I need some help as I am concerned in a possible issue with the front wheel Bafang 8fun 250W motor. I have noticed what feels like an intermittent rubbing sensation that feels like a brake block making contact to a buckled rim. After having rim trued up & brakes adjusted, it is still there. I have loosened up the brakes to eliminate them & rubbing sensation is still there. So I now know the rim & brakes are not the cause of the rubbing sensation I feel & unsure if it is meant to be there in the motor hub.

 

I have looked further into what could be the cause & noticed the wheel rocks sideways on its spindle of about 1-2mm, but as I am unfamiliar with motorised wheels I am unsure if this meant to be like this as I know it's not meant to be on standard bikes & I don't want to open up the motor to see just yet as could be a warranty issue. Could anyone please advise as I wont use it until I am sure its not going to damage the motor & both dealer & manufacturer are taking ages to get back to me. So looking at fellow pedelecs who might know & have experience of this.

 

See photo included of the hub, the movement is the spindle itself. Shown in the photo as red is the centre line of the spindle & in green is the approx movement of about 1mm. The wheel does spin freely as a wheel with a motor built in would. When spinning the wheel in the air, the rubbing sensation is not there. Its only noticed when cycling & under load of using the bike. The motor is working fine but I am concerned the rubbing sensation I am feeling could damage the motor & why I aint riding it atm until I know for sure so need to find out ASAP as to what it could be & then how to resole it.

Probably needs a new wheel bearing, which should be located in a recess on the cover plate. Undo and remove the cover plate to read the bearing part number. Cost of bearing is £1.20 - £3 off ebay from UK sellers, simply tap out and tap in with rubber mallet or hammer and wooden block as a buffer.

 

My bearing issue in this thread.

http://www.pedelecs.co.uk/forum/threads/bpm-bearing.25474/

If it moves in the way you've shown, it's knackered. Probably not a good idea to ride it like that. I've seen a couple of similar motors that had double shims next to the bearing, so that when the side-plate was tightened down, it put excessive side load on the bearing and made the motor a bit stiff. The bearing had failed in one of them and the other was new.

 

Your's looks like the screw-on side-plate, which is very difficult to dismantle without the special tool.

 

If you do dismantle it to replace the bearings, check the end-float afterwards. Once dismantled, the bearings are very easy to replace and cheap to buy on Ebay.

If you carry on riding on worn bearings, is there a risk of the rotor rubbing on the stator with that amount of bearing play?

Yes.

As I've said, I ain't riding it until I know what's going on. I won't be touching it as likely invalidate any warranty on bike or have the tools to open it. But it seems all agree it is bearings & will look at it to be repaired by reputable mechanic for the manufacturer of the eBike.

 

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I'd be surprised if they repair it. I bet they don't even have the tool to get the side off, but you never know. Is the motor from a kit or an OEM bike and which one?

Well I can't see why they wouldn't repair it considering their business is solely eBikes, the motor is part of my Momentum Upstart. Built at factory as an eBike & electrics & frame still under warranty.

 

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Well I can't see why they wouldn't repair it considering their business is solely eBikes, the motor is part of my Momentum Upstart. Built at factory as an eBike & electrics & frame still under warranty.

 

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Ring them up and ask if you can borrow the tool then. I bet they don't even know what it is.

 

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Well after no help from manufacturer & no-one locally can work on it I decided I might as well attack it with hammer & chisel to get cover plate open & check the bearings. But before I managed to check bearing it was discovered that the cover plate was slightly undone due to the grub screws had failed.

 

So I did up the cover plate, tapped it slightly with hammer & chisel to make sure its tight & problem was resolved, ordered new grub screws & all looks OK again. So after all that it never was the wheel bearings & a cheap repair after some hassles, not fussed tho as I have my ebike back on the road.

 

Was it a left-hand or right-hand thread on the side-plate?