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Thread: 4L80E fluid pressure

  1. #1
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    4L80E fluid pressure

    I am making my own electronic controller for a 4L80E and want to continuously monitor the transmission fluid pressure. There is a 1/8 pipe thread port for checking the pressure during trouble shooting. Does anyone see why I can't screw an analog pressure sensor in that port permanently and monitor it with my controller?

  2. #2
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    Welcome to the forum missouri100.

    There was some dicussion in recent months about add-ons to ports
    although I believe it was for temp. Do a search and will likely turn up.

    I am curioous to hear why you are making your own controller.
    How far have you got with that ?

    My thought would be that on the 80 the crowding and risk to damage
    would be a little more than the 60. Plan on putting an electrical sensor
    on it or running oil to dash/controller ? Scale would have to be upwards of
    325psi to handle reverse conditions even if fwd is nowhere near that.
    Have you considered getting a combination of tran temp and pressure
    control solenoid inputs to make yourself a "health meter" of sorts.
    Notice you have machine noted, are you good with electronics too ?

    Does this mean you are firing your ECM or is this a shift kit deal ?
    Figure how to let ECM know what's happening ?

    What ever it is you decide, and whatever stage of it you're in,
    be aware this place loves pictures of these cool projects.

  3. #3
    Senior Member Crmzendrgone's Avatar
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    Definitely love pics!! and would love to know how the project is going.
    sig by crmzendrgone

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    I build custom automated machines for industrial applications. That includes the fabrication and controls. The transmission is going in a stock car. Rules won't allow an ECM of any kind. I am going to make just a simple inexpensive controller using a microcontroller. I plan on controlling the torque converter, pressure control force motor, and shift valves. I will monitor the fluid temp, gear output (A,B,C), and the output shaft speed. I want to monitor the pressure but there isn't an existing pressure output. I am going to use little potentiometers as inputs to adjust any variables in the controller, like shift speeds and fluid pressure control. Right now I am collecting all the electronic components to condition all the inputs and outputs to the microcontroller. I expect the controller to cost about $60-$70.

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    Welcome to the forum Mr Mizzoo. Nice to see another Non Texan for a change. I am outspoken and can take the heat, but the Texans are so overpopulated here, I thinks its everyone else in the world vs the Texans and we, the rest of the world are probably still out numbered.
    Last edited by hotrodpc; 10-23-2009 at 09:12 AM.
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    Senior Member Crmzendrgone's Avatar
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    So that explains why Texas is so big
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    So when you say stock car, are you reffering to a race roundy round car or stock as in a daily driver? If you can really make your own controller for a 4L80-E, for $60-$70. Let me know how it works out. I may be you first customer for one, with a little profit added to the cost of course. If its for a race car, I am thinking the T400 would be a much wiser choice. Do you really need OD? If so, you can get around that need for a controller by going with a full manual valve body, and if a race car, probably driving it as such anyway. I don't know to many racers that put it in D, and leave it there. It will shift hard but so what, racing is not for comfy, and it will help the trans run cooler too. Do keep me updated on that controller though. I am very interested in that.
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    The 4L80E is because they are supposedly bullet proof. The racing is roundy round on a 3/8 dirt track. I don't expect to get out of 2nd. The good thing about the 4L80E is both shift valves are off in 2nd so I won't be draining the battery. Can't have an alternator in the car. That's the rules. I also like the torque converter control. The track starts muddy and dries out during the races. I think the converter control will come in handy. I have another 4L80E that is going into a GMC on ton behind a cummins 6. The 6.5 diesel that was in there was junk. Apparently they didn't make a very good one in 1996. That is really why I started investigating the controller.

    Good Ole MIZZOU plays the Texas pronghorns tonight on the TV. I am not really looking forward to it.

  9. #9
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    Me too, and I hope Mizzou wins. By all rights, TX should beat the snot out of OU, but didn't.
    You may be doing alot of work and spending alot of cash you don't have to. A Turbo is bullet proof too. Now there are some things that you should do to the 400 too. There are also some 4L80-E parts that will actually interchange into the T400 and make the 400 better also. The 4L80-E is also going rob gobs of horsepower and torque for the motor. The 400 takes enough as it is, but you are taking even more to turn the mass of the 4L80-E, also even heavier. IF you are doing roundy round, I would for sure go with the T400 and beef up a couple things and you will good to go. There are also some areas where the 400 is going to be stronger than the 4L80-E, one of those being the torque converter. What kind of converter control are you reffering too? As in going to lock it up and unlock it? You know there is such a thing as a variable pitch T400 too, that you can hook to a switch. Switch off, your stall is at about 16-1800. Switch on stall is about 23-2500 RPM. But no lock up. I am thing in that rough type of play, that 4L80-E conveter might be the first weak link there. Not 100% certain, but fairly certain. Maybe something you should look into. I know it will sure save you a chunk of cash to go T400.
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