MXUS 1000W Side panel cracked, what now?

Hello,

I have a MXUS XF40 30H (1000W) hub motor. Don't know how, but my drive side bearing disconnected from the side panel. I have about 7000 km on this drive and looks like that was the weakest part that gave up.
Is there a site that sells parts like these?
I have talked to a person who could weld it back. Have anyone before done similar repairs? what are the tolerances for stator not to rub against the magnets? I'm a bike courier, so I need to be back and running as fast as i can, repair would be the best solution.
Any thoughts?


Thanks

I don't know where you live but I just bought 1 of those motors from Grin Technologies in Vancouver BC Canada, they might have side covers.

goatman said:

I don't know where you live but I just bought 1 of those motors from Grin Technologies in Vancouver BC Canada, they might have side covers.

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Checked them out, but shipping would be expensive as I'm from east EU.
They have side cover for nine continents motor, maybe fits. Shows out of stock unfortunately. I will ask.
Thanks.

Is your bike rigid frame or has suspension?

lacookie said:

I have a MXUS XF40 30H (1000W) hub motor. Don't know how, but my drive side bearing disconnected from the side panel. I have about 7000 km on this drive and looks like that was the weakest part that gave up.

Click to expand...

this happens usually because people with motors tend to leave their rear shifter in the farthest outboard gear (the highest gear), and then if they do pedal hard especially at startups from a stop, without shifting down to the low gears first, there is a prying action that occurs against hte cover from the freewheel.

eventaully that fractures the cover around the bearing, just like you describe.

Is there a site that sells parts like these?

Click to expand...

the only place i know for certain would be mxus themselves, in china, but you have to be sure to get the same version cover since whatever newer version they may be making now may not fit it the same.

grin tech http://ebikes.ca might have some spares, again make sure it's the same version.

I have talked to a person who could weld it back.

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make sure they take teh bearing out first, or the heat from tig welding the aluminum will damage the bearing. and make sure the cover is not on or near the motor while they do it (or slag will get in the motor and damage it).

they should also re-heat-treat teh cover after welding, or else the whole area around the weld will be lower strength than it used to be.

what are the tolerances for stator not to rub against the magnets?

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it's usually quite a small gap. measure the outside diameter of your stator, and hte inside diameter of your magnets. subtract them, and divide the result by two. thats the airgap.

lacookie said:

They have side cover for nine continents motor, maybe fits.

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unlikely, but since the 9c "is" an mxus-designed motor originally afaik, it might at least be the same diameter. the lip near the magnets and placment of holes could be the same in that case, but the bearing size and lateral distance from lip are rpobably different.

Thank you all for your responses, great help.

I noticed that some magnets have scratches on them, does that decrease the performance or is that something i should not worry about too much?

amberwolf said:

lacookie said:

I have a MXUS XF40 30H (1000W) hub motor. Don't know how, but my drive side bearing disconnected from the side panel. I have about 7000 km on this drive and looks like that was the weakest part that gave up.

Click to expand...

this happens usually because people with motors tend to leave their rear shifter in the farthest outboard gear (the highest gear), and then if they do pedal hard especially at startups from a stop, without shifting down to the low gears first, there is a prying action that occurs against hte cover from the freewheel.

eventaully that fractures the cover around the bearing, just like you describe.

Click to expand...

Was thinking about single speed setup for a while now, this convinced me now.
Does bigger motors improve on this? Thinking about MXUS 3k Turbo.

rockstar195 said:

Is your bike rigid frame or has suspension?

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Front suspension only, trying to save money for EEB frame. Was not convinced I needed an upgrade, but this gives me an excuse to get one now, since full suspension would help with longevity most likely.

lacookie said:

I noticed that some magnets have scratches on them, does that decrease the performance or is that something i should not worry about too much?

Click to expand...

