found cracks in rear hub motor side cover

P

potna

10 mW
Joined
Jun 26, 2022
Messages
27
i have a "4"kw rear hub direct drive by ebikling, i suspect it actually a 3kw, 45h magnets 155mm dropout required.

i was chasing down a noise, when people hear it they ask if my bike is broken, but it still has full power

i suspected bad bearings, and i am pretty sure the bigger bearing that is on the brake side is bad, its not super smooth, i can feel inconsistent rolling and hear noises associated with the feel, if i spin the bearing by hand with the bearing removed from the hub.


how ever, on the freewheel side of the motor, there is a side plate disk cover thing, and it is full of tiny cracks.

the cracks do not pass all the way through to the outside of the cover, they mostly seem to come from the reinforcement areas of the star shape thing that holds the bearing.

i do run what might be called high power, i run 66.6v 44ah lipo, but i normally only go about 30-35mph but for a solid 50 minutes to work and the noise gets worse as the ride continues, especially if am hard on the throttle. when i am the hardest on it, i will give it 120amps but only for a few seconds here and there. i did have issues with spokes, but i am using better spokes now i think.

could these cracks also be part of the noise i am hearing?
should i be concerned?
how did these cracks get there? abuse? weight? heat? poor design?
seems like i saw the cracks the first time i took it apart to glue the magnets back down, but i didnt pay attention to them

could i have put this back together wrong some how which lead to damage? seems like would be hard to do wrong. i use a big puller to gently take this thing apart.


if i need to get a new cover, where would i find one?

appreciate the input
 
Screenshot_20220917-090813.png

Do the cracks look like this? If so, I think my motor has always looked like this inside. I feel like it's from the manufacturing process, but I don't really know. But I do know that it hasn't gotten worse over the years & I will regularly push 6kw thru this 1500w motor...
 
I've seen them before on 9C and other Motors looks like they were done in the casting phase I bought the 3000 watt e-bike League motor because they said that the rim is also for Rim brakes when I got it I can tell the rim was not for Rim brakes that I got it up and running and all it did was make a bunch of noise because the rim was so bent and no the rim did not have machine sides and he didn't understand what I meant by that.

I had so many problems with that ebike lean kit I had to send it back the rim was so out around it would go down like a Fred Flintstone wheel
Thud thud thud.
I have a castle 3540 and it always made a thud. I think it's a bent axle ?
How old is the motor ?
 
problemaddict said:
Screenshot_20220917-090813.png

Do the cracks look like this? If so, I think my motor has always looked like this inside. I feel like it's from the manufacturing process, but I don't really know. But I do know that it hasn't gotten worse over the years & I will regularly push 6kw thru this 1500w motor...
Click to expand...

yes, almost exactly like that, i do think one of my "cracks" is deeper than yours, but you have way more cracks than i do, but yes they are similiar

i feel much better about it seeing others with the cracks, misery loves company, right? lol
 
999zip999 said:
I've seen them before on 9C and other Motors looks like they were done in the casting phase I bought the 3000 watt e-bike League motor because they said that the rim is also for Rim brakes when I got it I can tell the rim was not for Rim brakes that I got it up and running and all it did was make a bunch of noise because the rim was so bent and no the rim did not have machine sides and he didn't understand what I meant by that.

I had so many problems with that ebike lean kit I had to send it back the rim was so out around it would go down like a Fred Flintstone wheel
Thud thud thud.
I have a castle 3540 and it always made a thud. I think it's a bent axle ?
How old is the motor ?
Click to expand...

my motor is just about a year old, maybe 11 months in total, maybe 4k miles at about 35mph most of the time
 
potna said:
how ever, on the freewheel side of the motor, there is a side plate disk cover thing, and it is full of tiny cracks.
Click to expand...

Can you post a good, clear, high-resolution, well-lit picture, of both the inside and the outside of the cover? Preferably taken in direct sunlight?

