[Al Skierkiewicz]

Steven,
The method you have pictured is really an OK way to hold down the motor. The end bells are soft but should not fail if you tighten the clamps. I would be sure to use something to prevent the motor from turning in the clamps. A "V" block or some other device that will bite into the motor housing. The outside structure of the motor is steel but you need to remember that the magnets are glued inside the black part of the motor. There is very little internal clearance between the magnets and the armature so any deformation of the case will push the magnets closer to the armature or will actually crack the magnet.