Magic Pie 4 failing after a week?

[RooGM]

Hey guys,

I've had my MP4 for not much longer than a week and put about 40km on it so far.  It was completely silent when I bought it and then I started to hear an electrical whirr as it bedded in after some use.  It has now started giving me a grinding or rattling sound.  It's not all the time but it can be heard most of the time when riding.  When the bike is on a stand in the house it still makes this grinding or rattling or crunching sound at certain RPMs.  For example if I give it full throttle and then bring the throttle back down gradually it will start to grind at some point.  I'm not sure if grind is the most accurate verb but that's what it sounds like.  Could it be a bearing issue?

Thank goodness for this forum because it seems that once purchased there is no customer support on these motors.

[Martins108]

Check if you have fitted your wheel correctly. It could be that noise is coming from when scratching near mudguard or fork. At least I had similar trouble when I first fitted wheel. After short inspection I understand that space between one leg of fork and motor is too tiny and from time to time its touches and create grind noise.

[RooGM]

Thanks for the reply but it's definitely not that.  I did some more tests and found that when pedalling the noise does not happen.  It only makes the sound when freewheeling.  Nothing externally appears to be rubbing on anything else. 

[RooGM]

Can anyone point me in the direction of a how-to for correctly opening up the Magic Pie to check everything looks ok inside?  And if I did do this would it void my warranty?  No instructions are provided with these things.

[Bikemad]

If it only makes the noise when freewheeling it is probably the freewheel itself touching against either the hub or the frame/axle washer. Check out this post for more details.

It might be that the freewheel has screwed itself on further with use and is now too close to the hub casing. When this happens the freewheel tries to turn with the wheel instead of ratcheting freely and can sometime cause the pedals to spin if you remove your feet from the pedals while coasting.

See  if you can reproduce the noise by pedalling backwards and take a close look at the freewheel and try to locate the cause of the rubbing noise, or if you can slip the chain off the freewheel you can then check that it spins smoothly.

If the noise is definitely not external and you think you may need to open the motor, I suggest you contact Gary first to clarify the warranty position.

Alan
 

[RooGM]

Thanks for the reply, Alan.  I have the supplied spacer ring between the freewheel and the motor and also another spacer between the other side of the freewheel and the frame so the freewheel shouldn't be able to rub on anything.  After more riding I have found that the issue is not present at the beginning of the journey but takes a while to begin (at least 10 or 15 minutes), as if it only happens when things start to warm up a bit.  The odd bit is that the sound stops immediately when I pedal along and when I'm not pedalling the sound only presents itself some of the time. 

[Bikemad]

The next time the noise develops, stop the bike and try turning the pedals backwards by hand and see if the noise occurs, and also check that the chain remains consistently tensioned along the top run between the chainwheel and the rear gear cluster (freewheel).

If you slowly turn the pedals backwards the chain tension does not stay constant (i.e. it intermittently varies between tight and slack along the top run) it means the freewheel mechanism is either touching somewhere it shouldn't, or there is insufficient free play (or perhaps a foreign object) in the freewheel's internal bearings.

My gut feeling is that the noise is probably the freewheel rubbing against the outer edges of the washers due to a lack of clearance between the end of the freewheel and the spacer washer/s inside it:



If the freewheel does not appear to be touching here, it might still be worth squirting a small amount of spray grease in there to see if it makes any difference.

Alan
 

[RooGM]

As usual Alan, thank so much for the advice.  I am going to need to go for a few more rides to investigate the points you mentioned and report back.