Think about what a swaybar is and how it works. I simplify the argument by
considering only one axle end of the vehicle. In order for the body to roll
with a swaybar attached it must carry some portion of the inner unsprung
weight on that end of the vehicle with it, from which some resulting force is
transferred torsionally through the bar to the outside tire. With enough
tire grip and stiff enough bar the entire inner unsprung weight will be
carried; the inner wheel will lift off the ground if roll is great enough
relative to suspension travel. In reality, the end of the bar located on the
outside of the turn is, for all purposes, fixed. However, that's really
immaterial to the argument.
My argument states that the moments at the ends of the swaybar are equal, not
the forces. What is torsion, but a moment, which is force applied a specific
distance perpendicularly about a centerpoint of, in this case, a shaft.
Consider the moment equation derived from Newton's Law that for every
reaction there is an equal and opposite reaction. Assuming that the end
links connect to the suspension in identical locations, the body pivot points
are in identical locations, the diameter and shape of the bar is symetrical,
etc., etc. :
(A1xB1) = (A2 x B2) ... the summation of the moments must equal zero
where A1 = left force, B1 = left arm length, A2 = right force, B2 =right arm
length
which transcribes to A1 = A2 x (B2 / B1)
when the arms are equal length B1 = B2 then A1 = A2, the forces are the same
however when the lever arms are a different length the applied forces side to
side will vary based on the ratio of the lever arm lengths; the applied
forces are not equal. The end result is that you'll see a different amount
of roll in one turning direction than the other based on the bias of the
forces. It is the force from the outside bar end that will be transferred to
the outside tire (indirectly via the various connection points), so it should
be easy to see that outside tire loading will not be the same at the same
point of body roll side to side, hence handling balance side to side is
affected.
Further, very few street bars are the straight, Speedway-style type. Most
street bars comprise multiple bends, which changes their character
dynamically when compared to a straight shaft. When the bar lever arms are
identical the bending torsion is distributed equally throughout the bar about
it's center, resulting in an equal reaction from side to side. When the
lever arms are not equal the bending torsion will be biased more to one side
of the bar than the other. With a multiple bend type of bar this will result
in different dynamic reactions of the bar between the two turning directions,
resulting in an added roll bias force factor; dependent on the particulars of
the bar.
The again, what the h*ll do I know; I've been wrong before. Im certainly
open to opposing arguments.
M Sipe
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