MXUS 3000 Hub Motor - V1 V2 V3

markz said:
I got no clue but just maybe the pressure of the nuts push something inwards. Thats my guess.

You would think, but looking at the axle I can't see how that could be. The axle is one solid piece. I guess it just makes a perfect acoustic path for the sound to travel when tightened. But it has to be really tight before it makes that acoustic path, which makes me think that it is something else with pressure.
 
So what happens if you make a wooden "truing stand" frame, and tighten the axle up in that?

If it doesn't do anything, then it's the frame itself that's resonating.

If it still makes the same sound, it's something in the motor / wheel.
 
Merlin said:
Offroader said:
... When I remove the axle nuts the noise goes away. When I tighten the axle nuts back on the noise returns. I still have the motor inside the dropouts.


fits perfect what i said(resonance). probalby only qulbix "frames" have this "problem".
Yeah you may have something here, when I get my motor closed back up I'm going to be doing more testing.

I didn't believe this could have been the issue, but it makes sense as the whole frame seems to resonate with the motor.

I assume this means the motor is OK. The motor resonating I can deal with as it isn't that load and not easily to notice when riding.
 
One of my bikes has a resonant frequency with the motor at a certain speed. It is much faster than what you are describing around 15-17mph. I felt weird for a while, but now I do not even notice it.
 
I can tell for sure that on one of my bikes with V2 motor i also hear a resonance, but only when using regen and in a window of 10-5kmh.
it doesn't bother me..
 
I guess this resonance is more common and people don't hear it, I don't really hear mine when riding.

Now that I am sure it is just resonance and not something damaged with my motor it will bother me a lot less.

But there must be things that can be done to reduce it since making a tight connection to the swingarm seems to amplify it.
 
increase or decrease the mass or length of the swingarm. It is acting like a tuning fork.
 
Offroader said:
I would like to give an update about the hubmotor noise. When I remove the axle nuts the noise goes away. When I tighten the axle nuts back on the noise returns. I still have the motor inside the dropouts.

Any ideas on why this would happen? Is this like what Merlin said about motor resonating through the swing arm?

Just odd how it would not do this still with the motor still in the dropouts, I would think it would still resonate as it is still making decent contact with just the axle nuts loosened. But the noise really does go away once loosened.

Any way to fix this?


My guess would be that the noise is still there when the axle nuts are removed, you can just not hear the resonance.
Think of a guitar, vibrations and resonances are planted from the string to the body, wood etc. The tighter the strings are the higher the pitch.
Something similar might cause the noise you hear when you tighten the axle nuts. When tightened down properly the motor is now become anchored to the bike via the axle, drop outs and the nuts secure the connection. Any vibrations, resonances etc can now travel freely up the swing arm, where swing works like the body of the guitar or much like a tuning fork, amplifying the sound. And that is why madin(iirc) discovered sound deafening material inside swing arm helped.
 
Like its been said, its easy to build a sturdy wooden frame and place your motor in that and test it out without a load. Even flipping your bicycle upside down with everything in place, and running the motor, thats no load.
So if there is no sound in no load, then you need a load. Not sure how'd you'd do that, maybe have the tire lose some rubber or setup a home made dyno of some sort.
 
I think the problem is because of the swingarm. I decided to lightly tap my swingarm with no motor in it and it vibrates for a good 5-10 seconds. I can even feel this vibration on the side covers of the bike frame. Not only does it vibrate but if I listen closely I will hear it buzz.

Basically, the swingarm is acting like a tuning fork.
 
I tried to find out about swingarms and vibrations. Seems like this is a problem and some motorcycle manufacturers use Foam inside to cut down on the vibration.

Since most of the time it isn't a problem, nothing will probably ever be done about it for ebikes. It also seems that certain motors may make things worse like in my case.

You may be able to drill some small holes and fill it with foam, something I am not going to do.
 
Design flaw? The C washer or snap washer they use cuts right through the thick insulation, you can see a yellow wire showing. The snap washer is so tight and sharp it will eventually cut through the inner wires.

I'm not sure why they would use it to hold the wires secure.

I'll be using a Tie Wrap from here on.

The side covers fit on so easily with the Turbo with larger axle, lots of room for wires to go through.



 
OK progress once again. I still had the same ole problem with my PTFE Teflon phase wire, even with the grinding of the shaft. It did make it way easier to slide my wires in though, and easier to slide each wire back and forth as you will see below.

But early on I had an idea that paid off.

What I did was I shaved off a bit of insulation ~1" where the wires come out of the shaft, I did that on 2 phase wires. This enabled the wire to collapse flat and have enough roof for the cover plate to slide on down to the shell. Otherwise the insulation of the wire I have is far to durable, strong and thick; and will not compress or collapse like lets say your HobbyKing wire. It paid off in spades if I may say so myself.

Anyway that was the key ingredient for me.

Next step is to find a decent replacement for the insulation I took off. Lots available and I think I will go with a better quality heat shrink then what I have at home right now. I am going to try that underground stuff and/or fabric stuff.

A problem I did not realize - I will try to slide the wires up through the hole so I can properly repair. Right now I cant. Here is a picture. That wire source I have, is real slippery.

View attachment 1
 

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Quokka said:
Offroader, i put expansion foam in my swingarm. I copied that from one merlins raptor builds. I dont hear or see any vibrations

How big and where did you drill the holes to get it in the sides of the swingarm? Did you use a smaller tube to help direct it into the swingarm?

Thanks.
 
3 x 10mm holes as seen in the photo. It made a hell of a mess. A smaller, longer tube to direct the foam would be a good idea. Make sure to tape up the swing arm to make clean up easy. It just keeps oozing out whennit dries. I then siliconed on 3 grommets to keep out water. Dont know if this will fix your hum. Mine has never had any noises though
 

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Quokka said:
3 x 10mm holes as seen in the photo. It made a hell of a mess. A smaller, longer tube to direct the foam would be a good idea. Make sure to tape up the swing arm to make clean up easy. It just keeps oozing out whennit dries. I then siliconed on 3 grommets to keep out water. Dont know if this will fix your hum. Mine has never had any noises though


When using expansion foam, it does that, expands. It would okay to put the nozzle hose inside the hole and fill with foam, and then what ever comes out the fill hole, just cut flush when it dries and put your plug on then. The plugs look good and clean.
 
Maybe i am telling a stupid thing but... would not be easier to just make a small hole and spray in that liquit type of insulation that expands. Polyurethane i think is called.

[youtube]72h0eB7kGVE[/youtube]

Ups i think we are talking of same thing :mrgreen:
 
Offroader said:
Merlin said:
i did it and it wasnt a big deal + cheap.


Hi Merlin,

Could you explain what you did exactly and what you used? Did it make any difference?

Thanks.


sure...
thx on quokka reminder for my pics in my build.
i couldnt say what it was because it was from my company :D

scroll down to pic "9"

https://endless-sphere.com/forums/viewtopic.php?p=1145607#p1145607


this "expansion foam" come out of the small holes even 15minutes later. but thats good. that means it creeps in any tiny "space" inside the swingarm.
truly was not build for filling swingarms. but i worked so far for me and was a cheap try.
 
Finalizing my 18s Mxus 3000w V3 4T build. Kelly 7230S or Sabvoton SVMC72150? Any other under $300 shipped to Europe?
 
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