I realize that a Subaru newsgroup may not be the best place to get unbiased opinions, but.. :)
I have sometimes read that not all 4 wheel drive systems are created equally. I've seen them characterized as "just too late" as compared to the Subaru system. I am not technically knowledgeable, so I wonder if some of the more informed members of the group might help with a question about this. Is this a valid issue? What are the differences in 4WD systems?
Suppose my experiences with my Subaru have left me unhappy and wanting to try a different brand of automobile. Who else has a 4WD system that is comparable to that of the Subaru?
I've been buying Jeeps since '86 and Subarus since '96. The '86 Jeep was a dud and lasted 5 years. The '91 lasted 16 years. The '96 Subaru was a dud. The '03 Subaru is good. And the '07, well, the jury is still out as it has less than 3K miles on it.
The Jeeps are much better in punching through high snow. Otherwise they meet our needs just fine. We started with the Subarus as my late 80's mother-in-law could not get into the Jeep.
So, it depends on your needs.
BTW, my '71 XKE got me home in the '78 blizzard in NE when most got stuck; I drove 17 miles to get home from work. I think it was that the car was small and heavy so I got to the pavement through the snow. And the positraction rear drive was fabulous.
one time driving to a hilly are in the city in an 8" snow, in a RWD, I decided to take a street that was a more gradual hill than the usual, which was mighty steep, and got stopped half way up. A bus was spinning its wheels at the top of the hill. Headlights came up behind me, and kept getting closer, and next thing their bumper was on mine, pushing me up over the hill. It was a city cop in a Jeep, I believe an old Cherokee. When I got near where I was going, to see a GF who didn't want to drive in the snow. I couldn't get up the hill there. I Turned Around and Backed up the hill, like there wasn't any snow. Guess I made it a sorta FrWD.
Audi is the best of the best with their quattro system: I really miss my 98 A4 (stolen 3 weeks ago) in this icy winter weather. The 99 Legacy OBW is pretty good, but the Audi was far superior. And with 4 dedicated snow tires, it was perfect in the winter.
No they are not. One of the most important differences is whether the system is a 4WD (ie mostly FWD or RWD) or partial AWD or full-time AWD.
Audi Quattro, Mitsubishi AWD (Talon/Eclipse/Lancer EVO series) are all fulltime AWD with a center differential action, as AFAIK the various types of Subaru AWD. All these are (AFAIK) 50/50 torque split with the exception of some older Mitsu's which are 65/35 F/R.
The center diff is generally lockable in some fashion. Mitsu and some Subaru use a viscous coupler. Other Subaru's use a wet clutch system with electronic control. EVO's and WRX use (AFAIK) a Torsen torque split system. The advantage here is that when one end starts to slip, the centre locks up gradually.
Older Subaru and Mitsu used a simple Front/Rear lock system ie 4WD not AWD. Some have a viscous front diff too.
EVO and WRX have locking rear diffs, the base models don't usually unless optioned.
Then there's the Honda CRV system that's about 70/30 split, with a hydraulic clutch system in the rear diff that locks up gradually. ie the CRV is really FWD with occasional AWD.
The Chrysler/GM minivan systems use a system that runs off one side of the front diff, and it only works because the ABS system also handles the traction control. Torque split is about 80/20 at best, and they really are FWD system with pretentions of being AWD according ot the marketting departments.
There's the BMW system and Jaguar systems about which I know nothing at present. Anyone?
Thanks for all the responses. I wonder about Volvo as well... There was some video I saw that showed a Volvo going nowhere while a Subaru zipped by - although there was plenty of discussion about whether that was a fair comparison.
Yes, I wonder if the AWD listed as available for minivans is actually effective. As much as I have misgivings about Subaru (given my experiences of unacceptable reliability), the AWD has been an obvious benefit IMHO. A recent snowstorm confirmed that much...
If you meant 4WD for fast cars (like the Impreza STI) the Mitsubishi Evo has an even better system. But I think you meant slower cars.
Attention: only the longitudinal engined Audis have a center differential. The transverse engined* ones (A3, TT) have an Haldex system (based in a clutch) even when called "Quattro" which have issues** with the traction control.
[* BTW, this is an Audi/VW choice, not a technical need. Mitsubishi with the Evo, Lancia with the old Delta Integrale, etc. didn't have any problem fitting a center diff in the transverse gearbox.]
[** The clutch can only send power to the rear axle if it detects slipping of the front wheels. But if it detects slipping the traction control will brake the front wheels or slow the engine to stop the slipping. There have been cars (IIRC a Renault Scenic some years ago) in which the system simply didn't work (I suppose it was a victory of marketing over engineering). ]
4WD systems can have (in increasing order of sophistication):
- a mechanical rigid connection between the front and rear axles. This is the classical system (partial time 4wd). Can only be engaged in slipping conditions. I think most pickups still use it.
- some kind of clutch (electronic controlled or viscous coupling) between the front and rear axles. As I said above it has issues with the traction control system and it also means some waste of energy in normal conditions since the two axles need to rotate at different speeds in corners. I think many manufacturers are using it now (Volvo, BMW ?) and I have read here that some of the Subarus also have it.
- a center differential. This is the proper solution, because it can send torque to all wheels _before_ they start slipping but then it also needs some kind of locking (LSD, Torsen, manual locking, traction control) for difficult conditions.
