AWD test

[rqiu]

http://video.google.com/videoplay?do...8466&q=quattro (http://video.google.com/videoplay?docid=9072883197544018466&q=quattro)

Maybe you guys have seen this one. What is your opinion on this? I guess they turned off ESP on the A8 to fail quattro.

[Erik]

I think you can prove anything if you like ;)

[rqiu]

Found this thread at audiworld - interesting.

http://forums.audiworld.com/allroad/msgs/185843.phtml


I thought the current quattro (40:60 split) can send 100% of its power to either axle according to Audi's Filip Brabec.

Filip Brabec: The Torsen differential – the name comes from two words – "torque sensing," implying that it redistributes engine torque steplessly between front and rear. In the current quattro system Torsen can transfer up to 75 % of available torque to a single axle. The newest asymmetric quattro can do so up to 100%.

http://www.edmunds.com/townhall/chat/transcripts/audichat102705.html

[Ruergard]

Seen it a lot of times, and it doesn't make any sense to me...

[Speedou]

Don't know any facts, but I think thats happens if you don't use ESP and other end is on the air (or like on the video). But just push the ESP on and you are off...Who cares...never will be your problem when driving.

[KK265]

There is a place where my RS4 has traction with only front left and rear right wheel.2 others are on the air.With ESP off the front right wheel spins and i can not go away.When i engage ESP the things are better.Under enough spinning i can leave.With a previous Audi TT without ESP system on, this does not happen.The TT with Haldex, leaves away without spinning easily!!!Any ideas?

[Leadfoot]

To the best of my knowledge the TT's Haldex system has elec diffs front and rear, so even with ESP off it will get out no problem. The original Quattro system doesn't have diffs so uses ESP to counter this, turn it off and you just sit there.

[rqiu]

To the best of my knowledge the TT's Haldex system has elec diffs front and rear, so even with ESP off it will get out no problem. The original Quattro system doesn't have diffs so uses ESP to counter this, turn it off and you just sit there.

Leadfoot, you are correct. I did some reading on torsen afterwards. Inthis scenario, the rear axle is spinning freely, so torsen senses 0 torque, then the front axle also gets 0 torque because it is multiplied by 0. if ESP is on, it will apply break to the rear wheels, which will generate resistance to torsen, then front axle will get torque. If the driver apply break or use the e-break, it would do the samething.

[Kram]

Leadfoot, you are correct. I did some reading on torsen afterwards. Inthis scenario, the rear axle is spinning freely, so torsen senses 0 torque, then the front axle also gets 0 torque because it is multiplied by 0. if ESP is on, it will apply break to the rear wheels, which will generate resistance to torsen, then front axle will get torque. If the driver apply break or use the e-break, it would do the samething.


In fact it is the EBD (Electronic Brake Differential) that was incorporated in the ESP after 2001 models. On early models with only EBD, it can not be switched off, and this situation never occurs.
I don't remember when EBD was put on Quattro.:vhmmm:

[Tanner]

EBD (or electronic differential lock) was introduced with the fourth generation of the quattro system, I think it was in 1996. ESP was introduced in 2001 as an option and later as standard equipment.