Bafang crank engagement broke

I am trying to work out what this bit is even called.

Symptoms: a few nasty clicky noises and then while the motor still runs it isnt driving the chain wheel. Even worse and odd, i cant even pedal. obviously there is some magic between my work and the bafang. I took it off and then it worked. SO I put it back on, got 50 yards, and oit happened again, not even pedals will move the chain wheel.

Possible cause: I followed a national cycle route through a sand dune. I subsequently did two other beach runs before being told off by my cycling mentor. There is still grit everywhere.

Suggested solution: I have taken the cover off the crank area so I can see the small wheel from the bafang meshing with the large crank. Getting any further looks harder. I am proposing to attack it with WD40, try and run it on the work bench and continually spray with penetrating fluid, like buckets of it, then whack a load of grease back on and pray.

Freewheel clutch....Google it

KINNINVIEKID said:

Freewheel clutch....Google it

Click to expand...

many thanks. yes that looks like it, i need a lock nut spanner thing, i assume this honda 20/24mm one will do the job

so it is this freewheel clutching thing and the pawls, at least thats the consensus.
but i am having a problem getting the crank spindle out, i.e getting the locking nuts off. This is because i cant even see them, there is this cap in front of me, it had sealant on it, it has 6 depressions which arent really enough for a tool to get much purchase on, especially with rubber all over them. I brutalized the rubber, its there as a rust protector for this cap, but i cannot work out how to get this cap off.
Here is a pic
https://www.dropbox.com/s/jlh323n37d9fyye/DSCF0048.JPG?dl=0
its a BBS02 but the vids dont show this. Actually one has "remove the rubber seal", well its not a seal, its a cap, and it wont remove.

try wedging a small flathead screwdriver (or two) on the outside flange of the cap, then pry it out.

It's very likely to be damaged in the process and I advise you to order a few spares here:

http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bafang-bbs-axle-rubber-seal.html

note that in order to access the freewheel, in addition to the cluth's lockring plier, you will need a 4-tooth tool to untight the 2 locknuts below the rubber seal. You could do without by using 90° bent pliers. I tried, miserably failed and ordered the right tool.

it's is available on its own or slightly discounted with the ball bearings they secure
http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bafang-mid-crank-kit-bbs-clutch-replacement-washers-lock-nuts-ball-bearing.html
http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bafang-8fun-bbs01-bbs02-clutch-lock-nut-spanner-wrench.html

this tool is also available in the "Bafang Dealer Installation Tools" sold by LunaCycle
https://lunacycle.com/bafang-mid-drive-installation-tool-kit/

btw, the cluth you'll need to replace is also on GBK website:
http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bbs01-bbs02-pedal-finger-freewheel-for-replacement.html

last, if you plan to do a complete motor inspection / overhaul / greasing (strongly advised), I strongly suggest to get spare controller & motor gaskets as they too can be damaged when serviced:
http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bbs01b-bbs02b-controller-rubber-seal.html
http://www.greenbikekit.com/bbs-engine-non-asbestos-gasket.html