Cheap hub motor CZJB Noise

[yooper2001]

Brand new hub motor from China (can't return) thumps when turning.

All gears teeth intact.on planetary gears ring and center

Gears are oblique and opposite direction of bafang. (\ instead of / on 35t) so parts are a month away.

To test if it was loose magnets, I powered it with the hub apart, and the clutch off, and it spun smoothly, no thumping. I put the clutch on without the ring gear and cover. I powered it up, and it thumped when spinning.

I reinspected all teeth are fine. (Including the metal center gear.)

Everything spins fine when I turn it by hand, but obviously it's slow.

The questions I have are:

1. Does a loose magnet need a slight load like the clutch to clunk?
2. Can the clutch be bad?
3. Could there be too much slop in the gears fitting to the center gear and it skips?

I think try a new clutch.....center gear...then check the magnets (which are a pain due to it having a mid shaft exit cord...and trying to push the cover off enuff to get a puller under will be a pain.

Can a clutch be bad and seem good by turning it by hand?

Thanks for reading this I was hoping on fixng it,..not spending more than the motor and waiting for more than a month each time to get the next part.

My ebike is my first, and although I am electronic savvy, I have no experience with hub motors. This was supposed to be my replacement for my current one, which I inadvertently must have affected the coils with a square wave controller, as it didn't quiet all the way down when I switched back to a sine wave controller. It's got about 1k miles, and when this 'new' defective motor is fixed...I will address the noisy one.

ANY advice would be appreciated!

 

[amberwolf]

Brand new hub motor from China (can't return) thumps when turning.

All gears teeth intact.on planetary gears ring and center

Gears are oblique and opposite direction of bafang. (\ instead of / on 35t) so parts are a month away.

To test if it was loose magnets, I powered it with the hub apart, and the clutch off, and it spun smoothly, no thumping. I put the clutch on without the ring gear and cover. I powered it up, and it thumped when spinning.

Is it laced to a wheel? Or a bare motor?

if it's part of a wheel, the thump can be a nipple loose in the rim. Not an uncommon problem; the wheeelbuilder drops one inside and says screw it and grabs another and finihses the build, leaving the lost one to rattle around inside.

1. Does a loose magnet need a slight load like the clutch to clunk?

Not like that, but it needs high enough current draw in the stator to cause a magnetic field strong enough to pull it away from the rotor backing ring. That usually means an assembled motor and the load of it pushing against hte ground thru the tire.

2. Can the clutch be bad?

possibly, but a clutch doesn't normally make noises. It typically fails to grab hold.

If the clutch housing is cracked it might make a sound if something passes the crack as it slips, but once it's locked in place or if nothing slides or rolls past the crack it shouldn't make a noise. But a cracked clutch usually rpevents the motor from spinning the wheel under any load (even your hand on the tire).

3. Could there be too much slop in the gears fitting to the center gear and it skips?

probably not. But there could be a bit of debris from manufacturing in there, stuck in the grease on a gear tooth. can be tiny if it's enough to cause the gears to ride up over it.

The ring gear on the hub shell might thunk if it's key is missing, as the keycutouts pass each other while hte ring spins inside the shell-=-but the shell won't spin when the motor does if this is happening.

Can a clutch be bad and seem good by turning it by hand?

Yes, in that it could slip under higher loads than you can manually place on it, but it would not normally be thumpy.

This was supposed to be my replacement for my current one, which I inadvertently must have affected the coils with a square wave controller, as it didn't quiet all the way down when I switched back to a sine wave controller. It's got about 1k miles, and when this 'new' defective motor is fixed...I will address the noisy one.

If the phase / hall wiring combination is wrong, a motor will often be noisy and run "wrong" (too fast, too slow, too hot, too weak, etc). If the controller has an autotune or self-learn, try that. Otherwise, there are numerouls threads and posts here about finding the right combo.

 

[yooper2001]

First and foremost, THANK YOU for your reply and help.

