Re: Spring/Shock Combo's

[Huw Powell <human@nh.ultranet.com>]

> Me confused as well...
> > > The brace will conquer the body roll famously.  I bet the 4kq would
> > > benefit from a rear brace as well, but it occurs to me that my 2wd
> > > coupe doesn't have rear struts to brace anyway...
> > Can somebody please explain to me why a strut brace will reduce body
> > roll? 

OK, let me first point out that I don't know what the heck I'm talking
about here...

My observation is mostly based on what changed about my car when I
bolted that sucker on.  It stayed level while turning, radically so.  On
little turns, low speed stuff, it was like a lawnmower or something - it
just stayed level.  On harder turns, it dips a whole lot less than it
used to.  Is this body roll that has been lessened?

How does it do it?  I think the sway bar is doing as much as it can from
below, to apply opposing force to the control arms, trying to keep them
level.  (deep water warning - I can't swim!)  Since the suspension seems
to me to be essentially a parallelogram (or trapezoid?) in the lateral
cross section of the car pair of dimensions, stiffening the other long
side of the figure (the top) aids in the process.  Of course what this
"stiffening" amounts to dynamically is that as the parallelogram
(trapezoid!) is being pushed out of shape at one corner, the sway and
stress bars are transferring the force across to the opposite side, even
the opposite corner, to attempt to correct this distortion.

This all depends on the tendency of the strut towers to be able
(undesirably) to move relative to each other without something taking
corrective action.  The stress bar does this.  This relative motion I
would presume to be in all three dimensions, affecting caster, camber
and toe in.  Lessening this makes the car behave better while cornering,
by keeping the alignment of the tires where it is supposed to be,
relative to each other and the body.

Have I rented a clue yet?

Love to hear how close I am from someone who actually knows about this
stuff.
-- 
Huw Powell

http://www.thebook.com/human-speakers/audi-main.htm