X-drive vs. Quattro

[Skaala]

Originally Posted by ldin http://video.google.com/videoplay?docid=-6518118248698454614&q=audi+snow&pl=true watch that...believe that...enjoy that...fucking quattro that.

:good:

[dutchmasterflex]

Hmm.. maybe this is why those two test drivers crashed in the new TT...

[5vz-fe]

Originally Posted by Skaala Originally Posted by ldin http://video.google.com/videoplay?docid=-6518118248698454614&q=audi+snow&pl=true watch that...believe that...enjoy that...fucking quattro that. :good:

Amen

[StanAE86]

I think it's already been said, but my friend had this to say about the demo:

yep, they've discovered the coffin corner in the torsen's behavior; i.e.
3x0 = 0. the audi uses a center torsen differential.

the torque bias ratio is a multiple. if one side of the torsen
won't support any torque, no torque gets delivered to the side with
traction.

however, this test had to have been staged. the audi comes with ESP,
which includes EDL (electronic differential lock). this uses the ABS
system to brake the wheel that's slipping. using the EDL would have
effectively increased the torque that could be supported by that side
of the torsen, and now you have have a non-zero torque multiplication.
they turned it off for this demonstration, and that makes the demo
worthless. it proves nothing.

my '92 S4 does not have EDL, and it would have a similar problem as
shown in the demo. however, all i'd have to do is apply the brakes
(especially if it's the rear wheels that are spinning, in which case
i would use the handbrake - and i have done it before, on ice) while
giving the car some gas. the driver of the A8L in the demo could have
used the handbrake to get off the rollers, but he didn't know - or he
didn't do it because they were trying to show something.

the xDrive is a very good system, much better than the old AWD system
BMW had (which had no limited slip differential of any kind). it uses
a computer-controlled clutch-type limited slip differential in the center,
in addition to DSC (which uses the ABS to brake the wheel that's slipping).
the nice thing about xDrive is that you can tune the system's drive
characteristics to different driving situations. for example, you can
make it more rear-biased in dry conditions, and change to neutral or even
front-bias in slippery conditions.

however, this demo was just stupid. it reminds me of the segment that
dateline did in which they tried to show how unsafe GM trucks were, and
secretly used pyrotechnics in the gas tanks, overfilled them so that
fuel sloshed out, and left the gas cap off to make them explode during the
filmed demonstration. or that CBS segment on audi "sudden acceleration"
in which they had an engineer rig the transmission to shift into drive
by itself so they could film it.

[andreadebi]

Mitsu EVO IX the best AWD

[ae86_16v]

Originally Posted by Phobo Originally Posted by thepest At last!!! A prove! I always knew BMW's X-drive is better than the over rated Quattro. Yeah, they have the history and everything, but damn, X-drive kicks ass! Wanna see a quite old video where they drive an X5 against the old Audi Allroad and some other modells up a ski track? =)

That was before X-Drive if I remember correctly. That X5 had an open differential.

[ZfrkS62]

Originally Posted by ae86_16v Originally Posted by Phobo Originally Posted by thepest At last!!! A prove! I always knew BMW's X-drive is better than the over rated Quattro. Yeah, they have the history and everything, but damn, X-drive kicks ass! Wanna see a quite old video where they drive an X5 against the old Audi Allroad and some other modells up a ski track? =) That was before X-Drive if I remember correctly. That X5 had an open differential.

X-drive came out in 2004 with the X3. BMW had a 3 exclusive contract with the manufacturer (who i can't remember off the top of my head) but wasted 2 years of it before releasing the X3. The X5 got it that year as well.

[5vz-fe]

^What about the regular 330xi?

[ZfrkS62]

Originally Posted by 5vz-fe ^What about the regular 330xi?

I THINK the 05 xi got X-drive but i honestly am not 100% sure. Now they have it, but i don't know if they attatched it to the E46. It would make sense for them too though.

[Just_me]

The new bimmers from year 2006 got the second generation of X-drive.

First generation sucked but the new one is much better.

