Impulse Posted December 24, 2007 Share Posted December 24, 2007 yea, realistically probably not, but in theory yea Link to comment Share on other sites More sharing options...
Vimy101 Posted December 24, 2007 Share Posted December 24, 2007 Do any of the Subaru models have an AWD system equivalent to the Haldex XWD (4th generation Haldex)? This system has a computer controlled clutch type rear differential and center differential. They are claiming 3 tires can be on a low friction surface (2 fronts and one rear), and 80% of available torque can still be transferred to the 4th tire. The system will be available first in early 2008, on the Saab 9-3. http://www.haldex-xwd.com/ Sounds like a cool system but the simplicity of VLS in the Subaru set up has a certain mechanical elegance, IMHO. Less moving parts FTW. During a run to the donut shop a week or so ago, I tried to put the Subie drive system to a test. There are some decently steep hills in my neighborhood courtesy of the Fox River Valley. It was snowing fairly heavily (fairly wet snow) and the plowed streets in area had snow banks (fairly dense) over foglight height and about an inch of fresh recovering the road surface. I headed up one of the steeper hills and, from a slow first gear start with the clutch fully out, accelerated firmly but trying not to break traction. I was looking to see what would happen with the ride side wheels in deep snow and the left running on the cleared but still snow covered plowed area. Nothing happend. No wheel (tires are Contiextreme Conact AS) slip that I could detect. The car accelerated smartly up the slope. I even slowed right down for a stop sign (I didn't come to a full stop ) and re-accelerated again from an "engaging the clutch" start. Nothing happened again. That should be a good test of the Subie LGT AWD system. The open front diff never lost traction and the left rear wheel that should have the most power going to it didn't break either. I was impressed. Link to comment Share on other sites More sharing options...
outahere Posted January 1, 2008 Share Posted January 1, 2008 Maybe this video has already been posted, but I haven't seen it here . It shows testing of AWD systems on a roller ramp, to simulate driving up an icy hill. The vehicles tested are: '08 Forester '08 Legacy '07 Passat 4-Motion '07 Toyota Highlander '07 Honda Cr-V [ame=http://youtube.com/watch?v=t09ExAUgtyE]YouTube - All ALL WHEEL DRIVES are NOT created equal. (Subaru Vs Other[/ame] Link to comment Share on other sites More sharing options...
nm Posted January 1, 2008 Share Posted January 1, 2008 Maybe this video has already been posted, but I haven't seen it here . It shows testing of AWD systems on a roller ramp, to simulate driving up an icy hill. The vehicles tested are: '08 Forester '08 Legacy '07 Passat 4-Motion '07 Toyota Highlander '07 Honda Cr-V The "fail" of this is no torsen (quattro) system (The 07 Passat is Haldex). And unbiased? The lack of quattro itself is troublesome and there is the simple fact that any test can be set up to favor any AWD. There is a BMW run test video out there that "proves" X-drive is better than quattro. (BTW: X-drive is just pointless, I'd take a RWD BMW even in the snowiest region over x-drive). How? By turning off the EDL and refusing to use the brakes in its place (they put the rear wheels on rollers. EDL overcomes it by applying some brake which makes all power go forward. Manual itself says to lightly brake in cars without EDL,m which does the exact same thing) IMHO, I like Audi's torsen diff better. A bit less lossy than the viscious diff. I also suspect that its negligibly stronger (but only noticable at milage no one ever gets to) However, on all other counts they're pretty much equal. The fact that the LGT gets a rear diff seals the deal for me, EDL is just BS. Link to comment Share on other sites More sharing options...
