969 TH400 or a 4L80-E. Machine piston down to accept additional clutches.
The 4L80 uses a 34 element sprag, same deal as TCI or B&M sell for the TH400. If you get the older 400 drum, buy the sprag from bulkpart, or if you get the 4L80 drum you can use its sprag or replace with new.
Once again,
use the TransGo kit for desired level.
Be sure you retain the direct accumulator springs in both trans, to prevent problems. Don't let your builder leave them out like most do.
That's about all the stuff I can think of offhand. I'll post more later if something comes to mind.

Jake

Let the gurus start correcting me....

 

[chris718]

i see you made it to the 400 build sheets on our site kc2006. hope you found it interesting.

 

[kc2006]

thanks jakeshoe, very helpful.

Chris, yea i got the email about the price, very reasonable. I found a TH400 from a junkyard yesterday for $150 and it has a 30 day guarantee. But I still might go with yours.

 

[chris718]

no problem .