Originally Posted by email@example.com
2Doggs— motor shafts do break on several manufacturers' motors. I have had output shafts break on two Align 430L motors. Some people think that having the pinion too tightly pressed against the big drive gear contributes to these failures.
This was my first motor shaft failure, and quite a surprise. I'd never tried to do an auto on a 450 before. The shaft broke at the retaining clip groove, where there would be stress concentration. I wonder if it was fatigue failure. The pinion is obviously not perfectly balanced, since it uses a single steel grub screw. My maingear mesh was actually a bit on the loose side - I was intending to tighten it up. Previously, the same motor was suffering from the front bearing spinning in the housing, and after I sorted that out with some CA, there was evidence that the shaft was spinning in the inner race. Maybe that weakened it. All of the above are no doubt cheap motor issues, but at $12 a pop, they're almost disposable. Maybe I'll treat myself to a Scorpion one of these days!