urabus1995 Posted September 27, 2004 Share Posted September 27, 2004 I know this is probably a stupid question, but to be honest I really dont know the correct answer. I had a 1992 DL 1.8 wagon,manual trans. which was Front Wheel Drive, for normal road use. It was also switchable to Four Wheel Drive for off road " wet field" conditions. When the snow came, or the mud was really thick, I could also switch it into Low Range Four wheel drive. The only drawback to Four wheel drive use was that if you got bogged down and had to try and turn the wheels to get onto a drier bit of ground, it did not behave very well. It was as if the front brakes were on, when on almost full steering lock. I put this down to some sort of "locked diff "effect. Sorry to take so long, but my problem is that I now drive a 1995 Legacy wagon, which is described as AWD , not 4WD or 4X4 , as other makes describe their vehicles. Is my Subaru AWD the same as Subaru 4WD, as on the DL, or amI missing some important point here? I get the feeling from what I have read on here, that somehow they are not the same. If anyone has a link to a technical explanation of these systems, I would be most grateful. Cheers , John. (no Snow here yet !!!!!) Quote Link to comment Share on other sites More sharing options...
ScoobySchmitty Posted September 27, 2004 Share Posted September 27, 2004 A Legacy is AWD, which means that the engine will turn one of the axel sets (front or rear) with a viscous coupling. I'm pretty sure that the rear wheels are connected to the viscous coupling and the front wheels directly to the engine. By VISCOUS coupling, I mean the rear wheels, in slipping conditions, will turn as power is applied to them, sort of like how a torque converter works. BUT, there is NO PERMANENT LINKAGE between the front and the rear wheels, IE, no transfer case. So, you can't really go rock climbing with it, but you can certainly drive it through loose road conditions (dirt/gravel roads, snow, etc.) with ease. I hope this helps out. PS, the AWD is on ALL the time, and you do not need to worry about switching between HI and LO. In fact, there's no lever for it anyway:D Quote Link to comment Share on other sites More sharing options...
rweddy Posted September 27, 2004 Share Posted September 27, 2004 http://auto.howstuffworks.com/four-wheel-drive.htm Check that link out. Bascially 4 wheel drive is a part time only system, the wheels must turn at the same rate. In AWD there is a center diff that can allows wheels to turn at different speeds. Low range is a gear reduction unit that lowers the gearing in the vehicle, you can have this on both AWD and four wheel drive. Quote Link to comment Share on other sites More sharing options...
99obw Posted September 27, 2004 Share Posted September 27, 2004 There are many, many ways of transferring power to the wheels: FWD: Front wheel drive, open or limited slip differential. Good on-road, good in the snow, bad off road. RWD: Rear wheel drive, open or limited slip differential. Ok on-road, sucks in the snow, sucks off-road. Full Time 4WD: Open center differential, open or limited slip front and rear differentials. Good on-road, good in the snow, ok off road. Example: jeep 242 selec-trac. 4WD: Locked center differential, open or limited slip front and rear differentials. Bad on-road, great in the snow as long as the road is mostly covered, great off road. Example: jeep 231 command-trac, older subes, the '86 toyota tercel I had. Real AWD: These systems basically modulate the center differential torque transfer ratio in some way, whether it be viscous coupler or computer controlled. These systems apply power to the front and rear differentials all of the time. Great on-road, great in the snow as long as it isn't too bad, ok off road. Example: subaru AWD, jeep 249 quadra-trac, audi quattro. Fake AWD: I hate the fact that other auto makers call their part time AWD systems AWD. These systems don't put power to the (other) wheels until a slip is detected (too late IMHO). These are the AWD wannabees. I am pretty sure that the toyota real-time 4wd and gm versatrak are this kind of system. To me the ultimate off-road setup is one with a locking center diff and locking or limited slip front and rear differentials. An example of a vehicle with this is the jeep rubicon. To me the ultimate on-road setup is one with limited slip rear differential and viscous coupler center diff, this setup is found on some of the MT subies. As far as a compromise between the two, have to vote for the 242 selec-trac with it's full-time 4wd mode and locked in part-time mode. Quote Link to comment Share on other sites More sharing options...
rweddy Posted September 27, 2004 Share Posted September 27, 2004 Fake AWD: I hate the fact that other auto makers call their part time AWD systems AWD. These systems don't put power to the (other) wheels until a slip is detected (too late IMHO). These are the AWD wannabees. I am pretty sure that the toyota real-time 4wd and gm versatrak are this kind of system. Honda Calls in Real-Time awd To me the ultimate off-road setup is one with a locking center diff and locking or limited slip front and rear differentials. An example of a vehicle with this is the jeep rubicon. To me the ultimate on-road setup is one with limited slip rear differential and viscous coupler center diff, this setup is found on some of the MT subies. As far as a compromise between the two, have to vote for the 242 selec-trac with it's full-time 4wd mode and locked in part-time mode.Best every is the 94-97 Toyota Land Cruiser- AWD with Center locking diff, Hi and Low range and selectable Electronic Locking Front and Rear Diffs (Solid Axles) Much easier to drive than my cj7 w/ detriots front rear. Quote Link to comment Share on other sites More sharing options...
