[tech] swaybar question

[nealtovsen@yahoo.com (Neal Tovsen)]

Patrick, the bottom line is: "what do you want the car to handle like"? If
the car handles fine as it is, leave it alone. A stock 16v rear swaybar on
an 8v will not cause you to go flying into the weeds or make your car
"twitchy". It will make the turn-in a little better and it will understeer
less. If you drive the car at the limit (which few of us ever really do), it
will be more capable of swinging the rear end out...but you'd still have to
try pretty damn hard to do it. There are no safety issues involved here!

> The 16V is heavier than the 8V. Specifically, the front of the 16V is
> heavier. So, the front springs have a higher spring rate than the 8V
> front springs. (The rear factory springs are different also, but their
> spring rate isn't much different.) Higher front spring rate increases
> the front roll stiffness. So, with a cornering load more of the weight
> transfer will happen at the front causing the car to understeer. VW
> compensated for the stiffer front springs by increasing the rear roll
> stiffness with a larger rear sway bar.

Sorry, but no. Higher front springs do not increase roll stiffness if you
also increase the load applied to them. A 600lb spring with 600lbs on it
will compress 1 inch. A 300lb spring with 300lbs on it will also compress 1
inch. Presuming VW made proportional changes to the springs (which they
probably didn't exactly, but more-or-less), heavier front springs will
compensate for the heavier engine while maintaining the handling
characteristics. Swaybars do not carry weight, but they do influence the
transfer of it. The larger rear swaybar on the 16v makes the car understeer
less, which is appropriate on a car designed to be more of a "sports car"
than the 8v was.

Except for this, Dan's mostly right about his theory. However, he implies
that "the car is reasonalby balanced in it's handling from the factory",
which I disagree with.

Virtually all manufacturers develop their cars to understeer heavily from
the factory. This is to make the car more forgiving and therefore safer for
the average driver. This is especially true in the US market. Many imports
have smaller rear swaybars or softer rear springs in the US market than they
do in their home market because the manufacturer doesn't want to be sued for
a "twitchy" car that somehow caused an accident.

All VW's push horribly from the factory. You can increase rear roll
stiffness quite significantly to improve balance/handling without making
other changes to the system. On my 16v, I run the stock front swaybar with a
28mm rear Autotech bar. I also do quite a bit of autocrossing, so I prefer
the car to have more "eager" handling. :) Even with this bar, the car
understeers in most situations...with 65/35 weight distribution, this is
hard to overcome! However, while negotiating a slalom at maximum speed, I
can spin the car out if I don't balance the throttle properly.

The suspension *is* a system, and it should work together. However, this
does not mean that you have to take every part from the same manufacturer to
get good handling. That's a marketing ploy, but if you don't want to think
about it, it should work OK. All "packaged" setups are a compromise that may
or may not suit you. If you read the books and spend the seat time to play
with different setups, you can change the system to perform the way you want
it to. If that means using Neuspeed front swaybar and an Autotech rear
swaybar, so be it. Just make sure it is an educated decision...

Neal


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