We discovered an unfortunate failure with our Falcon motors today. One of our motors had completely locked up and would not spin even under hand power. When we opened up the case, we found that the shaft retaining screws had all loosened. One of them was so loose that the head of the screw was rubbing against the forward shaft bearing, and that friction sheared off the screw head and caused the bearing to self-destruct. The shrapnel then lodged itself in the rotor and locked the motor. When we disassembled our other Falcons we found that the same problem of the screws loosening was starting to happen; luckily we caught it in time before they also committed suicide. We did not replace the shafts on these motors; they have the factory shafts. We talked to another local team 1577 who is also using Falcons this year and found that they had the same exact problem: one of their motors broke completely and the others showed signs of this process beginning.
Here you can see the rotor with the sheared screw (we removed the other screws):
And here you can see the face plate of the broken motor compared to one that did not break yet. The loose screw seems to have gone through the bearing and rubbed the finish off of the face plate.
We contacted Vex support about the issue and they suggested removing all of the screws from the motors and securing them with loctite. Apparently this is also the solution 1577 used and they haven’t seen the problem come back. We are going to do this to all of our Falcons tomorrow. I highly suggest that any teams using Falcons this year take the time to make this repair so that they don’t end up with a $140 paperweight like we have.