repair/center a wobbling hubmotor

Sparfuchs

Sparfuchs

1 kW
Joined
Nov 22, 2020
Messages
305
Hello EV friends,
Recently i ordered a mxus 3k turbo in a 26" rim and a okfeet 1500w hubmotor in a 20" rim.
The problem is that both of the motors wobble around the axis. The biggest problem is that this also makes the break disk wobble and difficult to use. Another problem is that the motor "vibrates" at higher speed. Since i have no other motors yet to compare and the two motors have the same problem although they are different products from different manufactures, i thought this might be a common problem ? Is this normal and just a standard chinese quality or a unlucky production fail on both motors ? Does the qs205 also wobble a bit or is this better quality ?
Nevertheless i'd like to repair them. Do you have an idea if there is a proven method ?
I couldn't upload a video...any hints ?

Thanks for your help

Best regards
Sparfuchs, vienna
 
I have never heard of a new motor that has that kind of wobble...Not to say it couldn't happen, but two of them doing the same thing? I am thinking something else is going on, like a bent dropout or something. Can you post video and pictures of the wobbling problem? It would help us help you.

:D :bolt:
 
e-beach said:
I have never heard of a new motor that has that kind of wobble...Not to say it couldn't happen, but two of them doing the same thing? I am thinking something else is going on, like a bent dropout or something. Can you post video and pictures of the wobbling problem? It would help us help you.

:D :bolt:
Click to expand...

Thanks a lot for your reply.
I tried it with different frames and even if they were all bent it would not lead to that movement ;)
Without a video its imposdible to "see" the problem..but the page woun't let me upload. I says "
ERROR Invalid file extension". How do i solve that ?
 
Sparfuchs said:
........How do i solve that ?
Click to expand...

May have to post to YouTube and then link via the youtube button above (all the YouTube characters after the = sign)
Not sure how to do it otherwise....

:D :bolt:
 
e-beach said:
Sparfuchs said:
........How do i solve that ?
Click to expand...

May have to post to YouTube and then link via the youtube button above (all the YouTube characters after the = sign)
Not sure how to do it otherwise....

:D :bolt:
Click to expand...

i uploadet it as a zip file. not the best solution ..but works :wink:
 
I saw the video.

Now I am thinking it is more then one thing. First, are your dropouts perfectly square? Second, is the rim perfectly trued?

:D :bolt:
 
e-beach said:
I saw the video.

Now I am thinking it is more then one thing. First, are your dropouts perfectly square? Second, is the rim perfectly trued?

:D :bolt:
Click to expand...

Thanks for watching the video :)
Simple Answer: no and no :lol: but the axis definitely can't move and the unadjusted rim should not be the reason for a wobbling motor right ?
Don't you think the axis got bent at transport ?
 
The axle would be my next thought, although a bent axle would keep a properly trued wheel spinning on a constant axis, not wobbling.

It may have more to do with bad side-covers or beadrings.....

:D :bolt:
 
First that's not a MXUS 3k Turbo unless they've been totally redesigned. 2nd, that brake disc is either not mounted correctly or the mount itself is not installed in the motor correctly. Are you sure the brake disc goes on that side? It seems to be strange out so far from the side cover. Is that a hubmotor for an ATV or some kind of wide wheeled scooter? With the wobbly camerawork it's hard to tell if the motor itself has any wobble, and since the wheel seems to spin true and the wheel and motor are reasonably balanced, at least up to that speed, I think everything may be ok all the way up to that brake disc interface.
 
John in CR said:
First that's not a MXUS 3k Turbo unless they've been totally redesigned. 2nd, that brake disc is either not mounted correctly or the mount itself is not installed in the motor correctly. Are you sure the brake disc goes on that side? It seems to be strange out so far from the side cover. Is that a hubmotor for an ATV or some kind of wide wheeled scooter? With the wobbly camerawork it's hard to tell if the motor itself has any wobble, and since the wheel seems to spin true and the wheel and motor are reasonably balanced, at least up to that speed, I think everything may be ok all the way up to that brake disc interface.
Click to expand...

