flyinbrick
100 mW
Hi,
My BMC motor failed suddenly the other day on my commute. The motor is a BMC 600W. Best I can tell, it is a v2 speed version.
I got it used, then put about 2k miles on it at about 1500W - gradual starts with CA3 programming.
Symptom: when I throttle, I hear the motor spinning, but no propulsion. I can pedal freely with no problem. When I flipped the bike over and applied throttle, the wheel moved forward every so slightly, but something was slipping very badly. My guess was the planetary gears were barely making contact with the case teeth.
I disassembled the motor and this is what I found:
1. Clutch has green composite gears - some teeth chipped. The teeth did not appear to be ground down.
2. With the motor and clutch out of the case, everything appeared to spin freely with throttle application.
3. After pulling clutch out, the bearings on the planetary gears were in bad shape. Two were sloppy, one was binding (or maybe damaged while pulling out?)
4. The clutch appears to be functional - spins freely in one direction and I cannot get it to slip with my hands on the other direction.
5. put the clutch directly in the case - the planetary gears and case teeth meshed pretty tightly - teeth did not appear to be ground down.
So the planetary gear bearings are definitely bad, but the failure does not make sense to me. If the clutch and all the gear teeth appear OK, then what is causing the slipping? If the motor works and the spur gear is OK, by deduction, it must be something in the clutch assembly. But I cannot understand the failure and I don't want to install a new clutch to find that this is due to a different problem.
Can anyone help?
My BMC motor failed suddenly the other day on my commute. The motor is a BMC 600W. Best I can tell, it is a v2 speed version.
I got it used, then put about 2k miles on it at about 1500W - gradual starts with CA3 programming.
Symptom: when I throttle, I hear the motor spinning, but no propulsion. I can pedal freely with no problem. When I flipped the bike over and applied throttle, the wheel moved forward every so slightly, but something was slipping very badly. My guess was the planetary gears were barely making contact with the case teeth.
I disassembled the motor and this is what I found:
1. Clutch has green composite gears - some teeth chipped. The teeth did not appear to be ground down.
2. With the motor and clutch out of the case, everything appeared to spin freely with throttle application.
3. After pulling clutch out, the bearings on the planetary gears were in bad shape. Two were sloppy, one was binding (or maybe damaged while pulling out?)
4. The clutch appears to be functional - spins freely in one direction and I cannot get it to slip with my hands on the other direction.
5. put the clutch directly in the case - the planetary gears and case teeth meshed pretty tightly - teeth did not appear to be ground down.
So the planetary gear bearings are definitely bad, but the failure does not make sense to me. If the clutch and all the gear teeth appear OK, then what is causing the slipping? If the motor works and the spur gear is OK, by deduction, it must be something in the clutch assembly. But I cannot understand the failure and I don't want to install a new clutch to find that this is due to a different problem.
Can anyone help?