Re: How dry I am... (aka AWD performance)

[Dave Eaton <dave.eaton@minedu.govt.nz>]

now scott and i have discussed this point in private em's, but i thought
i'd bounce this on the list and see what sticks ;-)

in my understanding awd *does* improve cornering speeds, it has to because
it allows more of the tyres adhesion to be used for cornering because less
adhesion is needed for *traction* on the driven wheels.  ie in a rwd or fwd
car, only 2 wheels are driven meaning that, on these wheels, there is less
available adhesion for cornering grip.  the symptom of this, as we all know
is oversteer (loose) for rwd or understeer (push) on fwd. 

with awd, the tractive forces are shared over 4 wheels, meaning that the
wheels have more adhesion available for cornering meaning there *is more
grip available*.

i've seen this demonstrated at an audi driving day where a sharp (wet) corner
was taken at 100km/hr by a bmw 740i, a jag sovereign, and an s6 - all with
trailing throttle.  despite repeated attempts, neither the bmw or jag would
take the corner without spinning (oversteer ie. loss of adhesion at the rear
due to the driven wheels requiring more of the tyres adhesion for traction).  
the s6 took the corner comfortably, and would do so until about 120m/hr.

interesting when you think about it.

drive safe, drive quattro.  drive fast, drive quattro.

-dave
'93 s2
'90 ur-q


..>From: QSHIPQ@aol.com
..>Date: Thu, 16 Jan 1997 14:26:10 -0500 (EST)
..>
..>In a message dated 97-01-16 12:07:14 EST, you write:
..>
..><< AUDIDUDI@delphi.com wrote:
..> > ...AWD didn't improve their cornering at all...but allowed the cars to 
..> > EXIT corners much quicker...
..> 
..> 
..> 
..> Jeff:
..> 
..> I think this is exactly the point. Since the torque is split between
..> four tire contact patches instead of two, you can get more power down
..> faster, at the adhesion limit, exiting the corner with more speed.
..> 
..> I would also go out on a limb and say that, _by definition_, exiting
..> a corner faster = improved cornering.
..> 
..> Glenn
..> 
..>  >>
..>Ok with me tho, I might argue that in order for you to enjoy all that exit
..>speed, you better have the brake equation addressed.....  An M3 for instance
..>can enter faster-brake later, by definition, improved cornering, and since it
..>is 50/50, by definition can take the "correct" line vs the q line, improving
..>cornering....  So, in racing form, the quattro has the advantage on the exit,
..>but that really is all out racing form....  Given the mediocre brakes, and
..>not so hot weight balance, and the torsen, the advantage on the track/street
..>might be less than one might assume, Jeff's point entirely.....  The question
..>really becomes, at what hp is the q at the advantage.....  My own evaluation
..>is somewhere in the high 200hp range and above, minimum....  Below that, the
..>advantage is not to the q...  To do a q justice, brakes need to be addressed
..>to take advantage of your faster exit speed being a faster cornering speed vs
..>rwd, glenn...  
..>
..>Scott