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2001 Impreza L
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730 Posts
Today, I switched the output and input wires on the switch itself, and it looks like it did the trick.

At first I didn't know that I was driving with it on. Well, I kind of knew something was up because I felt binding in the steering as I was pulling out of my driveway. I went to an empty lot and did a 360. I thought to myself, why is it binding when it's on normal? I flipped the switch and felt the car move/shake. I did another 360 and it felt normal. Flipped the switch back on and felt the binding, and so on.

So it looks like it works. Thanks defcon5 for the awesome writeup!

Can you clarify what this "binding" means? Does that mean 50/50 split is engaged?

Thanks again!
 

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'99 OBS
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117 Posts
Discussion Starter #102 (Edited)
Can you clarify what this "binding" means? Does that mean 50/50 split is engaged?
Glad you got it figured out.:sunny:
The binding is casued by the fact that your center clutch pack (diff) is now completely locked up. When you make a tight turn, the front and rear wheels are travelling different distances over the ground, and creating a difference in rotational speed. Normally the center clutchpack is able to slip just a bit so that you never feel anything. With the mod, you've taken away that ability to slip - which you now feel as "torque bind"

Edit: Yes, when you feel that binding, you are locked in 50/50 - when you flip the switch and hear/feel the binding release, you're back in "normal" mode. Enjoy!
 

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2000 RS
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1,041 Posts
so is there a write up for the handbrake mod?

and quick question ive read through this whole thread and im mildly confused as to some of the conversations. was it said that this mod is not safe over 20 mph? or is that just me misreading?
 

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'98 Legacy Outback 2.5 AT
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7 Posts
I still cannot find the TCM :( Can someone give me a clue? Here original pics and new ones behind brake there's nothing and on passenger side only ECU.
Greetings, Guys!

I have European Legacy Outback 98 2.5 AT and... about 1-2 hours I cannot even find the TCM :)
It must be mounted right near the brake but... I have only bolts there.
Does someone have a clue? I have searched in left near fuses and in central console... found SRS and Cruise Control ECUs but TCM just hides from me :)
Everything else is working as it must be but...



 

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'99 OBS
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117 Posts
Discussion Starter #105
so is there a write up for the handbrake mod?
As of right now, there's no separate writeup for the handbrake mod. As I (and others) got farther into it, it became apparent that in order for everything to work correctly, the handbrake mod really should be integrated into the diff lock setup.
You can do one or the other quite easily - it's when you want both mods that it gets tricky.

was it said that this mod is not safe over 20 mph? or is that just me misreading?
The mod should be safe at any speed. I've driven on icy freeways at 45-50 mph with no issues. I'm not sure where the 20 mph figure comes from. Maybe it was a misunderstanding of the various torque splits at different speeds.
 

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'99 OBS
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117 Posts
Discussion Starter #106
I still cannot find the TCM :( Can someone give me a clue?
All of my information points to it being above and to the left of the brake pedal. It should be mounted longitudinally to the side of the car (oriented front to back). On it's end, you'll see three large connectors (black in color according to my service manual)
I see a big cluster of stuff to the left of the steering column in your pictures - my guess is it's in there.

I'm also going to send you a PM with some further info.
 

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2000 RS
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As of right now, there's no separate writeup for the handbrake mod. As I (and others) got farther into it, it became apparent that in order for everything to work correctly, the handbrake mod really should be integrated into the diff lock setup.
You can do one or the other quite easily - it's when you want both mods that it gets tricky.


The mod should be safe at any speed. I've driven on icy freeways at 45-50 mph with no issues. I'm not sure where the 20 mph figure comes from. Maybe it was a misunderstanding of the various torque splits at different speeds.
could you do the handbrake mod by inserting the fwd fuse but cutting the wires from it and bridging them to a spst switch on the ebrake so that when the ebrake engages its turned on and the fwd fuse is "reinserted" and when the ebrake is disengaged its on off and the system doesnt detect the fuse? i understand that you may have to add an inline fuse along the way to make sure that there are no mishaps but to me this seems like a simple solution. rig the ebrake to disengage the lockup and engage the fuse at the same time and that would work no?

i was reading something about above 20mph but it was probably in reference to before the mod. thats what really has me confused in this thread which posts refer to before and after.
 

