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King Song S22 motor stator slippage issue: more severe than expected


supercurio

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So what makes my wheel knock from the inside?  Might it wedge something inside so tight that it could make the stator slip?  This goes to my concern about tolerances between the magnates and the stator.   Even the best glue would be pathetic compared to mechanical interference at any speed.  Do I need to park this wheel?  Open the motor?  Get a recall-fix-model?  More possible to sacrifice now that summer is over.  ;)  

 

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Are you kidding me??? You sure in hell do not silicone any sensors in place inside any motor!!! This alone, cause me not to wants anything to do with this wheel!!! Enough of this pre-order crap... I am done... 

Edited by MetricUSA
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1 hour ago, MetricUSA said:

Are you kidding me??? You sure in hell do not silicone any sensors in place inside any motor!!! This alone, cause me not to wants anything to do with this wheel!!! Enough of this pre-order crap... I am done... 

I peeled off the white silicone that covered the hall sensors board in an older 18XL wheel. The hall sensors are actually sandwiched in between the stator coils at the outer periphery. Three wires run out of each sensor to the circuit board. The hall sensors looked really well embedded in there. The circuit board sits on top of a white plastic strip which are all silicone over. Even if the board moves, the senors will not. However, if the board move too much, most likely the wires will be stretched then break.

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2 hours ago, supercurio said:

@Elliott Reitz the knocking typically comes from a loose fit of the bearings which end up moving, measurably misaligned due to poor manufacturing tolerances of the motor side covers, instead of being held securely in place by friction. 

 

 

Progress update:

I learned that King Song validated a testing method and is now preparing a statement and guide.

Is also confirmed that their motor supplier's fix since July is expected to solve the stator slipping issue.

It really looks like Kingsong wanted to hide it under the carpet, if they really fix it since July. There was no communication about it.

And I hope it is true, but my confidence in the company is eroding. After the battery debacle with the "smart" BMS only fixed by software (cheaper), the sliders which need a do it yourself solution, this hidden motor issue fixed by ...more glue?...it is a lot to accept and believe on a 1 wheel device.

Edited by SamSuffit
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i kinda wondered if the plan to freight faulty motors via sea was just KS design to buy another month of time. 

Surely if they wanted dealers happy and riders rolling without issue they would eat some freight cost.

Many delays with KS announcements this whole way. 3rd party battery report?

I had a replacement motor sent to my dealer and the replacement date was pre July (I had just heard of the July fix then)

Maybe they weren’t aware of the issue when they sent it? 

 

A regular on my channel just reported a cut out with no warning, nearly broke leg.

His confidence is gone and he wants refund.

Shame. 

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3 minutes ago, Heyzeus said:

 

Sure quality control issues happened but I don't recall hearing about cutouts and or fires with the frequency that I've heard about them in the past few years.

It seems to me all the manufacturers are in a bit of an EUC arms race trying to get the newest fastest

It doesn’t bode well when speed goes one direction and quality control goes the other. 

 

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7 minutes ago, Forwardnbak said:

It doesn’t bode well when speed goes one direction and quality control goes the other. 

Eventually someone's going to get run over by a car when their wheel cuts out due to a manufacturing defect while riding 50 mph and they tumble into traffic.

And the only reason the company won't go out of business from that is because they're based out of China and lawsuit proof

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52 minutes ago, Heyzeus said:

And the only reason the company won't go out of business from that is because they're based out of China and lawsuit proof

Rider error would likely also kill a western company.

The market regulates the Chinese companies.

Edited by alcatraz
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40 minutes ago, supercurio said:

Progress update:

King Song decided to have an internal team focusing on this motor issue, and suggested I could contribute with input, so I will.

Beside everything we already talked about in this thread, I'll also try to come up with a list of items that will help solving this with concrete solutions.
If you already have your own list in mind (specific to the motor stator issue) feel free to chime-in!

2 examples I thought about today, which makes it hard to swap motors (and other issues like screws getting loose)

Define torque spec for the 2x4 motor screw and always use a torque wrench

  • to assemble the suspension frame to the motor hub in factory
  • to re-assemble after replacement, either by professional service or at home

I'm being specific here but I think 100% of the screws on the S22 should have an exact torque spec, not only these.

