Line Pressure Discussion (when is too much)
maybe this is why I keep blowing 4l60e's. I've had my tranny rebuilt by Mike Kurtz of Century twice now and I think it's going out again. I don't even go to the track. I've got a TransGo shift kit he installed on the hardest setting and MTI has done tuning. Maybe MTI jacked up the line pressure? I guess if my tranny is going out, I'm telling Mike or someone to take out the shift kit and if they can't, put it on the softest setting and then I'll tell MTI to put the shift firmness to stock if they messed with it. The first time my tranny went out, Mike said the converter shreded apart, could this have been from too much pressure? thanks
-Chris
-Chris
12 Second Club
Joined: Jan 2004
Posts: 527
Likes: 0
From: Chicago, IL
I actually had a conversation the other day with a Master Auto tech at my Pontiac Dealership the other day with this thread in mind.
He was putting in a new Tranny since my TCI 3500 fried the last one. I mean fried the bottom end, and melted the sun gears. He told me that the line pressure was controled by a solenoid that is controled by the factory settings. This solenoid responds to various amperage send to it, to open and close. The factroy settings allow this amperage to vary depending on your throttle position.
In factory settings the amperage never gets below .3 or .4 amps. (lower amps means higher line pressure) he showed me a 4l60E hooked up to the computer and the pressure never got above 250 or so.
Then he hooked up my car which still had the tuning in the program from the performance shop that installed the Headers and TC. It showed the amperage set permanetly at .1 He said that when you change the programming the pressure gets set at one Psi and doesn't change. Which is why you get the hard shifts at lower rpm's.
He aslo told me that the seals of a 4l60E are rated to around 425 psi. If you set the amperage of that solenoid to .0 you will get around 475 psi out of the motor.
Mine is running right around 420-430 psi. this is with a 90% max setting on LS1 edit.
He was putting in a new Tranny since my TCI 3500 fried the last one. I mean fried the bottom end, and melted the sun gears. He told me that the line pressure was controled by a solenoid that is controled by the factory settings. This solenoid responds to various amperage send to it, to open and close. The factroy settings allow this amperage to vary depending on your throttle position.
In factory settings the amperage never gets below .3 or .4 amps. (lower amps means higher line pressure) he showed me a 4l60E hooked up to the computer and the pressure never got above 250 or so.
Then he hooked up my car which still had the tuning in the program from the performance shop that installed the Headers and TC. It showed the amperage set permanetly at .1 He said that when you change the programming the pressure gets set at one Psi and doesn't change. Which is why you get the hard shifts at lower rpm's.
He aslo told me that the seals of a 4l60E are rated to around 425 psi. If you set the amperage of that solenoid to .0 you will get around 475 psi out of the motor.
Mine is running right around 420-430 psi. this is with a 90% max setting on LS1 edit.
Teching In
Joined: Mar 2005
Posts: 3
Likes: 0
From: Durham,NC
Originally Posted by offaxis
Im wondering how much pressure was applied when i blew the snap ring and the 3/4 clutches out of the drum. It tore the holding teeth (Tabs) right off. I have since gone to the vacum setup. BTW That was done with stock tranny settings. There must be something wrong that makes it spike like crazy.BTW it had happened to me 2 times.
I think someone needs to make a billet input drum.
I have started using the cryo input drums and so far so good.
TECH Apprentice
Joined: Apr 2002
Posts: 358
Likes: 0
From: Mahwah, NJ
So are the TransGo kits good or bad for our 4L60Es? A local guy who I might have do my converter installation says they're bad and always cause problems. I've always heard otherwise here (that they work great and prolong tranny life).
Last edited by Ragtop 99; Nov 23, 2007 at 01:57 PM.
Restricted User
Joined: Apr 2004
Posts: 377
Likes: 0
The problem with modifying the EPC solenoid, it raises the line pressure across the board, (light & WOT throttle). The Trans-Go Performance Shift kit, with the vacuum modulator is more progammable, across the board.
Last edited by Pro Built Automatics; Aug 13, 2005 at 04:52 AM.
I got moe down here in waco texas doing my tuning (uses LT1 EDIT) shoud l I have my shift kit taken out and just stay with the 2800 stall? and get it programmed for firmer shifts?
and..
Did you have it "on" when this happend steez?? this just happen this week or something I know both me and you have been asking about this
and..
Originally Posted by steez
anyone knowabout the performance mode button in the middle of the consel in 94 a4 trans am's? i blew my pump in my tranny, and now i think thats why. it makes the cars shifts ALOT firmer
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
TECH Resident
Joined: May 2006
Posts: 969
Likes: 119
If you use the Trans-Go boost valve, and the vacuum modulator, you can get anywhere from 225 - 255 psi. You will need to adjust the length of the modulator pin if you go over 235 - 240 psi., as this is more than enough to keep this transmission together, when done right.