Don't have experience with other AWD systems, but have owned a Pathfinder, Cherokee and Samurai, all with 4WD, low range and manual transmissions, and they were all very competent in snow, especially deep snow with their high ground clearance. However, the reason I'm posting is to say that my all time favorite "snow-mobile" was a 1965 Corvair. With 65% of its weight over the rear wheels, a limited slip differential and quality snow tires, it was absolutely unstoppable, despite the fact that I had lowered it about an inch for autocrossing. In deep snow, you just rammed through it until you carved a path. Used to go looking for the steepest hills I could find, and there are quite a few here in the Hudson valley, and it NEVER found one it couldn't handle. Only problem I ever had was an ice rut that put a hole in my gas tank. What makes the Subaru a so attractive to me is performance on any slick surface, especially when equipped with tires that perform well in rain (not the original equipment Bridgestones). With power distributed back to front and side to side, it's never at a loss for traction and immune to torque steer. Even on ice, where the conventional wisdom is that AWD provides no advantage, it gives you four driven wheels instead of two to catch a piece of dry pavement.
That's the difficulty with this terminology - AWD, 4WD, etc. They are used interchangeably and even to describe different systems. As noted above, even Audi's quattro system ( and VW's 4Motion) are 2 different systems, depending on which car you buy! As also noted, as far as I know, only the Audi longitudinal-engined quattro system, the Subaru AWD and the Mitsubishi EVO system are the only passenger-car full-time all-wheel drive systems. By this I mean that all 4 wheels are driven all the time. Systems like Mercedes-Benz 4Matic and BMW's X-Drive are
2-wheel drive with the other 2 wheels getting power when slippage is detected. Most systems advertised as 'AWD' are this - 2WD until AWD is needed.
The difference between AWD and 4WD is that the former is generally handled automatically while the latter is manually switchable. That's how I usually think of it and that is how the auto writers usually refer to the function.
Yes, as far as I am concerned, slower cars... probably a wagon (I've owned Loyale wagon and Legacy wagon). Someone at work has a tidy looking Audi wagon.
Yes, I agree regarding the terminology. So, would you say that the full-time all wheel drive systems are superior? I am assuming "yes". Are other
2wheel/4wheel drive systems any good at all? The impression I have is that they do little - but I don't really know. Would they be worth the added complexity/weight etc.?
To add to thread, I'll add my son's new Mercedes with AWD. He said it preformed well in recent snow. It's a beautiful car but cost as much as my 2 Foresters combined. His only complaint is that he is only getting
Furthermore, unless you have a limited slip d. like "vjp1" maybe RWD is best considered One Wheel Drive. Many times I've seen a car stuck in the snow spinning one wheel freely, with the other side immobile :-( By the way, will Front Wheel Drive perform the same? By this standard, how many wheels on my Forrester are really providing traction?
I currently drive Jeeps (both CommandTrac and SelecTrac), formerly a Pontiac Sunrunner (which is a Suzuki Sidekick) and Subarus (Forester currently and Impreza previously) which are a good cross-section of full time 4WD, part-time 4WD, and AWD, and not really surprisingly like Subarus the best...but my FAVOURITE winter cars were my 65 Corvairs (coupe and convert with autos) and 66 convert (with 4 sp).
-I once drove 35 miles/60 km in the 65 Coupe when there was 3 FEET of fresh soft snow, ie to bottom of side window. Under those conditions, the front end lifted off the ground and the wheels acted at 'rudders', and the rear wheels dug down. At about 15 mph/25 kph, it acted like a motorboat, and handled accordingly. Back off the throttle, and the front went down, exactly like a motorboat. On that particular 'necessity' trip, I was one of three vehicles on the road over 3 hours, and the other two were monster trucks with balloon tires and 2-3 ft ground clearance.
-I once pushed a police cruiser up a 5% icy hill with my 65 convertible with just a tied rimless tire as the pushing cushion.
-I regularly "parked" my convertibles nose in, in shallow ditches when regular parking spaces vanished in mid-winter...can't remember how many times people wondered if I needed a tow truck, but I just got in, shoved it in reverse, and backed out--never ever got stuck in Corvairs with big snow tires on them--and with stiff shocks, good radials and the right air pressure, they were just amazing in summer
Anyone know from personal experience if the Suzuki SX4 AWD 5 door hatchback m/t is as competent as a Subaru Impreza 5 door hatchback m/t?
Jim on PEI
Don't have experience with other AWD systems, but have owned a Pathfinder, Cherokee and Samurai, all with 4WD, low range and manual transmissions, and they were all very competent in snow, especially deep snow with their high ground clearance. However, the reason I'm posting is to say that my all time favorite "snow-mobile" was a 1965 Corvair. With 65% of its weight over the rear wheels, a limited slip differential and quality snow tires, it was absolutely unstoppable, despite the fact that I had lowered it about an inch for autocrossing. In deep snow, you just rammed through it until you carved a path. Used to go looking for the steepest hills I could find, and there are quite a few here in the Hudson valley, and it NEVER found one it couldn't handle. Only problem I ever had was an ice rut that put a hole in my gas tank. What makes the Subaru a so attractive to me is performance on any slick surface, especially when equipped with tires that perform well in rain (not the original equipment Bridgestones). With power distributed back to front and side to side, it's never at a loss for traction and immune to torque steer. Even on ice, where the conventional wisdom is that AWD provides no advantage, it gives you four driven wheels instead of two to catch a piece of dry pavement.
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