Help! Bafang HD - cranks not released when coasting

[mark_44]

I've just developed an issue on my trusty BBSHD. Basically when pedal assist kicks in (I didn't fit a throttle) , the cranks do not stop rotating unless the power is cut (e.g. braking or changing gear). Its as if I'm riding a fixed wheel bike with no freewheel - NOT GOOD!

I've tried turning it on and off, and am about to try and flash the controller again - but I worry it may be a mechanical problem. Pretty sure the chain ring did not go backwards if you try to back pedal the crank before - but it is now.

It's been a daily driver for the last few years so suggestions as to what might be the problem would be greatly appreciated.

Warm regards

Mark

 

[matthewslack]

I've just developed an issue on my trusty BBSHD. Basically when pedal assist kicks in (I didn't fit a throttle) , the cranks do not stop rotating unless the power is cut (e.g. braking or changing gear). Its as if I'm riding a fixed wheel bike with no freewheel - NOT GOOD!

I've tried turning it on and off, and am about to try and flash the controller again - but I worry it may be a mechanical problem. Pretty sure the chain ring did not go backwards if you try to back pedal the crank before - but it is now.

It's been a daily driver for the last few years so suggestions as to what might be the problem would be greatly appreciated.

Warm regards

Mark

Is your free hub working as it should? Is the problem at the crank, or the back wheel?

 

[Fordulike]

Probably the pawls in the final drive one way clutch are sticking.

I just did mine today, not coz it was sticking, but because it had become really noisy. Stripped down, put a smattering of grease on it and now it is whisper quiet.

Mine's a BBS02, so internally slightly different, but just YouTube BBSHD final drive stripdown. Can't see it being any more difficult than what I did today. Took half hour.

 

[mark_44]

Thanks for the replies.

I looked at a couple of YT videos, and the pawls looks a likely suspect. I've ordered a replacement.

I've not done any internal work on the drive since I got it in 2018. Is there anything I should do while in in there?

 

[Fordulike]

If everything else is working ok, I would just add a bit of grease to the large final drive cog. My BBS02 tends to throw it off after a few thousand miles and becomes noisier.

BTW, when I put some grease on my clutch pawls, there wasn't an ounce of lube on there. This makes me think, either there wasn't any put on at the factory, or very little was put on and it's disappeared over the years.

 

[Bonzo Banana]

Make sure you have the right grease anything too thick could cause the pawls to stick maybe not initially but as it gets more cruddy with time. In fact now I think of it don't you normally use a thick oil instead. I guess there is probably a recommended product to use.

 

[mark_44]

I got my new pawl delivered the other day from Elipse bikes. Fast delivery and reasonable price FYI

https://eclipsebikes.com/bafang-accessories-c-17_66/bafang-bbshd-pawl-clutch-freewheel-p-329.html

If anyone can recommend a suitable grease for this application - I'd appreciate it!

Thanks

 

[Fordulike]

I got my new pawl delivered the other day from Elipse bikes. Fast delivery and reasonable price FYI

https://eclipsebikes.com/bafang-accessories-c-17_66/bafang-bbshd-pawl-clutch-freewheel-p-329.html

If anyone can recommend a suitable grease for this application - I'd appreciate it!

Thanks

I just used some bearing grease that I had lying around. No need to pack it on, just smear some on with your finger around the outside edge.

 

[mark_44]

I just used some bearing grease that I had lying around. No need to pack it on, just smear some on with your finger around the outside edge.

Well, this fix isn't going quite according to plan! When a theoretically simple job becomes a PITA!

According to a couple of videos I've watched of BBSHD disassembly the outer case should just come off the axle revealing the pawls.

(@5:24)

- shows the cover coming off their BBSHD easily with the right crank arm still attached. But my cover appears to be stuck fast to the axle. I did try leverage and even tapping the axle with a wooden mallet to separate the two, but it doesn't appear to be going anywhere without major force.


This video

(@4:40)

- the BBS02 procedure looks more like what I'm seeing/feeling, where a circlip tool is needed to remove the magnetic cover to reveal screws securing the axle to the assembly housing the clutch.

Without being able to see what's going on internally, I'm guessing either he pawl is jammed - or even a tooth on the main reduction gear is worn/wedged, or (less likely?) I have some sort of revision on HD which uses a BBS02 type axle with screws in which I need to remove to access the pawls?

I'm a bit reluctant to use any more force than I have already to separate the axle from the front cover in case it is screwed in and I end up damaging something???

Any suggestions to move forward my repair would be much appreciated. Before this fault which happened instantly, I haven't had any issues with the motor - only some battery issues.

Thanks

BTW I got some grease - not much in there from the factory by the look of it.

 

[Fordulike]

I can't say for sure, but if it's anything like the BBS02, remove the circlip, pull off the PAS disc, unscrew the screws, pull out axle to reveal clutch thingy.

When unscrewing the retaining screws, use a good quality screwdriver, as they are quite tight and you don't want to damage the screw heads.