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  #1  
Old 12-24-2019, 04:06 AM
BelegUS BelegUS is offline
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JDM Legacy BG VTD tranny in EU VTD SVX - binding

Hello,

I'm facing rather expensive (so far) problem with my 1995 (1996?) Subaru SVX, originally equipped with VTD transmission. When it failed I swapped it for TZ102YBABA-CF transmission from JDM Legacy GTB (4.44 final drive). I kept EU SVX TCU originally mounted in the car. Car runs and doesn't throw any errors, but there is a binding when doing a slow turns (eg. three-point-turn). It was happening like that for two years since the swap with everybody saying "that's how it works with LSD rear diff" but now (after one diff gave up) I know it should not. The same thing is happening with new diff (4.44 of course, with VLSD). Slight whine can be heard from the diff during "lazy" acceleration. Old diff was whining like crazy on deceleration, and I want to avoid frying another diff or tranny.

Transmission looks to be more or less identical to SVX one, with one visible difference - (front?) speed sensor. EU SVX has two-wire one inside a tranny, and Legacy GTB had a two-wire one but on front bellhousing. What I did was wiring these two wires to original SVX loom in place of internal sensor two wires. No idea if it can work like that, though - maybe number of rotations internal sensor in SVX measured is different than rotations Legacy-type external sensor counts, and that is causing VTD/Duty C to operate improperly, resulting in binding?

I would like to check what each sensor measures, but I cannot connect to TCU through SSM - at all. With RS232 adapter I connect to ECU just fine (JECScan, sending commands manually) but all TCU returns to me is just some gibberish/trash data.

I also modified value in TCU code setting it for 4.44, just as b3lha advised in this post:
http://www.subaru-svx.net/forum/show...38&postcount=9
Car seemed to shift better after that change, but binding was still there. Also it hadn't fixed my speedometer being off by about 20-30%

Another option is that Duty C Solenoid / valve "simply" failed in this tranny, but before I make sure sensors measure correct speeds I don't want to do it. Finding a matching (JDM) part and someone who will replace it for me in Poland won't be easy.

Anyone can give some piece of advise, or helping hand?
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  #2  
Old 12-24-2019, 05:21 AM
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SoCoNoHa SoCoNoHa is offline
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Join Date: Nov 2016
Location: Southern NH
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Re: JDM Legacy BG VTD tranny in EU VTD SVX - binding

What year Legacy is the transmission from? It might have slightly different electronics/programming. Would it be possible to obtain the TCU from the/a same car the transmission is from?
__________________
1992 SVX LS-L - Classic Cruiser, needs love
^Pearl White/Black, 5MT

1995 Impreza L Coupe - Racecar
^Acadia Green, EZ30, Heavily Modified
1997 Legacy GT Sedan - Project
^Rio Red, 5MT, TD04, FMIC
2002 Impreza WRX Sedan - Another Project
^Black, 4EAT, Heavily Modified
2003 Outback H6 Wagon - Unsure/Donor?
^Maroon, 4EAT
2004 Outback H6 L.L. Bean - Daily/Parts Hauler
^White, 4EAT

1993 Nissan D21 Hardbody - Another Project
^Red, 5MT, 4X4
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  #3  
Old 12-24-2019, 05:28 AM
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SoCoNoHa SoCoNoHa is offline
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Join Date: Nov 2016
Location: Southern NH
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Re: JDM Legacy BG VTD tranny in EU VTD SVX - binding

What year Legacy is the transmission from? It might have slightly different electronics/programming. Would it be possible to obtain the TCU from the/a same car the transmission is from?
__________________
1992 SVX LS-L - Classic Cruiser, needs love
^Pearl White/Black, 5MT

1995 Impreza L Coupe - Racecar
^Acadia Green, EZ30, Heavily Modified
1997 Legacy GT Sedan - Project
^Rio Red, 5MT, TD04, FMIC
2002 Impreza WRX Sedan - Another Project
^Black, 4EAT, Heavily Modified
2003 Outback H6 Wagon - Unsure/Donor?
^Maroon, 4EAT
2004 Outback H6 L.L. Bean - Daily/Parts Hauler
^White, 4EAT

1993 Nissan D21 Hardbody - Another Project
^Red, 5MT, 4X4
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  #4  
Old 12-24-2019, 05:46 AM
BelegUS BelegUS is offline
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Join Date: Feb 2015
Location: Katowice, Poland
Posts: 8
Re: JDM Legacy BG VTD tranny in EU VTD SVX - binding

Quote:
Originally Posted by SoCoNoHa View Post
What year Legacy is the transmission from? It might have slightly different electronics/programming. Would it be possible to obtain the TCU from the/a same car the transmission is from?
According to:
https://legacypic.uk/transmission/se...ode=tz102ybaba
It's 93-96 transmission. I think it came from around 95-96 car, but have no way to make sure.

Regarding the TCU - I have one which I believe is from the donor car. The same binding on tight turning problem is happening when using it, also speedometer doesn't work at all with it (which is caused by, I believe, Legacy having speed signal conversion in speedometer cluster). Apart from that it seems to shift smooth and fine, similarly to the SVX one I "modded" with FD variable change.
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  #5  
Old 12-25-2019, 01:52 AM
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SoCoNoHa SoCoNoHa is offline
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Join Date: Nov 2016
Location: Southern NH
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Re: JDM Legacy BG VTD tranny in EU VTD SVX - binding

Well given the year of the trans I would think it's ok to use. And if both computers result in that binding feeling, it's probably safe to assume the duty solenoid C (awd) is to blame. If I recall correctly, I don't think replacing a solenoid is too difficult, although you'll have to drain the transmission fluid and get yourself underneath the car one way or another.
__________________
1992 SVX LS-L - Classic Cruiser, needs love
^Pearl White/Black, 5MT

1995 Impreza L Coupe - Racecar
^Acadia Green, EZ30, Heavily Modified
1997 Legacy GT Sedan - Project
^Rio Red, 5MT, TD04, FMIC
2002 Impreza WRX Sedan - Another Project
^Black, 4EAT, Heavily Modified
2003 Outback H6 Wagon - Unsure/Donor?
^Maroon, 4EAT
2004 Outback H6 L.L. Bean - Daily/Parts Hauler
^White, 4EAT

1993 Nissan D21 Hardbody - Another Project
^Red, 5MT, 4X4
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  #6  
Old 12-25-2019, 06:33 AM
BelegUS BelegUS is offline
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Join Date: Feb 2015
Location: Katowice, Poland
Posts: 8
Re: JDM Legacy BG VTD tranny in EU VTD SVX - binding

Quote:
Originally Posted by SoCoNoHa View Post
Well given the year of the trans I would think it's ok to use. And if both computers result in that binding feeling, it's probably safe to assume the duty solenoid C (awd) is to blame. If I recall correctly, I don't think replacing a solenoid is too difficult, although you'll have to drain the transmission fluid and get yourself underneath the car one way or another.
Thanks. Still the one thing that bothers me is that speed sensor - if internal two-wire EU SVX VSS and external two-wire JDM Legacy VSS produce the same type of signal, and if they measure the same rotations per speed. If not then I think it may be the problem as well?

On the other hand, theoretically I used the right Legacy TCU and VSS and it was still binding, but maybe wiring on SVX was wrong... but it makes no sense.
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