This is a brand new motor only..not laced. I meant to swap out the insides to my current Bike motor. I cleaned all grease..and there is no broken teeth or foreign objects. I powered it up with the ring gear/cover off ...just the motor and clutch...and it still thumps/clicks(a noise with a slight vibration/movement of motor) like 1 to 2 times a rotation...and it gets louder the faster it goes.
I took the clutch with the 3 planetary gears off and powered the motor...and it ran smoothly with no noise.

Since this motor is new... It does not have a point where everything worked. I did order a clutch with gears today, but it will take a while to get here.

Since I did rev the motor up without the clutch on, and it changed, it seems by what you said, the magnets should be good since it was different without a drastic load.

Maybe one of the plastic gears is warped/out of round?
Maybe the oblique angle is slightly off? You figure czjb would have SOME kind of quality control?
Hopefully the new complete clutch assembly will fix it.



As for my loud motor in my bike.. I got one of those sweet testers...and all my phases and hall sensors are nice and happy on the wheel on the bike. They caused the testers lights to light up in proper sequence I have good power, and its smoother than what it was with the square wave controller. Its just the motor hum is significantly louder than it should be...I plan on pulling the magnet cover when I get this new motor fixed and in the bike. Thanks again.

 

[amberwolf]

just the motor and clutch...and it still thumps/clicks(a noise with a slight vibration/movement of motor) like 1 to 2 times a rotation...

If it is once per motor rotation, then the problem is at the sun gear or the motor shaft leading to it or bearing supporting one or more of these parts. If it is some other number, that number will tell you based on tooth count ratio where the noise is.

You figure czjb would have SOME kind of quality control?

They do. Their QC testers receive the parts they ordered, fliter them out, and make warranty claims on them as needed. The same is true of most of the companies out there.

(GoldenMotor, a really big company in this business, once shipped out their magicpie motors with black battery positives and red battery negatives. This caused the expected chaos and destruction as they were hooked up backwards to batteries by pretty much anybody that bought one. Eventually they started sticking + and - labels on them, but they didn't change hte colors, so the problems didn't really stop, since nobody is not going to assume that the battery wires are red positive black ground/negative, and will assume the labels are wrong. :lol:

As for my loud motor in my bike.. I got one of those sweet testers...and all my phases and hall sensors are nice and happy on the wheel on the bike. They caused the testers lights to light up in proper sequence I have good power, and its smoother than what it was with the square wave controller. Its just the motor hum is significantly louder than it should be...

Keep in mind the tester doesnt' *necessarily* show you the best combination for the motor and controller. Depends on the tester design, and if it was built correctly itself, etc.

If the controller has an autolearn feature, that is the best way to make it work correctly.

If the controlelr is an FOC controller, it normally has to be setup specifically for that motor--either via an autotune routine (in software or by wire pair connection, etc), or by manually tuning it in the software for that specific controller.

Some ocntrollers, even sine, may also just not be as quiet as others. Dpeends on how they drive the motor, how they are designed, etc.

There are also dual-mode controllers, where if they have any problems driving hte motor sensored, they fall bakc to sensorless, and this is usualy noiser, and often goes to trapezoidal (square) operation instead of sine.

 

[yooper2001]

If it is once per motor rotation, then the problem is at the sun gear or the motor shaft leading to it or bearing supporting one or more of these parts. If it is some other number, that number will tell you based on tooth count ratio where the noise is.

I don't visually see anything wrong with the sun gear, but I can see that effecting the clutch making noise.

Anything else would have made the noise with the clutch off right?

There are also dual-mode controllers, where if they have any problems driving hte motor sensored, they fall bakc to sensorless, and this is usualy noiser, and often goes to trapezoidal (square) operation instead of sine.

