Re: Opinions on Antisway Bars please...

[Randy Walters <RandyWal@xxxxxxxxxxxxx>]

Nathan Harris <nathan_c_harris@domain.elided> wrote:

>I have an 86 325es and would like to stiffen it up for
>autocross and maybe some track use.  I already have
>40mm lwer springs and Bilstien (sp?) Sports on all 4
>corners.  But when I saw some pics of me at the autox
>the car was leanong alot more than I thought it did. 
>The spoiler was almost touching the ground.  So, with
>the obvious rear sway bat mount problems, what is the
>general consensus on whether these are good upgrades. 
>Thanks,  Nate

 The problem with tearing the rear body tabs off seems to be
caused more by using soft springs with a stiffer rear aftermarket
swaybar, and i can see why (them tabs are whimpy!).  As long
as you have stiffer springs,  you can get away with larger swaybars
(but i'd still keep an eye on those tabs regardless).  But these
cars are heavy and the swaybars don't do a lot for limiting body-
roll.  For that you'll need even stiffer springs then what you have.
Swaybars are more for fine-tuning the car's handling than reducing
body-roll.  Your particular car should already have the larger factory
swaybars (325e Sport versions should have the 20mm front bar
and either a 12mm or 14.5mm rear bar).  If you do indeed already
have the 14.5mm rear bar and 20mm front bars then there's not
a lot to be gained by going to even larger bars. The springs are
what's allowing the body roll.  Personally,  the largest i would
go is an adjustable 22mm front bar and either the stock M3 
14.5mm rear bar or one of the smaller aftermarket 16mm
adjustable rear swaybars.   There are some 19mm rear bars
out there but i wouldn't go that big unless you get the rear
swaybar mount re-inforcement kit.  I'm against using this
kit unless the tabs are already starting to tear (or are about to).
FWIW i'm running a Racing Dynamics adjustable 22mm front
bar and a stock E30 M3 14.5mm rear bar and the car rotated
very well on course with the H&R springs.  

 I assume your 40mm lower springs would be about the same stiffness
as the H&R and Eibach sort of lowering spring, and these springs simply
are not enough to keep the car flat on the autocross course.  I've run my
car in stock form and later with various spring and swaybar combos and
even with my larger-than-stock swaybars and H&R springs the car leaned
badly on the autocross course (like you i saw pics of myself on course and
i was shocked at how much body-roll the car had!)  I would have thought
the H&R springs would keep the car much flatter than that but no.  There's 
a few pics of it leaning in this configuration on my PhotoPoint Photo Album
thingy.

 So i went full-boat and installed a Ground Control adjustable spring setup
so i could run a much higher spring rate and that has finally harnessed my
excessive body roll on course.  The ride is a lot stiffer now but it's actually
not that bad around town, and on the open road the car is a lot more
planted than with the H&Rs.  My current spring rates are 450# front 
and 600# rear.   My autocross friends all report that the car is *much*
flatter on course now, and my times are a second or two faster right 
off the bat.  The stiff springs made a bigger improvement than any 
other mod i've tried to date. 

Randy Walters
89 325is DSP

http://albums.photopoint.com/j/AlbumIndex?u=153582&a=1200064

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