If the scratches are circumferential, all around the rotor magnets along a line, then some bit of debris is likely stuck in there and grinding between the magnets and the stator laminations--there will also be a similar line along the laminations in the same place(s).

if the scratches are random angles and lengths, it's probably just manufacturing damage. if they're just surface marks and not gouges, it doesn't matter. if they're deep enough to penetrate the nickel coating (if it's peeling around the scratch edges), then eventually the magnet inside will corrode if exposed to moisture.

if the scratches are all sideways, lined up with axle, then they're also probably all on one side or small area, and are likely from pulling the stator out, as it scrapes on the magnets.

etc.

but anyway, unless they corrode from penetration of the nickel coating, they're fine.

lacookie said:

Was thinking about single speed setup for a while now, this convinced me now.
Does bigger motors improve on this? Thinking about MXUS 3k Turbo.

Click to expand...

no, they don't.

the problem is because the side covers of hubmotors are big flexy aluminum plates (and often poorly cast of unknown quality materials), unsupported except at the edges and the center. and since the freewheel just hangs unsupported out far from the cover, then all pulling by the chain tugs the cover--the farther out, the worse the problem, but it happens in all the sprockets.

adding a bearing in the outer end of the freewheel, to the axle, will fix this, but that's really the only easy fix. this has been done now and then, as a diy fix, and posted about here and there on es.

(cassette types of hubs do this already, or at least they do on bicycle hubs; motor hubs may or may not do it so you would have to check directly in each one to be sure).

redesigning the cover and motor inside would be the other way to fix it...but that's a lot of work and time, etc.

See if you can find a local welder where you live and have it fixed!
Should be very cheap and quick.

hkj said:

See if you can find a local welder where you live and have it fixed!

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i guess you didnt read his original post?

lacookie said:

I have talked to a person who could weld it back.

Click to expand...

I had the panel welded since mxus did not want to sell me side panel on alibaba.

The guy that I contacted about welding my side panel seemed confident, but did not know anything about hub motors. I wanted to have my ebike back and running as soon as possible so I took the gamble. Fear was that welding this sort of part would end up with wobble in side panel as metal tends to deform when welded.
That is what unfortunately happened, there was some deformation.

He had an Idea, but said that he doesn't have the tools and skill to do it. It involved putting the side panel on a spinning machine then heating the panel and using something like bearing to guide panel into proper form.
His work was more expensive then I intended at first and spending more money is not what I would like to do especially if there is no guarantee about the final result. Since in my country there is no one that works on hub motors on that level there is no service where I can ask for fixed well performing hub motor as part of final agreement understandably.

I have put together the hub with the wobbly side panel and there is slight rub as there should be. Most likely magnets and stator touching. Rub seems slight so I might just try my luck and hope that it grinds out itself.

I could seeing the rub marks pry the panel using axle in the other direction to cancel the place where it rubs, but I guess would more likely just break the panel again rather than achieving my result. (Heating and then doing it could help?)

Here are some pictures of the side panel before and after.

lacookie said:

He had an Idea, but said that he doesn't have the tools and skill to do it. It involved putting the side panel on a spinning machine then heating the panel and using something like bearing to guide panel into proper form.

Click to expand...

that might wokr, but it may alos introduce mroe cracks (taht you can't see) in the metal.

I have put together the hub with the wobbly side panel and there is slight rub as there should be. Most likely magnets and stator touching. Rub seems slight so I might just try my luck and hope that it grinds out itself.

Click to expand...

where are the scratchmarks from the rubbing? if they are between magnet and stator then it means the cover is no longer round, and tha'ts tough to fix.it actually affects motor operation because the airgap on one side is twice as big as the other so torque is uneven.

if it's btween windings and side of cover, that;s worse, but easier to fix. worse cuz if you rub the insulation off the windings and they short to the cover, you can destroy your controler blowing up the fets. the inslation can be reapplied if the windings aren't worn down in the copper part. if it wears the copper then the resistanse of that seciton is higher and high currents thru it will heat it more. easier to fix cuz you can just sand the cover down in just the area it is leavng marks on it, until it doesn't leve marks anymore.

I could seeing the rub marks pry the panel using axle in the other direction to cancel the place where it rubs, but I guess would more likely just break the panel again rather than achieving my result. (Heating and then doing it could help?)

