Motor could not run smoothly in any of the 36 combos. Help!

[tmho]

Looks like you trashed the bearing, should be fixable if you just replace that bearing. I don't think you warped it.

Worst case, buy a new bare motor, and just swap out the core.

Hi, may I know why it is the bearing being damaged instead of the rotor is warped? When I pulled the rotor out with the puller, I found the rotor not coming out evenly. Also, now from the rotation as shown on the videos, so I think the rotor is warped. When I disassembled the motor in the first time, I found one of the bearings was not turning smoothly, and I had replaced it. May I also know how to avoid damaging the bearings?

 

[fechter]

The spokes on the rotor are easy to bend. It should be possible to use something like a C-clamp to squeeze the high spot on the rotor and bend it back into shape. You might be able to bend it just with hand pressure. A dial gauge would be great for checking the trueness after tweaking.

Like truing a bike wheel, it's important to be able to measure the runout. If you don't have a dial gauge, you could try a stiff piece of wire taped to the housing such that it almost touches the rotor. While turning, look at the spacing of the gap between the wire and rotor to determine where the minimum and maximum gap are.

 

[tmho]

The spokes on the rotor are easy to bend. It should be possible to use something like a C-clamp to squeeze the high spot on the rotor and bend it back into shape. You might be able to bend it just with hand pressure. A dial gauge would be great for checking the trueness after tweaking.

Like truing a bike wheel, it's important to be able to measure the runout. If you don't have a dial gauge, you could try a stiff piece of wire taped to the housing such that it almost touches the rotor. While turning, look at the spacing of the gap between the wire and rotor to determine where the minimum and maximum gap are.

Sorry, may be I used the wrong word. "Rotor", I mean the rotor of the motor, not the rotor of the disc brake. As you can see from the video, the part which rolls, I then call it rotor of the motor. If I have mixed up stator and rotor, please advise.

 

[fechter]

Yes, I was referring to the motor rotor. The part with the magnets.

In the video, it looks to have quite a bit of runout. It should be possible to bend the rotor back into a straight position by pushing on it with enough force. You just need to be careful not to push in a way that will bend the magnet ring. The magnets are very brittle and crack easily if bent. You want to bend the 'spokes' that hold the magnet ring to the shaft. These are just sheet metal. You might be able to squeeze with a C-clamp or pry outward with a screwdriver to try to get it even all the way around.

I've bent one by accident before and was able to bend it back.

 

[tmho]

Hi fechter, it's my mistake not reading your suggestion carefully. Just by looking at the word "spoke", I thought you are referring to the spokes on the wheel.

Will follow your suggestion to see if I can fix the rotor.

 

[dogman dan]

I just assumed that using a puller properly, you'd not be able to bend up the part. If you'd said you had used a tire iron to pry on it, then yeah you can wreck one.

You are there, if you say it's bent, it's bent. Nothing to lose now trying to bend it back.

 

[tmho]

I have tried fixing the warped rotor using a C-clamp with the motor fixed to the bike as shown in the below photo. (Actually, the fixing was done with the gears not removed. The photo was taken later with the gears removed, just to show how I used the C-clamp in fixing). The task was difficult because most of the time, the rotor returned to the original warped shape when the C-clamp was released. Anyway, there was a bit improvement in both the rotor's shape as well as the noise when the motor is running, but still I do not think that was acceptable.

 

[tmho]

I then removed the gears and ran the motor again. There was no difference and so I think the gears is not the cause of the problem. I then further separated the rotor from the stator. I could not find any scratched/rubbed marks on the rotor and the stator. I put the rotor and the stator back together and run it again on the bike. I found that the motor was running smoothly, which made me happy. I found that the axle nut was just hand tightened, so I tightened the axle nut again with a wrench. But after that when I ran the motor again, it just ran not as smooth as the axle nut was just hand tightened. When I loosened the axle nut again, then the motor could run smoothly. I do not know why such happnens. Could somebody explain why? Below are the links to the videos showing those situations.

https://youtu.be/8YREGwRALFw
https://youtu.be/TrEN76XYxCU

 

[fechter]

The C-clamp is what I had in mind. Looks like it made some improvement.

Since the metal springs back when you release the clamp, you have to bend it a bit more than straight so it springs back to the right position.
While squeezing with the clamp, you might try prying on the opposite side of the rotor to get a bit more bend. It should be possible to get it very close to perfect.

Tightening the axle nut must be pushing on something that changes the clearance. This might be hard to track down if it only happens with the motor fully assembled. Looking for rub marks is a good approach. One method is to put some pieces of scotch tape on the suspect areas, reassemble and run, then take it apart and look for rub marks on the tape.