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'98 Legacy Outback 2.5 AT
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7 Posts
FWD fuse is actually grounding the pin on ECM so probably relay must be used. Anyway probbaly not hard to accomplish (after find the tcm :) Schema from 98 Legacy wiring
 

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2000 RS
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so instead of an inline fuse its best to use a relay for the handbrake mod in combination with the 4eatdccd mod. (im calling it that because its really the same concept of a driver controlled center differential.)

why would a relay be nessicary? i can see a spdt switch instead to trick the the tcm into thinking there is a fuse inserted or that there is no fuse but i would think with no fuse there is no current and no need for a dual throw. a simple on off would do the trick and thinking more on it there realyl woudlnt be even a need for a fuse just a switch to bridge output wires for the fusebox along that fuse.

im not edumicated on wiring this is my personal figuring it out going on so i probably dont even know what im doing but id like to know. would this maybe work?
 

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'98 Legacy Outback 2.5 AT
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7 Posts
I have not checked hand brake schema but I think that relay can be wired to hand brake indicator light and ground the wire of TCM.
 

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2000 RS
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hmm. i was thinking more to take apart the handbrake and make the release button a switch as well for the fwd fuse. wouldnt that take some thinking away from it and make it more instant?
 

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'99 OBS
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117 Posts
Discussion Starter #112
I'm trying not to get too involved in this particular aspect of the discussion, but I should jump in quickly to clarify my earlier statement.
There are a million ways to implement the mods outlined in this thread - Ony, your handbrake idea will work just fine. I've run a very similar setup even before I came up with the switch idea. Plain old wires and fuses will work just fine. Relays offer more flexibility, and are a more elegant implementation, but not at all necessary.
Additionally, you can certainly whip up a custom "4eatdccd" with both features (diff lock and handbrake) Indeed, that's the very spirit of this thread - DIY.

When I said that things really should be integrated, what I meant was that for the cleanest, easiest installation, integration is the only way to go. The wiring involved in making both features work is cumbersome to say the least, and likely more than most people want to take on. I think everyone should be able to experience their AWD car's full potential, so my aim is to make a kit that will allow them to do just that, but with minimal installation headaches. That's not to say it can't (or shouldn't) be done without the kit, because it can.

The DIY spirit is what makes boards like RS25 so great. So with that in mind, get out there and tear into your car:cool: When you're done, post it here and show us what you've come up with.
 

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'07 forester x
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Just wondering if you had any more progress on the "full" package with the led light bar and possibly adjustable torque split? I would be intrested if it will work on my '07 forester x, I'd also be willing to test it out if it hasn't been done yet. I am good with electronics but I would just pay for it if you want to sell it, if not do you plan on posting a parts list and shcematic?

Thanks, and great write up! you should do this for a living or something.
 

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'98 Legacy Outback 2.5 AT
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It seems that I don't have TCM :) It is not there on mine and another car like mine (European Outback '98 EJ25D AT) and on Legacy 2.5 Limited '97 AT. At Subaru Fast by VIN for "Unit Assembly AT Control" it says that I don't have and ECU (22644AA670) is named "UNIT ASSEMBLY-AT AND E.G.I.CONTROL". In the list of "AT Control" applications it gives some Legacy and Imprezas with 1.8, 2.0, 2.2 engines but not with 2.5. The strange thing is that ECU looks not much different but I am not sure because have'nt compared with another. If someone can give some thoughts if really Ecu is also for AT Control and if he is with EJ25D and have or does not have TCM, or have seen somewhere wiring diagram of ECU with TCM integrated???
 

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'99 OBS
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117 Posts
Discussion Starter #116
Just wondering if you had any more progress on the "full" package with the led light bar and possibly adjustable torque split? Thanks, and great write up! you should do this for a living or something.
Thanks for the kind words jpfiero - I'm afraid no progress has been made lately. It seems to be the fate for all cool 4EAT mod threads to suffer some setbacks - it appears mine is no different. I don't want to bore everyone with a sob story, but I figure a little background couldn't hurt (and I'll get a chance to vent)
Bottom line is that I got laid off and have run out of cash to continue the R&D for this project. I'm still on the board and I get updates for this thread, so if you've got questions, I'm happy to help. I'll still be working on the project, but it will be intermittent at best until my cash flow is back up.
If this were a higher demand project, I could set up a PayPal donation site, but I really don't think it has enough of a following to warrant that. I could be wrong - if there are people out there that want to see this continue PM me. If there's enough interest, I'll set something up.

