[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: Real Quattro II

Dave E writes
>some examples of similar awd systems to the haldex come to mind:
>1) nissan atessa (used in the skyline notably the gtr -aka godzilla) where
>100% rwd usually then torque sent to the front axle on slip to a 40% limit.

rwd to awd
>2) lamborghini ditto.3) porsche c4
rwd to awd
>4) the 1997-98 toyota corolla wrc rally car (toyota looked at the haldex,
and ended up delevoping something very similar).
rwd to awd

The first question we must ask, based on "similar" technology, is, why fwd to 
awd?  A baseline chassis dynamics problem?

>not sure how you can say whether or not the haldex is "an active
>differential in terms of performance or advantages".  i personally have yet
>to drive one, and when i do next week (s3) will prpbably find it quite
>different to it's other implementation (ttq) when i drive that.  afaik, very
>few people on the list have actually driven a haldex quattro.

And you will compare it to what?  I think you can say it based on the history 
of it's use, and the baseline that fwd to awd gives what in terms of chassis 
character.  If the haldex locked goes 50f/50r you have understeer, then more. 
 If you have haldex locked 25f/75r you have understeer, then oversteer.  
Sound familiar?  This isn't real quattro, this is fwd with extra traction.  
>From it's baseline design, we know what the inherent handling of the car will 

>fwiw, in a strictly classical definition the haldex is not active, rather
>semi-active, but increasingly levels of computer control/management of the
>traction envelope is the future.  it's here already in edl, 

Kinda here in EDL.  EDL doesn't cross the center axle in the quattro 
application, so it's 2 independent EDL in an awd platform.  Making EDL an 
"Active differential" redefines the term, it's only "active" to an open diff. 
 But audi is also redefining "quattro advantage" with a haldex which isn't 
even awd.

I'm all for better traction, but haldex, in the fwd>awd form, seems to be 
accepting baseline chassis dynamics that are the reverse of Haldex history to 
date, and creates the safety of understeer and more understeer.  Better or 
worse than U-O-U...?  Anxiously awaiting your test drive report dave.

Scott Justusson