Bafang crank engagement broken

[Mark Lester]

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 it 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. I have now ported to a new fancy pants bike, but the motor has had may be 100 miles to ingest this sand.

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.

 

[nemesis]

Sounds like the clutch has gone,i have the BBSHD and it is fairly easy to replace.

 

[Deleted member 4366]

This shows you how to disassemble. The clutch/free-wheel ratchet is in video no.3. That's the thing you need to look at.

 

[Mark Lester]

yes, i need a locking tool dont i. 5 quid in 3 weeks from china, 22 quid in a few days from nearer, or 47 quid from halfords. and presumably a new clutch.

 

[Deleted member 4366]

It could be that the pawls are just stuck because of rust after water ingress, especially if you've been near salt-water. It's absolutely fatal to take any electric bike on the beach. Tell your mentor to get stuffed next time he/she leads you in that direction.

You don't need any tools to get these motors apart. If you have a slotted ring nut to undo, get a socket the same diameter and use an angle grinder to grind two dogs on it. Get a cheap socket set from one of the tat shops that sell cheap tools if you don't have a socket to grind.

 

[Mark Lester]

i havent an angle grinder. my mentor told me off for going on sand. fyi it was national cycle route 33 at breen. i may take it to my car place to get it off, but not at this time on a friday afternoon.

 

[Fordulike]

yes, i need a locking tool dont i. 5 quid in 3 weeks from china, 22 quid in a few days from nearer, or 47 quid from halfords. and presumably a new clutch.

Don't even need a special tool. I use a pair of long nose needle tip pliers. Bought mine for £1 from Wilkinsons. Just make sure the tips of the pliers are small enough to fit in the slots of the lock ring.

Loctite threadlocker blue 242 is your friend when you reassemble. The lock rings don't stay locked otherwise.

 

[Mark Lester]

well there's no point in waiting for the post from shenzen, I may as well try what i can. right now i cant even see this locking nut, not sure if there is cap over it that i have to get off.
many thanks everyone for your assistance and moral support. the bike is fantastic and i have learned how to break most of it and make it again. but its all about the bafang

picture of what i am currently faced with
https://www.dropbox.com/s/ppp2auck45s86ck/DSCF0043.JPG?dl=0

 

[Mark Lester]

oh er, this guy is attacking it with a hammer

 

[Fordulike]

well there's no point in waiting for the post from shenzen, I may as well try what i can. right now i cant even see this locking nut, not sure if there is cap over it that i have to get off.
many thanks everyone for your assistance and moral support. the bike is fantastic and i have learned how to break most of it and make it again. but its all about the bafang

picture of what i am currently faced with
https://www.dropbox.com/s/ppp2auck45s86ck/DSCF0043.JPG?dl=0

Difficult to see on your pic, but once you get all that crud out, I'm sure you'll spot the first one. I say first, because on mine there's a thin lock nut, then a silicon washer, then the second thicker lock nut.

The first time I removed the gear assembly, the lock nuts were loose anyway. You may find you can spin them off, using the tip of a screwdriver in one of the grooves.

 

[Mark Lester]

its got 6 depressions which are barely more than marks. there certainly doesnt appear to be 4 nice holes to have a go at. it looks like some kind of cap but i cant get it of.

 

[Fordulike]

its got 6 depressions which are barely more than marks. there certainly doesnt appear to be 4 nice holes to have a go at. it looks like some kind of cap but i cant get it of.

Ehhhh?? Is yours a BBS01/02 or a BBSHD?

 

[Mark Lester]

i think its a 500W BBS02, thats what i bought. There was sealant on this plate, which i have brutalized off, hoping to find something to go at. but no.
But maybe its a "hybrid". saw one vid where he was trying to work out the gear from the motor, there are two, and he had a system with some old and some new stuff.

 

[Fordulike]

i think its a 500W BBS02, thats what i bought. There was sealant on this plate, which i have brutalized off, hoping to find something to go at. but no.
But maybe its a "hybrid". saw one vid where he was trying to work out the gear from the motor, there are two, and he had a system with some old and some new stuff.