 

[tmho]

The C-clamp is what I had in mind. Looks like it made some improvement.

Since the metal springs back when you release the clamp, you have to bend it a bit more than straight so it springs back to the right position.
While squeezing with the clamp, you might try prying on the opposite side of the rotor to get a bit more bend. It should be possible to get it very close to perfect.

Tightening the axle nut must be pushing on something that changes the clearance. This might be hard to track down if it only happens with the motor fully assembled. Looking for rub marks is a good approach. One method is to put some pieces of scotch tape on the suspect areas, reassemble and run, then take it apart and look for rub marks on the tape.

Will continue working with the C-clamp.

I only tightened the axle nut on one side. In my setup, when tightening the axle nut, it only lock the axle tightly onto the bike frame. There should not be any change in the clearance between the rotor and the stator, unless the axle was bent because of the tightening which seems not quite possible. Anyway, will try again to look for rub marks inside later.

 

[docnjoj]

This may be a pretty common problem (clearance on tightening nuts. The new front geared motor I just installed on my wifes trike had this problem, and I needed to put in a spacer and a few washers to get proper clearance. You can tell by hand rotation whether the clearance is too tight . Also by using ampmeter. Amp draw free running should only be around one amp or so. Good luck on your quest.
otherDoc

 

[tmho]

This may be a pretty common problem (clearance on tightening nuts. The new front geared motor I just installed on my wifes trike had this problem, and I needed to put in a spacer and a few washers to get proper clearance. You can tell by hand rotation whether the clearance is too tight . Also by using ampmeter. Amp draw free running should only be around one amp or so. Good luck on your quest.
otherDoc

Thanks for your suggestion. Please note that in my set up (for testing) as shown in the below photo, there is no clearance problem when the nut is tightened. I just tightened one nut which only made the axle more securely connected to the bike frame. The motor was not touching anything because of the tightening. From the ammeter of my power supply, the currents drawn in both cases were more or less the same.

 

[tmho]

I tried that several times. It seems the "not smooth" is vibration. And at the start of the motor, it is quite smooth, just at the speed increases, vibration noise comes up. Will that something like in cars, when the wheel is not balanced, the driver will feel vibration at certain speed? I mean since the rotor is warped, its center of gravity is not at the center, which will cause vibration. When the axle nut is just hand tightened, the vibration cannot be transferred to the bike frame, and so the motor appears to be running smoothly. But when the axle nut is tightened, the vibration can then be transferred to the bike frame. Also, at certain speed, the vibration resonates with the frame which make me feel the vibration or noise. Will that be possible?

 

[hydro-one]

replace all three hall sensors with honeywell ss41. one is parially damaged --it reads fine with meter . or you have water in your controller, wires touching each other inside--- or a phase wire shorted to ground somehow, likely a bad insulation on windings--- try testing with a highpot meter. or you have a partially shorted phase transistor. or a broken wire at the axle entrance that allows current from phase into hall wires somehow. check your wiring with a fine tooth comb . try another controller.

check --a bad phase connection or short , that and halls are my biggest guesses

 

[tmho]

replace all three hall sensors with honeywell ss41. one is parially damaged --it reads fine with meter . or you have water in your controller, wires touching each other inside--- or a phase wire shorted to ground somehow, likely a bad insulation on windings--- try testing with a highpot meter. or you have a partially shorted phase transistor. or a broken wire at the axle entrance that allows current from phase into hall wires somehow. check your wiring with a fine tooth comb . try another controller.

check --a bad phase connection or short , that and halls are my biggest guesses

Thanks for your comments. Originally, before I opened up the motor, I had prepared for replacing the hall sensors and the hall and phase wires. But when I opened up the motor, I found that the sensors and wires are packed so tightly that I do not have confidence in replacing them in the same way. I have already tested the motor with a new controller. Therefore, replacing the hall sensors will only be my last step to try.

 

[tmho]

Today, I assembled the motor back to the wheel without the freewheel and rotor of the rear disc brake. I put it onto the bike frame and test running it. I found that there is abnormal noise only at certain speeds, that means it can run smoothly/normally at some other speeds. Therefore, I just created another new post for this - https://endless-sphere.com/forums/viewtopic.php?f=2&t=78862.

 

[tmho]

I got my motor running smoothly this morning. Please see https://endless-sphere.com/forums/viewtopic.php?f=2&t=78862&p=1164449#p1164449 for details. Thanks for all your comments and suggestions.