Last edited by PBA; Dec 19, 2006 at 01:00 AM.
TECH Regular
Joined: Aug 2005
Posts: 430
Likes: 0
Originally Posted by PBA
If you use the Trans-Go boost valve, and the vacuum modulator, you can get anywhere from 225 - 255 psi. You will need to adjust the length of the modualtor pin if you go over 235 - 240 psi., as this is probably more than enough to keep this transmission together, when done right.
Last edited by Steve40th; May 6, 2007 at 11:51 PM.
TECH Resident
Joined: May 2006
Posts: 969
Likes: 119
If you use the Trans-Go boost valve, and the vacuum modulator, the only other source that will change line pressure is the Actuator valve. If you install these two parts, you will see very little variation in pressure between transmissions. Trans-Go offers an additional white spring here that will help eliminate the pump pressure variation that is common on EPC solenoid units, and will raise line pressure about 5-7 pounds. By the way, this white spring is not needed when using the vacuum modulator, as the modulator does not have the pump pressure variation as the EPC solenoid does. There are other variables, such as rotor, vane, & slide clearance, oil viscosity, etc., that will effect maximum line pressure. But these variables should only have a somewhat minor effect on maximum line pressure.
I have confirmed this with the old trans dyno as well. I believe that the key here is in the boost valve with the EPC controlled units. I still like the vac mod more but will do them both way's. We had this discussion on another thread about fluttering gauges. I'm sure you remember! Most people do not test as we do. PBA if you ever make to Chicago look me up. Vince. 
FormerVendor
Joined: Oct 2006
Posts: 3,123
Likes: 3
From: D-F/W
Hello,
I have been reading this post and others related to the 4l60e for some time and have some observations. I can say that we have been doing some testing ourselves and can confirm that there are indeed differences in max line pressures from unit to unit... even when pumps and valve bodies are swapped in unison from one case to another and then placed back into the same test mule (408 rwhp)... we have no trans dyno and limited access to a chassis dyno.
But... I can tell you the best feeling, performing units we have had are the ones operating in the high 190's and 2teens as observed using a manual gauge in reverse and in neutral with a WOT hit. But that is our experience.
I have been reading this post and others related to the 4l60e for some time and have some observations. I can say that we have been doing some testing ourselves and can confirm that there are indeed differences in max line pressures from unit to unit... even when pumps and valve bodies are swapped in unison from one case to another and then placed back into the same test mule (408 rwhp)... we have no trans dyno and limited access to a chassis dyno.
But... I can tell you the best feeling, performing units we have had are the ones operating in the high 190's and 2teens as observed using a manual gauge in reverse and in neutral with a WOT hit. But that is our experience.
12 Second Club
Joined: Feb 2006
Posts: 170
Likes: 1
From: Las Vegas
If I have had my car tuned with the shift firmness bumped up everywhere from part throtle to full throtle would I be stupid to have the EPC turned a 1/4 turn for some aditional shift firmness. My tuner said he raised it everywhere to the max that he felt was safe in his experience.
On The Tree
Joined: Apr 2010
Posts: 113
Likes: 0
Has anyone refined this over the years? I would like to crank um my solonoid that controls line psi. From what i have read i need to check my line psi as is before i mess with anything. think i need around 200durnig the shift, I do not have anthang done this trans Its a stock 4l60e behind a stock 5.3, In an s-10 extended cab. So far with a bad tune and no poisi i ran an 14.2 @97.... Not very fast but it was a 2.3 60 foot. and with my beatter tune with more timing i think it will run at least .3 faster The last run was with 3.43 gears and no posi. leaving off idle roling into it so it dident blow the tire off. Now its 3.73 gear and a i think its called an aluburn posi. Its all gears.
Last edited by mwg2600; Jun 23, 2010 at 11:05 PM.
See if anyone here knows the answer to this problem. My 2000 Automatic WS6 has a Shift Kit in it from the previous owner. It now operates normally but just before it shifts (all gears) it makes a very short grinding sound/hydraulic whine. It only does this under moderate to heavy acceleration. What could the problem be?
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Arapitis: This is an old thread which is not really related to your problem.
You properly started your own thread and I and hopefully others will try to help you there:
https://ls1tech.com/forums/automatic...need-help.html
You properly started your own thread and I and hopefully others will try to help you there:
https://ls1tech.com/forums/automatic...need-help.html
