>> My understanding is that these expensive shocks are used to compensate
>> for the low spring rates found on stock cars. Allowing any swaybar front
>> or rear would give the owner a much less expensive means for
>> accomplishing the same goal.
> I guess it could be argued that all shocks have some effect on spring
> rates.....or do they? My understanding is that sway bars do not.
Strictly speaking, shocks don't affect spring rates - with one great big honkin'
exception that I'll discuss in a second. However, you can use shocks to act like
stiffer springs/bigger sway bars in terms of roll resistance.
If you have one of those cars that gains camber in roll, there is a signifgant
advantage to limiting this roll - especially if the car cannot be set up with
much static negative camber - as less roll translates into less dynamic positive
camber.
Which, in English, means "the tire stays flatter on the ground, so it grips
more".
Normally, to limit roll you use sway bars, or perhaps stiffer springs (stiffer
springs brings with it the penalty of increased wheel rate, which if taken to
extremes translates to reduced tire complience, and the car "patters" and skips
over bumps) However, if you are not allowed to change bars or springs, you can
fake it with stiffer shocks. The stiff shock resists the roll for a little
while; it slows down the rate of change. If the manouever is over before the car
could fully compress the shock, then the shock has acted as a stiffer spring as
far as roll is concerned.
It doesn't help you any on long sweepers, but in quick transitions (and what is
autocross if not quick transitions) you wind up with more roll resistance, and
more grip.
But wait! There's more!
If you are blessed with a car that has proper silisto-style bumpstops (they look
like a cross between an accordion and a ziggurat) there's something sneaky you
can do with shocks. That bumpstop is really a *spring*, with a different rate
for each diameter change in each step of the ziggurat.
If you get shocks that are really, really stiff in rebound, then as you drive
the car the shocks will resist the suspension returning to it's normal ride
height - it "jacks down" until the car is riding on the bumpstops. Presto!
You've just lowered the car and stiffened the suspension!
If you're really really sneaky, you can build the shocks to be
position-sensitive. Measure the distance between normal ride height and the
bumpstops, and make the shock so that it has almost infinate rebound and no bump
over this range. Then, for each step on the silasto ziggurat, adjust the
bump/rebound so as to control the suspension for the spring rate of that
section. What you wind up with is a car that *instantly* jacks down onto the
bumpstops, and then drives like any stiffened, lowered car would.
Of course, no *human* would go to these lengths in shock design..... :)
(I don't know what amazes me more - that he did it, or that I was able to figure
it out after I talked to him and pored over his design for a couple of months :)
)
So anyway, allowing open sway bars in Stock (I actually like the idea for
"front, or rear, but not both, driver's choice") should in fact make the sport a
little more affordable for a bunch of people - the "shocks as fake sway bars"
crowd. It does nothing for the "shocks as dynamic ride height controls" crowd -
and those people aren't going to be hurt by a rule change; what's $300 in bars
when you've got $5000 invested in shocks?
Incidently, a full-on Street Prepared suspension is *much* more affordable. You
don't have to play silly games with dynamic adjustments, you just buy the
springs and bars you want, and get shocks that control them. There's still money
in R&D for proper spring and bar rates, but that's NOTHING compared to the R&D
money on designing position-sensitive shocks.
Thus endeth the lesson. :)
DG
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