Author Topic: loose hub  (Read 1665 times)

Offline ElectricStreet

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loose hub
« on: September 06, 2022, 02:12:50 AM »
Looks like the axle on my MP 4 is loose inside the hub.  The hub wobbles when you push against the rim.  Is this a common problem?  How to fix it? 

Offline Bikemad

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Re: loose hub
« Reply #1 on: September 06, 2022, 01:56:25 PM »
A small amount of movement is acceptable and should not affect the operation of the motor, but if the movement is excessive or accompanied by a loud bearing noise (or rubbing sounds coming from within the hub) it may require replacement bearings.

Take a look at the following photo and try to pinpoint the movement ("A" = Vertical, "B" = Twisting and "C" = Linear):



Movement of the hub in the "A" direction may indicate a bit of wear/play in the bearings or possibly a loose fit between the bearing and the axle shaft.
Movement of the rim in the "B" direction may also indicate a bit of play in the bearings or a loose fit between the bearing and the axle shaft, but can also be the result of loose spokes.
Movement of the hub in the "C" direction may indicate a bit of end float between the bearings and the axle shaft.

If there is no unusual bearing noise when the wheel spins, it may be possible to preload the bearings to reduce/remove unwanted movement by adding suitable shims (or even a rubber "O" ring) on the axle just inside of the right hand bearing.

How does your sideways rim movement compare with the movement seen in this video?

Alan