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it'll probably just break it. eiher immediately or create cracks that will break unpredictably after some peropd of time. it also only fixes the latter type of warp above, and not the stator/magnet type of warp.

Interesting repair topic. I wonder though: where do you live ? Here is europe, I know of no welder willing to do this kind of aluminum job for less money than it would cost to buy a new motor (actually more like 2new motors)....

For the weld itself, are you going to have it heat treated ? The HAZ of an aluminum weld is particularly prone to cracks if not treated properly, though as others pointed it out, there is no way to know for sure which alloy mxus used.

On a sidenote, 212 9c motors with similar power have side panels reinforcements. Maybe worth a swap ?

Don’t know if you still need one, but here’s a link for a side cover for sale for a 30H.

https://nexun.pl/motor-cover-cassette-side--bearing-for-mxus-30h

lacookie said:

I had the panel welded since mxus did not want to sell me side panel on alibaba.

The guy that I contacted about welding my side panel seemed confident, but did not know anything about hub motors. I wanted to have my ebike back and running as soon as possible so I took the gamble. Fear was that welding this sort of part would end up with wobble in side panel as metal tends to deform when welded.
That is what unfortunately happened, there was some deformation.

He had an Idea, but said that he doesn't have the tools and skill to do it. It involved putting the side panel on a spinning machine then heating the panel and using something like bearing to guide panel into proper form.
His work was more expensive then I intended at first and spending more money is not what I would like to do especially if there is no guarantee about the final result. Since in my country there is no one that works on hub motors on that level there is no service where I can ask for fixed well performing hub motor as part of final agreement understandably.

I have put together the hub with the wobbly side panel and there is slight rub as there should be. Most likely magnets and stator touching. Rub seems slight so I might just try my luck and hope that it grinds out itself.

I could seeing the rub marks pry the panel using axle in the other direction to cancel the place where it rubs, but I guess would more likely just break the panel again rather than achieving my result. (Heating and then doing it could help?)

Here are some pictures of the side panel before and after.

Click to expand...

what a madlad you didn't even remove the bearings...I'm literally about to try this same process cuz I don't have tools to get the bearing in and out.

I'm on my second 2 broken sideplate with my first motor, so I just installed a different style of hub motor. But I'd love to see if I can the first one up and running with this. Can you share what kind of welding type you used?

Tangential question: why are freehubs even a thing on electric motors? And not only a thing, but dominant from my observation.

It seems like most electric motors came about when 8-9sp cassettes were pretty much the standard. Freehubs even today are fairly limited in their selection to low end quality components in the 6-7 speed range. Whereas cassettes cover the whole spectrum.

Comrade said:

Tangential question: why are freehubs even a thing on electric motors? And not only a thing, but dominant from my observation.

It seems like most electric motors came about when 8-9sp cassettes were pretty much the standard. Freehubs even today are fairly limited in their selection to low end quality components in the 6-7 speed range. Whereas cassettes cover the whole spectrum.

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Perhaps you are mixing up freehubs vs freewheels. Most hub motors come with freewheels, and getting one with a freehub is usually a special order.


Personally I'd rather have a freewheel since it's a fully replaceable unit. Finding parts to fix or rebuild a freehub on a Chinese hub motor seem like a bigger deal. I felt differently until I realized how many miles you can put on these bikes, and how quickly those components can wear, even when not pedaling.

E-HP said:

Perhaps you are mixing up freehubs vs freewheels.

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I did. I meant freewheels are dominant with motors, while freehubs (cassettes) are even more dominant in non electric bikes.

E-HP said:

Finding parts to fix or rebuild a freehub on a Chinese hub motor seem like a bigger deal.

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I would not have expect these parts to be proprietary, but rather direct reuse of parts from normal rear hubs. They are visually and obviously dimensionally identical.

THe cassettes you can install on the freehubs are usually the same splines, and fit both, but because the motor and side cover are not the same as the bicycle hub shell, the parts for the motor freehubs are typically very different in design once you get past the splines on the outside.

There are a few threads around here of people trying to find compatible parts, and those with resolutions usually have to get a new side cover with freehub from the motor manufacturer/seller.