58 Sway bars: (Anti-roll bars)
Description
This article is from the VW Performance FAQ, by with numerous contributions by Jan Vandenbrande others.
58 Sway bars: (Anti-roll bars)
Reduce side to side roll. Essentially they increase the
spring rate when you turn, but leave the bilateral
compression rates unchanged. This also means that ride
comfort is hardly affected, in general a win-win situation.
Most newer VW have sway bars, but aftermarket ones are
stiffer (thicker) and are attached better. I personally
prefer sway bars that mount in almost stock positions (e.g.,
VW, Neuspeed, AutoTech) because they are easy to install and
do not require major modifications. There are other bars
made by H&H and Suspension techniques that have gained some
following. The general recommendation is to change the rear
sway bar first to reduce oversteer, or to replace them both
simultaneously. More recent sentiment has shown that for
certain cars (Corrados) the front camber changes are
significant and a front roll bar is the first to change
rather then the rear. Always keep in mind the racing
regulations in this regards.
From M. Sirota:
Conventional wisdom says that changing the rear swaybar
is a good thing. A bigger rear sway bar will move the
handling more towards oversteer, and will also help in
putting the power down on the way out of corners because
it will help to keep the inside front tire planted.
However, empirical evidence for A1 & A2 VWs shows that a
big front sway bar helps quite a bit, probably because it
pays big dividends in limiting camber change. A big rear
bar might do the same, but I've never tried it since I
only raced my VW in Stock category, and it wasn't legal
to change the rear bar. In short, on an A1 or A2 VW in
Stock-category autocrossing (where you are not allowed to
change the rear bar), run as big a front bar as you can
find.
[At a later date he adds]: Talk with any SCCA Solo II
autocrosser who runs a VW successfully in the Stock
category. In Stock, you can play with the front bar but
not with the rear -- and the secret is to run as much
front bar as you can. Makes the car MUCH MUCH MUCH
faster, *and* easier to drive. It's a big win. This is
a well-known fact. If you're not racing, or you're racing
someplace where it's also okay to change the rear bar,
then I can't offer any particular advice -- except that
you need more roll stiffness than VW provides, for sure.
In an ideal world, we'd only have one sway bar, and it
would be in the rear for a FWD car. However, in reality,
we almost always use two. If you could change everything
else (suspension type, pickup points, spring rates,
damper rates, geometry, corner weights, ackerman, roll
centers, CG positions, and a host of other things) you
might be able to design a perfect system where a rear bar
only would be a good thing. However, this is generally
impossible on production cars, and so we end up using two
bars just so that we can reduce roll without completely
screwing up the handling balance. As a side note, I use
both bars on my Formula Ford, too. I find that even
though I can tune it to be neutral with just one bar, it
feels much better in transients with two, probably
because the roll *rate* is more similar at both ends that
way. And I think they use bars at both ends even on
Formula One cars.
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