Ive read a little about it but I wanted to hear from some people familiar with the 4l60e. I know and rebuild 200-4rs but do not know the newer electronic GM trannys well. Im working on my sisters 00 Z28(lid/cat back and free mods). Shifts decent at WOT, no slipping from a stop on any shift at WOT, but from a 70 roll dropping from 3rd to 2nd it revs a bit before it grabs. I'm guessing the 2-4 band is not holding. Another weird thing, is it seems to be confused at certain throttle angles during the 2-3 shift at light throttle increments(was told this is common on 2000s?). Just as a test i hooked up my OTC4000e and found that it has a mode where i can increase the pressure by increments of 10%. I did the 10% increase and the shifting of the tranny is much much better. But its only a test mode. Its actually a bit too firm for her I'm guessing and i do not want to hurt the pump or have any other ailments of too much line pressure . So after searching i haven't found a conclusive answer. I know its a bandaid approach for a band that is probably not 100% but will turning the torx bit on the pressure solenoid 1/8th of a turn hurt anything? I do have a tranny pressure gauge i plan on hooking up to get a base pressure. I was reading an instruction sheet about installing an Art Carr shift kit and it recommended a 1/4 turn for "hard shifts" with their shift kit. Has anybody done this adjustment with success? Sorry for the length

 

yes you can turn it 1/8 to 1/4 turn and it will not hurt anything

 

where is this screw. My 4l80e has ro hit 3500rpms when shifting into second gear but when i have my over drive on it shifts smoothly.

 

The small screw is in the end of the pressure control solenoid at front of VB on an 80e however it will only affect line pressure firmness of shifts not shift timing in any gear selection. If delayed shift s the issue I would first look at the data and see when the shift is being commanded. in this condition..

 

I can honestly say this is the first time I've ever seen someone reputable recommend turning the EPC screw.

 

Mine is slipping 2-3/ 3-4 what direction to increase pressure { assuming that's what needs to be done }

 

Clockwise will increase line presure however I would not go more than 1/2 turn.

 

Damn, I went counter

 

I never ever used to do this on any units...

But I know PBA and a few other professional builders will make an adjustment if (and I mean only if) wide-open-throttle line pressure is not where is needs to be after all other modifications have been completed.

With no major leaks, and a very healthy pump (slide and rotor clearanced properly, new boost valve ***. and new spring, pressure regulator valve is not worn, ETC).

Some builders will make an 1/8" or so turn.

I recently only started do this on pre-1996 units if WOT line pressure is lower than needed (after all modifications are completed).
The new units normally control line pressure much more quickly and accurately (due to CPU improvements in the PCM).

Dana (PBA) and I were just talking about using a vacuum modulator about 20 years ago before the PCMs improved.

 

On a 60e, I'd use a .060 drill bit and make it fixed line LONG before I would ever retrofit a mod valve

 

In most cases we end up turning down if anything after dyno run, But the Person ask how to increase the line I assume as a short term fix to some other issue, And I have seen a few get some extra life using this method particularly with stock somewhat over powered transmissions,

 

After tear down and readjust, my transmission seems to be running perfect now, thank you.

 

I have an 87 cutlass supreme and rigged the harness with switches to shift manually. Now I've been told that it will only run at full line pressure. So can I turn counter clockwise to decrease line pressure? And if so, how much should I turn?

 

Fml!

 

I think you will burn your tranny when lowering pressure only to get smooth shifts
Better use some standalone controller for tranny to regulate pressure depending on throttle

 

Do not turn the pressure down to soften shifts. Either get a controller or consider a vacuum modulator . Also note max line without proper pump mods all the time can result in pump damage and or engine thrust bearing issues not to mention being very hard on internal hard parts such as roller clutch and input sprag .