JDM GC WRX/SVX 4EAT = Phase 1 VTD?

[James614]

So, I've been reading around a lot and from what I can gather, it sounds like some early WRX's (no idea what models/years) and probably all the JDM SVX's had the early version of the VTD 4EAT with a 36:64 F/R split, which means Phase 1 which SHOULD mean as long as I have a matching TCU and the speed signaling is right, I can run whatever the hell I want (yeah right... but maybe sometimes?)

Does anyone here know anything about these transmissions, or what exactly they would have come out of? And, most importantly, if I can get a JDM WRX 4EAT, it's TCU/wiring, match the rear diff ratio, possibly do some speedo cable and trans mount sorcery, and go from "FWD with some rear wheel push, sometimes" to a rear-biased AWD system fitting for a turbocharger sports sedan(wagon)?

Yes, I could do the 5spd swap. But I've come not to have AT's as much since I started Auto-Xing, and power-braking without blowing up the trans is fun. If I can get less FWD handling in my car with the slushbox, that would be tits.

[wtdash]

Learn something new every day.....

I'd check on the SVX and Alcyone forums.


GL,
Td

[mike-tracy]

There's only 1 guy I've heard of who imported a SVX tranny with VTD. It's on his USDM SVX. Hadn't heard of early JDM wrx trannies getting that, though.

-Mike

[PhyrraM]

Some of the early WRXs had VTD. I'm pretty sure I got one with my EJ20G swap. It came from a '93 WRX wagon w/TD04 and black slanty intercooler. Other than that I have no idea how common they were.

Notice VTD rear housing in second photo. Third photo shows VTD housing (right) next to standard (left).

[James614]

Wow, trans code and fender tag... That helps immensely!

Only thing that would be better is if i could tell be looking at the exterior of the trans. But this is great.

As far as running the trans goes, I'm thinking I'll have to just jump in whenever the funds and right parts pop up... Nobody likes imported 4EATs enough to document them.

[James614]

I'm gonna go ahead and assume that the "Y" in the 6th position denotes the VTD system, since it seems to denote the type of AWD unit Josh's FSM scan.

[James614]

Just from looking at overseas auctions of used auto transmissions, this was definitely not standard or even terribly common on the WRXs. The majority of them have the "Z" in the 6th position, which denotes the standard multi-plate clutch setup we have. So finding a complete swappable set with wiring harness (still not sure if the harness is needed) and matching TCU very well could be difficult unless you know an importer you can ask to look out for such a combo.

Lots of Twin Turbo Legacy autos have it (expectedly), but as far as I know the ECUs are wired different on EJ20H/R which makes me not want to run their TCU's on our ECU.

[PhyrraM]

Pull the diagrams and compare to ours.

You may not need the harness. There is a chance that the VTD control simply replaces the Duty C in a normal tranny. Might only need a tranny and proper TCU.

[James614]

I wanna say that is the case from the info I've read (VTD really just uses a reversed multipate clutch as the slip limiting mechanism in conjunction with a planetary gearset in the center diff to provide the rear bias). Please correct me if I'm wrong on that.

Even so, a VTD TCU would most likely come attached to it's harness from what I've seen if it's included with the trans. And I have no idea how to tell if its a VTD TCU if it doesn't come with the trans...

[Legacy777]

Yeah I've heard as well that some of the overseas SVX's had the VTD transmissions. As mentioned, it'd probably be a little difficult finding one. I think the wiring wouldn't be an issue, you'd need a diagram to ensure everything was going to the proper place on TCU....and you'd also need the VTD TCU, as the normal one wouldn't likely work.

[mike-tracy]

Here's some info about swapping it into an SVX: http://svxworldforums.com/forum1/1294-1.html
Since svx guys swap legacy 4eats into their vehicles, I'd imagine this to work the other way with not too much difficulty.

[PhyrraM]

I have the TCU and harness for the swap in the pics above. I'm not keen on selling the harness (yet) but feel free to PM me about the trans and TCU.

I can inspect and photograph the harness if you wish. I'm also willing to segregate the EJ20G engine stuff from the auto tranny stuff and sell them seperate (but you gotta give me time).