Stop reading here if you don't want the boring back-story...

**Boring Back-story**
As of June 6th, I lost my fairly cushy, well-paying job as a video/film editor. Living as I do, in the Detroit area, most of my clients were automotive. Well, we all know that the US car companies are in BAD shape. My thoughts on the domestic car manufacturers and the current state of unionized labor could fill a book, but I'll spare everyone that diatribe unless provoked. ;)

Over the last three years advertising budgets dropped, my work dried up, and after surviving multiple waves of layoffs, I finally got let go. Proudly, I was one of the last two to go - but pride can't pay my mortgage, car payments etc.... My previous employer turned itself inside out trying to stay open as long as possible, and while I'm grateful that they did, in the process they used up all the money for things like severance packages. Overnight I went from a near six figure income, to unemployment wages of 18k/year. If it was just me, that'd be fine, but I've got a wife and kids to look after. That ain't fun and the reserves won't hold out for long since we've already been using them for the last three years as things got worse. Being an adult is so much fun! :_sure:

I'm out of "play money" and won't be able to continue the 4EAT projects until things pick back up, or I find a new job. Again - I'm still here and happy to help. PM me or post here.
In the meantime, work will continue but updates will be sparse.

Cheers all,
Chris
 

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'07 forester x
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Really sorry about your job, I hope things will get better for you soon. I understand you have to take care of your family first, it sucks when the actions of some greedy people effect alot of good people that are just trying to support a family. lets hope that things turn around soon.

I'll keep you and your family in my prayers.
 

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IG: @RHD_Adventures
2005 Legacy GT Wagon 5 Speed
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Thanks to The Korean for letting me use his car as the lab rat. The prototype is installed and working in his car - though we have some issues to iron out. Once all the bugs are worked out on the new MkII, and I figure out how to make it "kit-able", I hope to have some ready by the fall (just in time for fun in the snow) Should be pretty cool - think 'printed circuit boards and real connectors'!
:banana::banana::banana:
I'm going to have to start checking this thread regularly. Thanx for helping... well installing and such! I never did get the chance. However, I still need to come back and hopefully you're still in lovely Detroit... well hopefully you got out, but ya! Um, I think I screwed your mod up the other night when I wasn't thinking straight after a long day at work and decided to take apart my center console and figure out why the FWD switch all of a sudden stopped working... bad idea is all i have to say... oh bother. I'll send you a PM as I lost your email and phone number... lovely.

On a more positive note... I've had a chance to now to play around with the switch and critique it I suppose you could say. I don't recommend the things I've done, but hey if you do don't say I didn't warn you. First things first... works fantastic on dirt and mud. I found a mudding spot in lovely downtown Detroit and decided to try everything out. Ebrake mod and 4wd are amazing in the dirt. 4wd in the rain... works awesome as well, but definitely wasn't paying attention and did a 180 with it turned on. Not sure if that was the cause, but hey it was on and it's never happened before. Owell. Also I've used it quite a bit on dry pavement up in Hell, around town (mainly the on and off ramps), and in general just flipped it back in forth. There is definitely a more "positive" feel on the handling part. Thanx again Chris!
 

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'99 OBS
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117 Posts
Discussion Starter #119
Glad to hear it was working as expected...until you broke it:p

PM replied - we'll figure it out.
 

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Some good reading over here. I have a 90 legacy so I dont venture over here much, seems i was missing out.

Anyways, I plan on doing this mod asap and integrating the handbrake but possibly at a later date. That would be strictly a rally cross toy and i think i've got a few months before the next season.

So can anyone help with wiring diagrams for a 90 legacy? I plan on using the DMM to find it via the FWD fuse but i wouldn't mind a double check.

defcon5-If you have any info about the handbrake stuff and how functional it is please shoot me a PM.

Thanks guys, can't wait to try this out with my new tires in the snow!
 
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