Richard B. Posted January 1, 2008 Share Posted January 1, 2008 The "fail" of this is no torsen (quattro) system (The 07 Passat is Haldex). And unbiased? The lack of quattro itself is troublesome and there is the simple fact that any test can be set up to favor any AWD. There is a BMW run test video out there that "proves" X-drive is better than quattro. (BTW: X-drive is just pointless, I'd take a RWD BMW even in the snowiest region over x-drive). How? By turning off the EDL and refusing to use the brakes in its place (they put the rear wheels on rollers. EDL overcomes it by applying some brake which makes all power go forward. Manual itself says to lightly brake in cars without EDL,m which does the exact same thing) IMHO, I like Audi's torsen diff better. A bit less lossy than the viscious diff. I also suspect that its negligibly stronger (but only noticable at milage no one ever gets to) However, on all other counts they're pretty much equal. The fact that the LGT gets a rear diff seals the deal for me, EDL is just BS. did they dumb it down since 2000? http://www.thecarconnection.com/Vehicle_Reviews/Sedans_and_Coupes/Volkswagen_Passat_4Motion.S180.A2163.html i always thought it was based on the regular quattro as well unless specified haldex. afaik only the small cars got the haldex. tt and the such. it seems to run the same until 50 mph which they didn't come close to in this test. i understand they aren't the exact same but pretty fricken close and i'm just saying that i wouldn't call it a haldex either. transverse engine mounting vs longitudinal. i do agree not a 100% accurate comparison but then again, the other manufacturers shouldn't be pretending and getting weak stuff in the market. i think they got sick of audi and subaru taking all the glory for awd. i think great marketing for a crappy product does come into play quite a bit. but yes, for 100% fairness, a a4 quattro should have been used. Link to comment Share on other sites More sharing options...
nm Posted January 1, 2008 Share Posted January 1, 2008 b5-b5.5 (1998-2004.5/05--wagon) were Torsen It has a longitudinal motor. On a 4motion passat basicxally every drivetrain and suspension part (except shocks and springs, though teh passat can mount these parts too) shared a part number with an A4 or A6 (some of the rear stuff was A6 due to some extra weight). The center diff only had the audi rings on it and no VW symbol. B6 2005/05.5 is haldex. it has a transverse motor B6 passat is now based on an extended golf platform, not the A4s like the B5/5.5 (The B5s cut into audi sales massively, its also why you don't see as many VW/Audi dealers, AoA hates them). It has haldex like it platform mates. One of many reasons I didn't buy another passat. Currently no production VW car (I don't know anything about the t-reg so I'll exclude that) has torsen. B5 passat was the first and last (the Phaeton also had torsen). Link to comment Share on other sites More sharing options...
outahere Posted January 1, 2008 Share Posted January 1, 2008 Apparently, a viscous coupling can be designed to give more than a 20X torque amplification! Here is an abstract from the Jan 2003 Journal of Tribology: A Comprehensive Study of Self-Induced Torque Amplification in Rotary Viscous Couplings Journal of Tribology -- January 2003 -- Volume 125, Issue 1, pp. 110-120 Sankar K. Mohan Advanced Engineering, New Venture Gear Inc., 6600 NVG Drive, East Syracuse, NY 13057 Bandaru V. Ramarao State University of New York, Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210 (Received February 21, 2002; revised June 13, 2002) Rotary viscous couplings with interleaved, perforated plates and viscous fluids are used in automotive systems to transmit torque. During operation, viscous dissipation raises fluid temperature, lowers fluid viscosity and causes the torque transmitted to drop monotonically to unusable levels. Couplings designed with certain plate geometry exhibit a reversal of the torque trend with temperature, and transmit increasingly high torque even under continuous operation. Such couplings achieve torque amplification factors in excess of twenty, compared to earlier couplings. This torque amplification phenomenon has been utilized by industry without fully understanding the mechanisms involved. A comprehensive theory is proposed to explain the complex sequence of events that results in this "anomalous," but useful phenomenon. Mathematical models are developed for each interdependent process. A visual simulation tool is used to model the intricate dynamics inside the coupling. Results from the simulation model are compared with experimental findings. The various thermodynamic, hydrodynamic, structural and mechanical processes are delineated and tested with a combination of theoretical analysis, computational simulation and experimental observations. The proposed theory identifies, defines and explains the conditions necessary for initiating and sustaining the self-induced torque amplification. The hypotheses are validated by the reasonable agreement of the model with the test results. Link to comment Share on other sites More sharing options...