Keep in mind I'm not 100% it's a VTD, but it seems to match photos I've seen. Let me know if you want photos of the TCU or harness.

[James614]

This was kind of a spontaneous idea that turned out to make some sense. So I need to make sure I can save enough for the trans+shipping+TCU+extras, which will take a while. And in that time I need to STILL think this is more worthwhile than a 5MT swap.

[James614]

I'm reading an interesting post on a Forester forum about a guy who did an MPT to VTD conversion simply by assembling an all-new VTD tail-housing (presumedly a used one would work just as well) and sticking it on his Forester in place of the MPT unit. Naturally this is dealing with Phase 2 transmissions, but if a Phase 2 MPT TCU can work with with a Phase 2 VTD tailhousing, then I can't imagine it wouldn't work the same with Phase 1 since our TCU doesn't have as many dynamic inputs for it's behavior of the C solenoid.

Reading about his experience, he basically leaves the FWD fuse in and enjoys the 45:55 open diff better than the MPT setup on dry conditions. With his FWD fuse removed, the TCU is a little unhappy (different F and R VSS signals, I don't think this would be an issue in Phase 1 transmissions) but ultimately behaves well. No mention of limp-home behavoir, just an AWD warning light.

I'm getting deployed very soon on short notice, so I won't be around until X-mas/next year, but eventually I'd like to look into trying something like this if a Phase 1 VTD tailhousing is available at the time. It would be much cheaper to ship and much less labor-intensive. And it would open up the possibility of using the same VTD unit on later replacement transmissions when mine inevitably goes out.

I know some of you guys have very good knowledge of the 4EAT. Any idea why this wouldn't work for us?

http://www.subaruforester.org/vbulletin ... ion-37441/

[James614]

He does eventually stick a VTD TCU in there. But still, it seems like getting VTD by no means requires a transmission swap. A JDM WRX trans would be nice for the 4.11s, but apparently I could get a 4.44 Outback trans and add VTD to it if I wanted :-p

[Legacy777]

Interesting! Good info, thanks for sharing.

[James614]

Okay, crazy idea: Does anyone know if a Phase II tailhousing will bolt to a Phase I transmission? I know the Phase II's have an extra VSS in there, but that should be inconsequential to a phase 1 trans/TCU.

My thinking is that since Phase 1 VTD units are a scarcity (unless you buy a complete working JDM TT Legacy unit, the only commonly available import with it), one could instead find a much more common phase 2 VTD tailhousing from a WRX, FXT, or Outback and use that. If it fits, you'd have a 45:55 F/R ratio instead of 36:64, but still better than 100% front torque with lazy rear transfer.

[Legacy777]

You may be blazing new territory there. If no one else has done it, and you decide to do it, let us know how it goes.

[James614]

I'm currently looking to see if anyone around here has a blown VTD 4EAT (Phase II) I can score for uber-cheap to try this with. My C solenoid is starting to make things bind a bit in parking lots, so I'm gonna need to break my tailhousing open regardless. I can't think of why it wouldn't work, as long as the splines for the output shafts didn't change.

[James614]

Whenever I search for info on the pre-02 JDM WRX VTD system now, this topic keeps popping up. Not helpful

Also not helpful are local yards, they have no clue what they have. And then they're only open when I have to work. I'm certain I can find a VTD tailhousing locally eventually, but I'll be hard since I'm pretty sure I'm the only person in this region who knows or cares about specific tailhousings on Suby automatics.

[James614]

http://www.catherineandken.co.uk/sti/wrx.html

WRX models and their engine/trans codes. This is the first list I've found that gives you 4EAT trans codes for overseas early WRX's. Although all imported V1-V4 WRX 4eats available from auctions aren't VTD as this list implies they would be.

[2pot]

Hi
I've got 2 auto jdm wrx's. '95 and '96, both with 4.11 gears and vtd. The tcu is code 'MW'.
Been uprating them steadily for some years.
Will try and help if I can.
Started with the Transgo shift kit
HTH
Unless you've given up?

[James614]

I'be already got a JDM 5speed swapped. In for the better part of a year I couldn't find anyone with the old VTD transmissions and gave up.

[James614]

FWIW though, from what I read about what people have done with Foresters and SVXs its all plug and play if you have the VTD TCU.