WRX 5 speed tranny computer controlled?

mbtoloczko · #1 03-22-2003, 10:35 AM

Is any aspect of the WRX 5 speed computer controlled? In particular, I'm wondering is the center diff is computer controlled like on the SVX, and if so, will the SVX TCU interface with it and control it? Anyone here know the answer?

Thanks,

Subafreak · #2 03-22-2003, 03:06 PM

Only a few special WRX STIs had driver controled centerdiffs. I'm not sure what is required to make the system work but it has nothing to do with the TCU. Two very different things.

mbtoloczko · #3 03-22-2003, 03:18 PM

Quote:

Originally posted by Subafreak
Only a few special WRX STIs had driver controled centerdiffs. I'm not sure what is required to make the system work but it has nothing to do with the TCU. Two very different things.

I was asking if the center diff is computer controlled. Not driver controlled. Isn't the 4eat diff computer controlled?

Subafreak · #4 03-22-2003, 04:25 PM

Yes the 4eat diff is computer controled, and no the WRX 5speed is not computer controled in any way.

Phast SVX · #5 03-22-2003, 05:17 PM

Quote:

Originally posted by Subafreak
Yes the 4eat diff is computer controled, and no the WRX 5speed is not computer controled in any way.

If it is then im in trouble

#6 03-24-2003, 08:28 PM

Subaru 5 speed trannies are mechanically controlled. That goes for the WRX as well.....

Dave

svx_commuter · #7 03-25-2003, 10:38 AM

The SVX USA auto trans does not have a center differential for front to rear axles. It has a clutch pack called a transfer clutch that slips to allow for the difference in the front and rear axle speeds. When the transfer clutch is fully engaged there is a 50/50 torque split front to rear.

The WRX automatic and WRX 5 spd does not use this method. It has something else that allows more torque to go to the rear wheels. Maybe similar to the SVX auto sold to the rest of the world and not the USA.

oab_au · #8 03-25-2003, 03:39 PM

The manuals use a Viscous diff, as John says.

There is a different set up in the STI 2.2 what uses a variable center diff what is controlled by a thumb wheel on the console. I would think that it would be the same as the European 4EAT diff, that would need a TCU to do the job.

Harvey.

Ps. do the later US Legacy, Impressa, 4EAT use the transfer clutch or a center diff?

#9 04-01-2003, 12:11 AM

The SVX was the first Subaru to use a VTD transmission, that is, it varies torque distribution via electronic control of the center "diff" clutch packs. The TCU controls this action automatically depending on gear and load, i.e. the lockup into 50:50 in manual mode in low gear.

There has been some headway into designing a control circuit for this feature of the VTD transmissions currently found in the latest crop of Subaru Outback automatics and also in the WRX automatic. The R&D is being done by several members of NASIOC.com and I will have to do some searching to find out where they are in that process, it has been some months since I saw the threads. I remember they stated that it was their belief that it would work on all Subaru VTD transmissions including the SVX since they all share the same basic electronic design.

To put it more simply, this would give us a thumbwheel to dial torque split from 50f/50f to 10f/90r or any point in between at will, while driving. That would be a neat trick.