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BBSHD - drive turning but not engaging fully (sometimes), pedalling works fine

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    BBSHD - drive turning but not engaging fully (sometimes), pedalling works fine

    Over the past week or so, I've been having a strange problem in the mornings where I start pedalling and the BBSHD motor kicks in, but the motor itself doesn't seem to actually engage internally. The clutch/freewheel on the drive side seems to work correctly and I've checked inside and it looks okay on the drive side.

    Also after a few jerky starts, (motor sounds like it is spinning quickly internally but not engaging, then it suddenly "catches"), it will work fine for the remainder of my 12.5 mile journey and probably the journey home. Initially, I thought it might be the freehub on the rear wheel (as I've previously had that problem), but I've cleaned and re-greased the freehub and the problem still occurred this morning.

    My question is twofold:

    Q1. Does the BBSHD have a clutch/freewheel type thing on the motor side? (I don't think it does, as I can't see it on any of the tear downs)
    A1. Yes the nylon gear has a one way bearing (see youtube video here: Given the failure mode, and the fact the clutch on the drive side is fine. I've ordered a couple of replacement nylon gears.

    Q2. Could this be a problem with the nylon gear (although if it is, why does it only happen in the morning, and why is it then okay for the rest of the day).

    I've got a spare motor but it is for a smaller bottom bracket, I can probably just swap the internals (I assume only the housing and axle for the pedals are a are different length in the 100mm drive) , but I thought I'd ask to see if anyone else had a similar problem before opening up the motor part.

    Only done about 300 easy miles so far
    Last edited by briangdd; 10-22-2018, 01:49 PM.