This is kind of like the difference between stressed skin and tube frame
structures.  The cast bellhousing is like a stressed skin structure.
Stressed skin is more elegant, and somewhat prettier from a laboratory
standpoint, offering some slight advantages in structural efficiency
(depending on the materials and manufacturing process) - lighter
weight.  The Tracy Crook structure might be more like a tube frame
structure..  Easy to see what's inside, easy tooling to construct,
rugged (not easily dinged/dented), easy loadpath analysis and maybe
slightly less structurally efficient than the stressed skin design (but
probably not much in this case).  It's quite possible that if you made
the bell housing style thin enough to realize any lighter weight via
structural efficiency, it wouldn't be rugged enough in service, or would
be very difficult to manufacture (tough to cast something thin enough to
be lighter).  These ideas have been discussed before..  Sorry if this
seems like extraneous review.


Regards,

Matt-

Well they are high pressure die cast which is way beyond what we can afford.
We are talking $200,000 to $500,000 for the molds. The mechanical properties
are far far better than sand cast.
-- 
Paul Lamar ...No rotor no motor.

Paul,
There is one new option, which I haven't investigated yet and that's High
Pressure forming i.e. using high pressure to form from plate. This is a
relatively new technology and would be an ideal compromise for a shape like
this - even better than High pressure cast type as it would be stronger and
possibly thinner and lighter

I assume the tooling is again prohibitive!?
George (down under)


Or spinning. I looked into spinning but it was not cheap.

-- 
Paul Lamar ...No rotor no motor.

Paul,
I looked at spinning as well, but the more you have to add by welding the
more distortion you have as well as the labour costs.
I will look into this pressure forming - but don't hold high hopes for a
cost effective solution.
Pressure forming will allow a certain amount of stiffening ridges to be
created- as in the Mazda cast bellhousing, however I assume these wouldn't
be high -.5" at the most I assume, otherwise you may be thinning out the
material too much.
I figure using 5mm thick plate with some sections thinning to 3 or 3.5 would
do the job, perhaps starting with even 4mm as plate is much stronger than
anything else . One would have to add some mounting point thickeners, but
there should be little if any machining.
I'm wondering if your up to taking one of your drawings and converting it to
flat plate to see what sort of area material we would need as well as
weight.
I also wondering if we could look at thinner wall chrome molly and compare
the weight. I don't know what thickness would be needed in chrome molly ,
but it sure would be strong!!
I will check out the costs and feasibility.
George (down under)


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