2009 Audi A4 Avant B8

[Cody Forbes]

Torsen center diff, open front and rear diff. It has EDL which means it clamps the brakes on the wheel or wheels with the least traction to transfer some torque to the other side.  

Google "Audi ssp 962103" to find a PDF of the self study guide that describes all Quattro systems up to the EDL based systems. The only upgrades since the early 2000's have been the below and only the first applies to your car.

- moving the engine rearward in the chassis 6" by rearranging the transmission internals to move the diff forward. This started on B8's.
- RS5 introduced the new crown-gear center Torsen with variable torque bias front to rear. I think it's still the only car with it, or maybe B8.5 S4's can get it optionally.
- "Sport Diff" rear differential which is standard on RS cars and optional on S cars starting with B8. It's a complicated arrangement of torsens and clutches that allows torque split to be changed left to right (torque vectoring).

You can also look for Audi SSP 991803 which is the B8 A4 vehicle introduction. It will direct you to Audi SSP 997703 for more detailed drivetrain info (B8 A5 introduction) so get that one which you are at it.

-Cody Forbes (mobile)

On Sep 22, 2014, at 10:59 AM, Nick Lawrence <nick at beol.net> wrote:

> Can somebody point me to an accurate description of how the quattro system works on a 2009 A4 Avant.
> Thanks
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