How Quattro Works?

General Discussion
#1

So today I got stuck in the snow in my 2000 Audi A6 4.2L. It got me thinking how the quattro system truly works in my year car. Heres a sample pic : Using it as reference to my car.

http://i.imgur.com/5N9O2Qr.png

Ok the the wheels circled in Green where touching the ground when I got stuck. The Passenger front was on the ground along with the drivers rear.

The wheels circled in Red where not. The drivers front was just freely spinning when in gear a idle. The passenger rear was the same way but not as bad.

Now heres my question. When I hit the gas in Drive or Reverse the tires in red (that are not touching the ground) were spinning hardcore, but the tires in green that were touching the ground were not moving what so ever. Like NO POWER was being delivered to them. Why is that? In my eyes that seems ass backwards. Im sure I would have got out if the tires touching the group actually moved, but they didn’t. It just kept spinning the two that were not even having any contact with anything. In the end my brother in his Subaru had to pull me out. Embarrassing

#2

I remember on my 3.0l when the front drivers side axle broke the car went no where. Said i was doing 60mph sitting still. So I have figured it the differentials in the car. There not locking diffs. Is there a upgrade so this doesn’t happen?

#3

That’s right, front and rear are open diffs (you’re a c6?)

There’s an electronic diff lock that will brake the spinning wheel but I can’t say it really works in the extreme, and you can’t turn ESP off then.

#4

It’s because all of the diffs are open diffs.

#5

2000 Audi A6 C5 4.2L V8, Automatic, NO ESP.

#6

is there any upgraded diffs for the car? Locking or limited slip?

#7

I believe Stasis offers (or offered) a rear LSD.

#8

it works just fine in 99.99% of situations.

Make sure you don’t get yourself in the 0.01% where it doesn’t work well, and you’ll be fine. If you had both front wheels on the ground it would be fine. Both rear would be fine. One wheel off, fine. One wheel of each axle off, the open differential screws the pooch and you go nowhere, like a broken half shaft.

The key for your wheels to drive the car is to keep them on the ground.

bad

http://pictures.topspeed.com/IMG/crop/201001/road-accident-result_600x0w.jpg

bad

http://kwtv.images.worldnow.com/images/13999747_BG1.jpg

good

http://www.gauntlet.net/audi/dragday/drag3.jpg

good

http://audirevolution.net/addons/albums/images/507021191.jpg

#9

lol i was not driving like an asshole…i was backing out my driveway.

#10

In an scenario like you mentioned, you could try pressing the brake with 1 foot and the gas with the other. Or if you’re in a manual, pull the e-brake, lock the center diff and try. That may apply enough clamping force on the wheels in the air to turn the wheels with traction.

Are you running an O1E trans?

#11

2000 Audi A6 C5 4.2L V8, 5 Speed Automatic (TIP) with PRD432 Shifter, NO ESP.

#12

I realized that after I posted. lulz

#13

lol

#14

This is pretty common, had a buddy get truck in his 4WD truck going across a ditch diagonal. He didn’t have a rear locker.

Don’t worry about upgrading anything, unless you plan on doing this a lot. Like Saki said this was one of those .01% times.

#15

I’m guessing all four of his wheels were on the ground :slight_smile:

Like the others said, not having all your wheels on the ground is rare and will impact your ability to move lol

I managed to tow a 911 from a snow bank in half a foot of snow myself. My 4 wheels were on the ground though :slight_smile:

#16

funny, a friend towed an A8L out of a snowbank the other day (FAST tow…using his Cayenne Turbo S!). Same deal as vinnie. Not all four on the ground. Hell 3 will do. 2 no bueno.

#17

understood…thanks for the info.

one other question…is it possible to retrofit ESP?

I have a 2002 Audi A6 3.0L that is junk. Has ESP system in it.

#18

Here is my smart guy moment of the year…

Your car has ASR anti slip reduction you cant turn it off you have to pull your abs fuse…
If one tire spins too fast the entire system will unlock and nothing will work…As me how I know… I broke an axel last winter. Esp wouldn’t have helped In your situation. .

Here is a video showing the wheels spinning…I saw it a long time ago…not sure it helps here but if you didn’t know what it looks like…

http://audirevolution.net/videos/24/b7s4-drive-line

#19

It sounds like Vinnie got high centered. In that case you are screwed unless you can either push out the snow/ice from under the car or have the car pushed/pulled off the snow/ice enough to get the wheels in better contact with the ground. 4WD Dodge and Chevy trucks have a similar problem with getting stuck in the mud and digging ruts. They will spin one front tire and the opposite rear tire while the other tires don’t move.

My S4 has limited slip differentials in the front and rear along with a modified 4:1 center diff and if I break an axle the car will not go any where. I haven’t gotten high centered to be able to test this problem yet but I would rather not have to find out.

#20

[As an aside, Suby’s also have variation. :slight_smile:

My '02 WRX had two diffs (center and rear), and could do donuts around one front tire (called a Scoob-nut). I got it stuck once in a drift where the rears were were elevated, and one front free-spun. Whoops. A civilian Humvee just happened to be passing by and snap pulled me out. Crazy story.

My '05 STi had 3 differentials and felt like a snow-mobile. Never got close to getting stuck, but the low front lip didn’t care for deep snow.]