More..Upper stress bar questions

[onesixv@juno.com (Eric L Ellis)]

I understand your point when speaking of the two point bars, but have you
taken the 4 point Neuspeed bar into consideration?  Just wondering.

Eric
"Good, bad...I'm the guy with the gun!"
http://www.geocities.com/blitzkrieg16v
AOL IM:  OneSixV
http://www.geocities.com/onesixv

On Sat, 15 Jun 2002 07:06:31 -0700 "Larry" <rocco16v@netzero.com> writes:
> After reading recent posts about rear stress bars, I started 
> thinking
> (uh-oh...).
> Does that item actually perform a useful function?  Oh, I know many 
> of you
> report impressive handling improvements resulting from the 
> installation of
> one, and I was seriously considering putting one in my own roc.  
> But, after
> looking carefully at the rear suspension design, I don't believe 
> they can be
> of much benefit.
>   Yes, they certainly minimize the movement of the rear 
> damper/spring unit's
> upper mounting points, but only in one plane, that plane being 
> directly
> towards and away from each other (>< or <> aka the x-axis).  The 
> big
> question is:  what stresses would make these two mounting points 
> move
> together/apart?
>    Lateral forces from cornering are completely absorbed by the rear 
> axle
> mounts (axle-to-floorpan). No lateral stresses (x-axis) can be 
> present at
> the top of the damper/spring units because these units are attached 
> to the
> body and the rear axle with flexible attachments.  When the rear 
> axle moves
> slightly sideways during cornering, the damper/spring units just 
> pivot
> slightly in their upper and lower rubber bushings and absorb this 
> movement.
> The bottom of the d/s unit moves in the x-axis with the axle, but it 
> pivots
> on the mount, therefore it cannot transfer x-axis forces to the top 
> of the
> d/s unit. (Okay, it does transfer very small amounts, because the 
> mounts
> have some stiffness, some resistance to that flex, being made of 
> rubber or
> polyurethane.  If the mounts were Heim joints, there would be zero 
> transfer
> of force).
> 
> The only significant stress on the upper mount (at any time) is in 
> the
> z-axis; a VERTICAL direction (^), which the stress bar cannot 
> control.
> I realize that this may unleash a flood of responses telling me how 
> wrong I
> am, but before any of you do that, be sure you can back up your 
> postion with
> more than "Hey, all the racers use 'em and they can't all be wrong!" 
> or "I
> put one on my car and could really tell the difference."  Those are 
> not
> valid, defensible engineering positions.
> 
> Any thoughts?
> Larry  sandiego16V
> 
> ----- Original Message -----
> From: <Cmr446@cs.com>
> To: <scirocco-l@scirocco.org>
> Sent: Saturday, June 15, 2002 12:28 AM
> Subject: Upper stress bar questions
> 
> 
> >   I need opinoins or reasons on which is the better design for an 
> upper
> > stress bar;
> > the solid type like the Eurosport, Neuspeed or ABD model, or an 
> adjustable
> > one like the Autotech bar.
> > Carl
> > 77rocco
> > 89fox
> 
> 
> 
> _______________________________________________
> Scirocco-l mailing list
> Scirocco-l@scirocco.org
> http://neubayern.net/mailman/listinfo/scirocco-l
> 

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