ciper wrote:b3lha Can you provide me with some sort of document to prove the SVX in other regions had the VTD differential? I have been arguing this for years and the idiots on Nasioc can't accept that the impreza was NOT the first car with the better center differential.
I originally found this out because someone has a drag racing forester and was able to easily swap the two tail shafts with no modification to the transmission itself. Yes they are phase 2 4eat
This thread on the SVX network contains a link to, and translation of, a japanese document
http://www.subaru-svx.net/forum/showthr ... post485067
I have three JDM SVX in my driveway with VTD. Two of them manufactuered in 1991.
ciper wrote:
I assume you live outside America? Do they have junk yards where near by? Would you be able to grab a tailshaft from a phase 1 VTD 4eat? I'd like to try an mpt to vtd conversion.
I am in England. Older Subarus are rare here, especially automatics. I think the SVX was probably the first VTD and only 224 were ever sold. I can't even find parts for my own cars.
ciper wrote:
On a separate note i believe you are incorrect about the VTD TCU not being able to function with an MPT differential. I know for a fact that the phase 2 VTD and MPT differentials are interchangeable along with there TCU. The lockup may not be at the best points but they do function.
I'm not sure I understand what you mean. If you use the correct TCU for the transmission, then it should work fine, except for wiring differences.
For USDM units, the wiring is all the same. But the European and Aussie box has a different type of speed sensor to the JDM and USA box. The wiring is different and the two types are not easily interchangable. That's what I was referring to above because the code "FF" that the OP originally mentioned is for a European TCU.
As for using a VTD box with a MPT TCU, or vice-versa. People have done it, and it's drivable and the AWD doesn't work properly. The amount of drivability varies because some VTD boxes use a N/C C solenoid and some N/O.
If you have a look at the website in my sig, you'll see that I've reverse-engineered much of the TCU programming, shift maps, torque converter maps, etc. I haven't figured out the AWD lockup code yet, but there are certainly important differences between MPT and VTD.
ciper wrote:
From what I know the speedo cluster outputs a signal just like the electronic sender mounted externally on MPT AWD and 2wd 4eat which outputs a signal just like the five speed manual and six speed sti trans. On cars with an electronic speedometer the TCU does a conversion based on final drive to give the right speed display.
I don't know how the Legacy speedo works. Is it cable driven? On a JDM or USDM SVX, speed sensor #2 (in the front diff) supplies a square ware to the ECU, TCU, Speedo and several other units. On a Euro or Aussie SVX, speed sensor #2 (inside the gearbox), supplies a sine wave to TCU. This is not compatible with the ECU or Speedo. The TCU modifies the sine wave into a square wave and feeds it to the ECU and Speedo. The speedo cluster doesn't output anything.
ciper wrote:
I would be willing to bet money that the VTD 4EAT on the SVX and the MPT 4EAT are the same transmissions forward of the tail section.
Yes, they are very similar. I know someone who has fitted a VTD tail onto his MPT box and I'm currently programming a custom TCU for him.
) the way it is.
I double/triple checked everything. I did swap TCUs just to be sure , especially since that is an easy thing to check. One thing to note is one of the TCUs had "FF" on it in big letters and the other had "HU" on it. Not that it made any difference. 
I've driven another auto with the "FWD" fuse installed so this shouldn't cuase any problem like this, and I don't see the missing half of driveshaft cuasing shifting problems either. HELP! 