99obw Posted September 27, 2004 Share Posted September 27, 2004 Honda Calls in Real-Time awd Doh! Thanks, I was thinking of the RAV-4, which of course is a honda, not a toyota. Sorry to insult toyotas like that. Quote Link to comment Share on other sites More sharing options...
powderhound Posted September 27, 2004 Share Posted September 27, 2004 The Rav-4 is a Toyota (built in Japan BTW) The CRV is the Honda with fake AWD. Quote Link to comment Share on other sites More sharing options...
99obw Posted September 27, 2004 Share Posted September 27, 2004 CRV, RAV-4, obviously I can't keep them straight. I'll shut up now. Quote Link to comment Share on other sites More sharing options...
Setright Posted September 27, 2004 Share Posted September 27, 2004 There is no international governing body that has stipulated what constitutes AWD or 4WD. The things written in this post are based on opinions, and not certifiable facts. How many wheels does a Subaru have? Four. If "All" of them are driven, surely it's four-wheel-drive. AWD is a marketing babble. More Opinon: I prefer to divide them into full and part-time 4WD. Both can be accomplished in different ways. The "Torsen" diff that Audi/VW used to use in the "Quattro" and "Synchro" models was full-time. The new "4Motion" system is part-time. I was a big fan of the old system, and wish Subaru would use the Torsen diff in the center. However, the Haldex clutch in the center of a 4Motion car is a sell out. I would contend that either you want 4WD or not. Would anyone want to shut off their ABS? Quote Link to comment Share on other sites More sharing options...
ScoobySchmitty Posted September 27, 2004 Share Posted September 27, 2004 The way I've always seen it, Setright, is that 4x4 or 4WD is seen on trucks and older Subies, and has a SOLID MECHANICAL link between the two axels, that being the transfer case. IE, it's a bad idea to run 4wd on a truck on a dry pavement road. AWD, on the other hand, may be marketing babble, but it helps to distinguish between two similar but seperate types of drive systems. AWD uses a center differential that uses a silicon based substance to provide the link between the two axels. I'm not familiar with the Torsen diff, so I won't go into that, but if it is a HARD, MECHANICAL link between the front and rear, I would venture to call it 4WD, not AWD. Anyway, just the way I've seen it since acquiring my own little runner Quote Link to comment Share on other sites More sharing options...
Setright Posted September 28, 2004 Share Posted September 28, 2004 Torsen is an acronym for "Torque Sensing". It distributes torque away from an axle that is starting to spin faster than the other. It's really cool. The system is 100% mechanical, using a bunch of planetary worms gears and something that looks like a normal diff, to do the distribution. It reacts faster than most electronic systems, simply because it's always connected. (In principal, the Sube silicone thing has a delay too.) Torsen is full-time, on road, four wheel drive. AWD to you ;-) And since Audi has cast it aside, it's time for Sube to take it over!! Quote Link to comment Share on other sites More sharing options...
Setright Posted September 28, 2004 Share Posted September 28, 2004 Here's a good pic: http://www.kfz-tech.de/Bilder/Kfz-Technik/Achsantrieb/Torsen-Differenzial01.gif Quote Link to comment Share on other sites More sharing options...
urabus1995 Posted September 29, 2004 Author Share Posted September 29, 2004 Thanks everyone for all of that input. Even with the small amount of " pedantic" disagreement, I do now understand the fundamental difference between AWD and 4WD. I was a great fan of the systems in my 92 DL, only got stuck when mud was so deep that the floor of the car was floating on it. Having said that---however, I have never yet felt my 95 Legacy loose any traction whether in the wet or loose gravel. It has never really been tested in snow to any real depth. I think that is where the Legacy will let me down, it will not be in its drive system, but the fact that the general clearance under the car is so low, by comparison to the DL that it will get stranded by depth rather than grip. Quote Link to comment Share on other sites More sharing options...
Setright Posted September 29, 2004 Share Posted September 29, 2004 I have had some amazing fun in 1st and 2nd gear, sliding around on compacted snow - Legacy EJ22 MT. Never experienced any tendency to spin just one axle and stand still. Always predictable handling. Winter is coming up and this will be the first time I take the Impreza into snow :-) Quote Link to comment Share on other sites More sharing options...
urabus1995 Posted September 30, 2004 Author Share Posted September 30, 2004 I have had some amazing fun in 1st and 2nd gear, sliding around on compacted snow - Legacy EJ22 MT. Never experienced any tendency to spin just one axle and stand still. Always predictable handling. Winter is coming up and this will be the first time I take the Impreza into snow :-) Good luck with the Impreza ! Should be a load of fun. I just hope you dont rip the front "skirt" off it in the snow, cos its probably even lower than my Legacy. All my friends with their JDM, STi , etc " imports" running on 18" rims find that they end up going nowhere fast, due to having too much power and not enough grip. If you ever cross the sea to Scotland, check out my stepson's collection of nice fast cars, or visit his website Powervehicles.com for a preview. I know he has sold a couple of JDM Supercars to clients in Norway and Sweden. Thanks for your wisdom John Quote Link to comment Share on other sites More sharing options...
Setright Posted September 30, 2004 Share Posted September 30, 2004 Girlfriend and I are planning a trip to Scotland. We have both been before, and would love to go back soon. She spent four months in Glasgow, at uni. By the way, I run winter tyres from around now til April. So far, I haven't gotten stuck. Imp doesn't have more than the standard front skirt, and I have not lowered the suspension, since I live in town, I would scrape my belly on all the speed bumps :-( Quote Link to comment Share on other sites More sharing options...
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