Date: Sun, 12 Jul 2015 11:47:23 -0700
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Was... Why new tires should go on the rear. now: Some
thoughts on car control and traction..LVC..little van content
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I know the Vanagon is remarkably well balanced, especially for such a
versatile vehicle. As mentioned in my post, the "Traction Equation" (that
is what some performance driving instructors call it) is simple, but
dealing with it is incredibly complex..
.
'Simply' doing any one thing to 'catch' a sliding vehicle is, like I said,
isn't that simple..... It might work for one vehicle in one situation in
one type of skid...but there are thousands of variables to consider...
The traditional Porsches, the VW Beetles, the Splitties and even the Bay
busses, those were on one end of the extreme, and were "poster vehicles"
for the unique traction characteristics of rear engine rear wheel drive
vehicles...Once you got em pointed right, they were remarkable in how much
drive they could put down to the surface, But they spun like
tops...remember those? Cool toys, Tops...but I digress again...
The Vanagon is much better, for sure...So are the Porsches with the
radiators up front like they do now, and electronic traction control and
competition ABS, etc etc..........The 928 Porsche did it another way: with
the transmission hanging out behind the rear wheels to achieve a near 50/50
weight distribution...
But to explain a little more about "stopping a spin-out" by simply
getting off the gas..... I'll add some more of my take on it......(delete
now if this isn't Vanagon enough for you)
The different types of spin-out or traction loss can be best understood
by experiencing them first hand...like on a dry lake bed or a skid-pad or a
snow covered field with nothing to hit and no obstacles at all...If you do
not like what you feel, you can alter the handling, to a certain
level...that level being limited only by money....I think there is a
Splitty bus around that laps the Nurburgring about as fast as a new
Lamborghini or a twin turbo Porsche...Cubic dollars, Euros..will do most
anything....
But here goes..
.I'd guess the most likely traction loss that was the main subject of the
original post was entering into a corner too fast and losing control...In a
Vanagon. That would probably start with the front wheels plowing ahead
when you needed them to turn the van.....That is what the engineers wanted,
for better or for worse...
The next type spin or slide would be, probably, (and this was what was
mentioned as "simply let off the gas and steer into the skid) when you are
trying to go uphill on slick surface, or if you have a big motor, giving it
too much gas and spinning the wheels by applying too much power...
The one I outlined in my post, especially pertinent to the 911s,
Beetles and such, but also, in a lesser degree of severity, to any
vehicle....is when you are under steady throttle in a corner, but going too
'hard', too fast...and the traction limit is exceeded at the rear of the
vehicle, for any number of reasons, and they lose traction first...could be
old hard bald tires back there, could be a bump in the surface, could be
inadvertent steering input, poor shocks bad alignment.......all kinds of
reasons for it..
Simply dropping the throttle in this type skid WILL cause the vehicle to
transfer more of it's weight to the front tires, which already have enough
traction. It will also subtract weight from the rear tires, take away
downforce and traction at the rear.
(This is the Traction Equation...I'm no math fellow so I won't attempt to
express it as a real equation, but there is only so much grip in the four
places where your tires touch the road, and there is also a fixed amount of
mass for the total vehicle, and there is the centrifugal force created by
the speed and the radius of the turn..it is all there and you can not fool
any of it...change any of the equation and the other factors need to change
to make it balance out again) .
Now, .since the mass is still there, but the rear tires are now
un-weighted, almost waving around in the air ...(an exaggeration, but look
at some images of racing cars under braking and many do have airborne
inside wheels) the sliding rear of the vehicle has even less ability to
follow the front, the Equation has changed, and the rear end, it will
accelerate it's rotation, kinda 'snap around' if you would....
Sorry for the thread stealing...
On Sun, Jul 12, 2015 at 9:27 AM, <szpejankowski@gmail.com> wrote:
> Don, check the weight distribution of a passenger Vanagon. It's nearly
> 50/50. It's no Splitty or 911.
>
> Then add about 350 lbs of humans over the front wheels and the picture
> changes even more.
>
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> Wysłane z iPhone'a
> >>
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