Rubber mounting the birdcage compounds the problem, not alleviate it. The
roof plate, quarter panels are bonded to it with the quarter panels also
bonded to the floor. The floor in turn is rubber mounted to the frame. In
theory, the body/birdcage uniformly 'floats' on the chassis. In reality, not
enough developmental work was done to properly 'tune' the system. Even so,
it will to some extent attenuate the high frequency modes from the
suspension, but will aggravate the flexing of the bodywork.
Better, IMO, to rigidly mount the birdcage and 'float' the panels on the
cage with elastic bonders such as is used on the new Vettes. This is called
constrained layer damping construction, where dissimilar materials are
connected with a flexible medium, and has proven to be far superior in
attenuating wide bandwidth modal vibrations. It will also help in the
expansion/contraction cracking problems from extremes of temperature.
Had Bricklin originally used flex agents when bonding the fiberglass to the
acrylic panels, etc, cracking would be the exception rather than the rule.
GM
----- Original Message -----
> I don't think I'd worry about the strain on the birdcage, but using the
body
> as a stressed member and having it crack does worry me.
>
> I think I'll probably stay with rubber because my new suspension is going
> together with heim joints in place of the rubber bushings, plus pretty
> low-profile tires, so I expect there to be quite a bit more very short
> duration, high-intensity loads (ie: vibration or shock) propagated through
> the frame. I think that isolating the body from that a bit might be a
good
> idea, but I'm open to suggestions.
>
> I don't think that forces like hard cornering (that build up and die down
> relatively gradually) would hurt the body, but I am concerned about say,
> moderate cornering at high speed over rough pavement.
> --
> Phil Martin
|