crossmember update (more pics..)

[Dan Bubb" <jdbubb@ix.netcom.com (Dan Bubb)]

I have a theory here, so y'all get out your flame throwers!
The theory is based the fact that I've had my Scirocco for 18.5 years and
have always driven it hard. Not slamming shifts, but alot of WOT and high
RPM downshifts. In other words, I've had as much opportunity to crack my
chassis as anyone and to date, with 240,000 miles, NO cracks.
The two powertrain mounts that do the most to dictate the position of the
engine are the side mounts. They sag with time. The rear and front mounts
can be adjusted to accomodate this sag to some extent. But, if they're not
adjusted they end up supporting most of the weight when their main function
(imho) is to resist powertrain torque. So, if you never adjust your front
and rear mounts and don't replace your passenger side mount regularly, you
have an abnormal load on the front and rear mount. The front is the least
able to take the load, so cracking results.
Did you all know the front mount was an after thought. The Scirocco was
originally produced without a front mount. A retrofit was added to the '75
Scirocco, and the current mount design started in the '76.
So, that's my theory! Adjust and replace your powertrain mounts often.
Dan

>If this were the case, why is
> my crossmember cracked on the bottom rather than the top? Tension causes
> cracking, not compression (or at least it takes a great deal more
> compression to crack sheet metal in general)
>
> Could you clarify your statement?
>
> Thanks,
>
> -Toby
>
> On Mon, 3 Mar 2003, Allyn wrote:
>
> > > First of all, the force vector acting on the crossmember points
straight
> > > down.
> >
> > umm, during a downshift perhaps, but the major load is in the upward
> > direction, during acceleration. i think this makes your whole
explination
> > backwards (as far as tensile/compressive stresses), but it will work
just
> > the same.
> > Al
> >
> >
>
>
>
> _______________________________________________
> Scirocco-l mailing list
> Scirocco-l@scirocco.org
> http://neubayern.net/mailman/listinfo/scirocco-l