The mechanics of manual valve bodies...
05-14-2005, 02:49 PM
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The mechanics of manual valve bodies... So although this isn't a ls1 related question...you guys at least know your stuff about manual valve bodies...
I'm in the process of converting a e-trans to a tiptronic type of shifting, and I have a question about line pressure:
The line presure currently is controlled by a PWM solenoid, more current, less line pressure. At full throttle, this is maxed (0 current)
My current plan is to just let this stay off, and keep full line pressure all the time.
Will running full line pressure hurt anything, assuming sufficent cooling? With M1 ATF and a big'ol trans cooler out front, it should be kept cool. The line pressure modulation is primarily for smoother shifts when tooling around town, but since I'll be tapping around gears anyway with the paddles, I'd think full line pressure and and totally slip-less trans would be fantastic. But will something pump related be damaged? I can't see how it could be, since the trans is designed to run full line pressure when the pump is spinning at 6000RPM---I doubt the lines would see maximum duty pressure even with the solenoid shut off at 1-2 grand--the pump simply wouldn't be spinning fast enough. If the only downside is harsh engagement... then its fine by me.
So any tips you guys can share...
I'm in the process of converting a e-trans to a tiptronic type of shifting, and I have a question about line pressure:
The line presure currently is controlled by a PWM solenoid, more current, less line pressure. At full throttle, this is maxed (0 current)
My current plan is to just let this stay off, and keep full line pressure all the time.
Will running full line pressure hurt anything, assuming sufficent cooling? With M1 ATF and a big'ol trans cooler out front, it should be kept cool. The line pressure modulation is primarily for smoother shifts when tooling around town, but since I'll be tapping around gears anyway with the paddles, I'd think full line pressure and and totally slip-less trans would be fantastic. But will something pump related be damaged? I can't see how it could be, since the trans is designed to run full line pressure when the pump is spinning at 6000RPM---I doubt the lines would see maximum duty pressure even with the solenoid shut off at 1-2 grand--the pump simply wouldn't be spinning fast enough. If the only downside is harsh engagement... then its fine by me.
So any tips you guys can share...
05-14-2005, 03:01 PM
#2
The line presure currently is controlled by a PWM
I've thought about this too and the only part stopping me from making a manually operated electric trans is the pressure solinoid.
Have you thought about just using a vacuum modulator in place of the electric solinoid?
I think you need some pressure regulation,
The force motor is basically a pressure bleed off.
I had a 4L80E hit 500+psi at 1300 rpm with a functional force motor. It broke my reverse servo.
A transmission guy showed me a 4L80E case that had a worm track blown out due to high pressure, also a cracked direct drum in one, a broken direct piston in another and the seals blown out of another one.
Now depending on what you're working on...they do make a pressure limiting boost valve for the 4L80E.
But to answer your question about high line pressure, yes there is a such thing as too much.
05-14-2005, 04:47 PM
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Ooops, neglected to mention this isnt even a GM trans, its a Volvo/aisin warner 
To clarify what you're saying about too much line pressure: If I shut off the solenoid that controls the line pressure (there is one on this particular trans) the line pressure will be equal to that at full throttle. I wouldn't be raising the line pressure higher than what its designed for at the factory. Are you saying that stock-WOT line pressure will be too much for crusing and idle RPM and load?
To clarify what you're saying about too much line pressure: If I shut off the solenoid that controls the line pressure (there is one on this particular trans) the line pressure will be equal to that at full throttle. I wouldn't be raising the line pressure higher than what its designed for at the factory. Are you saying that stock-WOT line pressure will be too much for crusing and idle RPM and load?
05-14-2005, 04:59 PM
#4
Well I know nothing of those transmissions.
I do run a non electronic th400 with a plug in place of the vacuum modulator. It gets full line pressure all the time. I have been told it'll wear the pump and other things out sooner, but I have seen no evidence in the past 2 years it's been like that, non daily driven.
I look at it this way, if you have enough spare parts, don't need 100% reliability and have the time to experiment, then do so.
Thats the fun part IMO.
I do run a non electronic th400 with a plug in place of the vacuum modulator. It gets full line pressure all the time. I have been told it'll wear the pump and other things out sooner, but I have seen no evidence in the past 2 years it's been like that, non daily driven.
I look at it this way, if you have enough spare parts, don't need 100% reliability and have the time to experiment, then do so.
Thats the fun part IMO.
05-14-2005, 07:23 PM
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Originally Posted by jxaxsxoxn
Well I know nothing of those transmissions.
I do run a non electronic th400 with a plug in place of the vacuum modulator. It gets full line pressure all the time. I have been told it'll wear the pump and other things out sooner, but I have seen no evidence in the past 2 years it's been like that, non daily driven.
I look at it this way, if you have enough spare parts, don't need 100% reliability and have the time to experiment, then do so.
Thats the fun part IMO.
I do run a non electronic th400 with a plug in place of the vacuum modulator. It gets full line pressure all the time. I have been told it'll wear the pump and other things out sooner, but I have seen no evidence in the past 2 years it's been like that, non daily driven.
I look at it this way, if you have enough spare parts, don't need 100% reliability and have the time to experiment, then do so.
Thats the fun part IMO.