Need transmission tuning advise, please

[Schmieder]

I'm now entering the transmission tuning stage of my turbo project. Actually more like fine tuning.

My questions are this...

For a 4t60-e, how far can I safely increase the shift pressure? Some specifics, my shift pressure at 280 lbs/ft is (1>2)36, (2>3)28, (3>4)45

note: I am using torque management to limit max at 280 lbs/ft to aid in trans longetivity.

From what I gather, I need to increase pressures when I add more power.

What is the fastest shift speed the 4t60-e is capable? I have a setting of (1>2)0.225 sec, (2>3)0.200 sec, (3>4)0.250 sec.

Any advise on what/how to tune the force motor current, both positive and negative?

Also, when tuning the shift points what condition is better to be meet first, mph or rpm? I understand the shift speed needs to match the rpm but what should be first? Should my pcm hit XXmph then the matching rpm or visa-versa. Because the two will never be perfectly aligned, there has to be some sort of scheduling process.

btw, she is running great. I got the first two coats of paint on. The final will be sprayed with an HVLP in a few weeks. I have to wait that long for a cure so I can buff the paint down before final coat. But so far, the color scheme is fantastic. Lots of compliments. I will post up pics later today with hopefully a video once I get the tranny tuned in better.

[robertisaar]

want to explain how you're using PCM tuning to increase line pressure in a tranny that doesn't have a pressure control solenoid?

[95SleeperAcheiva]

I think he means a 4T65. Had me going there for a minute too, wondering how all this time of me going over my 4T60 why I never heard that before.

[Schmieder]

want to explain how you're using PCM tuning to increase line pressure in a tranny that doesn't have a pressure control solenoid?

No 4t65, I have the 4t60-e. Atleast, that is what comes stock with the 96 GPse. Though the trans was replaced 3 years ago. I'll be darned if I have a 4t65 already. Where exactly is the info on the trans where I can determine what trans I have?

I'm confused...I haven't made any changes to line pressures yet. So if it isn't possible, then it isn't...lol

But what about Force Motor Current? It says those tables are used to determine the current applied to achieve desired line pressure in relation to trans temps. Couldn't line pressures be adjusted via these tables?

Or is that a feature in the PCM that isn't utilized?

How about Shift Pressure Tables? Any advise on how to tweak them for more performance?

Thanks

[robertisaar]

knowing GM, that's because they added a bunch of things before any of the drivetrain was able to use it. if you max out or completey zero out any of those tables, i would wager nothing different would happen if you're running a 4T60E...

all of those things only apply to trannies that have a PCS/Force Motor.

in a 60E, shift time is controlled by how quickly the shift solenoid can go from full open to full closed, which is less than 100ms IIRC. line pressure is controlled by the vacuum modulator.

[Schmieder]

knowing GM, that's because they added a bunch of things before any of the drivetrain was able to use it. if you max out or completey zero out any of those tables, i would wager nothing different would happen if you're running a 4T60E...

all of those things only apply to trannies that have a PCS/Force Motor.

in a 60E, shift time is controlled by how quickly the shift solenoid can go from full open to full closed, which is less than 100ms IIRC. line pressure is controlled by the vacuum modulator.

So what direction of PSI/inHg would I need to go to increase line pressures?

Reduce vacuum = ? less line pressure ?

While WOT, what needs to be done to increase line pressures?

[robertisaar]

if you want more line pressure(and you definitely need it with a beefier motor to keep the clutches from killing themselves during shifts), you'll need an adjustable vacuum modulator.

the vacuum modulator changes line pressure dependant on one things: engine vacuum(or at least simulated vacuum if you're creative enough). in a N/A car, more throttle means less vacuum, which means more line pressure. in a boosted car, it would be wise to block the modulator from seeing boost(check valve) unless it can withstand it.

[3400-95-Modified]

I was a little confused when starting to read this too, then the thread straightened itself out

I have an adjustable modulator on mine and you can use that to beef up the pressure some, and also I've replaced my line boost valves with high ratio ones meant for the 3.8's and Quad motor cars with the 60e that also had high gear ratio's... I did this one time before and liked the shifts I got from it and also since I am running the Quad 4 gear ratio setup then I figure I should try out those valves

Making your shifts quicker can be done by shimming your 1-2 and 2-3 accumulator pumps that are in the pan area of the trans... Just a few thick washers below the springs help out quite a bit.

I've also swapped out all my shift valves for the sonnax replacement anodized ones that should help prevent side loading and wear. I did all these same things on my first trans I did and I was quite satisfied and I just never did it on this one the first time around... But now I am since I have the time. I'm hoping for the same result as the last setup.

[Schmieder]

if you want more line pressure(and you definitely need it with a beefier motor to keep the clutches from killing themselves during shifts), you'll need an adjustable vacuum modulator.

the vacuum modulator changes line pressure dependant on one things: engine vacuum(or at least simulated vacuum if you're creative enough). in a N/A car, more throttle means less vacuum, which means more line pressure. in a boosted car, it would be wise to block the modulator from seeing boost(check valve) unless it can withstand it.

So what would be the result of bleeding a small amount of pressure into the modulator during boost? Would it induce the opposite effect of vacuum reducing pressures? I already have a check valve preventing positive psi to the modulator, but I could also add a line past the CV with a reversed CV and a controlled bleeder valve. So a small amount of dialed in positive psi could be applied only during boost.

