KUpolo

I also posted this in the B7 forum, but I thought this may be a better place...

I think I understand how they work from this:

http://science.howstuffworks.com/gear7.htm

but what I guess I don't understand is how does the Torsen T-3 differential system in my S4 feel torque slippage on the wheels and transfer the power to adjust.

http://www.torsen.com/products/T-3.htm

any engineers care to take a stab at explaining this to me?

ub2slw

The Torsen differential uses the axel(s) that has the least amount of torque to determine the total amount of torque available that can be redistributed. The maximum torque that can be sent to the an axel is 3 times the torque at the spinning rear axel. The spinning wheels make the worm gears spin faster thus binding

ub2slw

the quattro generation IV system...the center torsen sends the power forward or back, the OPEN diffs in the front and rear axels send the power from side-to-side... IIRC Quattro generation III had a Torsen middle and rear differential and an open in the front. So it's possible to even have torsen diffs all around.

AudisAPlenty

The only Audi with a rear torsen was a V8, and no Audi came with torsen diffs all around.