It is a 3 mode controller. I pulled the hall plug...and it ran obviously sensorless. I could not figure out a safe way to make it square mode...but the other controller was the same except square and sensorless only...and the sine wave controller is smoother and slightly quieter only.. But I am glad to know not all sine wave controllers are silent. Maybe I'm over analyzing it.

Thanks again

 

[gromike]

Run it and see what happens.

 

[amberwolf]

I don't visually see anything wrong with the sun gear, but I can see that effecting the clutch making noise.

Anything else would have made the noise with the clutch off right?

A bearing might not, if it requires the loading of the bearing in a specific way to cause the problem. A bearing may also have a probelm with a ball in it, or a roller, and that can "travel" around the circle and click or whatever in more than one place, or in a pattern that doesn't match that of any parts it supports.

 

[docw009]

Can you record it (video preferred) with your smart phone and upload the file to youtube or a server?

 

[yooper2001]

Can you record it (video preferred) with your smart phone and upload the file to youtube or a server?

I was a little intimidated....but I did it.. no camera stand....just a box...as I had to hold the hub and operate throttle
Anyhow....here it is....easier for you guys to see than to read

 

[amberwolf]

Ok. From that video, it almost has to be a bit of debris or malformed or damaged rotating surface. I can't tell any rotation-point-relative info as it is spinning too fast (would need to be much slower down to the very few rpm level).

If you hold the motor in your hand, and the sungear in the fingers of the other, then manually rotate the sungear by hand with them, feeling for anything. Even the tiniest non-smoothity might be your problem. Note the sungear will backrotate the motor in either direction, so it may be really hard to turn against the magnets.

If there is complete smoothness, then hold the clutch in your hand, and stick your finger into the hole for the sungear. Slowly manually rotate the clutch around your finger in whichever direction it will spin (one way should lock the clutch, the other should freely rotate), and feel for any non-smoothity. If there is none, then there has to be some interaction between the sungear and the clutch that's causing it.

You may have to "push" against the clutch in different directions as you do this to feel it.

 

[yooper2001]

Ok....I just got off the phone with CZJB...after about 5 minutes with the desk clerk as an interpreter....I resolved the issue...
I guess it's good I was able to fix it. But bad they have the problem

Come to find out they just had a bad batch of plastic gears come through with some teeth longer than others...with the use of a micrometer.. I found and shaved the problem teeth with a scalpel.. and the noise went away!
The teeth had no marks..but were about 1/16 inch longer only on one end.

Hopefully someone can see this post and learn if they have the same problem.

Oh...and here is my louder sine wave controller fed motor..lemme know what you think.

Amber wolf, I did the self learning trick with hooking the two wires...and it was already connected correctly...it just went reverse...then back.

 

[amberwolf]

The good news is that a problem like that would solve itself over time. Either the teeth would wear down to be more even, or the extra pressure on the roots of them would crack the gear. :lol:

If they did that to the metal gears it wouldn't work that way, but the plastic ones would.

A whole 16th longer at one end (presumably meaning toward one flat side of the gear itself vs the other) is pretty bad--that's a really awful job of creating a mold or a machining process that should have been caught by the first person even looking at it.

 

[amberwolf]

Oh...and here is my louder sine wave controller fed motor..lemme know what you think.

Amber wolf, I did the self learning trick with hooking the two wires...and it was already connected correctly...it just went reverse...then back.

Then it's probably running as well as it's going to with that controller.

Another thing: some more advanced controllers operate sensored at start, and switch to sensorless above a certain motor RPM. With a geared motor that runs several times faster than the wheel, that can be at a VERY low wheel speed.

The ones I have actually seen doing that are FOC and have setup software to do all this configuration, no wire-jumper-pair, so yours is probably not one of them....but it could be a feature adopted by some cheaper controllers, and could cuase noise or other problems with geared hubmotors. If the motor runs quieter at lower speed, it could be that (if it's not a mechanical issue inside the motor itself).

Most geared motors are fairly noisy, though helical gears improve that significantly (but are less efficient because of the sideloading power wastage in the gearing).

