Bafang BBSxx - fault finding and fixes

[byebyepetrol]

With 2700km under its belt my BBS01 has been faultless.

Until last week; leaving for work 100m from home, under very slight downhill pedal pressure I heard a faint "crack" and now the cranks freewheel in BOTH directions.
I got home under power

Any diagnosis gratefully received.

I haven't pulled it down yet, I'm coping using conventional bikes.

 

[Teh Stork]

You will need to replace this clutch. It is 40 USD from greenbikekit. Additional needle bearings and other stuff might need to be replaced. Hope you can find the time to document your repair if you do it yourself.

 

[opperpanter]

With 2700km under its belt my BBS01 has been faultless.

Until last week; leaving for work 100m from home, under very slight downhill pedal pressure I heard a faint "crack" and now the cranks freewheel in BOTH directions.
I got home under power

Do you mean you got home *with* power or *without*?

 

[byebyepetrol]

Under power = "with" power.

Thanks for the advice Teh Stork.

If I replace this part will it fail in 2700km again?
At $50 a pop it doesn't make the BBS01 all that attractive.

 

[byebyepetrol]

Upon further investigation It looks like the end-bell gave way under pressure internally. The ratchet "ring" seems to be the culprit; as the cranks rotate the ring
wants to undo and force against the end-bell casting.

Any suggestions for how best to fix this?

 

[byebyepetrol]

It looks like the assembly will have to be replaced. Thankfully it's $70AUD inc post (emax.com.au)

As for removing the crank I had a bloke look and couldn't find any detailed instructions so I "winged" it.

On the non-drive side, use needle-nosed pliers to remove outer lockring then seals/ ballrace face then inner lockring and the order of components is thus:

Which leaves just rhe ballrace looking at you. This means you can now remove the crank.

Crank assy looks like new.

Bearings all seemed AOK

 

[dbaker]

Thank you for posting the pictures. Truly worth a thousand words

 

[alfantastic]

Byebyepetrol, just out of interest, how well were your crank bearings greased from the factory?

 

[speedmd]

How hard did you need to hit it to break the end off the steel bearing cap? This looks to have Magilla written all over it. :lol: Like the little digs in the bb taped end of the shaft also. We found our torture tester!

 

[Teh Stork]

Very interesting photos.

I believe that the screws holding the chainwheel hasn't been properly tightened. This led to the chainwheel loading the end-bell going through a load-cycle every revolution of the chainwheel. The cracked surface sure looks like it suffered fatigue. Given 60Hz cadence and a km covered every 2 minutes (120 cycles per km) - your end-bell went through 325000 load cycles

 

[byebyepetrol]

The grooves in the BB tapered faces are to prevent the cranks from coming off. 5 mins with a Dremel; it's a simple trick that works a treat.
Without them the crank bolt kept coming undone and this way you don't need Loctite.

As for bearing lube Alf; it's been smooth and quiet for the 2700km and the races all look like new.

Chainwheel screws were tight.

I reckon something has come adrift inside; the ratchet ring (the ring the pawls engage with) is threaded and it only took 100m of cycling
for it to undo and force against the endbell. For some reason it came adrift.

I'll pull it apart when I get the first chance.

FYI Here's the build thread for the bike: http://endless-sphere.com/forums/viewtopic.php?f=4&t=64837

 

[bono]

Just wanted to follow up on my case:

- Paul (em3ev) agreed to repair the motor under warranty in the US (without sending the motor to China)
- gears which were replaced maximum 500 miles ago are wore out
- I asked about photos of the worn gears, will upload when I receive them

Do you have any suggestions what is going on with this unit? Replacing gears every 400-500 miles sounds like crazy for me...

Thanks!

I got response from em3ev. Paul suggested that I send the kit to China and he would refund costs of the part only. I will pass and I will contact Bafang directly. I do not count on much, but I will just share my regrets.

Thanks, I have seen this on the website. I asked Paul about replacement, but he did not response yet. I will report back when I hear from him. Thank you!

Given the history I'd remind Paul of the problems and list the history for him. I'd personally call bullshit on this one. From my view he needs to stand tall and make the good with a new motor. This is VERY disappointing... This is the service I'd expect from a discounter, not a premium reseller like EM3ev.

 

[tomjasz]

Replacing the motor and gears and then replacing the gears a second time seems crazy. I'm surprised this entire unit isn't replaced by Paul. You are certainly calmer than I'd be...

Just wanted to follow up on my case:

- Paul (em3ev) agreed to repair the motor under warranty in the US (without sending the motor to China)
- gears which were replaced maximum 500 miles ago are wore out
- I asked about photos of the worn gears, will upload when I receive them

Do you have any suggestions what is going on with this unit? Replacing gears every 400-500 miles sounds like crazy for me...

Thanks!

 

[Lurkin]

I need to put mine back together, but I'm not sure sealants/lubes to use. I've enquired with Em3ev and Bafang directly without response. Given the bikes been in pieces for almost a month, patience has run out. Am I on the right track?:-

Lithium Grease - TF2 Lithium grease
Moly grease - Penrite moly grease? Does this need to be anything special?
transparent grease on needle gears?
white sealant on controller wires?
locktite on motor shaft - Loctite 641
locktite on bolts - Loctite 242

Any ideas of the best place to buy replacement clear silicon washers?

