Jim Simone

In fact, one of the advantages of TorSen over the locking differential is that ABS can be used simultaneously with all-wheel drive. It's apparently one of the reasons why Audi changed the Quattro system to use TorSen in the center diff instead of a locker.<p>If you want to stir up some real controversy, just post this topic on the Quattro List. They'll love it! ;-)<p>(I'm just kidding here. You'd be totally smoked if you post this subject on the Q-list. However, I'm sure you can find all the opinions you'd want if you do a search on "torsen".<p>Jim

Scott G

You can spin the tires on an A4Q in the snow or on ice. The front drive is the only version with anti slip for the drive wheels. The quattro shifts traction to the tires with the best traction. I had this conversation with some folks from Audi while in Germany at an Audi event. If quattro had traction control you wouldn't be able to do those fun spin outs in parking lots.

E

Wrong! EDL is anti-spin and Quattro (this gen) has EDL

E

"Quattro system" has anti-spin - it's called EDL. It is a software extension to the ABS system and only works on a per-axle basis. Once Audi introduces yaw control, the system will be intelligent enough to react "beyond the single axle". As EDL stands now, it senses wheel spin, activates the ABS "pump", applies the brake at the spinning wheel to transfer power to the opposite wheel through an OPEN differential. If there is "zero" traction on both left and right wheels of one axle, the brakes are applied back and forth between the two wheels at a high rate. This is the way it works for the front axle and the rear axle. EDL does not lock the open differential - EDL is a misnomer. Locking means that the right and left sides of an "axle" are rotating at the same speed. Audi used to do this on their rear diffs in the PAST.<p>The center differential, which resides in the transmission, is a TORSEN. It also does not lock. It redirects engine "torque" to the axle with the MOST traction. This transfer capability only works if there is some (I forgot the ratio.. maybe 7:1) traction available at the axle with the least traction. If this ratio is not maintained, the TORSEN acts more like an open diff. THIS IS WHY THE BRAKE SYSTEM IS USED.<br>The brake system helps the TORSEN maintain its effectiveness, when traction is near zero on it's open diff "axle". <p>E <p>