Yose Power 48v 350W rear hub motor metalic sound causing alarm.

[Klang180]

Hello all

I have had this kit for about 6 months now and until recently was using it a couple of times a week to do about 15miles in that week. All was going well and am broadly happy with it (wish the acceleration was a little more rapid but that is minor).

With the recent circumstances I was using it less including a a few weeks without any use. I recently took it out for a couple of rides and notice that when I put maximum power through it i.e. assistance level 5 or using the throttle on max I get a metal scatching sound eminating from the hub. It sounds a little bit like metal filings or a bit like a circular saw in the distance but isn't as consistent. If I use assistance level 3 or part throttle it is as quiet as normal. Performance and battery life as as normal but it is a disconcerting noise.

I wouldn't be able to swear that I have never heard this sound before but now it is definetly more noticeable. If no one has any idea I will try to get it up on the rack and a video posted to help better diagnose.

Any suggestions on what I can do?

 

[Benjahmin]

This will sound strange but, check the motor plug. Look for any signs of heating, distortion in the housing etc. Take it apart and look to see if any of the 3 biggest pins show signs of heating, any green or blackening. When you put the plug back together make sure it is inserted all the way to the indicator line.
Odd motor noises, vibrations and what can sound and feel like resonant vibrations are mostly caused by a resistive phase connection to the motor. I heard this on this forum and thought that it couldn't possibly be the case for my motor. I ignored it and twice stripped the motor down to regrease it with no effect. Then I replaced the distorted 3 phase connector and, hey presto, no more vibration.

 

[PC2017]

I would check your spokes thoroughly to rule them out as the problem.

 

[Klang180]

This will sound strange but, check the motor plug. Look for any signs of heating, distortion in the housing etc. Take it apart and look to see if any of the 3 biggest pins show signs of heating, any green or blackening. When you put the plug back together make sure it is inserted all the way to the indicator line.
Odd motor noises, vibrations and what can sound and feel like resonant vibrations are mostly caused by a resistive phase connection to the motor. I heard this on this forum and thought that it couldn't possibly be the case for my motor. I ignored it and twice stripped the motor down to regrease it with no effect. Then I replaced the distorted 3 phase connector and, hey presto, no more vibration.

That is the last thing I would have checked but having taken it out today and noticed it yet again I will definitely give it a go. Now to just work out exactly what you mean by the motor plug

 

[Klang180]

I would check your spokes thoroughly to rule them out as the problem.

Hmm I would be surprised if this is the case as it only ever makes the noise under power and only then when it is working hard i.e. up a hill or against a headwind. I will check though as it cannot hurt.

 

[PC2017]

I will check though

My 350w Yose rear split at the spoke nipples rendering it useless and it happen again to the guy I sold the internal motor to, to fix his, lucky he had another wheel as a spare. It made one hell of a noise which if I didn't spot the spoke issue I would of assumed it was the motor at first glance.

The YOSE front hub 250w that I am running at 48v, at the moment is strangely much better build quality all round and I purchased this a year before the 350w rear... I started with another brand front so I tend to prefer front hub, the main reason being better weight distribution with me being a heavier individual.

 

[Benjahmin]

There will be a plug somewhere near the motor itself. It's there so you can disconnect the motor to take the wheel out for repairs etc. without removing loads of wiring. It may be round with something like 9 pins in it, 3 will be larger. Be careful, when plugging back in, to check that the alignment arrows are - well, lined up. It is oh so easy to bend the small pins, as I know to my cost.
Do check your spokes while you're at it. Simply pluck each one like a harp string. They should give a sort of ping and all sound about the same pitch (left and right will sound slightly different to each other) any that give a dull sort of slapping sound are loose. It's surprising what a horrible noise a few loose spokes can make, especially when the torque of a motor is applied.

 

[Klang180]

My 350w Yose rear split at the spoke nipples rendering it useless and it happen again to the guy I sold the internal motor to, to fix his, lucky he had another wheel as a spare. It made one hell of a noise which if I didn't spot the spoke issue I would of assumed it was the motor at first glance.

The YOSE front hub 250w that I am running at 48v, at the moment is strangely much better build quality all round and I purchased this a year before the 350w rear... I started with another brand front so I tend to prefer front hub, the main reason being better weight distribution with me being a heavier individual.

Oh wow that is quite compelling, ok I will definitely check this. I suppose the fact it only happens under load and not in the stand may lend itself to the spoke theory.

 

[Klang180]

There will be a plug somewhere near the motor itself. It's there so you can disconnect the motor to take the wheel out for repairs etc. without removing loads of wiring. It may be round with something like 9 pins in it, 3 will be larger. Be careful, when plugging back in, to check that the alignment arrows are - well, lined up. It is oh so easy to bend the small pins, as I know to my cost.
Do check your spokes while you're at it. Simply pluck each one like a harp string. They should give a sort of ping and all sound about the same pitch (left and right will sound slightly different to each other) any that give a dull sort of slapping sound are loose. It's surprising what a horrible noise a few loose spokes can make, especially when the torque of a motor is applied.

Thanks, I will take a look. Stupidly I've been disconnecting the motor nearer the controller to remove the wheel so it would be useful to know where this is anyway.

Right spokes and power connector, thanks for giving me things to go on.

 

[Klang180]

Just an update. I put the bike up on the stand and in doing so noticed it was pretty grubby and so gave it a nice clean, degrease and relube. Once this was done I ran the motor on max power and nothing out of the ordinary could be heard. I went around the wheel and checked all the spokes and they all pinged with a decent pitch. I did however notice that the disc brake was slightly rubbing and so went ahead and adjusted that. after that I went for a quick spin and tried to make it make the noise but to no avail. I will have to wait until I can take it for a longer outing but I may have to face the embarrassing proposition that the noise was coming from the disc brake and not the motor , even more embarrassing considering I am a part time bike mechanic!

In my defence, the noise happened under power and then only in more strenuous scenarios so I thought it couldn't possibly be the disc brake, which did occur to me to start with. However my working hypothesis is that the disc brake was slightly maladjusted or had worked itself slightly out of position and the freewheel wobble that is inherent in this flawed system meant that it pronounced the wobble when under greater strain and thus caused a metallic rubbing sound as the rotor hit the pads.

I am not entirely convinced by this theory as it is probably wishful thinking and disc rub shouldn't sound metallic but at present I have no way to know until I take it for another spin. I will report back and hopefully this time with video to support it.

Thanks for your help guys.

 

[PC2017]

working hypothesis

Ooh I do hope you are right, I had a creaking noise every few miles each ride so I stripped down the suspension forks, did a full clean and re-grease and it's now creak free, thank the stars as it was really getting on my...

 

[Benjahmin]

Fault finding is a funny psychological process.
You have to pose a hypothesis, then test to check whether it's correct or not. Problem comes when one gets wedded to the hypothesis and carries on looking for prove of it's correctness in the face of 'confusing' test results, that are, in fact, pointing at something entirely different. I think the ability to drop the original thought and pursue an indicated track is a mark of mental skill and agility.
I'm an electrician by trade, so been there, done that, still get wrapped up in false trails - even after many years.

Klang, at least you've now eliminated one possibilty. One step at a time.