I dont have an L but i have done alot of research about the 4r70w tranny... and i think all trannys would be the same in this instance. I have heard that it is bad to increase line pressure without a shift kit or valve body because you are cranking up the pump and trying to push more pressure through the small openings and holes of the factory valvebody that was not designed to flow that kind of pressure. When you do a shift kit or new valve body the orfices are inlarged in order to "mechanically" fix the shifts. this basicly increases the pressure by makeing holes larger...... then if you crank up line pressure on top of a mechanical modification it is actually not as bad for the pump because the pump is not working as hard.... because of the enlarged holes. But.... most people dont increase line pressure with a shift kit because it makes the truck shift too hard, and still adds some wear on the pump that is really not necessary. i hope that made some sense and that i explained everything right. good luck with your tranny, you will definately love the feel of the firmer shifts that a new VB will give you

-steve

 

This article by Greg Evans explains the funtion of the accumulator/valve body, and line modulators.

http://powersurgeperformance.net/shift.htm

Quote from his article :
" If you change the Line Modulator Boost Valve and raise line pressure throughout the body, the individual shift bores are no longer "tuned" properly and the reaction in the shift bores will be out of calibration for the elevated line pressure."

So, when you change the springs in the accumulator valve, you are raising line pressure.

I would like to get a straight answer as to how a chip can alter the shifts without raising the line pressure.

 

^^^

 

Good luck on this request ... It's basically
"Performance Enhancements are a result of <insert Tuner here> Technology ..."

As Grandpa use to say, "Just because it hasn't broken yet, doesn't
mean it isn't gonna!"

<grin>

Cliff

 

Shift duration. and thats about it.

Raising the line pressure is bad for it, well atleast my 3 broken transmission said so anyway. I would beleive anything greg evans told me that had to do with a transmission.

 

Factory tech were are you?

 

Raising the line pressure with a chip makes the pump so the work, using a mechanical shift kit lets the valve body boost valve boost the line pressure after the pump using what the pum is giving you anyway. The pump at a given RPM gives you more than you need but dumps some of it off as RPMs rise, which releases tension in the pump, boosting it in the valve body happens after this has occured, which is why the pump is not carrying the load.
I tune the valve body for a straight stock PCM, which is how it works best, have your tuner leave ALL transmission setting stock and it'll work fine.

Hope this clears it up,

G

 

 

When you say ALL tranny settings do you also mean the torque reduction or just the line pressure?

Thanks,
Sammy

 

ttt

 

Both, the torque reduction is in there for a reason. For a picture of what it does, ask RTKILLA to show you the pictures of his intermediate clutch, it was pretty toasty.
G