Greg Hardy

Does the new A4 use Torsen or Haldex?

Danimal

Torsen.. The only Audi thats Haldex is the TT

Audiwi

I think S3 use Haldex too.

Toronto B6 -OnEighty

what is haldex (if anyone could explain it please) i know how torsen works tia

Zed 2.0

Golf 4mo, TT, A3...

Mike@Ikon Motorsport

Haldex is FWD until traction is lost, when power is routed to the rear. I think it was "European Car" that said Haldex was more suited to all weather conditions than performance, whereas Torsen worked well in both situations.

Mike

Toronto B6 -OnEighty

thanx again

der Delfin '02

For the TT, Audi adopted a new system developed by a Swedish component maker called Haldex. The system uses a multi-plate clutch as the center differential for splitting torque between the front and rear axle, similar to the PSK system that Porsche 959 pioneered in 1986 (read AutoZine Technical School for more details). ABS sensors are employed to detect wheel spin, providing information for the computer to determine how much torque needed to be distributed to which axle, then implement the torque split by actuating the multi-plate clutch. Theoretically, nearly all the torque can be sent to either axle.


---taken from : http://autozine.kyul.net/html/Audi3.htm

Ditto what Rival Schools wrote... it's normally FWD, then when traction changes... the Haldex computer transfers power to the rear axle throught that multi-plate clutch setup.

Torsen is purely mechanical... "worm gears" and it requires a longitudinal mounted engine... TT's and S3's are transverse (90 degrees of A4s)
(talking 1.8T's here of course)

Hope that clears things up.

DRG

It's the only non VW-group car I know of that uses this system.

DRG

In addition to what's mentioned here, an important feature of Haldex is that the difference in wheel rotation between front and back causes a pressure buildup, that the computer controls via an electronically-actuated relief valve (thus controlling the torque transfer).
A slight gearing difference between front and rear is built in in order to force a slight rotational mismatch between the Haldex front and rear shafts, to keep the system "primed" and ready to actuate at a moment's notice - after only 15 degrees of wheel slip.