[Al Skierkiewicz]

Woody,
It sounds as if you have some weight to spare but heatsinks on the outside of motors are very inefficient for cooling. The majority of heat is built up inside the motor armature due to high current. That heat is only conducted to the outside of the motor by radiation, a little convection and conduction through the motor shaft via the bearings. If you are experiencing heat on the CIM motor, you have raised the temperature of not only the armature but the magnet and outside case structure as well. I would guess that if the case were above 100 degrees, the internal temp might even be twice that. The motor will simply not last long with that stress. You should really look at the motor curve as it applies to your design. When you get into the finals, you might not survive with the repetitive heating of the motor as matches get closer together and driving becomes more difficult.