RWD biased AWD systems..

#1 12-14-2003, 09:33 PM

So i just saw a commercial on television for a new Infiniti which is just RWD when most other AWD cars are powering the front wheels.. are there any other awd sistems which do that?

lambrogini?
nissan skyline? probably the same thing as an infiniti g35 anyway.. but the i-car doesn't have turbos

porsche?

any cheap cars with the rwd/awd setup?

-adam

Andy · #2 12-15-2003, 12:44 AM

UK SVX?

GreenMarine · #3 12-15-2003, 05:38 AM

No no no.... The SVX's have the same power distrabution all over the world... It's not 90f/10r like most of us have heard... It's 60f/40r..... And yes there are some RWD biast AWD systems out there... Porsche, the Audi Quattro system, Lambrogini.... All of them favor the rear wheels over the fronts...

Andy · #4 12-15-2003, 05:43 AM

Quote:

Originally posted by GreenMarineSVX
No no no.... The SVX's have the same power distrabution all over the world... It's not 90f/10r like most of us have heard... It's 60f/40r

Does anyone have any proof of this?

solarsvx · #5 12-15-2003, 09:02 AM

audi has the same set up FWD plat form along with the subaru and such

skylines are RWD plate forms along with some other cars out there,

Shadow248 · #6 12-15-2003, 10:51 PM

I know this probably isn't what you're looking for cause it's a truck, but the Chevy Silverado SS is "RAWD"

mbtoloczko · #7 12-16-2003, 12:32 AM

Quote:

Originally posted by Andy

Does anyone have any proof of this?

The R&T SVX guide says that the 4eat with the multiplate clutch-type center diff has a 60f/40r torque split when cruising. This may or may not be the actual torque split at cruise. R&T has been wrong on many occasions. There are other sources that quote 90f/10r and 80f/20r torque split with the clutch-type center diff. For instance, here its quoted as 90f/10r:

http://www.cars101.com/subaru_svx.html

The non-USDM SVXes have a different style of center diff, and the power distribution is more rear-biased. Here is some info on the non-USDM SVX center diff:

http://www.subaru-global.com/about/parts/06.html

Andy · #8 12-16-2003, 03:11 AM

Quote:

Originally posted by mbtoloczko

The R&T SVX guide says that the 4eat with the multiplate clutch-type center diff has a 60f/40r torque split when cruising. This may or may not be the actual torque split at cruise. R&T has been wrong on many occasions. There are other sources that quote 90f/10r and 80f/20r torque split with the clutch-type center diff. For instance, here its quoted as 90f/10r:

http://www.cars101.com/subaru_svx.html

The non-USDM SVXes have a different style of center diff, and the power distribution is more rear-biased. Here is some info on the non-USDM SVX center diff:

http://www.subaru-global.com/about/parts/06.html

May thanks for that. The last link is the 1st bit of evidence that I have seen about the UK spec gear driven central diff. Any more posts on this would be appreciated as it would help to explain the different handling characteristics we have.

Andy · #9 12-16-2003, 03:57 AM

I have found a few more pieces of evidence and information, but I cannot find any proof, one way or the other.

http://www.imprezawrx.org/editorials/981027/awd.html

http://www.ravensblade-impreza.com/t...s/pdf/pdf.html

oab_au · #10 12-16-2003, 04:17 PM

Quote:

Originally posted by Andy
I have found a few more pieces of evidence and information, but I cannot find any proof, one way or the other.

http://www.imprezawrx.org/editorials/981027/awd.html

http://www.ravensblade-impreza.com/t...s/pdf/pdf.html

Good links there Andy. What are you looking for, proof of what.?

Harvey.

oab_au · #11 12-16-2003, 05:36 PM

When we quote torque splits of 90/10 front /rear. this is just the way we define the two different types of AWD units.

We could also say it is 100/0 when the FWD fuse is fitted. This clutch type AWD can deliver torque to the wheels 90/10, 80/20, 70/30, 60/40 and locked up 50/50. It depends on the amount of transfer clutch pressure that is applied. No pressure 100/0, full pressure 50/50. The trade off is the higher the clutch pressure and the torque split, the more the center diff can not accommodate a difference in wheel rotation. Binding will occur, so it will use a lower pressure under normal driving to prevent binding. In a tight corner it will be biased to front drive.

The epicyclic center diff uses a different number of teeth on the front sun and planet gears than the rear sun and planet gears. This difference is in the ratio of 36 front 64 rear. This can also vary to 40/60, 50/50.

The main effect in the way the car will handle is in the amount of torque that can be applied in cornering. Because all the rear drive has to be delivered through the same clutch, that has to allow wheel speed difference. The US clutch type can't use a lot of rear
drive in corners. The Euro diff type uses gears to transmit drive to the rear wheels, the clutch is only there to prevent wheelspin. So that the 36/64 Torque split can be applied in corners and still accommodate the difference in wheel rotation that happens.

Harvey.

shoden · #12 12-16-2003, 09:14 PM

Several Subarus currently use a rear biased AWD system... actually a couple of different systems. The Outback VDC, Legacy GT automatic, Forester XT automatic, and Baja Turbo automatic all use a system called VTD (Variable Torque Distribution) that combines a hydraulic transfer clutch with a planetary gear set to provide a 45/55 front/rear split. The other rear biased system is on the WRX STi, which provides a 35/65 front/rear split. Both of these can of course adjust to a 50/50 split.

The other Subaru systems are the familiar 4EAT with 90/10 up to 50/50 front/rear split, and the 5spd tranny with the viscous coupling providing a standard 50/50 split, variable up to 0/100 or 100/0.

Andy · #13 12-17-2003, 12:43 AM

Quote:

Originally posted by oab_au

Good links there Andy. What are you looking for, proof of what.?

Harvey.

Thanks for your info Harvey. The proof that I am looking for (purely out of interest) is as in your statement 2 posts above. I am sure you are correct, but cannot find any definitive evidence of this. Short of getting my fingernails very dirty, are there any documents, manuals etc which detail this.

(I can strip a gearbox, no problem, but then I get stuck!!)

#14 12-17-2003, 02:49 AM

BMW's AWD system is 20/80, well cya

Quote:

Originally posted by alacrity024
So i just saw a commercial on television for a new Infiniti which is just RWD when most other AWD cars are powering the front wheels.. are there any other awd sistems which do that?

lambrogini?
nissan skyline? probably the same thing as an infiniti g35 anyway.. but the i-car doesn't have turbos

porsche?

any cheap cars with the rwd/awd setup?

-adam

oab_au · #15 12-17-2003, 02:50 PM

Quote:

Originally posted by Andy

Thanks for your info Harvey. The proof that I am looking for (purely out of interest) is as in your statement 2 posts above. I am sure you are correct, but cannot find any definitive evidence of this. Short of getting my fingernails very dirty, are there any documents, manuals etc which detail this.

(I can strip a gearbox, no problem, but then I get stuck!!)

OK Andy, have a look in my locker under technical, there are scans of the Aust WSM that show the internals of the box and the write up that explans the operation. Bit of a jumble in there.

Cheers.
Harvey.