Fix the motor screw countersunk contact patch

Identified by sco on Telegram in this series of messages

Mismatch in screw countersunk angle results in a poor contact batch between the screw and the suspension frame, as seen here:

S22 motor screw countersunk contact patch 1S22 motor screw countersunk contact patch 2

Quoting sco:

 

 

To everyone commenting: generally I hope that this thread can remain focused on motor issues instead of diverging into the generic industry-wide quality discussion, but I understand it can also be relevant sometimes. Please do your best 😄

Not just countersunk hole issue but also different type of loctite used in places it seems, making dissassemly near impossible in places, like my suspension lugs.

 

 

 

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8 minutes ago, Rawnei said:

Not just countersunk hole issue but also different type of loctite used in places it seems, making dissassemly near impossible in places, like my suspension lugs.

On my first attempt with heat gun (highest temp, long time) I could not get the motor screws to open. On my second try I just used WD-40 and they opened easily. 

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39 minutes ago, meriwald said:

Any proofs of that? Sounds like misinformation to me. Like PR statement from the college book, rather than real action  ks is a small company, they literally have 4-5 people who is actually able to deal with it. How can you dedicate a team when all you have is 5 people to dedicate )) what is it, a team of 2?  Because 3 already dedicated to controller issue?🤣

I understand the skepticism. The person I talked at KS showed good results in making things happen internally so far.
It can't be seen since there was no public result yet, so that's why I'm sharing updates here, for stuff that's hopefully relevant.

39 minutes ago, meriwald said:

As some smart users already said here, shims need to be installed to stop the issue. To understand that there is no need for dedicated "internal team" and focusing on anything.

A few in the Russian community started to look into solutions to prevent the stator to slide without having to replace the full motor, or until they can get replacement motors. They might try some and I'm looking forward what they come up with, although it's probably out of lack of confidence that the problem will be solved in a timely manner.
I'm not sure the solution you propose here is practical however. Realistically, motors presenting the defect will need to be replaced and that's about it.

39 minutes ago, meriwald said:

So this update, not sure what is the source

But, you'e talking to the source here, it's me. Hello 👋

Edited by supercurio
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Context for those with no experience in this type of environment, about teams:

In many companies (tech or others), commonly following some kind of agile methodology, it's often that you form a team to focus on solutions that needs to be found in an inter-disciplinary manner. The team will typically exist temporarily.

It means a few select people will take some of their working time, have meetings and generally the mandate to prioritize work on the task instead, taking some time away from their usual assignment.
At an organizational level, people don't just decide by themselves to work on something they think is important. The process is to form a team with its own goals, made of people picked from other teams, and still in them.

In this instance I expect sales and technical managers as well as my contact who has excellent english speaking skills and has been on the same page as me regarding safety goals, and probably support from engineering.

It doesn't mean that it becomes a "dedicated team" with people being taken away from what they were doing before and re-assigned 100% to this. That would be disruptive and unproductive when waiting on dependencies: engineering, testers, suppliers, dealers, customers.. especially with timezone differences.

 

Edited by supercurio
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22 hours ago, Elliott Reitz said:

So what makes my wheel knock from the inside?  Might it wedge something inside so tight that it could make the stator slip?  This goes to my concern about tolerances between the magnates and the stator.   Even the best glue would be pathetic compared to mechanical interference at any speed.  Do I need to park this wheel?  Open the motor?  Get a recall-fix-model?  More possible to sacrifice now that summer is over.  ;)  

 

Yes. You should open the motor and look at what may be loose. You should probably stop riding unless you are willing to risk a cutout at any time. And factory installed glue is 100% ok and is the industry standard as long as it is...actually applied. 

The glue, or epoxy, whatever it is goes all over the aluminum hub on the exterior of the stator, and the plastic insulator that the coils are mounted to is the other surface. There is so much surface area there, that it will hold any and all forces that the motor torque could output. 

 

You mentioned screws to lock it in. I dismissed that at first, but looking at a spare S18 motor I have, it looks possible if done expertly. You would need to drill and tap thru the center of the coil, into the stator hub. Then be lock tite'd in place and make sure none protrudes out the top. 

But a new motor would be way easier. 

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If the bearings are loose within the side covers, and a new part is not available, Green Locktite Bearing Retainer can be used and it will hold them in place 100%. I've used it to do some questionable repairs on industrial machinery and it holds up! 

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Thanks @NErider for the suggestion.

It was reported for at least one case that there was some grease where the bearings are supposed to stay in place. I wonder if that was used during assembly or leaked from the extra seal nearby.

Bearing retaining compound might be worth a shot!

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That's cool, how will they spread the test and make it available to end users? Looking forward (or maybe not) to perform the test. 😬

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