Motor spins fine when wheel lifted, but makes ugly rattling sound when on the ground.

[marsines]

Hello, help needed, I couldn't find where is a problem.


Motor: 350W 48V no brand Chinese motor.
Millage: 2000 KM

Issue: Motor/wheel spins fine when wheel lifted, but when I put the wheel on the ground or drive bike,
motor/wheel makes an ugly rattling sound, especially when just starting to accelerate, but it looks like it doesn't
affect torque or total speed.



What I already did/tested:
- tested hall sensors, looks like all working fine (switching between 5v and 0v).
- disassembled wheel and applied new grease, didn't detect any broken parts (from internal gears).
- removed chain, rear disk brakes, to eliminate possible side sounds.


I find out that the rear cassette slightly moving, can it be the wheel motor axle bent, and this why I get that rattling sound?

Video: https://files.catbox.moe/skc9r2.mp4

 

[markz]

Might be a wrong combination of phase and hall sensors, or a cooked motor.

 

[spinningmagnets]

Sounds like the shaft bearings to me. Just a guess...maybe pull it apart?

 

[marsines]

Sounds like the shaft bearings to me. Just a guess...maybe pull it apart?

If it's bearings, shouldn't the same rattling sound will be when the wheel is lifted? Also that rattling sound is only when I engage electric motor, when I ride without motor activated there is no rattling sound.

 

[spinningmagnets]

Yea, you're probably right...

 

[e-beach]

.....If it's bearings, shouldn't the same rattling sound will be when the wheel is lifted? ...

I would say, "not necessarily." If there is no pressure on the bearing while the wheel is lifted it will spin without the extra forces that are applied when the wheel in on the ground. I know it is a big hassle to pull the motor covers open again, but it sounds to me like a bearing has gone bad and is grinding itself while weight is on the whole wheel.

Or, something is rubbing in the wheel while weight is on the axle.

 

[marsines]

.....If it's bearings, shouldn't the same rattling sound will be when the wheel is lifted? ...

I would say, "not necessarily." If there is no pressure on the bearing while the wheel is lifted it will spin without the extra forces that are applied when the wheel in on the ground. I know it is a big hassle to pull the motor covers open again, but it sounds to me like a bearing has gone bad and is grinding itself while weight is on the whole wheel.

Or, something is rubbing in the wheel while weight is on the axle.

Looks like it's not bearings, disassembled the motor today again and found that all magnets lose. video: https://files.catbox.moe/xvkyxo.MOV

Can I glue lose magnets with Moment super glue? Or whats is the best glue for that.

 

[e-beach]

Well, that sucks. So it was something else that was moving....What you need is a high temperature, high strength epoxy. There are some threads about that. However, the orientation of the magnets is very-important. I would mark every other magnet with a permanent marker before you start anything. Then when you remove them, take extreme- caution not to allow them to slam together because they can crack which might change the orientation of the magnetic poles. And, use extreme caution not to crack them when you glue them back.

Do this, in the box in the upper right that says "google search" enter this: endless sphere + loose magnet

You will find a bunch of threads on gluing magnets back.

Good luck with it.

 

[Firedog]

Be sure to check for even spoke tightness. I've had similar experience....quiet off ground, rattles when weight on wheel. Proper trueing made it always quiet.

 

[E-HP]

Can I glue lose magnets with Moment super glue? Or whats is the best glue for that.

JB Weld might be a decent choice. Rated at 550F/287C continuous. The halls on the stator would be cooked way before the motor housing gets that hot.

Are you riding up a lot of hills?