best th400's

[achevy1978]

anyone know what the best th400 years had the most clutches and best sprags in them... motor home ones??

also dual feeding one, i see taking the 2nd ring off the carrier but im lost as to the drum seal. are they talking the one in the center hole of piston?? also i read where someone said dont block any holes in case or carrier while some say use a cup plug in case or tap and plug carrier....

thanks

[VileZambonie]

Get the ATSG 3L80 / 400 manual

[Engineer]

Look for a TH400 (actually TH475) from a bread truck. The G/P30 series vans had the best tranny. Straight cut planetaries. -They are noisier in the reduction gears, but it is what it is.

If you are talking about the direct clutch dual feed mod.......you do need to put the plug in the valve body, and the separator plate or the oil will simply exhaust through the open reverse valve. (IIRC) Been a while since I did it.

Look at this article, with pics:
http://jakesperformance.com/site/mobile?url=http%3A%2F%2Fjakesperformance.com%2FTH400_Rebuild_Tech.html#2837

Are you searching for a TH400 right now? If so, any TH400 will handle a lot of power. Unless you are pushing north of 500hp with a big block the TH400 from granny's '75 Caprice Classic will handle most street engines with a good aftermarket cooler.

[achevy1978]

tried that link but didnt work... im lost as its said to remove both the the 2nd sealing ring and another one..is it the center piston lip seal they are talking about ??

thanks

[Engineer]

The one on the direct drum is the one you want to leave out. The two sealing rings on the direct piston must be installed or you will have a massive internal leak.

On the center support you will want to leave off the sealing ring second from the top, but leave the rest.

To make the dual feed direct clutch work you can do either the center support sealing ring mod or the clutch drum sealing ring mod. You don't have to do both. But if you do both it won't hurt a thing. It is like filling a bucket of water with two hoses instead of one.

Try this link, maybe this one will work:

http://jakesperformance.com/TH400_Rebuild_Tech.html?no_redirect=true

[Engineer]

Since we are talking direct clutch, and you asked about sprags......

All but the earliest TH-400s had the intermediate roller clutch on the back of the direct drum. If you find a TH-400 with the roller clutch I wouldn't use it, but it is not the end of the world.

Buy a direct drum from a 4L80E. These all have a 36 segment sprags in them, and most likely the direct clutch will accept 6 friction discs. 95% of the TH-400s you find will use 5 direct frictions. A 6 disc direct drum (it is actually the piston that is the magic part that makes it a 6 disc clutch), with an intermediate sprag is rare. However 4L80E direct drums are available everywhere including new at your Chevy dealer.

[achevy1978]

thanks...i just ...checked the input shaft paly  while trans is hanging and got 70 tho... so to take that up
put a shim behind the pump but i read somewhere that if you get too thick it does something but cant remember