blabla on AWD

[Ti Kan]

AFAIK the Audi TTq/A3q/S3 Haldex system is used as the center differential.
The rear diff is a conventional open diff.  The side-to-side torque
distribution is accomplished via EDL (electronic differential lock)
which uses the ABS system to selective brake a wheel as necessary.
On these Haldex cars, under ordinary (non-slip) conditions they are
primarily FWD.  Torque is only directed to the rear when the fronts
lose traction.  This is quite different than the traditional quattro
systems used on other Audis.

-Ti
01 S4 2.7 biturbo (coming)
96 A4 2.8 quattro
84 5000S 2.1 turbo
80 4000 2.0
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti at amb.org
 //////  http://www.ibiblio.org/tkan/
///

Peter & Rebecca Lines writes:
> I'm a bit confused about the Haldex systems.  In my job (Automotive R&D) I 
> have seen older Haldex brochures that show the thing setup as a rear diff. 
>  The power comes in through the pinion, turns the ring gear, and then two 
> separate Haldex clutches distribute the power to the halfshafts.  I have 
> seen some newer brochures that show it as a single clutch that is mounted 
> between the prop shaft and the pinion, then a more conventional open or 
> limited slip diff. for the side to side bias.  In both setup's the front 
> wheels are driven directly by the engine.  This latter setup can control 
> the torque balance front to rear, but not side to side.  The first setup 
> controls front/rear bias and left/right bias at the back, but is probably 
> more expensive.  Anybody have a TT quattro? (stupid question).  Okay, 
> anybody ever tear apart the rear diff on a TT quattro?  I'm curious which 
> version Audi is using....  Don't bother asking anybody at the dealer....