Hey all ..last week we were in qualifiers at our local Friday night club race. In between rounds my boy noticed that burn smell from an overheated motor as it passed by him. Holy crap!! 280°. Although I'm no Rotor Ron, I do know a bit about motors. Well, taking apart a brushless motor is straightforward. Finding the reason for the heat is proving difficult. Now, its just as easy to forget it and buy a new motor. Which I did, but I do wanna know why. At first I thought it was a stuck bearing. But it all looked good.. I put it on my buddies analyzer and it showed the same numbers as before it got hot, although I didn't run it to get up to temps. ABC timing is on the money as well. At 40° timing, it never got hotter than 140 and it would stay there after a 7-8 minute practice blast. Any ideas?

Do you use a motor cooling fan?

to large of a pinion gear

Did you check that the drive train was spinning freely with the motor removed? A busted bearing anywhere in the hubs or gearbox can cause the extra heat too, not just in the motor.

Drivetrain binding, overgearing, failed motor fan, bad gear mesh are the common causes.

too high timed....

Wow thanks for the replies!! New tlr 22x-4. With a fan that was on. Box setup for gear. Although its not a stretch to accept I missed something, I keep our buggies pretty well maintenenced. My between round checklist ya know.. The motor wasn't timed too high. The can said 40 but I'm pretty sure actual was 35 or so. Plus, the Temps never got over 140. 130 even. I couldn't find anything binding. Possibly a bad mesh although the spur seemed fine if I remember. Oh well, the mystery continues. Thanks everyone..

i cooked a motor on my 22x-4 when the wire from the motor fan got caught up in the pinion/spur mesh. so not only did the motor not have a fan, the wire created drag. i have since changed the routing of the fan wire.

Just a thought - I had a intermittent problem with a touring car where the fan was very close to the motor. It appeared the motor magnets caused the fan to stop, and moving the fan back fixed the problem.