quattro digest, Vol 1 #4292 -

Larry C Leung l.leung at juno.com
Wed Dec 4 14:45:27 EST 2002

Same disclaimers as Brett, except I have been an instructor at
regional Autocross schools.

Generally speaking, the "plow" (understeer) you are experiencing
with RWD, FWD or AWD cars is caused by entering turns at too
great a speed.

Brett's description was correct, the car's attitude is NOT what
causes it to turn, grip does. This even applies in Physics (which
I teach). As soon as the front begins to slide, you don't have
grip, and the only way to get it is to SLOW DOWN. Brett's description
on recovery is also correct.

As he also stated, lifting throttle MID turn will cause weight transfer
from the rear of the car to the front, meaning that the rear will lose
grip. Since the car has begun to rotate into the turn, the loss of rear
grip CAN cause a spin. With experience it can be used to rotate
the car to tighten an arc (to a degree) but the risk of spinning is
reasonably great with a short wheelbase car with the same consequences
as below.

Sliding around a turn with the front loose as well as the rear (such
as power sliding RWD, handbrake turning FWD or even AWD) just
widens the arc of the turn, which could mean either running off the
road (witness many an SUV doing the only offroading it'll ever do)
or worse, into some innocent driver of another car.

Enter a turn slowly and apply power such that you maintain your
desired arc after you reach the apex of the turn. For most street
cars, the apex is usually PAST the middle of the turn. If you want
to have fun and you don't have the time/$$$ to attend a school (such
as NEQ's) consider finding a local RallyCross or WinterCross, where
experimenting is much safer (cones don't hurt like cars and solid objects
do) and there are usually people there whom would be willing to help


> Date: Wed, 4 Dec 2002 12:30:43 -0500
> To: Sean Ford <audi_99_a6q at yahoo.com>, quattro at audifans.com
> From: Brett Dikeman <brett at cloud9.net>
> Subject: Re: Let's talk about quattro driving in the snow
> Cc: Suffolk GameServer LAN <suffolk.associates at verizon.net>
> Scott, let me know if I say anything really stupid here :-)
> Disclaimer- I'm not an expert(I'm not an instructor, either),
> you're
> responsible for your own driving, blah blah blah yadda yadda.
> At 5:08 PM -0800 12/3/02, Sean Ford wrote:
> >This is my first winter with quattro. Just this morning, with fresh
> >snow on the ground, the front
> >slid straight and the car continued to move in a straight line.
> >Obviously, this isn't the best
> >situation when one is expecting to successfully complete a corner!
> Actually, it's a lot better than the alternative(oversteer.)
> Understeer is what happens under power, and it's usually easier to
> correct in a FWD or quattro, because in both cases, your
> instinctive
> reaction(get off the gas to 'slow down') is a good thing.
> >I've driven both fwd and rwd cars in the snow. FWD will lose the
> >front, but a quick pull on the
> >emergency brake will swing the rear around.
> Pull the handbrake, and now you've lost all FOUR wheels :-)
> >Once I lose the front with quattro, what is the best way to rotate
> the car?
> You shouldn't be thinking of 'rotating' the car(angle doesn't get
> you
> around corners, GRIP does), you should be thinking about regaining
> control(ie, get the car pointed the way it's travelling) and
> stopping
> if necessary.
> Two reasons:
> a)if you DO hit something, you're hitting it in the worst possible
> way, with the side of the car or at some angle other than head on.
> Cars and restraint devices are designed for head-on collisions.
> This
> applies even if you're going to go into traffic; if you've got
> understeer and you're heading into the oncoming lane for example,
> and
> you decide to rotate the car by inducting oversteer, that places
> about 4-5" of car between you and a car coming at you with a
> differential of at least 40-50 mph...versus several feet of metal,
> crumple zones, airbag, seatbelt, etc.
> b)if you get the wheels gripping, you've at least got a prayer of
> slowing the car, and every bit of speed you can bleed off is speed
> your body, your car, and the other object don't have to deal with
> later.  Sideways?  You're a passenger on a slip'n'slide.
>    When Chris Miller crashed at Watkins Glen, he did the right
> thing-
> he got the car going straight, and just whaled on the brakes,
> because
> he knew he wouldn't make it.  The result was that right until he
> hit
> the foam wall, his nice big porsche calipers were slowing the car
> and
> his nice sticky tires were working 100%.  Between that and the
> foam,
> he walked away without a scratch and the engine was fine save torn
> mounts and cracked tbelt cover(body was a complete loss from the
> mirrors forward, pretty much.)
> >  I recall some advice warning against lifting off the throttle
> >because the engine braking on the rear wheels could cause
> >an unwanted spin.
> The warning is for lifting mid-turn, near the limit of traction or
> if
> you're in a slide. It causes a weight shift to the front of the car
> OFF the back wheels, which will cause oversteer.
> >  Though, if I don't lift off the throttle, the front will simply
> continue to
> >push.
> The correct behavior, for when you've got understeer, is your
> natural
> reaction- to let off the gas pedal.  It transfers weight forward
> and
> gives you more grip up front.
> >Interesting from a dynamic, after-the-event, point of view.
> Frightening from a
> >happening-right-friggin'-now point of view.
> Come to a NEQ winter driver school.  Bring the missus, too.  You'll
> learn a lot, and have a blast.  Heck, look what I learned just
> picking cones :-)
> Brett
> --
> ----
> "They that give up essential liberty to obtain temporary
> safety deserve neither liberty nor safety." - Ben Franklin
> http://www.users.cloud9.net/~brett/
> http://www.apple.com/switch/
> --__--__--

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