Torsen AWD slippage

[dmiller@iea.com (Doug Miller)]

>On 19 Jan 97 at 9:00, Doug Miller, in part, wrote:
>
>> The advantages on the street would go to AWD due to the ability to cope
>> with a wider variety of situations at a higher throttle setting without
>> upsetting the vehicle's balance.

And Gene wrote:

>And I have my own anecdotal evidence:  Near where I live, there's a
>marvelous L-R-L sequence, snaking up a hill in less than 200 yards. The
>asphalt is in vile shape, with lots of holes & patches where it vanishes
>into the gravel shoulder.  My wife's former Z-28 (she now has an AWD turbo
>Talon) would dance all over the place (more or less predictably), skipping
>from bump to bump.  My ur-Quattro & my present Galant VR4 gave the feeling
>of digging in, grabbing hold, leaping forward, totally under control, and
>the only thing limiting the rate of knots uphill was responsibility - the
>whole right side of the road being lined with houses.  Late at night, with
>someone to run interference, I've run this route at a shocking rate of
>speed, and AWD just gets more stable.
>
>Similarly, when the first big snow falls, I would take the Z-28 to the
>nearest large & vacant parking lot & practice doing doughnuts.  Ever try
>to do a doughnut with AWD?  VERY hard, requires serious throttle & wheel
>brutality, usually not very good doughnuts, either, as control returns too
>damned fast.  Nevertheless, I go out each winter & do my duty....
>
>The viscous diff on the Galant's AWD takes a noticeable amount of time to
>warm up & to lock up.  My ur-Quattro had a better front-to-rear balance.
>Anybody got a comparison on this stunt with a Torsen?
>Gene R. Rankin / Madison, WI / USA

Yes, my A6Q Wagon has a great f/r balance.  On snow, sharp throttle inputs
in turns kick the back end out nicely, but it is controllable and can be
held this way as long as your right foot stays down.  Lifting causes a
similarly benign straightening, rather than the drop throttle oversteer
common to RWD or the sudden straightening of a FWD at the limit.  I think
the Torsen does a great job of providing torque splits while allowing for
some speed differences of the drive shafts.

Having said that, I got on some impossibly steep snow the other day and
wished Quattro still had the locking rear and center diffs.  There is
something to be said about having everything possible turning at the exact
speed. In my system, slippage has to occur to activate the traction control
devices preventing one wheel from spinning too much faster than the other
wheel on the same axle. Not the same as having *zero* speed differential on
the rear axle with a locked diff.