Question about SVXs AWD

Ottobon · #1 03-14-2007, 11:21 PM

I recently read a article about a australian racing team that ran the R32 skylines back before they where banned, apparently they overrode the 4wd system in favor of a manual torque adjust knob (its late i don't know how else to explain)

anyways the story talked about feeding different ohlms into the G meters and it made me wonder if something like this could be done on a SVX,

what i need to know which way subaru went about setting up the 4wd sensors, did they use wheel speed sensors? or G meters etc?

anyways i currently don't own a SVX but have thought about buying one a few times (had atleast 1 great test drive in a clean 95 LSi) and if i could devise a way of manually adjusting the amount of torque front to rear then i may be all over teh car again, i seriesly would like to own one of these cars someday. anyways if this idea goes kaput then ill probably just keep loving my 1st gen mr2s and alfa romeos

on a bit of a off-topic question: i know the SVX is a wonderful grand tourer, but can it still be aggressive enouph that you sometime feel the need to act like a animal?

ensteele · #2 03-15-2007, 12:35 AM

Quote:

Originally Posted by Ottobon

i know the SVX is a wonderful grand tourer, but can it still be aggressive enough that you sometimes feel the need to act like a animal?

Oh yes, it can happen now and again.

nextse7en · #3 03-15-2007, 01:16 AM

This here topic is 'a gonna get moved.

As far as the question, the way in which our transmissions (USDM models I'm talking about here) split torque will ensure that no more than 50% of power is ever transfered to the back wheels. (front wheels are turned mechanically, rear are driven by viscous coupling (I believe) On paper there is no reason why you cannot override the signal and ensure a 50/50 split at all times. You would need to get a pinout for the TCU, and find which wire to piggyback, and what voltage to send.

Excellent question btw, I'll be interested to hear more information from my fellow members. (and I'm sure I'll be corrected on at least one point.) my only concern would be premature wear.

LAN (aka longassname) would be a good guy to ask about this.

-Patrick

svxfiles · #4 03-15-2007, 01:29 AM

Quote:

Originally Posted by nextse7en

This here topic is 'a gonna get moved.

As far as the question, the way in which our transmissions (USDM models I'm talking about here) split torque will ensure that no more than 50% of power is ever transfered to the back wheels. (front wheels are turned mechanically, rear are driven by a multi plate transfer clutch(I believe) On paper there is no reason why you cannot override the signal and ensure a 50/50 split at all times.
-Patrick

However you would have a car stuch in 4 wheel drive all the time.

This is fine if you do not turn.
But if you turn having the front wheels turning at the exact speed as the rears it would force one end to LOOSE traction!
The front and rear wheels travel different distances in a turn.
At light throttle the SVX averages about 75%FWD and 25% RWD.
Floor it, or get into slippery stuff and it's 50/50.

nextse7en · #5 03-15-2007, 01:33 AM

Thanks for the correction, svxfiles. I knew there was something off there.

svxfiles · #6 03-15-2007, 01:39 AM

No problem.

It's 3:39 in the morning,,,,,Whats a life?

Mr. Pockets · #7 03-15-2007, 08:35 AM

Quote:

Originally Posted by nextse7en

This here topic is 'a gonna get moved.

As far as the question, the way in which our transmissions (USDM models I'm talking about here) split torque will ensure that no more than 50% of power is ever transfered to the back wheels. (front wheels are turned mechanically, rear are driven by viscous coupling (I believe)

Sorry, no. You're close, though.

The front wheels are geared, but torque is transferred through an electronically operated clutch, not a viscous coupling. When more pressure is applied to the clutch, more torque is sent to the rear.

Here's a simple explanation. The car determines how much torque is sent to the rear by comparing the speed sensors in the transmission. One speed sensor watches the front wheels and the other watches the back wheels. WHen the fronts slip, it applies more pressure to send torque to the rear. When the rears slip, it backs off. The change happens before you notice it. Or, rather, it should. If the transfer clutch is worn the fronts can slip for a bit before it happens.

Subaru 5MT transmissions do use viscous couplings, which require no electronics. I don't know about some of the newer, more fancy manuals like the STi, though. Since you can adjust the torque split on that one, I suspect it has an actual center diff.

And, yes, I'm moving this thread to Tech Q&A. Please post in the appropriate forum. If you want to discuss modifying the transmission, well, we have another forum for that.