This will let us see what kind of thing you're seeing, if they're really cracks or not.

i did have issues with spokes, but i am using better spokes now i think.
Click to expand...
Do you mean using thinner spokes (than the typical too-thick 12g spokes usually used on OEM hubmotor wheels), like 14-15g butted or double-butted spokes?

If not, what specifically has been changed from, and what was it changed to?


how did these cracks get there? abuse? weight? heat? poor design?
Click to expand...
We'd need to see what you're seeing before we can accurately comment. They may not even be cracks, but may simply be molding or manufacturing marks of some kind, which are not all that unusual in cast metal items.




if i need to get a new cover, where would i find one?
Click to expand...
Depends on the cover. Without seeing the whole cover, in context with the whole motor, I wouldn't know which one might fit it.

Some companies sell parts, some only whole motors (for some the cost is so close to the same you might as well buy a new motor for parts). Sometimes you can find a broken motor for sale (even here on ES) and use it for parts.
 
That just looks like some casting patterns, that can happen on sand molds or on plaster molds (probably on some other casting techniques too), but I'm no expert.
What I would do is to sand a small portion and then see if the cracks are just surface defects or if they go deeper.

I wouldn't worry too much about that. But as aberwolf rightly said, it is hard to be sure with just one picture.
 
Dui said:
But as aberwolf rightly said, it is hard to be sure with just one picture.
Click to expand...
At this time, we don't have *any* pictures of the OP's cover. The one posted in the thread so far is someone else's. ;)
 
amberwolf said:
Dui said:
But as aberwolf rightly said, it is hard to be sure with just one picture.
Click to expand...
At this time, we don't have *any* pictures of the OP's cover. The one posted in the thread so far is someone else's. ;)
Click to expand...

Ah lol indeed, I thought it was the OP.
Well lt's wait for one then. I can't believe someone would ask such question without giving us at least a pic, seems a bit strange to me :lol:
 
I'm a jeweler I do silver and gold 14 karat 18 karat 22 karat 24 Karat white rose gold and a silver Smith sincere agev15 sand casting and Navajo carving casting. So can look like cheap metalbl or not comparable companies of metal and compounds. CHEAP. Or same as 500 watt motor. Si.

I have a rinng for A W. Yes an a A.W. ring yes actual amberwolf . Can you get his ring size and you can give it to A.W.
Thanks
 
amberwolf, you have given me much to look into. i guess i am new here, and could post pix, but i can tell you that the cracks look exactly like the one picture some one else already posted. i did take a ton of pics, but i used artifical light, if i was to use day light i would have to wait until tomorrow. i was starting to get the impression that they are not cracks.

as far as spokes, i went with the same gauge, but from some company in the usa makes them, i assume they were better than chinese spokes.
i also bought a spoke tension tool and made sure they were all the same tension, and i havent broke a spoke since.

i did not know the oem spokes were too thick, i read that the thicker ones tend to brake more. i ordered and install 12 gauge 155mm long stainless spokes. i hope i didnt make another mistake with this.

i do have one more and new question:

i removed the cassette side bearing using a punch and hitting it from the other side.

i ordered timkim bearings using the exact size that i measured with my digital caliper. the new bearing is an exact match to the old.

the new bearing seems too big to fit into the plate, so i sat the old one next to the hole,, or over it, and it seems too big as well, but this is the very bearing that i removed from the plate.

i measured the inside diameter of the plate where the bearing goes and it is 35mm, but the o.d. of both the old and new bearing is 40mm.

this makes me feel insane, how can a 40mm squeeze down into a 35mm hole?


i also bought a new bearing for the other side, the side with the brake rotor and the new bearing fits snug by hand, by hand it went about 1/2 way into where it needs to go, and i planned on tapping it in with a hammer and piece of wood.

this is how most bearing installations go, but how in the world am i supposed to fit a 40mm bearing into a 35mm hole?

did the oem smash this bearing in there? is this why the bearing seems to have failed so fast?

is the plate supposed to stretch open a bit to fit this bearing?
 
