In a message dated 4/10/02 9:20:35 AM Central Daylight Time,
From: Bob Pariza <bpariza@yahoo.com>
Subject: A/R bar question...
<< My real question, for anyone who would like to reply, is: Is there such a
thing as too much roll-stiffness, and if so just what does it get you? I'm
looking at bigger a-r bars, but there are lots of choices. Fortunately for
me, they all seem to come in f/r sets, so I'm anticipating that the fore/aft
balance was done by someone with a clue (as opposed to me). I've found some
aftermarket 'bars that claim to be 40% stiffer than the factory "road race"
bars and am wondering if perhaps that's a bit much, hence the question. Will
"too much" roll stiffness get me more weight transfer to the outside tires
resulting in an earlier slide as the overworked outside tires give up? Or,
will planting them harder (hopefully smooth transfer so that we don't rush
past the limit, as described above) make them stick better? Or (final
option) does everything depend (meaning that the only way to find out is to
buy them and try them)? >>
Yes, you can certainly have too much sway bar, but how much that is depends
on many things. On my rear drive Celica with a modest 2% front weight bias, I
tried a huge set of bars, and on smooth surfaces they were great. Body lean
was barely 1 degree at about 1G. The springs I was using at the time were on
the soft side, so it actually work kay on the street. the front bar was
actually a stock WS6 Trans Am bar. My Celica only has a front axle weight of
1400 lbs. The front of the T/A is probably more like 2100 lbs. The problem I
ran into was setting the shocks to work in different conditions. The shocks
had to be stiff to control the bars, but then they would over power the
springs. If I softened the shocks to work with the springs, then they
couldn't control the bars. Basically I ended up with a car with a very high
limit, but any bump would send it sliding.
Currently I am back to stock sway bars, but 325 lb/inch front springs, (my
Eibach pro kits were just 185 lb/in) and the roll rate is only a tick softer
than the big bar setup. The rear setup also went through a similar change at
the same time. 130 lb/inch springs and a 1 inch bar down to a 5/8 inch bar
and 275 lb/in springs. The car is much more controlable when it hits bumps.
Lean is about 1.5 degrees at 1G. A bit softer in roll than before, and I may
go up a bit more with spring, but I am trying different alignments first to
see what works.
If you are on the smoothest surface on earth, then huge roll stiffness will
work, but just like springs, you need some compliance to make it over bumps
without loosing traction.
Compared to street driving, you probably can tollerate a bit more bar for
autocross, so I would guess any "street use" sway bar set will not be
unuseably stiff. Many street bar sets may also be dialed in for a bit of
push, for liability sake. You know, there is noone on the street qualified to
drive a neutral handling car.
Gary M.
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