Howdy,
On Mon, 2 Aug 2004, Dick Rasmussen wrote:
> I'm assuming that you have determined that none of the famous BMW bushings
> and mounting points are worn out or broken and that the hubs, etc. are ok
> and nothing is loose. Also, I assume that any "rubber" in the steering
> system (rack mounting or steering shaft) is healthy and not deflecting
> excessively.
Well, all the stuff I know about seems to be fine...
Control arm bushings look to be ok. Ball joints & such seem to be ok. I
did notice something that struck me as weird though... More on that below.
> I'm also assuming that your expectations of what should happen are
> realistic based on your experience and on Sam's, etc.
>
> Personally I don't think dead shocks would cause the problem due to being
> "too mushy".
>
> My suggestion/guess is that you have a major bind problem somewhere in the
> front suspension as you turn in to a corner. Either a shock is binding or
> some other aspect of the front suspension is binding or is much too stiff
> (way beyond what stiff springs/bars could cause). Or the shock, etc. is
> bottoming due to lack of travel or the spring is coil binding. Maybe the
> sway bar is binding or running into something. Or the control arm pivot
> bushing is binding. If the control arm bushings are still stock did you
> torque them with the suspension at ride height or at full droop?
>
> As a result the outside front wheel rate goes to "infinity" and the tire
> slides. I actually had that problem with a Stock Datsun Z when I added hard
> rubber sway bar end links to a relatively stiff front bar. Car would
> "randomly" slide the outside front tire on turn in. Went back to stock
> rubber bushings and the problem went away.
This is interesting.
Because I was wondering similar things.. I.e. if something was worn/sloppy
on the front end, I did the standard "check the ball joints check of
lifting the car until the front tires were a few inches off the ground,
then taking a 4' long steel bar, stick one end under the tire, and
levering up against the bottom of the tire. The test is to be sure that
the only movement is the suspension compressing.
For whatever reason, I decided to try to compress the suspension some.
Bear in mind, with the coil over's and stiffer front springs, the springs
are floating free for the last couple inches of strut travel. Both front
wheels were also off the ground.
It required a _lot_ of force (like, me lifting up on the bar for all I was
worth) to compress the suspension much at all, and even then I don't think
I ever got to the point where the spring actually made contact with the
upper seat.
At the time I wrote it off to the swaybar bushings being stiff and
resisting the motion. Your comments have me wondering if it wouldn't be a
good idea to unbolt the front bar and try it again / clean & lubricate the
chassis bushings.
The main thing that's making me doubt the shocks is that adjusting them
doesn't seem to have any affect whatsoever. The guy I got them from is
someone I trust though, and I know they were working when they left his
car a year or two ago (I'd driven his m3 with this exact suspension, and
was quite pleased with how that car turned... But he was on real tires
also...)
Anyway, I think I'll investigate the front end a bit more and maybe play
with alignment prior to spending money on struts that I don't have...
Thanks for the thoughts (to everyone else as well!)
Mark
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