Strange noise MP5

[Dias]

Hi again, im here with (another) issue ...

First thing is my freewheel which keeps wiggling, probably a minor problem. A friend of mine who is much more experienced with bikes told me its kinda normal. Have this happened to anyone else? I need to re-center my wheel too but I fear that the hub axle is bent.

The other problem is worse. I started hearing something like spokes "popping" at first (could be the need to re-center), thought its my brake which is usually the source of problems at first. I retightened it and noticed a loose disc screw. I was like "aah, this is it". Nope. Actually I started up my bike and it made a jamming sound. Had to tweak it for a while so I could get back from my work, after a while it seemed ok. I was a bit low on battery (50.4V 12s LiPO, 46V when I got home - at this voltage motor gets weak) and 2km away from my home it "jammed" twice when I throttled more than 70% uphill. The motor havent stopped completely but it sounded like something "tightened the drive", similiar to braking with a huge force with a rubber. 

This is how my motor sounds now: https://streamable.com/fe8ox

It sounds like there is something in the way that makes the scrubbing sound (same sound appears when there is no brake).

Any clues? Hope I can repair this cause I cant imagine my life without a bike . Thanks a lot.

Update:
Found a similar video here: https://www.youtube.com/watch?v=CUR3yMhu1BA wiggling included, but the sound of mine is more intense.

Update 2:
Another video here, very similiar sounds to mine: https://www.youtube.com/watch?v=QC6Ej7_NZIY

Freewheel problem then?

[Bikemad]

The axle is very unlikely to be bent, and even if it were bent, it would not cause the wheel to run out of true.
The wheel rim can usually be correctly centred by tensioning or loosening certain spokes as required to get the rim running perfectly concentric with the axle and laterally true.

The wiggling freewheel is not bad enough for me to be concerned about it, and it may not be possible to improve/cure it without changing side cover/s and possibly the motor ring too.

It would be nice to know what was causing the jamming sound, and what exactly it was that you tweaked to improve it?

I'm also a bit confused as to what could have "jammed twice" at higher throttle to cause the huge braking force. 

If the rubbing noise disappears when you pedal (like the noisy freewheel bearings in the update 2 video) it will be a problem within the freewheel itself. Replacing the freewheel may cure the noise, but it is unlikely to make any noticeable difference to the "wriggling".

If the rubbing noise is still audible while pedalling, it could be the side cover rubbing against the black protective sheath on the Hall sensor wires inside the motor:



You can just see the circular rings on the inside of the cover of my MPIII where the cable had been gently rubbing against it:



I simply drilled a small hole in the stator to allow a cable tie to be used to hold the cable tight against the stator, which prevents it from rubbing against the inside of the side cover:



This is what it looks like from the other side of the stator (with the access plate removed).



Your motor seems to be rotating quite freely in your video with no obvious signs of binding.

Alan
 

[Dias]

Thanks for your response Alan. I finally managed to solve the problem yesterday.

Spokes popping had nothing to do with the problem and I identified the sound correctly, tightening spokes fixed it (obviously this sound only appeared while I was riding the bike)

The sound you could hear in the video was made by disc brake screws. Regular (at least I think they are) screws are probably too long and were rubbing the drive inside. I loosened them and the sound stopped.

Hope there is nothing wrong inside the motor because this sound appeared after 2000 km. Logically, something had to move - either disc or something inside the drive to make this noise appear. I had no problems after 30 km so if someone has this problem: check your disc screws guys.

[Bikemad]

Hopefully the end of the bolts won't have worn too far into the controller heatsink to reach the internal electronics.



Place a washer under the head of each bolt to prevent the bolt from reaching the controller.

If the end of the bolts has been burred over so much that the bolts won't come out, simply cut a slot in the washers using a hacksaw (or angle grinder with a cutting disc) and you should be able to easily slip the washers in place without removing the bolts completely. 

It's not a good idea to run with loose disc bolts. 

Alan