RE: TT Impressions from Europe

["Dave Eaton" <Dave.Eaton@clear.net.nz>]

well, it's true about the haldex.  it is not a "true" awd system as we know
and love quattro in it's present incarnation.  however, using the haldex as
a "hang-on clutch" in the manner of a viscous coupling is imho, the way of
the future.  it offers significant packaging advantages (size, weight,
weight distribution and cost) in a fwd-based car.  it also offers the
ability to computer control the clutch relatively independently of the
mechanics of slip.  so it goes some way towards an "active" setup.  while a
fully active setup would generally use some independent mechanism for the
generation of hydraulic pressure (or electrical power) to operate the
clutches, the haldex, by using the slip to generate the pressure is very
efficient (back to packaging and cost again).  but the setup allows the use
of various sensors directly (e.g. lateral g, abs, throttle position etc.)
rather than as a relatively indirect "feedback loop" as in quattro edl and
other production systems.  the advantage that this gives you is in the
ability to modify the handling dynamics of the chassis using the control
unit.  for example, if you want the car to exhibit turn-in oversteer (as
audi seem to have done with the ttq), you simply allow torque to go
rearwards when you detect corner entry, otherwise you let the throttle valve
in the haldex bleed off the pressure and it stays fwd...

it also allows you to neatly circumvent the archilies heal of the v-c setup,
which is it's behaviour under braking (which have to engineered around).

interestingly toyota ("active torque control awd") and gkn ("visco-lok")
have both developed very similar devices to the haldex.  the toyota wrc
rally car has been using their hang-on clutch for the last 2 years in
competition mounted on the rear axle.  there is certainly nothing wrong with
the behaviour of this car.

also bear in mind that cars such as the nissan gtr have been using this sort
of approach for years simply because it allows them more scope in modifying
the behaviour of the chassis.  nissan ("atessa awd") for instance, has
basically a rwd setup, keeps torque to the rear axle on corner entry and
starts moving it to the front on corner exit.

verdict on the ttq will have to wait until a number of us have a chance to
drive it.  the arrival of the ttq here in nz has been put back to december
while the tt fwd is arriving next month.  the reason for the delay is very
high demand.  all tt's have been pre-sold (sight unseen) here in nz for the
next 12 months.

"evo"" magazine (are they still alive?) featured a long drive of the ttq and
the torsen 20v ur-quattro in their 1st issue.  they loved the ttq, but
preferred the ur-quattro.  details of this test will be in the archives.
autocar have tested the ttq and given it 4 stars, and also tested the s3
against the wrx and gave the wrx 5 stars over the audi's 4 stars while
noting subaru's deficiencies in refinement and nvh.  georg kacher in "car"
loved the ttq, but "car" wasn't so positive on the s3.

dave
'95 rs2
'90 ur-q

-----Original Message-----
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Date: Wed, 12 May 1999 09:48:05 -0400
From: Alexander van Gerbig <avangerb@zoo.uvm.edu>
Subject: TT Impressions from Europe

Was talking to my foreign Audi fans, UK and Germany, about the TT.  I
was very excited to announce to them that it was finally here in the US,
and to my disbelief they both sneered and snickered(well in terms of
typing on ICQ).  I asked what the laughing was about and they explained
this, the TT is sub-par for a sports car.  They were skeptical about the
quattro label on the trunk, since it has got Haldex, not a true quat
component, and they commented on it has not that hot.  The guy in
Germany has test driven one and said nothing short of "eehhh it's ok."
He commented on an article that put the TT vs. Z3.  Z3 flat out won he
said.  TT got blown away in most categories.  I was skeptical about all
this, but the Brit confirmed the TT isn't that great.  A touring car at
best, no sports car.  Any thoughts on this guys?  Just wanted to know
what other Audi peoples thought about the TT.  Thanks.