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presslab

4EAT paddle shifters?

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I thought i explained how things worked.... but a long thread who knows. What i will tell you is expect that the tranny wont last for the life of the car with just home grown paddles. Youll be bypassing everything that gives the tranny long life.

 

google endwrench transmissions and read up on it there.

 

good luck

 

nipper

I read through everything in the thread. In fact, read everything in about 5 different threads, and the endwrench site. There aren't really any insights into when, how fast, reasoning for the different things. I'd just take my best guesses and then check them if I just knew what each thing actually does, but I don't know. The best descriptions I can find are simple things. I can't really duplicate programming for "open, smooth and lock-up" of the lock-up clutch if I don't know what the duty cycles and purposes are for the three settings.

 

Actually lock-up and overrunning I have a bit of a grasp on. The line pressure is what I have no idea about.

 

As for reliability, I don't care. I hate the 4EAT in my XT anyway. It's a terrible transmission. I plan on putting in a 5 speed manual eventually. I have a Bachelors in Electronics Engineering and just want a fun project to work on for now since my job is not in the field.

 

These are my thoughts based on what I read.

 

The overrunning clutch is for engine braking. If SS-3 fails Subaru says there will always be engine braking but does not mention any other bad effects, so for paddle shifter I think the overrunning clutch should always be engaged.

 

I have seen aftermarket controllers simply control line pressure DS-A using throttle position.

 

For lock up DS-B I have also seen aftermarket controllers create a "5 speed" where "5th" gear is 4th with the torque converter locked up. Otherwise the torque converter is not locked. When locking up DS-B should be modulated for a smooth transition.

 

 

For PC they have soundcard oscilloscope software, maybe this is good enough for your needs, and not sure if Mac has that option. I'm using a HP 54600B I picked up for $75. :lol:

I kind of figured SS 3 might be a 100% kind of thing to just gimp by. I'm hoping to find out when Subaru does or doesn't engage it to give more normal operation, but maybe not. Meh

 

Where have you seen the controllers? I'd like to read up on them and see if they can explain why. Like mentioned just above, this is the part I really don't understand.

 

I believe it was Nipper that said leaving the torque converter unlocked would kill mileage, and I tend to agree. My thoughts for DS B were to keep it locked until you shifted or took your foot completely off the gas. No idea if that good idea or not though.

 

And where did you get an oscilloscope like that for $75!? Those things are worth multiple thousands.:slobber:

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i have little to offer about how the TCU performs what it does and how it controls things.

 

the 4EAT performs okay without even having the TCU plugged in. i've been driving for quite a while with some lengthy road trips thrown in there as well without even having a TCU on my 4EAT.

 

i tossed in a duty C switch so i can control DC and 4WD. so i'm sure you could start small and work your way up just fine by controlling shifting, then lock up, then overrunning.

 

if you wanted a controls type EE project wouldn't the engine be more fun and useful? you could actually have some gains there in performance, gas mileage, and you could keep it since you're plans are to ditch the 4EAT anyway. then you could build one and sell it to me too!

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it's already been done... The person that i know that's done it has no intention of publicizing any details.

 

What a info hog!! Share the wealth, whats the point of keeping it secret? Or just want to be :cool:?

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i have little to offer about how the TCU performs what it does and how it controls things.

 

the 4EAT performs okay without even having the TCU plugged in. i've been driving for quite a while with some lengthy road trips thrown in there as well without even having a TCU on my 4EAT.

 

i tossed in a duty C switch so i can control DC and 4WD. so i'm sure you could start small and work your way up just fine by controlling shifting, then lock up, then overrunning.

 

if you wanted a controls type EE project wouldn't the engine be more fun and useful? you could actually have some gains there in performance, gas mileage, and you could keep it since you're plans are to ditch the 4EAT anyway. then you could build one and sell it to me too!

 

Sounds like it really is totally fail-safe!

 

Nono, sell the 4EAT to me, I actually quite like mine. :burnout:

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Psyko,

As far as the oscilloscope goes, most of my scope use is on the plain vanilla analog two channel variety. But, for this application, all the signals of interest would likely fall into the audio range. At that point you could use a digital audio workstation to get a multichannel, recording scope. Almost an analog logic analyzer.

 

You'd have to do a little calibrating to get a voltage value to the waveform, but that shouldn't be too bad. And, depending on the analog section you might have issues with signals close to DC since most audio stuff doesn't care about DC.

 

But, there are many workstations, and Macs are a preferred platform for many. USB might limit your channel count, but with firewire you should be able to get plenty of channels.

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i have little to offer about how the TCU performs what it does and how it controls things.

 

the 4EAT performs okay without even having the TCU plugged in. i've been driving for quite a while with some lengthy road trips thrown in there as well without even having a TCU on my 4EAT.

 

i tossed in a duty C switch so i can control DC and 4WD. so i'm sure you could start small and work your way up just fine by controlling shifting, then lock up, then overrunning.

 

if you wanted a controls type EE project wouldn't the engine be more fun and useful? you could actually have some gains there in performance, gas mileage, and you could keep it since you're plans are to ditch the 4EAT anyway. then you could build one and sell it to me too!

Without a TCU everything would be at 0 volts and 0% duty cycle, so that would probably be the best initial default. Eh?

 

I’ll probably throw a potentiometer and 555 timer circuit to control duty C for full diff control. You’re right about controlling shift and moving up from there. That’ll probably be the best course of action.

 

Maybe someday I’ll mess with engine control. For now I’ll stick with the transmission because I think it would be cool to have paddle shifters and give people somewhere to start from if they want to do it too.

 

Thanks.

 

Psyko,

As far as the oscilloscope goes, most of my scope use is on the plain vanilla analog two channel variety. But, for this application, all the signals of interest would likely fall into the audio range. At that point you could use a digital audio workstation to get a multichannel, recording scope. Almost an analog logic analyzer.

 

You'd have to do a little calibrating to get a voltage value to the waveform, but that shouldn't be too bad. And, depending on the analog section you might have issues with signals close to DC since most audio stuff doesn't care about DC.

 

But, there are many workstations, and Macs are a preferred platform for many. USB might limit your channel count, but with firewire you should be able to get plenty of channels.

I acutally probably don't really need anything too special. I was just terribly spoiled in school with top notch Agilent power supply, function generator, digital multimeter and dual input oscilloscope with logic analyzer built in.

 

Looking at the computer oscilloscopes... Some can be painfully expensive.

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Just wanted to bump this thread. I've decided to use a Legacy TCU. It's currently wired in and working okay; the AWD is having a few problems. It basically disables AWD at about 15 MPH. I believe it is due to the R&P/tire size difference in the Legacy. The front/rear speeds aren't quite matched up, about 6% error.

 

I have downloaded the Legacy TCU ROM through the Select Monitor interface. I've been disassembling the ROM and I've identified the const for the vss1, and I believe I can correct the 6% error which I hope will fix the AWD problems.

 

The Legacy TCU should have better control of the AWD than the GL10 TCU, it already works better at a standstill. It has a Motorola 68HC11 which is a much easier to deal with CPU than the GL10 which is some Hitachi CPU.

 

The eventual plan is to add my own paddle shift code to the ROM, there is a lot of unused space in there. There should be a couple inputs available for the paddle shifters.

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