Noisy Bafang hub motor

[jamesm113]

I'm new to e-bikes, but am an avid mountain biker and do a decent amount of repairs/maintenance myself.

1000W Bafang hub motor, bike is an Ariel Rider X-Class 52V. Bike had about 40 miles on it when I purchased it used. About 70 miles on it now.

Motor makes a sound (almost like a click) around 18-20mph to ~25mph. No noise at lower or higher speeds. Video of the sound: https://photos.app.goo.gl/mgTYnp8yekSyq917A

I've:
* Trued both rotors - they are not dragging. Unplugging the interlocks, the noise remains when brakes are applied
* Re-routed the the motor cable to maximize the clearance between the rotor bolts and the cable
* Removed the motor and pulled the clutch kit. Cleaned and re-greased all the gears with SHC 100. Confirmed no damage to any of gears or any contaminants. The gears seemed a little under greased from the factory
* Discovered a small amount of in/out play in the freewheel, but from what I understand this is normal.
* Confirmed no noise is made if wheel is in the air

Googling around, it sounds like maybe a lose magnet could be a culprit? Any other things I should check?

 

[jamesm113]

Ok, got a puller long enough to pull the rotor.

Everything looks good to me. Couldn't see any evidence of contact between the rotor and the magnets. I also tested each magnet for looseness and didn't spot any looseness.

I'm kind of at a loss as to what could cause the noise at this point.

If I bounce the rear wheel with no motor in it, the freewheel makes a clank. Pulled the freewheel, no more clanky rear wheel. It doesn't seem like it has that much play off the bike, but I can try running the bike with no freewheel to see if the noise goes away.

 

[jamesm113]

I also noticed the j hook part of the spokes do not look properly seated on the non-freewheel side of the rear wheel.

 

[PCeBiker]

I just finished re-greasing my motor.
It's supposed to help quiet the motor but I haven't riden the ebike yet.

My motor was making a similar noise to yours.

Installed Corn Head Grease in my new Luna Z1 Bafang Ultra Mag

Certainly !!!

forums.electricbikereview.com

I also noticed the j hook part of the spokes do not look properly seated on the non-freewheel side of the rear wheel.

I'm just guessing, but the spoke holes in the motor could be oversized to allow the spokes to pull at different angles if the motor is strung in different sized wheels or if it's double crossed, single crossed or even no cross.

On the other hand, there was a Das-Kit motor that was drilled for 12 gauge spokes and strung with 13 gauge spokes and the spokes were breaking at the j hooks.
The wheels had to be restrung with the proper spokes.

I don't think that there's any spokes bigger than 12 guage, so if you have 12 gauge spokes they should be the right spokes?

 

[jamesm113]

Let me know if your re-grease job fixed the noise. Mine certainly did not.

What's weird about the spoke issue is that only one side is like that. The other side looks perfect. I'll measure and compare the spokes tomorrow.

 

[PCeBiker]

I've got another e-bike with a proprietary Das-Kit fat motor that is apparently a rebranded MXUS motor that appears to have the same dimensions as my Bafang motor.

That motor is quieter than my Bafang motor.
I haven't had it apart, so I don't know how it's different inside.
It's got the larger motor plug so it's a 750 - 1000 Watt motor, and apparently it's "geared for torque" so it may have a different gear ratio.

 

[PCeBiker]

Let me know if your re-grease job fixed the noise. Mine certainly did not.

That's going to be a while.
I won't be riding it until spring, and maybe later if I don't start getting my e-bike put back together soon.

What's weird about the spoke issue is that only one side is like that.

That's strange?
Check the gauge of the spokes.

Only thing that I can think of is the "dishing" of the wheel to center the rim.
The freewheel adds width to the motor.

 

[Chargeride]

Ooh, good luck with that, do you have access to temp fit another controller, Ive had weird hub noises caused by by god knows what that was cured by a new controller.
Unlikely but its worth a try to rule it out.

Magnets are usually the cause, but thats if youve really cooked the motor repeatedly.

 

[PCeBiker]

, Ive had weird hub noises caused by by god knows what that was cured by a new controller.

I didn't think of that.
I know sinewave controllers are a lot quieter than square wave controllers.

My Das-Kit ebike has a sinewave controller but I'm not sure about my new Voltbike and it's controller?

I'm kinda thinking it might just be a Bafang thing?
It doesn't sound like it's grinding or anything?

Kids would love the vroom vroom sound and Harleys make lots of noise on purpose.
They tried to patent the sound, but they couldn't © "noise".

 

[jamesm113]

To be clear, I don't mind the whine/hum noise. I assume that's somewhat normal.

It's more of a click that happens around 18mph to 25mph that seems to match the wheel speed.

 

[Chargeride]

Its hard to hear on the video, does it get louder with more power added?

 

[PCeBiker]

To be clear, I don't mind the whine/hum noise. I assume that's somewhat normal.

It's more of a click that happens around 18mph to 25mph that seems to match the wheel speed.

I sort of heard a couple of clicks, but I just thought that was your hand on the cellphone or something?

I'm thinking the noise is coming from somewhere else or something else nearby?

The sucky part for me is trying to locate the source of noises that only happen when I ride the e-bike.
I've damn near run off the road a few times trying to aim my ears around trying to find it.
Some vibrations travel through the frame and make noise somewhere else.
My creaking steering stem wouldn't stop making noise until I realized my seatpost was also creaking.


Is there any way that you can mount a bluetooth mic or something on the frame to help locate the noise.

 

[Chargeride]

You always end up with the process of elimination
It strange to consider that a hub motor especially is also a loudspeaker, you have the same setup.
The controller is pulsing a sort of three phase into a coil sat in magnets that is attatched to a hub thats tightly connected by spokes to a large rim.

Ive just given myself an idea, connect an amp to the the phase wires and.....

 

[PCeBiker]

I would think that a higher pitched clicking noise would be coming from outside of the motor housing?

 

[Chargeride]

My mate broke down on his motorbike at 2am alongide the miles long Blundell estate wall, he started pushing, after a few minutes he could hear something walking in the dry leaves on the otherside of the wall.
Bit creepy, so he sped up..it sped up.

He started to run, it started to run.
He reached a break in the wall, the noise stopped.

It was a tight bit in his chain echoing of the wall.

 

[PCeBiker]

I remember hearing a clicking noise from my brakes only when I was driving with a wall beside me. (like crossing a bridge)

It turned out to be a chunk of rust on my brake rotor hitting the dust shield.

It took me weeks to figure it out.