pic: Team 612 Teaser

[MrForbes]

or....don't forget to put cooling holes at the gear end of your motors! Notice the openings around the orange ring, to let air flow into the motor. The cooling fan at the other end of the motor can't do it's job if you block the cooling slots at this end.

The part that gets hot is the part inside that turns. By the time the heat gets to the outer case, it's too late