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Hollow bore motor bearing failure Thread


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10 minutes ago, Planemo said:

Yes, many motors could have a bit of debris floating about. And theres tight tolerances between magnets and stators in all wheels. This includes the RS, MSP and MSX.

The point is that any intolerance due to bearings shows up this issue. The real issue isnt debris, its bearing slop.

If the problem goes away without loads being applied to the bearing (as you suggest) then the problem absolutely points to the bearing being the problem. I am unsure how you say it isnt.

i get your point, as a point that everyone seems to be making repetitively. if that rationale was soundly deduced, the problem would get solved once anyone followed the solution (by the common rationale, the solution is to replace bearings = knocking sound gone). but that hasnt been the case as far as im aware. some people replaced their bearings, and the sound did not go away, or it came back. at this point they thought to double down on their rationale, and believe that the second bearing replacement failed. i entertain those possibilities myself, but..msp and msx dont have hollow bores, despite the same rotor/stator assembly. this is my assumption, im not well versed on those wheels but i believe they are similar. i dont know if those wheels ever had a noise issue like the one the RS gets. i digress. 

im not suggesting the problem (assuming we agree: is the noise) goes away on bearing decoupling. im suggesting that if a bearing spins freely without any noticeable warping, or binding whatsoever, upon decoupling,  then even if the bearing slop exists, it does not exist to cause the problem (noise), and can be omitted as applicably negligible, as the bearing itself seems to function fine. the problem (noise) is somewhere further down the mechanical linkage AFTER the bearing is coupled, toward the end result of the tire spinning. i should make a youtube video i guess, to document my own experience of things. but i am not that invested to edit things haha..typing is so fast! in any case, if you still disagree, im open to listen to your opinion, because i may learn something still. but otherwise, *shrugs* i guess you guys are right. appreciate the feedback though @Planemo

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Hollow bore/centreless/hubless motors will always wear out faster than traditional axle motors, given the same bearing material for the following reasons: Being further away from the centre, eac

I'd like to bring up two points that add to the shortcomings of the hollow motor design.   First, if you look closely at the black part, the outer housing of the motor you will see that ther

We're comparing two designs: MSuper with bearing size 6203 MSuper with bearing size 61824 Everything else about the bearing loads are equal: Same rider weight Same pedal

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My original rs knocked but it was replaced by eWheels so I didn't get to open it up. I don't think it was bearings as there wants a grinding noise and one foot riding on each side didn't make it go away. 

There was a pic of an excessive amount of white goop in the motor hanging down and hitting the coils. In my case this seemed to be the most likely cause as it was RPM dependent. 

My new RS has been trouble free but only has 200 miles on it. 

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I potentially have a stupid question..... Why are they making the bore size so big? Is it not possible to have a smaller sized bore, thus smaller sized bearing and still be able to run thick cables through them? Making them less prone to failure or am I missing something?

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the failure is not related to size, bigger bearing have lot of pros compared to old one, new hollow motors runs way more smooth compared to old generations.

We still don't know 100% what the problem is, could be bearing, mounting or something else, newest gotway wheels seems fine

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19 hours ago, StealthPhoenix said:

- feeling for any binding or feeling for amy warpage. But everything feels smooth and great. This was before i even cleaned the dust and small sandy particles between the bearing and motor cover that u can see in the video. 

https://streamable.com/4o0cze

All the garbage in that gap! :o

4o0cze.jpg

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I try to report my experience: as soon as my RS was delivered to me I got on it and after about 15km I started hearing the famous perfectly rhythmic tock tock rock.  At the suggestion of a friend, after returning home, I disassembled and pulled out some motor cable and the famous tock is gone!  Clearly I was happy and blamed the problem on the cable.  The fact is that the famous noise showed up three more times and finally disappeared.  (for the moment ?!) My RS took no hits, no water, nothing ... That's are the fact... Meaby we are all talking about two or more different problems with one only true: poor quality! Poor quality control, poor material, poor building process, poor customer assistance. 

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I think I figured out a better way to explain what I was trying to say. Forgetting about the size of the bearings imagine you moved the smaller bearings much closer together so that the space between the bearings is equal or less than the diameter of the bearing. Now you have no torsional stability because the bearings just want to twist out of place. They proportionally reduced the space between the bearings drastically by increasing bearing diameter so much and not increasing the space between them.

It's almost like there's just one big bearing now and every time you step on 1 foot plate and not the other the bearings try to twist out of place. To create the same stability with the big bearings as there is with the small bearings they would probably have to be spaced a foot apart LOL. 

I'm not sure why they went so big with the bearings? I thought it was just to accommodate larger wires? They could've accommodated larger wires with just a slight increase in axle and bearing size.

I hope they come to their senses with this hollow motor thing sooner than later. 

If you look at motorcycles, they are much heavier and go much faster, they have smaller bearings that are proportionally spaced much further apart. 

