T-400 direct clutch piston, NO checkball

[Gregaust]

In the process of building up a 1976 T400 and have upgraded the direct drum to early style to suit 34 element sprag. This has left me with no checkball in either the drum or piston. I have an aluminium piston and drum holds 5 frictions.
Does anyone sell an aftermarket piston with a checkball or am i best to find an early piston to suit or any other options?
Thanks for any assistance.

 

[turbobitt]

you can drill a bleed hole into the drum, maybe .070" in the lowest corner near the seal area about 45 degrees out.

 

[Gregaust]

I have a .040" bleed hole drilled already but would like the checkball too since it will seal off and limit the bleed off during clutch apply.

Isn't a .070" hole a lot to bleed off ?

 

[Gregaust]

I just been look on the CK performance website and see they list a direct drum with no checkball reqd in the piston. Anyone know what is done there ? I'm just nervous to drill too big a hole in the drum

 

[SSedan64]

I just been look on the CK performance website and see they list a direct drum with no checkball reqd in the piston. Anyone know what is done there ? I'm just nervous to drill too big a hole in the drum

Look through this post I think it's explained.
http://www.turbobuick.com/forums/transmission-talk/255286-th400-build-pictures.html

 

[Gregaust]

Thanks i did read there but forgot that bit. I am just nervous to run with no checkball. I'm studying now seems Don likes the Checkball and small hole and Chris prefers just a large hole @ .062 or 1/16".. Decisions decisions. Maybe i'll stick with the .040" i have Wish was easy to find an early piston then all would be solved.

It's all on page 3

http://www.turbobuick.com/forums/transmission-talk/255286-th400-build-pictures-3.html

 

[blackplague]

don't worry!!! a .040 bleed hole will be fine. Run it as is.

 

[Gregaust]

Thank you will do..Is going together this weekend ,that was the last little prob to sort out.