Re: Front sway bar

[Iain Mannix <mannix@privatei.com>]

On Fri, 14 Feb 1997, Chris Taylor wrote:

> >>Needless to say, everyone backed me up.
> >
> >Not everyone;).
>
> Well, regarding NOT getting a thick front bar.

Right.  Shine is onto something, really - but they are by no means the
originator of the concept.  I believe a large problem aassociated with the
"no bar" concept is this - people are using no front bars without taking
into account what must be done to the rest (rear) of the suspension.
Limiting body roll is critical in a VW to handling - if body roll is not
somehow limited, the front tires roll off their contact patch.  Keep in
mind that the "hot" SoloII Stock class setup for VWs is a BIG front bar.
Not 22mm big, but bigger, in some cases.  In Stock, front bars are free,
rear must be stock (so if it came with one, you can use it.  If the car
never had one from the factory, you cannot put one on).  Bob Tunnell put a
2.25" front bar on his Rabbit - yes, the diameter of your TT exhaust - it
was called Mongo.  The idea was to limit body roll as MUCH as possible, so
grip could be attained in high G situations.  It worked, he won ES that
year at Nationals.  So, to answer Shine's question "Why would you want to
put a front bar on a car with 65% of its weight on the front wheels?" the
answer is this - to limit body roll.  Apparently, BTs bar was set up a bit
"loose" to let the car turn in, to negate initial understeer, but then, as
the car rolled, the bar came into play, severly limiting body roll, thus
helping preserve camber.  Now, the absence of a front bar can work, IF the
springs in the front limit body roll enough.  That's pretty stiff.  It
arguably would be better than a 2" swaybar wrt exit traction, but in
Stock, this was not an option.  So, in SP, SM, or simply modifying the
cars to make them as fast as possible, there are a few ways to do it -
IMHO, if you are going to go the "no bar" route, the front springs have to
be WAY stiff.  I believe that ride quality suffers from a street
standpoint with springs this stiff (500ish pounds, almost 2x stiffer than
Nspeed Race).  So, my vote for the "ultimate" street setup would be to use
a 22mmish front bar, 28mm rear (and then some, personally), and Race
springs at least - lowering springs are a bit soft IMHO, and in some cases
lower the car too much.  Race springs do not necessarily mean "bad ride."
Ask Shawn.  I have Races in the front (and stiff rear), and Konis with
poly bushings - it is stiff, but not unbearable.  WIthout the super stiff
rear springs, my car rides pretty well.  The poly bushings contribute to
the moderate stiffness as well.

Bonuses of the no bar/lowering springs/good shocks setup are these - less
complexity, less weight, great turn in, good traction exiting corners.  I
personally don't feel that exit traction is all that important on the
street - I've never had a problem with it away from the autocross courses.
IMHO, if exit traction is an issue on the street, I'm driving too fast.
YMMV.  I've chilled out a LOT on the street since I started autocrossing.
A car without a front bar and soft lowering springs (for reference, I
consider all "lowering" springs to be soft - they're stiffer than stock,
but in relation to what the car does in corners, they're soft) will
ultimately understeer - the rear of the car will roll enough that the car
will understeer a bit - on the street, it might feel as though the car is
balanced, at the limit of adhesion (which the fronts probably are).  This
is good - much as we like to be cool and say "my car oversteers at the
limit" this is really, IMHO, bad.  My car does in fact oversteer at the
limit, which is scary on the street.  If you're in a steady state corner
in my car, and the car starts to let go, you  have a short time to GET ON
THE GAS before it goes backwards.  Ask Kevin.  He's seen it at an
autocross, I had a day of oversteer.  Blah.  Now, if you lift in my car,
well, consider it akin to nailing the ebrake - the car rotates - not a
little, but ROTATES.  Spin city.  My car has become VERY specified to
autocross, it is not really a good street car anymore - if you come around
a corner with sand, well, set up, flatten the go pedal, and hope the front
pulls you through.  Hope for UNDERSTEER.  It can be driven fast, and on
the autocross course, it is very drivable, because you are planning on
driving AT the limit.  Unfortunately, on the street, driving at the limit
means the car is about to go around.  I have to tiptoe on the street.  A
setup like Shine recommends, with a big set of springs, 28mm rear bar, no
front, is probably good for the street.  My setup includes an extra rear
bar, big springs, 22mm front bar set up a bit loose, so the car turns in,
but once into the bar, it stays flat.  It works for me.




>
> >I'll post more on this later, have to do stuff.  Basically, Shine has a
> >viable (but not be all/end all) setup for roadracing, imho.  I'm not sold
> >on the "no front bar" for autocross.
>
> Dooohhhhhhh!  That's right.  Shrine was referring to road race, not autox.
> Sorry.  Eagerly awaiting your responses on the best STREET (zippin' around
> town) setup.


OK.  So what am I saying.  Basically, the common 22/28/spring/shock combo
is probably the easiest/most bearable street combo - the car will
ultimately understeer, but comfortably.  Oversteer can be provoked by a
lift in a turn, or a little lfb. This does not mean the car "oversteers."
A car that CAN oversteer through certain inputs is drastically different
than one that OVERSTEERS.  Saying a car oversteers at the limit means that
you do nothing - just drive into a corner too fast - and the rear lets go
first.  This is not really desirable for the street, because the stakes
are too high.  I'd prefer a car that ultimately understeers on the street
- not a plowing pig, but one that will essentially save you if you are too
hot - I remember taking a friend for a ride, got a little light on a cool
road (KW - with Randy by Horsetooth), and the car began to understeer a
little - this gave me the time to lift and brake a little, rotate the car
comfortably, and continue on.  That was without the second rear bar.  In
its current form, the fronts would have stuck, the rears would have
drifted out, off the side of the road, car spinning, I hate to think what
would have happened when the rear wheels tried to get out of the dirt,
back onto the pavement.  Inverted operation, most likely.

So, what do I think the "ultimate" street setup is?  Probably
22/28/lowering.  If not, 28rear/race/no front bar.  From my experience,
either one will result in a good street car with easily provokable
oversteer, if you WANT it, but won't be as likely to bite - it won't let
you know it is letting go by spinning.  Basically, either setup will be
aggressive enough to spin if you make a mistake, and performance will be
adequate on the autocross track, but autocross(ultimately) and
street(ultimately) are two very different things - on the track, you want
the car to oversteer, on the street, it is better to have to
uncerimoniously back off, slow down, and keep driving - as opposed to
crashing.  Just my .03.


For autocross/street, if you want to be fast, I say use a front bar.  Just
me.  Some are very fast without one.  For me, I like the bar.  WHen I say
autocross/street, I should qualify - autocross being the primary concern,
street being the means you get the car to the track.  With a setup like
mine, driving fast in the canyons is potentially destructive (so I don't
do it anymore - too risky).

  Hope this helps, to sum up - when setting up a car for street/aggressive
driving everywhere, set your defaults to understeer - you might need it
someday.  If you screw up big, and essentially tell the car to do what it
wants, make sure it is going to push just enough to let you bring it back.


Mannix (I could go on all day.......)


>
> L8R!
>
> Chris Taylor
> '87 Scirocco G60-to-be
>
>       Virginia Polytechnic Institute
>           and State University
>          College of Engineering
> chtaylo4@vt.edu ::::: chtaylo4@aol.com
>
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