Edited by pontoonpete
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6 hours ago, NordEstEuc said:

I try to report my experience: as soon as my RS was delivered to me I got on it and after about 15km I started hearing the famous perfectly rhythmic tock tock rock.  At the suggestion of a friend, after returning home, I disassembled and pulled out some motor cable and the famous tock is gone!  Clearly I was happy and blamed the problem on the cable.  The fact is that the famous noise showed up three more times and finally disappeared.  (for the moment ?!) My RS took no hits, no water, nothing ... That's are the fact... Meaby we are all talking about two or more different problems with one only true: poor quality! Poor quality control, poor material, poor building process, poor customer assistance. 

Poor engineering!;)

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8 hours ago, RagingGrandpa said:

All the garbage in that gap! :o

4o0cze.jpg

Now mix some water in with that sand! I would say that some extremely abrasive paste! That has nowhere to go except into the bearing! Especially when under centrifugal force during high speed!

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I'm sure mines collecting garbage in the same place, I like riding off road more than on road. 

Now I understand why holes drilled there to let the crud, amd water drain out while the wheel is spinning makes sense. Ray Rokni has a video up on youtube showing the holes. 

 

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5 hours ago, pontoonpete said:

If you look at motorcycles, they are much heavier and go much faster, they have smaller bearings that are proportionally spaced much further apart. 

I really dont think the distance between the bearings makes any real difference whatsover. The problem is not having an axle linking them.

On the hollow bearing, any weight which is placed outside the centreline of the bearing will try to rip the inner race from the outer race. See my first crude drawing:

07202191316.thumb.jpg.a3f49072c67c595b32a02fbf9bed9ba6.jpg

If there was an axle linking the two bearings, this angular force would pass along the axle and be supported by the opposite bearing. Crucially, this force is now transferred into a radial load, which is what the bearing is designed for. See my next crude drawing:

07202191219.thumb.jpg.6ab69d36d01867149afc4dcc413106e9.jpg

The only long term solution is to use a bearing designed for axial loads eg a conical roller bearing.

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4 hours ago, Chriull said:

So the two bearings are already linked by an axle!

Yes, but this axle is made from poor quality materials. So i think that this is more "soft bed" for bearing than axle ;)

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@Planemostill has a point. The bearings might not be able to handle side force as well. 
 

With one foot on and one foot off:

It seems to me that on a smaller bearing almost all of the force is translated to up and down. The force on one side would be up and the other side down , while with the larger bearings ( same sized balls) more of the force is side to side. 
 

Maybe my thoughts are more psychological and the ratios are bothering me more than anything. 

Edited by RockyTop
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Wow, I have a deposit down on a RS 19 HT that's scheduled ship in the next couple of days. This thread (among others) has me seriously second guessing that decision. I didn't go with the V11 because the tech hasn't had time to mature enough to warrant dumping my hard-earned cash into it. It really sounds like the same thing applies to these new hollow bore motors, be it in the V11 or the RS. Back to the drawing board I guess, and by drawing board I mean, trying to convince The Boss (wife) that I need to spend $2800 on a Sherman. Many thanks to everyone who's weighed in on this. It sounds like you saved me a bunch of headache.

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12 minutes ago, pontoonpete said:

Ah. But we disagree in two areas:

  1. There is no 'pivot point' in the center of the bearings.
    Loads enter at the pedal, and leave at the tire... nothing dictates that the center of rotation be between the bearings.
     
  2. Your example changes the spacing between the two bearings. But MSP vs MS-RS have the same spacing.

(For these two reasons, I think your motion arcs are misleading...)

.02

  

3 minutes ago, WheelyBad said:

Wow, I have a deposit down on a RS 19 HT that's scheduled ship in the next couple of days. This thread (among others) has me seriously second guessing that decision.
...
need to spend $2800 on a Sherman.

Why not $1550 on a new, tried-and-true MSX?

https://forum.electricunicycle.org/topic/20801-msx-with-2500w-motor

Edited by RagingGrandpa
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5 minutes ago, RagingGrandpa said:

Why not $1550 on a new, tried-and-true MSX?

 

Believe me, I thunk the thought. If I could find one anywhere with any kind of a warranty like eWheels offers, I'd jump on it. Maybe I'm behind the times, but throwing $1500 at "green and fashion travaling" shop on aliexpress seems foolish. Am I wrong?

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7 minutes ago, RagingGrandpa said:

Ah. But we disagree in two areas:

  1. There is no 'pivot point' in the center of the bearings.
    Loads enter at the pedal, and leave at the tire... nothing dictates that the center of rotation be between the bearings.
     
  2. Your example changes the spacing between the two bearings. But MSP vs MS-RS have the same spacing.

(For these two reasons, I think your motion arcs are misleading...)

.02

I thought all your specifications on the bearings was great! And makes a very good point that there are more issues than just the bearings.

I do standby my thought process though.

I just want to highlight that something needs to be fixed so that we get reliable high-quality wheels because electric unicycles are just so awesome!

 

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Why not MSP over MSX?--quite a bit newer/nicer while being just before the bearing issue introduced with the RS. My go-to advice until this gets resolved on the RS has been to look for an old-stock MSP (or buy a used MSP from one of the many people upgrading to Shermans).

Edited by AtlasP
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