999zip999 said:
I'm a jeweler I do silver and gold 14 karat 18 karat 22 karat 24 Karat white rose gold and a silver Smith sincere agev15 sand casting and Navajo carving casting. So can look like cheap metalbl or not comparable companies of metal and compounds. CHEAP. Or same as 500 watt motor. Si.

I have a rinng for A W. Yes an a A.W. ring yes actual amberwolf . Can you get his ring size and you can give it to A.W.
Thanks
Click to expand...

i have no idea of what you are talking about, is this some sort of bot troll?
 
potna said:
this is how most bearing installations go, but how in the world am i supposed to fit a 40mm bearing into a 35mm hole?
Click to expand...

Well it is not possible at all.
Either you took some wrong measurements, or you're trying to put the bearing into the wrong side of the plate.
Here again, pictures would help. It's not like picture are expensive, don't be shy! :wink:
 
potna said:
i guess i am new here, and could post pix, but i can tell you that the cracks look exactly like the one picture some one else already posted. i did take a ton of pics, but i used artifical light, if i was to use day light i would have to wait until tomorrow. i was starting to get the impression that they are not cracks.
Click to expand...
If they look just like the pic from the other poster, then they're almost certainly just casting marks (defects where hot metal stopped flowing against the cooler mold surface before it could fully flow evenly). They don't usually cause failures, unless they're somewhere on a part that is repeatedly stressed, which doesn't usually happen on these covers.

(it *can* happen on the freewheel-side cover around the often-steel threaded insert in the cover, if a rider pedals with enough torque in a high enough gear so it keeps warping the side cover in that area until it fractures and breaks, but even this is not very common).


For future use, note that pics of a problem / part can be extremely helpful in troubleshooting a problem, requiring less time and speculation and explanation on both sides. ;)


as far as spokes, i went with the same gauge, but from some company in the usa makes them, i assume they were better than chinese spokes.
Click to expand...
Possibly; couldnt' say not knowing which companies are being compared. (probably couldn't say anyway, I don't have experience of ordering spokes and building wheels from very many companies; I have more experience rebuilding wheels I already have with parts I already have)


i did not know the oem spokes were too thick, i read that the thicker ones tend to brake more. i ordered and install 12 gauge 155mm long stainless spokes. i hope i didnt make another mistake with this.
Click to expand...

If theyr'e not breaking in your usage, and not damaging the rim's nipple holes, then there's no problem.

The problem happens when the rim can't handle the tension required for the thicker spokes, and breaks or deforms around the nipple holes, and then the spokes lose tension, and the various problems can begin to happen. Since the rim is then damaged the spokes involved can never be retensioned correctly (or wont' stay that way), and stuff starts breaking, often at the J-bend (elbow) at the spoke flange.

If you have further problems later on, first carefully examine the rim itself for damage aroudn the nipple holes (or just replace it) and then use 14/15g butted or double-butted spokes, and you should end up with a stronger wheel that will last a lot longer.




i removed the cassette side bearing using a punch and hitting it from the other side.

i ordered timkim bearings using the exact size that i measured with my digital caliper. the new bearing is an exact match to the old.

the new bearing seems too big to fit into the plate, so i sat the old one next to the hole,, or over it, and it seems too big as well, but this is the very bearing that i removed from the plate.

i measured the inside diameter of the plate where the bearing goes and it is 35mm, but the o.d. of both the old and new bearing is 40mm.

this makes me feel insane, how can a 40mm squeeze down into a 35mm hole?
Click to expand...
It can't.

It sounds like something is wrong in the way one or the other is being measured--you could easily see a large difference in size of 5mm, which is 2.5mm on either side.

If it tapped out very easily, with little force required, then the bearing can't be even much of an interference fit.