Simple beveled gears may be a little quieter than straight-cut, but they can also be noisier if they don't have bearings to deal with the sideloading, vs straight-cut gears.

 

[yooper2001]

Well today I was wiping down the bike with the louder motor after getting caught in the rain, and by chance had to move the crank while in proximity to that little 20 inch wheel....and heard some crackling.....come to find out the freewheel rear bearings are gone. Literally, there are at least 3 or 4 gaps...They do indeed howl when the wheel moves fast, so hopefully next week when the new one comes in, it will be quieter.

 

[amberwolf]

.come to find out the freewheel rear bearings are gone. Literally, there are at least 3 or 4 gaps...They do indeed howl when the wheel moves fast, so hopefully next week when the new one comes in, it will be quieter.

Most of the freewheels I've ever opened up are not full of bearings. Only a few have had a complete circle of them.

Doens't mean this isn't a problem in yours...but something to keep in mind.

If it helps

Rebuilding Bicycle Freewheels

Information on SunTour Perfect, Pro-Compe and New Winner freewheels, which were very common on 1970s and 1980s derailer-equipped bicycles and which offer a great variety of options for sprocket sizes, and compatibility with Shimano 7-speed index shifters: how to perform maintenance, restoration...

sheldonbrown.com

normal set

Don't fill the race completely -- leave room for two or three more balls.

 

[yooper2001]

Yep....I should have said BIG gaps.....so big...the back side of the freewheel would rock side to side like a belly dancer and crunch.....and quite a few samples of the bearings weren't spherical anymore. I got me a new 11-32 teeth one that will help both low end and ghost pedaling too. I'll be opening bike parts for Christmas!

Thanks for the good advice Sir!

 

[amberwolf]

Yep....I should have said BIG gaps.....so big...the back side of the freewheel would rock side to side like a belly dancer and crunch.....and quite a few samples of the bearings weren't spherical anymore.

That usually happens when debris has gotten into the bearing races, and then ground hte bearings to bits.

 

[yooper2001]

It definitely got dry, as I thought they were sealed bearings and did not take the freewheel off to grease it...I just hit 1000 miles. It was a very cheap bike.
I will look at the new one when it gets here and adjust my maintenance.
*edit*
I guess after research just flushing with WD to remove grit regularly should work. I live in Montana. Dry and dusty carries lots of grit that probably wore it down and the constant wind prevented me from hearing any grindy noises. I did flush it initially...and that made it much worse...so I took it off, and discovered the horrid shapes of the bearings. It's good that the freewheels are dirt cheap, and easy to install

 

[amberwolf]

Even with grease, dust and debris will get into any unsealed bearing over time, unless there is some form of gasket to prevent it. I've never had a freewheel with a seal, though they probably exist.

Also...if you use excessive grease in a freewheel (more than just enough to stick the balls to the races during reassembly), then depending on your environment it will eventually "clot" and cause the pawls to stick down. If all pawls stick, it doesn't drive the wheel via the chain anymore, just slips. If only some stick, then the rest are taking more load than normal, and if a lot of torque is applied they may fail (either locking hte freewheel or causing it to just slip are the usual results, sometimes intermittent operation).

I'm in phoenix, az with flinty dust and metal dust / fragments everywhere (here in the city), so I just accept that the stuff is going to wear out and replace stuff as it fails.

I don't lube the chain, for instance, because it ends up causing more total drivetrain wear from the grit on the rollers and the sprocket teeth than if I clean it when I get it and then leave it all dry. It's also much cleaner to do roadside fixes for derailed chains taht way. It's dry here most of the year, so I'm not worried about rust. I just have to dry things out after the couple or few rains I have to ride thru, or the once-a-year-ish flash flood that drowns the bottom foot or so of the trike.

Wheel bearings--those I make sure stay greased, and clean as needed, except for hubmotors which are usually sealed bearings that I can just oil.