 

[Lurkin]

This wonderful forum is to loosely moderated for that to happen. Now before anyone gets frustrated by that, I appreciate that attitude most of the time. I also understand that moderators give a LOT of time to this place. Perhaps a new thread or two and a Bafang moderator? OR we work together and create a FAQ for moderator approval? It sure would be nice to find information without spending and hour to flush something out.

Another concept I'd really like to see...On ModernVedpa we had the attitude that n00bs were just that, and many times people are weak in search skills, don't have proper nomenclature, or for a variety of forgivable reasons can't find information. We NEVER answered by saying "do a search". Rather we, those who had been around a while, and knew our way around, always took a moment to point a questioner to the appropriate thread or post. If we didn't have the answer we let someone who did chime in. In that culture we considered "go search" a dickish answer. The way to grow interest and the group is being helpful. If you don't know and can't help, stay out and let someone else but never answer if not linking or helping.

If you can help a new user, please do so. If you know a past topic that would help them and don't mind pointing it out, please do so. Otherwise, just move on -- don't take it upon yourself to be the Search Cop.

I agree.. curious there is a moderator who seems to particularly like doing this without regard for how little time others have to read it all. Personally I think the search facility isn't quite what it's cracked up to be.

An FAQ is not required. You could do as I have been... update the wiki. If the wiki was actually updated with new information, people can be referred there to read it....

It will probably need reorganizing over time. The area I have updated drawfs the other write ups about other mid drives... But it certainly has the capacity to be a central repository for useful information. I intend to trawl though the threads on bafang units and continue to update it.

 

[Samd]

Lithium grease.

 

[Lurkin]

So... Bafang has responded - there is actually four different types of grease used in assembly. I have updated the wiki with their details. Will add the MSDS sheets as well as soon as I can figure out how to get it to allow uploads of pdfs.

 

[ginekolog]

Hi Guys,
https://youtu.be/e-qjojAQPzM
Is this something normal and I am too paranoid or this is something wrong with the motor?

Thanks!

My first post on this interesting community.. hi all

I have similar noise as you when pedaling. With motor power is quiet. It was quiet on begining also when pedaling. I took unit apart and found reason for noise: small metal gear( that is driving big gear ) looked fine on sight but when I tocuhed it found problem. Edges of gear teeth are sharp and worn. Thats why gears make noise because when you pedal faster than motor, other side of gear teeth touch and make noise. Grease was good in all areas.

This gear is failing:
http://www.greenbikekit.com/accessories/bafang-8fun-spare-parts/bafang-8fun-mid-crank-kit-bbs01-bbs02-iron-gear-replacement.html

I have unit 4 months with 1000km, its dated 2014-10. I ride it hard offroad, big uphills with 30% grades and on somtimes on full power . My dealer said that gears are not coverd by warranty and are considered consumption material . It seems to me unit is not designed to withstand full power for too long time.

I love riding it, it gives me superb climbing power + 52 km/h on flats. GREAT fun, bike is only 22kg. But i did not think it would worn out so fast.

For now I will not change gear.. thinking gears will adapt to eachother and wear will stop. Is it possible? If not, I will change it.. from link above it seems bafang made version2 of gear.

Follow up on problem above. I guess metal gear is failing because of crank wobbles too much. I have lockrings tight but it still moves ~0,5 mm left right . I should not move at all imho like on my other bikes. Crank arm moves 1 mm back and forth towards frame.

Do you have same problems? Are needle my bearings with bad quality control perhaps?

 

[DaDo.Bzz]

My chainwheel also moves quite a lot from/to frame. Also have clicking sounds when accelerating full throttle. I remember I read to tighten freewheel to final gear, will it help? Do we have step by step how to dismantle freewheel? As all the bearing looks good, also motor is silent when removed main shaft.

What is your opinion, could clicking sound comes from nilon gear? I have spare one, but I need to dismantle full motor and not sure if I am in a mood to go for it.

Anybody know where to order wreewheel in Europe?

Thanks guys for a good job here.

 

[speedmd]

The inner lock nut on the bb shaft is most likely not adjusted properly. There are thrust bearings on each end that should be just touching and not allowing the shaft to move much axially. You may just need a slight adjustment if the bearings are still intact.

 

[DaDo.Bzz]

Yep, bolts were loose one turn, will put loctite there. Bearings and flywheel looks good, what do u hink? Bafang is not much reliable, can not checking it and tighteen it every 500km. Lets see if clicking sound will be gone, will update.

One more stupid q, how to insert pictures here, still get just links.

 

[DaDo.Bzz]

Posting rotating pinion while it is opened.

http://youtu.be/RDPD2Lbd3SY

 

[tomjasz]

There are two versions, of that small gear shaft, a later update supposedly corrected problems. That said there have been reports of the newest gear being more robust.

 

[DaDo.Bzz]

What's the purpose of the locktite on the bearing? - Is it to "lock" the shaft into the bearing at the base of the Stator?

I also have to ask the question: Where did the O-ring come from on my motor, if there isn't a slot for it?

How many pole pairs has BBS02 750W?

 

[DaDo.Bzz]

Guys so clicking noises under full power gone! Again noisless, I am happy!