If it took a bit of doing to get the bearing out it might be an interference fit, in which case cooling the bearing and heating the cover and then installing the bearing while both are opposing temperatures will usually let it fit right in.

But in neither case could it be a 5mm difference in size, to be able to fit in there at all.

If it helps, this page
https://www.skf.com/us/products/rolling-bearings/principles-of-rolling-bearing-selection/general-bearing-knowledge/bearing-basics/basic-bearing-designation-system
has a lot of info about bearings and designations, etc., that may help in finding replacements in the future. (often bearings are marked with a standard set of numbers that give you the info needed to replace them; it may be laser-etched into a race edge and hard to see without direct sunlight and/or good magnification).


i also bought a new bearing for the other side, the side with the brake rotor and the new bearing fits snug by hand, by hand it went about 1/2 way into where it needs to go, and i planned on tapping it in with a hammer and piece of wood.
Click to expand...

Just make sure you tap it in only by the outer race, not the inner one. If you apply pressure to the inner race to seat the outer one into a hole, the races and/or balls can be damaged and ruin the bearing. :(
 
Those tiny cracks looks like the heat cracking I see in gun barrels. See if I can dig up a pic.

Op, did you cook the motor ever?
 
gobi said:
Those tiny cracks looks like the heat cracking I see in gun barrels. See if I can dig up a pic.

Op, did you cook the motor ever?
Click to expand...

probably, the hub motor has a thermistor, but i could never find a display to turn that data into a display for my handle bars. the glue did let loose on the magnets when i first got it about a year ago. i was able to re-glue them back in with a high temp epoxy and most likely have pushed even more power into it and havent had an issue with the coming loose. i normally cruise at about 1.2kw, but i sometimes push it to 9kw for a few seconds here and there every once in a while.

i plan on doing that statorade thing and heat sinks, but not until i see what the temps are now
 
amberwolf said:
potna said:
i guess i am new here, and could post pix, but i can tell you that the cracks look exactly like the one picture some one else already posted. i did take a ton of pics, but i used artifical light, if i was to use day light i would have to wait until tomorrow. i was starting to get the impression that they are not cracks.
Click to expand...
If they look just like the pic from the other poster, then they're almost certainly just casting marks (defects where hot metal stopped flowing against the cooler mold surface before it could fully flow evenly). They don't usually cause failures, unless they're somewhere on a part that is repeatedly stressed, which doesn't usually happen on these covers.

(it *can* happen on the freewheel-side cover around the often-steel threaded insert in the cover, if a rider pedals with enough torque in a high enough gear so it keeps warping the side cover in that area until it fractures and breaks, but even this is not very common).


For future use, note that pics of a problem / part can be extremely helpful in troubleshooting a problem, requiring less time and speculation and explanation on both sides. ;)


as far as spokes, i went with the same gauge, but from some company in the usa makes them, i assume they were better than chinese spokes.
Click to expand...
Possibly; couldnt' say not knowing which companies are being compared. (probably couldn't say anyway, I don't have experience of ordering spokes and building wheels from very many companies; I have more experience rebuilding wheels I already have with parts I already have)


i did not know the oem spokes were too thick, i read that the thicker ones tend to brake more. i ordered and install 12 gauge 155mm long stainless spokes. i hope i didnt make another mistake with this.
Click to expand...

If theyr'e not breaking in your usage, and not damaging the rim's nipple holes, then there's no problem.

The problem happens when the rim can't handle the tension required for the thicker spokes, and breaks or deforms around the nipple holes, and then the spokes lose tension, and the various problems can begin to happen. Since the rim is then damaged the spokes involved can never be retensioned correctly (or wont' stay that way), and stuff starts breaking, often at the J-bend (elbow) at the spoke flange.

