Bafang BPM front hub motor cable replacement

As mentioned in a previous post I damaged the cable for a Bafang BPM front hub motor. I found various instructions on the web for strip-down instructions – notably this strip-down on Endless Sphere.

My motor isn’t exactly the same as any of the stripdowns I’ve seen – mine is a front hub 250W motor without sensors. I’ve put some details here if only for me when I need to do this job again!

The cover plate comes off easily enough and the motor unit can then be pulled out of the hub. Note any washers between the outer hub and the motor unit!

Two shim washers on the non-wire side of the hub

The clutch and planetary gears can be pulled off. The sun gear can then be unscrewed from the motor and the circlip underneath it removed.

The key that stops the sun gear rotating on the shaft can be pulled out with a pair of pliers.

I didn’t have a suitable puller to get the stator out of the motor casing so I followed the suggestion in the post on Endless Sphere and used a puller located in the tapped holes on the sun gear. The stator is kept in position by the magnets so there is no possibility of tapping the stator out.

Home made puller

Note that the circlip underneath the sun gear must be removed; the sun gear is then refitted and the puller fitted. The puller worked well with no tendency for everything to twist sideways.

With that done I could remove the axle by removing the three screws on the wire side of the stator and tapping the axle out with a wooden drift.

Axle removal from stator

There were various bits of glue to remove – some soft black stuff around the wire where it emerges from the axle and some very hard blue stuff that held the wires in place near the omega clip. Both came off easily – the soft black stuff just pulled off and the hard blue stuff could be prised off with a small screwdriver. There were also 3 bits of wire tying the wires to the stator.

Hard blue stuff holding the wire in place. It chipped out easily with a small screwdriver.
Time to start cutting wires and soldering

So it is now all apart. Next step is to cut the old wires out and solder in the new wire. I’m just going to use the existing cable – it is plenty long enough even with the broken bit cut off. I will also try to round off the end of the axle so it doesn’t cut the cable so easily next time.

I’m not sure about replacing the glue – soft black and hard blue – presumably something is required if only to stop the omega clip from falling out. More research required.

1 thought on “Bafang BPM front hub motor cable replacement

  1. Pingback: Bafang BPM front hub motor cable replacement part 2 | Martin's Blog

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