I was a little confused when starting to read this too, then the thread straightened itself out

I have an adjustable modulator on mine and you can use that to beef up the pressure some, and also I've replaced my line boost valves with high ratio ones meant for the 3.8's and Quad motor cars with the 60e that also had high gear ratio's... I did this one time before and liked the shifts I got from it and also since I am running the Quad 4 gear ratio setup then I figure I should try out those valves

Making your shifts quicker can be done by shimming your 1-2 and 2-3 accumulator pumps that are in the pan area of the trans... Just a few thick washers below the springs help out quite a bit.

I've also swapped out all my shift valves for the sonnax replacement anodized ones that should help prevent side loading and wear. I did all these same things on my first trans I did and I was quite satisfied and I just never did it on this one the first time around... But now I am since I have the time. I'm hoping for the same result as the last setup.

Thanks, I will look into doing that stuff mentioned. Shimming seems easier that I originally thought. I have washers of various sizes and all the tools needed. I just need to get a new gasket for the pan.

[3400-95-Modified]

Try to get the rubber replacement gasket, not the cork one... Those blow... The rubber is almost as good as the metal covered with rubber stock one... Just make sure to not tighten it down too much, don't want to squish the gasket out the sides.

Also I don't think adding positive pressure to a vac modulator will do the opposite... the only thing it may do is blow the diaphragm out of it.

[robertisaar]

from my understanding of a vacuum modulator, and even though i could probably get a VERY accurate description in just a few seconds, is that the diaphragm inside of it works very much like a FPR: full vacuum reduces pressure quite a bit, 0 vacuum(barometric pressure) gets up to a certain number, and adding PSI beyond that will further increase pressure.

i just don't know how much pressure can be used against it without seriously comprimising lifespan.

[torq455]

install the TransGo shift kit and use Dex VI. amazing difference! i'm going to experiment with a couple of shims. put them where other instructions say to do with my type of converter. you shouldn't need to crank up the line psi much. a few percent will give you a noticeable change, especially with the TransGo kit. check it out below! The left is the stock set up. to the right, TransGO set up. 1-2 has less springs, and 2-3 has more.the orange spring up top both pistions are orange, then white. orange is stiffer. i also replaced the white spring with the orange one. good luck!

[3400-95-Modified]

That's a trans go 4t65e kit, it does not apply to a 4t60e. Sorry.

Unless someone has figured out that accumulator pumps from a 65e will fit the 60e case you can't use those springs shims or pistons... the don't fit our assy.

I have one of those kits and I tried to fit it once and I believe it didn't work. I could check it again to see if I just opted out because of it looking so different than what I had in there.

As far as a 60e trans go kit, you will get a few new valves for the valve body, A procedure on how to change the TCC lockup pressure to lessen the slip with that, and then some plugs and drills for some holes on the valve body spacer plate, as well as springs for th TCC valve, a de-burring procedure for that valve and some other tweaks. They always refer to the 60e kit as a shift correction kit. It should not change the firmness of any of the shifts.

As far as my accumulators go, I'm also using doubled up springs in the 1-2 valve. I took the stronger 1-2 outer spring and I bought two of those and then I bought two of the 2-3 inner springs, so now in each accumulator I have the dual spring setup, but using the stronger of the two outer springs. This did improve the shift quickness and quality. Somewhere around 98 or maybe 97 they changed the configuration of the accumulators from what I have in my 96... so just be aware that you may not have the same setup as I do.

In taking apart the trans however I did find some excess wear on my 2nd clutch drum teeth that go against the reverse reaction shell... I may swap that drum out for a better condition one that I my have somewhere.

So be a little bit careful on how high you do go with shift firmness... I'm not sure which shift change could have caused this wear, or if its just typical for how much power I was trying to push through it.

[torq455]

That's a trans go 4t65e kit, it does not apply to a 4t60e. Sorry.

Ohhhhh DUUHHHH! I forgot. You can't use the kit from the 65E in the 60E. The accumulators are different. Did you shim the pistons at all, or increase line pressure?

[Schmieder]

Try to get the rubber replacement gasket, not the cork one... Those blow... The rubber is almost as good as the metal covered with rubber stock one... Just make sure to not tighten it down too much, don't want to squish the gasket out the sides.

Also I don't think adding positive pressure to a vac modulator will do the opposite... the only thing it may do is blow the diaphragm out of it.

Right, I don't trust cork anyways. I use a torque wrench in all areas where there are gaskets.

Only real concern I have is saving as much ATF as possible. Quality synthetic ATF at 8 quarts gets pricey I'll get as much as possible through the trans cooler lines first. It's a shame there isn't a drain plug like there is on the oil pan.

Positive pressures, I had a feeling it wouldn't do any good but I had to ask just to be sure.

Thanks, sorry if I was grouchy in the ID my Trans thread.

Ohhhhh DUUHHHH! I forgot. You can't use the kit from the 65E in the 60E. The accumulators are different. Did you shim the pistons at all, or increase line pressure?

I did no modifying to the trans internals yet. Only a 9.5K BTU cooler w/ temp gauge and new synthetic ATF.