If you have further problems later on, first carefully examine the rim itself for damage aroudn the nipple holes (or just replace it) and then use 14/15g butted or double-butted spokes, and you should end up with a stronger wheel that will last a lot longer.




i removed the cassette side bearing using a punch and hitting it from the other side.

i ordered timkim bearings using the exact size that i measured with my digital caliper. the new bearing is an exact match to the old.

the new bearing seems too big to fit into the plate, so i sat the old one next to the hole,, or over it, and it seems too big as well, but this is the very bearing that i removed from the plate.

i measured the inside diameter of the plate where the bearing goes and it is 35mm, but the o.d. of both the old and new bearing is 40mm.

this makes me feel insane, how can a 40mm squeeze down into a 35mm hole?
Click to expand...
It can't.

It sounds like something is wrong in the way one or the other is being measured--you could easily see a large difference in size of 5mm, which is 2.5mm on either side.

If it tapped out very easily, with little force required, then the bearing can't be even much of an interference fit.

If it took a bit of doing to get the bearing out it might be an interference fit, in which case cooling the bearing and heating the cover and then installing the bearing while both are opposing temperatures will usually let it fit right in.

But in neither case could it be a 5mm difference in size, to be able to fit in there at all.

If it helps, this page
https://www.skf.com/us/products/rolling-bearings/principles-of-rolling-bearing-selection/general-bearing-knowledge/bearing-basics/basic-bearing-designation-system
has a lot of info about bearings and designations, etc., that may help in finding replacements in the future. (often bearings are marked with a standard set of numbers that give you the info needed to replace them; it may be laser-etched into a race edge and hard to see without direct sunlight and/or good magnification).


i also bought a new bearing for the other side, the side with the brake rotor and the new bearing fits snug by hand, by hand it went about 1/2 way into where it needs to go, and i planned on tapping it in with a hammer and piece of wood.
Click to expand...

Just make sure you tap it in only by the outer race, not the inner one. If you apply pressure to the inner race to seat the outer one into a hole, the races and/or balls can be damaged and ruin the bearing. :(
Click to expand...

sorry, i am unfamiliar with this format, i have been on reddit for some time and not used to how to make sure you see this.

i unraveled my bearing mystery. before i ordered new bearings, i stopped by autozone and asked them if they had bearings. they dug through the bearings for a while but came back with mine and said they couldnt find a match. they accidently swapped my smaller bearing with one of theirs that had a 5mm larger od.

so when i got home i looked at the bearings and between part numbers on the bearings, including the wrong one, and my measurements of my bearings i ordered new bearings. so then i had a stack of the wrong bearings. this was driving me insane. it took me several hours of trying to figure this out as i almost forget about going to the automotive store.

i went back to the automotive store and explained to the clerk what happened and he let me go digging for the bearing and found it and gave his back.

i really appreciate the input and will be better prepared with pix next time as i am surely not done getting this bike just the way i want it.
 
potna said:
i unraveled my bearing mystery. before i ordered new bearings, i stopped by autozone and asked them if they had bearings. they dug through the bearings for a while but came back with mine and said they couldnt find a match. they accidently swapped my smaller bearing with one of theirs that had a 5mm larger od.
Click to expand...

That's a new one I haven't run into before. :)

It might drive me nuts, too!
 
Dont take my word on it but i think the cracks are unequal cooling in the cast as the oxidizing layer forms while cooling after been formed its surface deep normally, i had a mxus 3k brand new with them and was concerned had i damaged it taking the motor apart and went down the same rabbit hole.

Ultimate answer would be fake a broken bone and ask the local a+e to xray the piece.
 
Spam ME ?
I been casting since 15 or 48 years ago.
My first casting[attachment=0]166388685450149293761.jpg[/attachment.

I now do silver and gold I have a 2,000 degree klin.
Spammer ?
 

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Ianhill said:
Ultimate answer would be fake a broken bone and ask the local a+e to xray the piece.
Click to expand...
Dye penetrate inspection is likely more practical.
 
maybe not the same cause but looks alike huh?
 

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