Re: Anti-roll bar diameters

[albert jenab <jenab@xxxxxxx>]

At 02:30 PM 2/23/99 -0500, Jay Sala <jsala@domain.elided> wrote:
<snip>   

>Who would have
>expected the M3 to have a smaller front bar than a 328i??!!

Roll stiffness is not solely a function of bar diameter.  The spring
stiffness plays a big role, as well as length of the lever arm acting on it
due to how the bar is attached to the suspension.  The pick up points for
M3 vs. 325is front bar are different (at least in 95 they were).  M3's
attach to a flange on the body of the strut.  Don't know if the lever arm
is longer vs. 325 though.  I am pretty sure spring rates are different too.

Some tuners sometimes put smaller bars on after putting stiffer springs on,
as total roll stiffness would be too high at that axle otherwise.  This is
just to maintain the existing balance of the car.  Then there's the whole
front/rear bar tweaking to get understeer/oversteer right.

Anyway, swapping bars on the same car with all other factors fixed is what
you need to do to make comparisons valid.  Good info nonetheless.
- -Al
95 M3

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