dubga

iTrader: (8)

Since I bought this car back in December I have felt that it shifted a little softer than it should. I had a 95 TA when it was new and it shifted much firmer, especially from 1-2 and at WOT. So I have been doing some reading about line pressure and bought myself a pressure gauge and took some readings this evening.

Idle in P,N,D - 55 lbs
Idle in Reverse - 80 lbs
Cruising speed flat terrain - 55 lbs
Moderate acceleration 125 lbs
WOT acceleration - 175 - 225 and bounces back and forth wildly

It shifts fine, no delays, no sluggishness, no slipping, tc seems to lock up like it should...just doesn't shift as firm as it should be. I just want to make sure that if there is a problem I fix it before it becomes a real problem.

I found a site that says this kind of thing could be a bad epc solenoid, bad boost valve, bad seals, etc. Any tranny experts have some advice?

96 TA

performabuilt

iTrader: (25)

things like rear ratio and such affect how the car feels shift wise. Your presures look on but the bouncing would worry me a little . The only time we see that on the dyno is if the fluild is a little low make sure its at or just above the crosshatch. The epc appears to be working based on the info you have given. You might consider having the line uped a little in tuning or a shift kit .

dubga

iTrader: (8)

So you don't think those pressure readings are low? Here is something I got from another site regarding 4l60e pressures:

"Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve with a Transgo 0.500" boost valve (easy fix in pan)."

Granted, this is a site that focuses on gm trucks, but I figured the TA's and Camaros would have high pressures too. I am not arguing with you or doubting you...you guys have a good rep around these forums...just trying to learn. What do you think about the boost valve recommendation.

Your feedback is greatly appreciated.

performabuilt

iTrader: (25)

well the idle presures are a bit lower than what we see on our units. but the max presure is within the normal range of a stock 4l60e. I would certainly try the bosst valve but also note someone could have lowered your base presures in tuning if its ever been tuned .

joecar

Try this: get someone with tuning software to do these things:
- increase shift pressure tables (say +20%) for 1->2, 2->3, 3->4,
- reduce shift time tables (say =0.2s) for 1->2, 2->3, 3->4,
- reduce shift torque reduction tables (say -20%) for 1->2, 2->3, 3->4.

dubga

iTrader: (8)

I hadn't considered that someone could have softened the shifts with tuning.

Well I have a tune on the way from Trifecta. I didn't ask for the "firm up shifts" option and the gt tuner is already on the way, but maybe if I contact them they can add that into the program and email it to me. I don't know how that gt tuner works but I assume I could load a new program on it from my pc if it was emailed to me.

Thanks for the advice guys!!

Badazz 97 TA

iTrader: (18)

Do you have a stock torque converter or a higher stall? higher stalls tend to make the shifts feel softer, when really there the same. Not sure if thats your problem, but just throwing that out there

dubga

iTrader: (8)

Far as I know it is stock TC.

dubga

iTrader: (8)

Isn't that part of the torque management? I thought that could only be adjusted on 99+. Mine is a 96.

dubga

iTrader: (8)

You were right about the pressure bouncing. It was a little low on fluid. I always check it with the car running, but this time I let it get warmed up good and checked it. Now the wot pressure holds steady at about 195. Idle pressures are still the same. I emailed Trifecta and he said he would send me another tune with the firmer shift points and let me try it both ways and see what works best.