There should be no need to brutalize anything to remove the large gear assembly, unless you bought this second hand and the previous owner smothered it in sealant.

 

[Mark Lester]

its new. or was. i will talk for bga who i got it off. they really just do batteries but sell bafangs and the cables.
all i have done is take some sealant off.
i have now shelled out 2 grand on this project and i really do want to get on a tow path now *sob*. i'll buy another flippin motor now if thats what it takes.

Incidentally, and I know you all know this but for anyone just arriving, you NEED a throttle. a touring e-bike is going to be not far short of 30kg. i use the throttle for launch as well as walk assist. they should just say "you have to pedal if you want to go over 5 mph". So its got to be bafang.

 

[Mark Lester]

here is another pic of this axle. The end looks a mess now as i have tried hacking the rubber off, I will put sealant back on it if I ever get it off, it's there as a rust protector as this bit is facing the world obviously.
I have ordered a new clutch from greenbikekit, but it aint going to be much use if we cant get in.
https://www.dropbox.com/s/jlh323n37d9fyye/DSCF0048.JPG?dl=0

edit:
"facing the world obviously", it has to be screwed in or it would just fall of, there is clearance between the crank arm and the end of the axle housing. Everything else on this axle needs screwing in with real feeling, something easily unscrewable will fall off before i get to the edge of town.
I have enjoyed calling myself an "engineer" for most of my adult life, but I am not. I am a computer programmer. If there isnt a vid, or two, showing me how to do stuff I get stuck very quickly.

 

[Fordulike]

here is another pic of this axle. The end looks a mess now as i have tried hacking the rubber off, I will put sealant back on it if I ever get it off, it's there as a rust protector as this bit is facing the world obviously.
I have ordered a new clutch from greenbikekit, but it aint going to be much use if we cant get in.
https://www.dropbox.com/s/jlh323n37d9fyye/DSCF0048.JPG?dl=0

edit:
"facing the world obviously", it has to be screwed in or it would just fall of, there is clearance between the crank arm and the end of the axle housing. Everything else on this axle needs screwing in with real feeling, something easily unscrewable will fall off before i get to the edge of town.
I have enjoyed calling myself an "engineer" for most of my adult life, but I am not. I am a computer programmer. If there isnt a vid, or two, showing me how to do stuff I get stuck very quickly.

This is getting mysterious, as it really isn't that difficult in removing the gear assembly. Some of the later models have a revised silicon seal to help prevent water getting into the bottom bracket. I wonder if that is what you are trying to remove?

Anyway, that seal should just come out using a small tipped flat headed screwdriver to prise it out. If someone else who has a later model can confirm this.

If there is no seal there, then running a small tipped flat headed screwdriver around the channel (as shown in your picture), should reveal the slots that you use to unscrew the lock nut.

 

[Deleted member 4366]

I was thinking the same. what's the point in showing a photo of it before all the grease and dirt has been cleaned out. Once it's clean, you'll see what you're up against. Try petrol to clean it quickly and thoroughly.

 

[jarob10]

The end looks a mess now as i have tried hacking the rubber off
.

Just persevere

The dust cap is sacrificial - it's just a rubber coated steel washer. Once the rubber is completely removed, the remaining steel part can be removed with a magnet.

Following a similar repair, I ran without a dust seal whilst waiting for gbk to send a spare seal

 

[Mark Lester]

This is getting mysterious, as it really isn't that difficult in removing the gear assembly. Some of the later models have a revised silicon seal to help prevent water getting into the bottom bracket. I wonder if that is what you are trying to remove?

Anyway, that seal should just come out using a small tipped flat headed screwdriver to prise it out. If someone else who has a later model can confirm this.

If there is no seal there, then running a small tipped flat headed screwdriver around the channel (as shown in your picture), should reveal the slots that you use to unscrew the lock nut.

many thanks.
yes but its stuck and i cant get a flat head under it. but will man up to it again now and see. i have squirted wd40 all round there in the hope it would start to free. it was brand new, someone must have seen it like this.