Craig Boyle writes:
>So let's suppose we have a stock FWD car with soft
>suspension that easily gets way up on 2 wheels and
>sometimes rolls all the way over (at least one in
>Florida did...)
>
>Would adding single adjustable Koni's, run full stiff,
>make such a car more or less likely to roll over?
>Assume no other suspension changes. Why?
Not sure I have a definitive answer (opinion) to your specific shock-brand
question but, generally, shocks which are stiffer on both rebound and
compression will reduce both the rate of roll and the actual total degree of
roll in quick autocross-like turning. As such the increased resistance to
roll will, tend, to make the loaded tire(s) break loose earlier in the roll
cycle, thereby reducing roll-over potential.
>
>I'm assuming the two classic autox rollover cases are:
> 1) Right turn at the end of a long straight
> 2) Overcorrection after losing it in a fast slalom
Actually, over the rears I've witnessed more RWD roll-overs, but then, over
those same years there have been a lot more RWD cars competing.
Have, only, minimal personal seat time in front-drivers but, have observed
the classic situation for potential FWD roll-overs on a number of occasions.
The situation, in both cases, where I actually saw a complete "demo" went
something like this:
1. The driver is relatively new to our activity, autocross might be the
first time he(she) has really pushed the car. (Have, actually only witnessed
"HE" roll-overs)
2. The obvious "first" thing THE car/driver needs, to be competitive, is
sticky DOTs. Right? Wrong! Seat-time's needed. (this is probably an
un-intended benefit of our SFR Novice classes allowing only street tires)
3. At the end of a fast section, put in a hard left followed by a
tighter hard right. The driver gets into the first turn too-hot and the
high-CG, softly suspended grocery-getter rolls hard into the left, gets in
too-deep on the corner and, when the driver trys to recover from that
indescretion, the rebounding inertia, coupled with a severe right-turn
(recovery) maneuver puts the car "up" on the front left wheel/tire, distorts
the tire/suspension, possibly catches the rim on the ground, and guess
what-- in no time at all, lots of dents and fluid leaks, a bit of which is
sometimes the color of red.
4. If the fast section is going, even slightly, downhill or, even worse,
if the right part of the left-right transition is off-camber, disaster is
not far away.
Seasoned autocross course designers avoid these kinds of "traps".
Interestingly, but probably only coincidentally, the two FWD roll-overs I've
observed were at Divisionals, maybe the "newbys" were trying too hard.
The first was in the 80's at the Boing lot in Kent Washington. In that case
the "car" was a Renault Le Car, the driver was a big guy (increase in the
already high CG) and, even on that level, relatively, low-traction surface
the "demo" was complete with broken arm, and red fluid, as a result of,
trying to use said arm to stop or, possibly, slow the roll-over.
The next was in the early 90's at one of our own SFR Divisionals, at
Candlestick Park. In that incident a Golf did the "trick". I seem to recall
that there was some evidence of left front suspension deformation after the
roll. The location, on the course, of that incident was on a, relatively,
level section but, as you all know, the 3-Com surface can generate pretty
high traction when its "clean". I don't remember if this was a second day
incident or if the same path in the incident area was used both days.
However, a large turn-out, two-day event, such as a Divisional, does clean
up a surface when the same path is used both days. Another reason to pay
attention to the safety of course design.
Don
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