Hello john in CR, thanks for your respond :)
1. I don't know what design you know but i have never seen a different design anywhere yet and its a 100% original mxus 3k turbo. 2. I dont, know if there is a "more correctly" way to mount a disk brake than tighten the screw cross ways ? There is just one side to mount it..on the other side there is the thread for the cassette. The disk is a little bit out because i used a spacer to have enough space for the brakes. I tried to hold the camera as steady as possible, that's the best result i was able to. Maybe i'm to old for using a smartphone (25) :p
But anyway, even if you ignore the brake disk you'll see that the motor wobbles. The side cover wobbles parallel to disk, hast to be something with the motor. The rim itself is spiked in not that bad, so it compensates the wobbling hubmotor a little bit. I opened it up to check the inside now.
Do you think in case the spokes are to tight it could affect the motor case ?
Thanks for your help :thumb:

Ps: it didn't work to upload pictures so here is the link to the motor i bought :

https://www.aliexpress.com/item/4000288190575.html?spm=2114.12010612.8148356.15.5e331e44tzMoea
 
Yes, the Aliexpress looks like a MXUS 3k. My computer smashed your video strangely, so between the spoke flanges looked like about 100mm, and the brake disc appeared strangely spaced wide.

For a motor itself to have wobble then one or both bearing cups in the side covers are not properly centered when they were machined and there's not really anything you can do to correct it. My guess is that the side cover on the brake disc side was not properly mounted in the lathe for machining.

Maybe you can try sending a better quality video to the seller and they can provide a new cover for free or a cheap price.
 
John in CR said:
Yes, the Aliexpress looks like a MXUS 3k. My computer smashed your video strangely, so between the spoke flanges looked like about 100mm, and the brake disc appeared strangely spaced wide.

For a motor itself to have wobble then one or both bearing cups in the side covers are not properly centered when they were machined and there's not really anything you can do to correct it. My guess is that the side cover on the brake disc side was not properly mounted in the lathe for machining.

Maybe you can try sending a better quality video to the seller and they can provide a new cover for free or a cheap price.
Click to expand...

i already opened a dispute on aliexpress but the seller wants me to return the motor and that costs me more than the motor itself to send it from austria to china.
The thing with the bad produced side plates was my first thought too. I could try to spin the motor what would make it to a kind of a leath and then file down the part where the disk is mounted.. or maybe just the spacer, so the motor stays original. So the motor still won't be perfect but i could at least use the disk brake.
Another Problem might be that the ball-bearing could be not pressed in centered to the limit.
 
I don't think a bearing not pressed all the way in would do that. With the video my computer decompressed I couldn't tell how far off the motor was. Motor looked to spin pretty straight and only the brake disk was way off. If it's only the disc mount, you may be able to grind or file it more true, or make a non-flat spacer.

I'd try to work something out with the seller for a new brake side side cover, which should be dirt cheap for them...or maybe someone on the forum has a burned up MXUS and could sell you one cheap, if you can't fix it yourself. Teslanv I think is the member who sold them and may have a burned one.
 
just a side thought....Did the rotor get bent in shipment?

:D :bolt:
 
John in CR said:
I'd try to work something out with the seller for a new brake side side cover, which should be dirt cheap for them...or maybe someone on the forum has a burned up MXUS and could sell you one cheap, if you can't fix it yourself. Teslanv I think is the member who sold them and may have a burned one.
Click to expand...


I'm already in contact with aliexpress to get a solution... But ist not that easy with them :wink:
 
e-beach said:
just a side thought....Did the rotor get bent in shipment?

:D :bolt:
Click to expand...

Hello e beach,
yes that's absolutely possible because the ends of the axis were not good protected in the box. But if you think of it, this should still not be a reason to wobble because the stator/(rotor?) is the motionless part. So it could make the whole motor crooked but not wobbling i guess, right ?
 
The rotor is the part of the motor that spins. For a DD hubbie like yours it is the entire outside shell. Damaging the axle won't create a wobble, though it might make the rotor rub on part of the stator. The stator is the stationary part with the copper windings and the stationary axle runs through its center.

I guess you could damage the side cover near the axle exit to put the disc brake mount on a different plane and make it wobble, but I think that aluminum is more likely to crack than bend under the kind of force required.
 
Sparfuchs said:
I'm already in contact with aliexpress to get a solution... But ist not that easy with them :wink:
Click to expand...

That's a waste of time, because you'd have to pay for shipping it back. You're likely to have more luck being more flexible directly with the seller where you pay something. eg The shipping for a new side cover along with an agreement to report the dispute as settled to your satisfaction.
 
As a way to discern the extent of the problem, I would take a steel rule and span it along the disk as much as the axle will allow for to see if it is bent. I would then slowly spin the wheel to see if the disk shows signs of being bent. Or, just take the disk off the wheel and lay it flat on a known flat surface to check for any signs of being bent.

It would confirm if it is part of the problem or not.

:D :bolt:
 
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