S-Mag clicking sound

[Flyhigh]

Hi.

After 4.500km my Brose S-Mag suddenly started to make a continues clicking sound on my Specialized Kenvo (2021). The sound is similar to a chain guide which is not well adjusted (listen to the attached mp3 file).
The sound is louder the higher the motor support is adjusted. It's entirely silent if motor is off.
The motor feeling is normal. No issues here.

It seems also to depend on the temperature. In the morning when it's colder also no sound, but in the afternoon the sound appears.

Any idea what the source of the sound could be and how critical it is?

Thanks for any ideas!

 

[Flyhigh]

The belt was finally torn apart a few days ago. Replaced it, now the sound is normal again. I already had some torn belts, but never noticed this sound, though.

 

[Oakhills]

That sounds like my Gen 3 Levo the last few rides, 3200 miles on the motor. I put in a warranty claim two days ago. Hope they decide to fit a new motor!

 

[Flyhigh]

Hello again. Its been a while. Still driving with this motor. It started making this sound again. Belt is ok. I noticed that it depends on the outside temperature and on the level of support. If its warm outside and in turbo-mode it happens more often. I figured out that the origin of the sound is the gearbox. In the attached video you see that the annular gear is quite loose. This cannot be normal, right? @Bearing Man with your experience, do you have an opinion on that? Any suggestions anybody?

 

[Bearing Man]

Hello again. Its been a while. Still driving with this motor. It started making this sound again. Belt is ok. I noticed that it depends on the outside temperature and on the level of support. If its warm outside and in turbo-mode it happens more often. I figured out that the origin of the sound is the gearbox. In the attached video you see that the annular gear is quite loose. This cannot be normal, right? @Bearing Man with your experience, do you have an opinion on that? Any suggestions anybody?

The ring gear is supposed to be like this, it's normal. Your noise sounds like it is coming from outside of the motor. This is the sort of sound a chainring makes when the spider bolts are not quite tight enough. The clicking noise is happening at a different speed or cadence to anything else inside the motor. The noise is also crisp and clear. If a noise comes from within a motor it is usually very slightly dulled or muted. The noise also sounds to be happening at around chain speed. If the spider bolts are tight but you have recently fitted a new chain without changing the chainring for a while, I would try a new chainring.

 

[Flyhigh]

Thanks you @Bearing Man for your quick answer. Did you click on the image? Actually its a gif-video file. You see that the ring is completely loose. I have another motor with the gear ring tighly fixed to the housing, that was the reason I was wondering if this could be the problem. I can imagine that a big torque leads to a slipping ring gear and that this could also make this kind of sound. I attached another gif-video which should make it more obvious.
The chain ring spider is fully ok. Also, if I reduce the motor support, the sound goes away. The new motor I installed is absolutely quiet by the way, so it has to be a motor problem...
Cheers

 

[Bearing Man]

Thanks you @Bearing Man for your quick answer. Did you click on the image? Actually its a gif-video file. You see that the ring is completely loose. I have another motor with the gear ring tighly fixed to the housing, that was the reason I was wondering if this could be the problem. I can imagine that a big torque leads to a slipping ring gear and that this could also make this kind of sound. I attached another gif-video which should make it more obvious.
The chain ring spider is fully ok. Also, if I reduce the motor support, the sound goes away. The new motor I installed is absolutely quiet by the way, so it has to be a motor problem...
Cheers

Yes, I clicked the image and the ring gear looked like 50% of the motors we have in the shop here, some are tight, some are loose and some are in between. The ring gear can't physically slip without exploding the planetary gear carrier, it also has a plastic alignment peg that sits deeper in to the motor housing. When the ring gear is under load, it's pressed against its stops by the force transmitted to it by the planetary gears.
When the belt cover is removed, you are removing the support for the top armature bearing, the armature should not be turned at this point because the armature magnets are hard against the stator coil plates. But I think your second picture shows what your problem is. If you watch the edge of the top planet gear (partially obscured by your piece of aluminium) it looks like the gear is not moving up and down when you rock the belt pulley back and forth. This is quite rare but can sometimes happen when the spigot that the gear is mounted on snaps off. The gear will just rotate around with the other two doing all the work. This would also match the speed of the noise you had.

 

[Flyhigh]

Thats it! Thank you for the diagnosis!

 

[Bearing Man]

Thats it! Thank you for the diagnosis!

You're welcome. Our partner in Germany can fix this for you if required. Worldwide Partners