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BIG idea? manual 4EAT? i know, just read


amp27

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so i was in english today and it hit me.

 

before you read any farther answer this. does the 4EAT shift electronically or by other means or force? i always notice my lights dim while up shifting?

 

if the tranny is not shifted by the TCU just stop and everything below this is useless

 

i have been doing stuff with the 50/50 spilt mod for the 4eat and i noticed they there are soliniods for each gear. 1,2,3,4. and since the 50/50 mod is based on the same thing(just changing voltages and stuff). i was wondering if you can wire the TCU to be fooled into thinking its shifting, when really are the gears are controled by swicths(think i could wire up some complex thing to it is just 2 buttons for down and up.)

sorry redom just had to speak cause no one i talk to understands me.

 

like i wish i had a copy of the solinoid layout and stuff but i dont. it is on the first page of this though http://www.rs25.com/forums/f8/t99075-4eat-diff-lock-switch-handbrake-mod-torquemada-lite.html

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I think you need to understand how an automatic trans. works Automatic transmissions shift by sending hydraulic fluid to vaious clutch packs and clutch bands that hold different parts of planetary gearsets. the fluids is directed via the valve body and solenoids and the fluid preassure is supplied by the fluid pump which is driven by the input shell of the torque converter. the solenoids that are in the valvebady are electronic and dont draw alot of current so shifting should not ause the lights to dim. the solenoids are just moving very small valves around so they dont need alot of power. Also, since the TCU is also electronic, it also should not draw over a few amps of current either so id look elsewhere for your light dimming issue.
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i think i understand what you are wanting to do, let me try and simplify the idea to ensure that i comprehend...

 

you want to make push button shifting by bypassing the TCU and directly controlling the shift solenoids, correct?

 

while this could theoretically be done, the TCU mixed with the ECU does a lot more than just send a signal to the solenoids in the transmission. for starters sensors, to include TPS, idle air controller, etc..., that tell what the external conditions are for appropriate shift points on the rpm scale...if you are wanting to do this for cool factor, it probably can be done if you know enough about electronics and circuit boards (cause you will have to modify these for this to work without throwing a CEL), but for pratical purposes this is not a good idea. but hey, this is your car and you can do what you want with it, and that is whole point of modifying it right? this is where innovation does come from, one persons idea that is experemented with and modified until it becomes pratical.

 

i'll give you a thumbs up for out of box thinking though :)

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yea junky you got it thats what its could be called. all this where you guys come in a tell me whats ups with the 4EAT tranny and how it phisicly works. i have been into electronics forever, they do everything!. but hmm. it is possible....its possible that its possible. just not as simple as the 50/50 diff lock stuff. hmm i wonder if you could just fake the TCU into a "all good state" with the sensors and stuff, kinda like the fake 17 ohms put on the tcm like in 50/50 . just bypass them. new computer that can be custom fitted like a tcm os. idk you guys are gonna tell me all the actual systems that are involed in shifting. if this worked it would be one less thing for manual driving. no clucthing. hmm i need a buddy that knows the 4EAT inside and out and the sensors and all that.

 

 

ha i own 100 % copywrite ha. unless some else does it before me..still my my idea. then ill go 50/50 percent with you. ha dreams just jokeing on this copy right stuff i just want credit. i would love to see it be done.

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anybody wanna get into a xmas break project?

 

i think the first thing that needs to be done is to fool the tcu into a state so that when the swicth is fliped the tranny is gonna shift for sure.

 

anybody know these trannys real good. i got the electric skill just dont know where to begin. i need a layout of the wire harnesses in the car. that would help so much.

 

my car is in the shop right now getting brake lines redone.

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if you really want to mess with this project, here is my recommendation to get started...FYI this list is rather expensive, but it keeps you from screwing up your current setup so your car will always be operational.

 

a complete wiring diagram of ECU and TCU (if they are seperate items) connected to each other to include all sensors.

you will need a spare automatic transmission, a duplicate of your current one

car battery

the relay/button setup you wish to experiement with

a place to work at (decent size table with plenty of light

rubber floor mat (some protection against electricution)

a complete subaru automatic transmission rebuild manual for your car

 

using the wiring diagram, you can use us and google to find out exactly what each sensor has to do with the transmission, input/output voltages, and what is sent to and from the TCU/ECU.

 

with the transmission repair manual you will be able to tear down and rebuild or modify the transmission (automatics are a bit more difficult than manuals, however if you are savy mechanically and know a deal about vehicles in general, you should be able to take apart a transmission without breaking it and learn the internals personally, and besides this is why you get a spare transmission, just in case ;))

 

the buttons, relays, and car battery are for you to mock up this system to insure that it will work in a car, hence car battery, 12V DC (might be a bit overkill, but hey*shrug*)

 

as for exactly how this automatic transmission works, i don't see it being much different than any other one, but i have never taken apart this one before. so i can't help you here

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