[sthatz]

Ok, first, VWs mostly use a Haldex system, not usually Torsens (Audi A3 and TT use the same Haldex coupling) but this is beside the point. The reason that this "demo" is fake or doctored is because for a while now Audi has been using EDL (Electronic Diff. Lock) in conjunction with ESP and the ABS sensory equipment to monitor and contract wheelspin/slip. True, a Torsen is a "torque multiplier" and a wheel or even Axel with 0 torque multiplied by any ratio transfers 0 torque. HOWEVER- Using the EDL and ESP, the quattro system would detect the wheelspin at any wheel and begin applying break pressure to reduce spin while simultaneously adding "resistance". Now, multiply the amount of "resistance" (which a Torsen differential now interprets as traction) by the ratio of the Torsion and there is actual power transfer! You see, EDL is called Electronic Differential Lock because the traction systems create the illusion of a locked differential through the use of the brakes. This is also the reason why Mercedes-Benz 4matic and quattro as well as xdrive can get the car moving when only one single wheel has decent traction; the brakes create electronic differentials allowing power to be sent to a single wheel. Now, spin all 4 wheels and you are screwed...Questions?....
Oh, BTW, Audi uses Torsens because they are faster to react in many situations than ABS sensors. Torsens are not cheap but Audi still uses them for a reason. IMHO, the combination of mechanical AWD with the fancy electronics filling in the potholes is the best combination. But after 2005, xdrive-quattro-and 4matic(and 4ETS++) are all very good systems, in fact with the right tires (because tires really do make all the difference in the world, as I have learned the hard way time and time again) all of these modern systems are pretty great. Subaru has several different AWD set-ups, some better than others. Let's not even start on the new Japanese stuff, I have already made this post long enough (sorry friends)...
Questions? email me at [email protected]

[gucom]

wow, congratz on making probably the most informative and useful first post ever on JW
thx for the explanation, and welcome here i guess...

[ae86_16v]

Originally Posted by mrmojo77 Ok, some empiric testing to the subject. Friend of mine tested the same with his VW Passat V6 4motion. It comes with a similar Torsen differential than A8. With ESP switched off the car didn't get off from the reels until the handbrake was used. With ESP the wheels spinned first a little and then the car got off the reels. So the test organisers in the video must have switched of the ESP from the Audi.

See Below. . .

Originally Posted by StanAE86 I think it's already been said, but my friend had this to say about the demo: [truncated] my '92 S4 does not have EDL, and it would have a similar problem as shown in the demo. however, all i'd have to do is apply the brakes (especially if it's the rear wheels that are spinning, in which case i would use the handbrake - and i have done it before, on ice) while giving the car some gas. the driver of the A8L in the demo could have used the handbrake to get off the rollers, but he didn't know - or he didn't do it because they were trying to show something. [truncated]

[Bernardo]

Originally Posted by ZfrkS62 Originally Posted by ae86_16v Originally Posted by Phobo Originally Posted by thepest At last!!! A prove! I always knew BMW's X-drive is better than the over rated Quattro. Yeah, they have the history and everything, but damn, X-drive kicks ass! Wanna see a quite old video where they drive an X5 against the old Audi Allroad and some other modells up a ski track? =) That was before X-Drive if I remember correctly. That X5 had an open differential. X-drive came out in 2004 with the X3. BMW had a 3 exclusive contract with the manufacturer (who i can't remember off the top of my head) but wasted 2 years of it before releasing the X3. The X5 got it that year as well.

Bosch its the manufacturer i think...at least for the DSC.

[dash]

Originally Posted by Phobo Originally Posted by thepest At last!!! A prove! I always knew BMW's X-drive is better than the over rated Quattro. Yeah, they have the history and everything, but damn, X-drive kicks ass! Wanna see a quite old video where they drive an X5 against the old Audi Allroad and some other modells up a ski track? =) Imho a mechanical AWD is always better than such a AWD that brakes when the wheel is loosing grip. But from what I know is that this only is important if your really really in trouble and I don´t mean with that just some snow on the road.

Exactly, German made a test on a ski track. X5 was so beaten by the Allroad which was the only car reaching to the top of the track. Forget all the offroad cars and their concepts of AWD, Audi's quattro is so damn good..