Quattro question...

[david968s]

I have just bought a B7 S4 and when pulling away with a lot of lock (such as at a junction) I get a grinding sound/feeling that seems like the tyres are scrubbing. Difficult to tell if it is coming from front and/or rear. Also, when turning sharply onto a steep driveway or parking lot, I possibly lift a wheel but I certainly get the same sound. I am sure it is nothing unexpected, but what is happening here - can anyone explain?

[Tame Technician]

If its only on full lock (or at least a large amount of steering angle) what you are feelings is the centre diff working, all Torsion 4WD Audi's do this.

Is a thread on this on R8's and RS4 somewhere. ...................

Found it

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[Tame Technician]

When your on full lock you are nearest the limit of how much the cetre diff can allow the rear wheels to go slower that the fronts. Because of this you can actually feel the action of the centre diff.

It looks like this.

http://www.youtube.com/watch?v=L9Le6Mvqez8&fea...

[david968s]

Mucho Gracias. I am new to 4wd so expected it was a "feature". Got any good links to a decent modern Quattro system explanation? I like to know what is going on and this the first car I have ever bought without doing much homework on it. I thought the drive split was 40:60 F:R in normal conditions with up to 100% to any wheel. So the noise I hear is just the centre diff transfering drive to or from the front/rear as a wheel lifts off the ground? And in slow manoeuvring with all wheels contacting the gound, is it just a differential wheel speed/wide tyre issue?

ETA - you added the second post while I was typing - thanks!

Edited by david968s on Tuesday 2nd March 19:18

[chr15b]

spot on, i've been noticing this and was worrying it was an issue with the steering! cheers