Richard B. Posted January 1, 2008 Share Posted January 1, 2008 b5-b5.5 (1998-2004.5/05--wagon) were Torsen It has a longitudinal motor. On a 4motion passat basicxally every drivetrain and suspension part (except shocks and springs, though teh passat can mount these parts too) shared a part number with an A4 or A6 (some of the rear stuff was A6 due to some extra weight). The center diff only had the audi rings on it and no VW symbol. B6 2005/05.5 is haldex. it has a transverse motor B6 passat is now based on an extended golf platform, not the A4s like the B5/5.5 (The B5s cut into audi sales massively, its also why you don't see as many VW/Audi dealers, AoA hates them). It has haldex like it platform mates. One of many reasons I didn't buy another passat. Currently no production VW car (I don't know anything about the t-reg so I'll exclude that) has torsen. B5 passat was the first and last (the Phaeton also had torsen). huh...guess they did "dumb it down". kinda quit looking at them after the B5 platform. wanted the s4 sooo bad back then. the gt for 10k less and 6.5 years later/newer will suffice. Link to comment Share on other sites More sharing options...
outahere Posted January 2, 2008 Share Posted January 2, 2008 Maybe this video has already been posted, but I haven't seen it here . It shows testing of AWD systems on a roller ramp, to simulate driving up an icy hill. The vehicles tested are: '08 Forester '08 Legacy '07 Passat 4-Motion '07 Toyota Highlander '07 Honda Cr-V One thing I found interesting in this video was how the '08 Legacy was able to go up the ramp with 3 tires on rollers, and only one tire (front or rear) on solid ramp. They didn't say in the video, but I assume this Legacy was an auto with VTD and VDC. Link to comment Share on other sites More sharing options...
SLegacy99 Posted January 2, 2008 Share Posted January 2, 2008 Ive done those tests in real life conditions...I love my symmetrical. Link to comment Share on other sites More sharing options...
outahere Posted January 2, 2008 Share Posted January 2, 2008 .......and I still want to see them run a 5MT with viscous diffs up the ramp. I'd like to see that too. I wonder if a 5MT Legacy with center and rear viscous couplings, and VDC (which I believe is optional on manual tranny '08 Legacies), could do the one wheel traction track, especially on the front with the open diff. The center VC can be locked up (hump mode), but I don't believe the rear VC can lock up. But maybe the VDC can compensate for that, and the open front diff? I wish SOA would put out a video showing the capabilities of their various AWD systems. Link to comment Share on other sites More sharing options...
AWD_Rules3830 Posted January 2, 2008 Share Posted January 2, 2008 well, symmetrical is a very good yet very simple AWD system. It has worked for subaru for a long time now and has never really let me down. I love my car ... basically. Link to comment Share on other sites More sharing options...
TSiWRX Posted January 2, 2008 Share Posted January 2, 2008 Oops, wrong post! <-- I love Winky, my "periwinkle" (ABP) LGT! - Allen / Usual Suspect "DumboRAT" / One of the Three Stooges '16 Outback, '16 WRX, 7th Subaru Family Link to comment Share on other sites More sharing options...
b4wantab Posted January 2, 2008 Share Posted January 2, 2008 I like to think of the Subbie manual trans based system as proactive while the auto trans system is reactive. That said, you will see more and more computer based awd systems. Programming is relatively cheap. You can build one system and make it behave like many different systems with programming. I see SOA dropping all manual systems except for Sti and Spec B. It may be 5 years or so off but I just have a bad feeling about it. All viscous diff are rated with a max torque transfer. Torque, not rotation, so they are defeatable in extreme situations. Never had any problems with mine, still "feels" great. Peace, Greg Link to comment Share on other sites More sharing options...
L7GT Posted January 2, 2008 Share Posted January 2, 2008 Ive done those tests in real life conditions...I love my symmetrical. err, dont you have open diff's all the way around?? I like this test better [ame=http://www.youtube.com/watch?v=Q7dVFY5CxT0&feature=related]YouTube - Subaru AWD vs. Everyone Else[/ame] Link to comment Share on other sites More sharing options...
NSFW Posted January 3, 2008 Share Posted January 3, 2008 well, symmetrical is a very good yet very simple AWD system. It has worked for subaru for a long time now and has never really let me down. I'd wager that Subaru has used a few different AWD systems over the years and called all of them "Symmetrical AWD." It's just a brand, it doesn't really denote anything in particular. Link to comment Share on other sites More sharing options...
Vimy101 Posted January 3, 2008 Share Posted January 3, 2008 I'd wager that Subaru has used a few different AWD systems over the years and called all of them "Symmetrical AWD." It's just a brand, it doesn't really denote anything in particular. Here's a great link that will answer many questions about Subaru symetrical AWD: http://www.subaru-global.com/about/awd/top/index.html Link to comment Share on other sites More sharing options...
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