My bike has an 8fun BPM motor I want to look into. I have removed 6 screws from the cover but it won't come off. Does anyone know if anything else holds the cover on?
8fun BPM motor noise
- Thread starter Den Johnson
- Start date
I came across this website ages ago, not sure if it will help you?
https://endless-sphere.com/forums/viewtopic.php?t=51237
https://endless-sphere.com/forums/viewtopic.php?t=51237
D
Deleted member 4366
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You have to remove all nuts from the axle. IIRC, there's one on the disc side that holds the core into the hub. When that's off, you can tap the axle through, and it comes out as a complete motor core with the side-plate attached. To remove the side-plate, you have to put the edge on blocks and tap the axle through. Obviously, you need something soft underneath because the core will drop as soon as it's free.
Note that most graunching and grinding noises are caused by the controller, not anything in the motor.
The reason I wanted to look inside is because the wheel turns easily forwards due presumably the freewheel but won't turn backwards unless you really force it and then it makes a scraping sound.
D
Deleted member 4366
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That can still be a fault in the controller, like when any mosfets are blown to short circuit. Did you try it with the motor disconnected?
Another cause is a short in the motor wire, like when it gets damaged where it comes out of the axle when you fall off.
when the wheel turns backward, the clutch is engaged and you feel the resistance due to the friction of the rotating motor core. The scraping sound is usually caused by one or more corroded ball bearings - the fix is usually to replace all the four ballbearings with new ones. You can clean and regrease them if their seals are still perfect.
To take the lid off, undo the 6 screws, rotate the lid about 10 degrees, then use a flat blade screwdriver to gently tease the lid upward. Do that 1mm at a time and around all the 6 screws. To replace the ball bearings, you will need some bearing pullers.
Can't remember but found my BPM side plate came off fairly easily as I had to replace the bearing in said side plate.
I did something similar as to which Woosh ahs mentioned I tapped the sealed bearing out and in with a 18mm bit of copper tube but a hex socket from a set will do the job as well.
The bearings casing has a number like 6002rs printed on it and are generic get them off ebay for a few £££ available in the UK .
I did something similar as to which Woosh ahs mentioned I tapped the sealed bearing out and in with a 18mm bit of copper tube but a hex socket from a set will do the job as well.
The bearings casing has a number like 6002rs printed on it and are generic get them off ebay for a few £££ available in the UK .
D
Deleted member 4366
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If the grinding noise was caused by his motor, it's going to be completely full of rust due to water ingress, but that normally jams the clutch too, which is why I think that the cause is elsewhere. Also, the bearings turn whether the clutch is engaged or not, but he only gets noise with the clutch engaged, so unlikely to be a bearing problem and if the bearings don't make noise, then it's less likely that the motor is full of rust because the outer bearings go rusty first. It either has a lot of rust on the rotor and stator, which is rubbing, or the cause is electrical.
Here's Scotty's one:
http://www.pedelecs.co.uk/forum/threads/dirty-rusty-bafang-hub.10532/
I've fixed about three motors with symptoms like OP described. In each case, it was fixed by attaching a new controller. It's dead easy to test whether it's the controller. You just disconnect it and the problem goes away. The problem is that all the symptoms are in the motor, so that's where most people look to fix it, but there's nothing in there to fix. I'm not saying this is what's wrong with OP's motor, but it should be eliminated as a cause before dismantling the motor.
Here's Scotty's one:
http://www.pedelecs.co.uk/forum/threads/dirty-rusty-bafang-hub.10532/
I've fixed about three motors with symptoms like OP described. In each case, it was fixed by attaching a new controller. It's dead easy to test whether it's the controller. You just disconnect it and the problem goes away. The problem is that all the symptoms are in the motor, so that's where most people look to fix it, but there's nothing in there to fix. I'm not saying this is what's wrong with OP's motor, but it should be eliminated as a cause before dismantling the motor.
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I got the lid off as suggested by Woosh. The rotor doesn't want to turn inside the stator. I wonder if there's a gearing problem . At the moment I cant see how the motor is removed from the housing . I expected some kind of circlip on the opposite side but there is nothing there.
D
Deleted member 4366
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It won't turn when you take the side off because you've removed the bearing, so the axle is no longer straight. You just tap on the end of the axle to knock the core out of the hub. You can hold the rim with your hands and bash the end of the axle on a wooden bench or something similar.
it's made difficult because the magnets are pulling on the rotor to keep it where it is. It is easier to put the spindle of the non drive side on top of a block of wood and push with both hands on the rim to force the rotor out.
Got the motor out. Need a puller to separate the rotor and stator. Think my son has it but he's 120 miles away. Will get there eventually