The sides being tapered (draft) seem to be the biggest problem,
especially with the internal concave section at the top - who
insisted on this again !? I'm wondering if it's worth it.

G'Day George,
 I "suggested" the shoulder for the mount, based on experience with VW
buggy engine mounts, where the bolts carry the loads in shear. The
threaded holes crack radially and then the bolts pull the whole thread
out like a plug. If it is a problem, then delete it. At assembly stage,
install a plate like a large washer on the inside to spread the loads;
but I doubt it would be as effective as the cast in shoulder. Dave McC,

Perth--

David,
Yeh!  I knew it was you just having a whinge, but got it solved now. However
I think the steel plate might be the better option. Personally I don't think
I would trust threaded aluminium here without a large washer and nut on the
inside anyway.
Went to the machinist and had another look to day - it's looking good.
The new chap was working on it as the foreman is away sick. This chap knows
the fellow who developed the Jabiru - sold him all the CNC machines he uses.
It would seem his (Jabiru developer) background is in engineering.
Small world.
George (down under)

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