Michael@Parker

Could someone fill in the gaps for me here. It is my understanding that the current Quattro drive system on the Audis (excluding the TT and A3, ofcourse) is fifth generation, and the xDrive AWD system on BMW is basically the third generation Quattro drive. Is this correct? Whats the difference?

kleinbus

Audi, Subaru and some other brands with Haldex coupler have no transfer case.

BMW and Mercedes haves transfercase (no matter you can't select high range/low range) and it is based rear wheel drive in normal conditions. Once computer senses revolution difference (more than going around the corner) between front and rear it activates front drive blah blah...

Most of us promotes our own brand and bashes others so all I can say is buy one you like to drive.

Which one is better? Generally it is as bad as your tires. I flew by BMW xi's and MB 4matic's while crossing Rockies last winter in bad blizzard with our VW Tiguan 4motion, only because we had true winter tires (not all season crap) and same thing was repeated at Big Bear in LA.

Michael@Parker

See, I knew the Audi brand uses the Haldex coupler, but how come some seem to think that BMW shares a similar system?

kleinbus

Haldex is generally speaking hydraulic coupler with multi friction disc's. Haldex is Haldex because their controller, pressure and structure but generally speaking, multi disc coupler structure is used by Japanise, Ford Freestyle (Taurus X) and so on.

BMW and MB uses hydraulic coupler but there ends the similarity to Haldex as major difference is the drivetrain layout. BMW and MB haves transfercase and shaft going to front to front differential.



Haldex cars usually are based on frontwheel drive and rear comes along when needed.

Audi uses Haldex in only two models like you said, A3 and TT because space issues. Rest (exept R8) haves Torsen center differential (Quattro) and R8 haves Visco center differential (instead of Torsen)

VW uses Haldex on current models and earlier is was Visco.



Photos just for reference as new Quattro haves 40/60 split

twoquattro

Pardon my late reply.
If you're pushing a car up a hill, it's nice if someone joins in to help. Nicer still if they were there from the start.

If the question is which is better, all things equal, any reactive system (Haldex) will be inferior to a full time proactive system (Torsen). With Haldex the skid or spin must begin before the other axle kicks in. Sensors, electronics and algorithms may smooth the transition, but it's there. Drive both in the snow and this will be readily apparent.

I'm not saying that Haldex is not good, but it's certainly not as good. You're 4motion Tiguan would easily best a FWD Tiguan through the snow, undoubtedly why you bought it. But you are quite right in noting that the reason your Tiguan goes better in snow than those BMW's and MB's is your choice in tires (and maybe the driver). Put good winter tires on the BM or MB and in really bad conditions, they'll out climb you handily, albeit at 2-3 times the price.

BTW, I don't believe that Subaru uses a Haldex system. They are full time AWD.


So yes, tires are everything. If the tire can't grip the surface, you got nuthin', no matter how many wheels are driving. That's where traction control is so misunderstood. Cutting power to a spinning wheel is great, but eventually that equals no forward motion.

kleinbus

Finally this topic came alive again... its alive... its alive...

TwoQ,

Yes you are right about sensors but similar algorithms, sensors and electronics is used on Beemer and MB to control the front drive and the clutch controlling the front power.

While I grew up at Acrtic Circle, I owned Mercedes G Diesel, one of the few vehicles that comes with all 3 100% mechanical differential locks and also some point huge 4x4 Chevy Suburban with 6.2L V8 Diesel few to name. I beated the crap out of those two, sank to river hood deep and got out of there and later sunk to hip deep snow somewhere in middle of unmaintained forest road in middle of winter, spent few hours showeling my way out and so on.

After all that crap, I can't really say which one would win when equipped with winter tires, Tiguan 4mot or MB 4matic or Beemer Xdrive as all of them are really good. I have driven MB 4matic myself and I had no complains about it, but right now only Mercedes I would buy is either G or Unimog so I traded the Tiguan in and got Q5.

Anyways, back to the snow. Power does not help with snow as I have driven 600HP 120000 lbs trailer combination trucks where I could lift up the rest of the tractor rear wheels exept one axle and that way load most of the tons to two dualies and it still slips if I wouldn't know how to drive on snow and ice.

Now this conversation becomes interesting when we get into reactions and what is reactive and proactive.

Good driver can be proactive through human eyes and "butt feeling" and observe what is happening ahead that allows person to act differently if needed.

Any vehicle that senses anything through wheels is always reactive as it have to slip, no matter how much, is it just a tiny split of degree or quarter revolution, it is still slip and difference comes how quickly system reacts.

Once someone develops scanning system that is able to behave like human eye and combined with artificial intelligency, then car may become proactive as it could observe and reach as needed.

With Quattro I tried my bald crappy all-seasons on ice and I really had to sharpen my senses to notice the tiny tiny twist car made (not sure is twish right term to describe tiny slip from one wheel) and then traction control light came ON, little wiggle and slip here and there and off I went with ESP light blinking.

Then I swapped to real winter tires and had to beat the crap out of it and still barely got traction control active.


Also you hit the spot with Subaru not using Haldex, Subbie haves few models that haves mechanical AWD (like Quattro haves mechanical Torsen) and then there is few models that are FWD based and rear comes along when needed (clutch system similar to Haldex)


Anyways, I would love to talk about snow and ice and spinning wheels and share hands on what have happen to me on my snow explorings while all I had was winch and aluminum snow showel (as plastic has tendency break) but that would be long and boring story ......

A400

As you stated, Haldex is not a full time AWD and will never have the traction of Torsen. IMO Torsen is about as good as is affordable can be and you do pay a premium. The thing I like about it is its extreme strength (holds over 500 lbs. of wheel torque in the O1E version and wwith a good center and rear diff, its better than anything I have driven thats full time. I am sure the Buggatti, and other hi end stuff may be comporable, but you are talking about the price of an Audi just for the tranny/diffs/sensors. For the money it is tops in my book, and not just because I own one.
Rod

tranquility

So in layman's terms, which sys is better?

dubes12

In laymen's terms... Audi invented all wheel drive. It was so good that in the early 80's when they were rallying against subaru, mitsubishi etc... Audis were staying on these crazy rally courses and all the other cars were flying off the tracks with little or no control. They cancelled rally races for a while because Audi had such an advantage over its rallying competitors. Audi was forced to share this crazy new technology with their competitors (Quattro or all wheel drive). Audi invented performance all wheel drive. They are the best by far. BMW's Xdrive is simply for winter traction not for performance. They came out with the Xdrive because they needed to have an option for winter climate customers... that's the gist of it. Audi by far!

kleinbus

If I may twist this around a bit....

Audi did not invent AWD.

The info I have gathered so far shows,

First 4x4 was build by Ferdinand Porsche (yes the founder or Porsche cars AND he was just 25 years old), this 4x4 was "truck" with electric drive with electric hubs and was build 1900. That time their truck was side of current NA mid size pickup.

First mechanical 4x4 was build 1902 by Spyker from The Netherlands.

Mercedes Build their first 4x4 on 1903.

1926 Mercedes and BMW made military 4x4's that even today can be said was way ahead of time (Real 4x4 with 3 lockers, 4 wheel steering, independent front and rear suspensions. They happen to be really similar to each other as German Army ordered some car manufacturers to build 4x4 by specific blueprints Army had.

Audi AG revolutionazed mass production AWD by inventing a way to convey power to all wheels and Torsen is not Audi AG invention. Torsen differential was invented 1958 by American Vern Gleasman.


Which one is best? Oh man this is endless battle so buy one you like to drive and drive the crap out of it, like my Q5 I got brand new, is 13 months old and I have already 28000 miles on it!!!!!!