any one know how big you can drill out 2-3 shift hole in 4l60e

 

.101 or about 1/8th inch .

 

and with the sonnix servo check ball

 

Ok what are you trying to accomplish then would be a better question I suppose?

 

I own a 68 amx that was built by amc
Ran a amc 390 for about ten years
Fun engine, same torque as a 426 hemi in its day
Ten years ago, I slipped a 350 Chevy with a b&m 250 supercharger into it
Ran turbo 350, then a 700r4 and now a 94 4l60e
So I have a 3650 lb car with 3.56 gears that’s pushing 600 hp
Converter is a 2800
The tranny has to date, wider bushing, 5 gear planetaries, and beast sun shell
Alto reds cross cut in the 3-4, the short apply ring, one piece backing plate8 clutch .075 coleen steels. The pump has been upgraded to a 13 vane c/w no break rings with a sonnax high rev spring for the slide, the reg valve is replaced with a transgo shift kit
Line pressure is at 280 psi
As I said before, sonnax servo check ball and 2-3 drilled to .150
This combo will flare 500rpm under full load on the 2-3 up shift
What is going to take to get rid of it?
What’s going in this round is the z clutches and Fairbanks servo
i also run a TCI controller

 

Well IMO 280 PSI is too much but not your problem as far as the flare.(230 psi max is IMO ideal)
As for the issue. Tighten the 3-4 set up to around .020 to .030 .
After that if you mean the fairbanks 2nd super hold it will limit accumulation on the 2-3 shift drastically and you should not have any flare issue. Thats exactly the way we bould ours (except for the 280psi) and we have not run into any flaring issue at all.
Frank at PerformaBuilt

 

sounds like i'm on the right track
3-4 clearance was .040
same combo before but line pressure was at 220
it flared 1200 rpm
did it twice smoked the clutches
wish i could kill power to engine on upshifts like it sounds you guys can do with chevy computers

 

Sounds like you are on the right track for sure

 

Ok new problem
Went with the Fairbanks servo fixed third gear full throttle shift
Had to replace spacer plate after that ,holes now seem to be to big for second and third shift. Still running 280 psi line pressure , 3rd gear cluthes are I think .060 borge warner and steels are standard coleen ,one piece apply 8 cluthes and same size backing plate.
Was having way to much fun until today ,it now slips or chatters in first gear ,or most gears. So im assuming it’s the forward cluthes or sprag. Last tranny had a mechanical diode sprag but that gave me a shake in third gear replaced it with a standard sprag.
Tear it out tonight to see what it is
If it is the forward cluthes is there anything out there to beef them up