Bafang BPM Dirty Greasy Rusty Motor

[Scottyf]

Full-throttle, Thanks very much for your help on this matter!

If there was a like or great help button I would have clicked it a damn few times. Thanks to you I should only be without electric for about a week Max.
This way I can now revive a motor and improve it a little to hopefully keep me on the road for a good while longer.

Thanks very much for your help once again.

 

[neptronix]

Um, how would chain and sprocket wear make a covered chain drive system more susceptible to water?

Never mind, you're right - chains don't wear any more in wet weather than in dry nor require more maintenance than my BPM hubmotor (which is zero in > 30,000km)

Argument closed

While i'm glad you haven't had any maintenance / rust problems with your motor, plenty of people have, and it's a very common issue.

Try living a place where it rains more often than not and see if you have the same results.

3 out of 4 of my hubs of various brands have accumulated small amounts rust inside them despite being ridden only a few times in the rain.. Oregon's rain is not friendly to hub motors, Colorado's salted road slush can cause some major rust in a hurry as well. I'd like something i can ride and not worry about in North America's climate.

I think replacing a chain and sprocket at double or even triple the "maintenance interval" would be a bit cheaper than replacing an entire hub motor, or the majority of the hub's parts, if you can get said parts.

 

[full-throttle]

No worries Scotty, check your seals and it will be just fine.

neptronix: So you are saying all the hub motors suck just because some of the ones you tried do? And you are telling me that a chain drive will require less maintenance?

I was the first BPM user on this forum and I clocked more miles than anyone else here with no issues whatsoever. In over 20 years of cycling I went through enough chains/sprockets/cassettes to buy a small car and know what makes them wear out. So keep your opinions to yourself.

Try living a place where it rains more often than not and see if you have the same results.

Do your research before you write. Melbourne's rainfall for the last year is over 1,000mm http://www.bom.gov.au/climate/current/annual/vic/melbourne.shtml#summary

 

[neptronix]

neptronix: So you are saying all the hub motors suck just because some of the ones you tried do? And you are telling me that a chain drive will require less maintenance?

Nah, not all of them, there are obviously some exceptional ones, like the BPM you have or Biohazardman's BMC. So far, that's two hub motors on the forum that are waterproof. Other side of the spectrum is kingfisher's pair of 9C hubs that looked like this after approx. 6 months of rain duty in the Seattle area:

http://endless-sphere.com/forums/viewtopic.php?f=30&t=34135

Justin's prognosis for the hub motors he deals with are not good either.
http://endless-sphere.com/forums/viewtopic.php?f=30&t=34972&hilit=justin

Summary: we've tried everything to get hubs to deal with Canada weather conditions & one guy had luck with drilled hub covers

I was the first BPM user on this forum and I clocked more miles than anyone else here with no issues whatsoever. In over 20 years of cycling I went through enough chains/sprockets/cassettes to buy a small car and know what makes them wear out. So keep your opinions to yourself.

Wow, my experience is quite the opposite as yours. 50km daily commute for 5 years in all weather and had no such problems at all. That includes some pretty hairy mountain climbs, meaning lots of leg-torque on the drivetrain.

Sorry, i won't keep my opinions or experience to myself. What's with you, guy? you get defensive / offensive at the drop of the hat. I'm not a frock hater or something, i have 3 hubs as of now I'm not here to bash on hubs either, just saying that if the previous poster lives in such conditions, with the same motor as you, and has water probs, he may want to consider a chain drive due to rainproofing possibilities i mentioned.

Try living a place where it rains more often than not and see if you have the same results.

Do your research before you write. Melbourne's rainfall for the last year is over 1,000mm http://www.bom.gov.au/climate/current/annual/vic/melbourne.shtml#summary

That's quite high but the area i came from, where i accumulated most of my hub motor rust, we get about 50% more rain in a normal year, sometimes more than that. Do you also deal with salt/magnesium on your roads? because that's what started pitting my MXUS motor some.

 

[Scottyf]

The motor still ran though. If it had better bearing seals It would have gone one without causing an issue.
There's very little rust because of the grease!

It even still worked when the bearing did collapse. It carried one running. At an extremly slower rate but it still did it.
I'm sure the rain resistance protections would see me through and stop the issues.

But I was posting it for advice. I've been given that and I don't really want to create a chain drive. Its to much bespoke hassle in my eyes. An there are more pro's to it. But i can't put the time in for it. nore is it that stealthy.

 

[Scottyf]

UPDATE:

New Bearings fitted

Ended up angle grinding the remainder of the race off. Then whacking it with a chisel.
Also swapped the smaller bearing as it was cheap and only a couple of quid for an skf obe in that size.

All in all it's cost £24 for the bearings.

However I do need to re grease it. Also it's quite audible to rotate now its been cleaned.
Is this just the lack of lube or is there a bearing inside the housings that I could swap out?!?

Used the following lubes

On my commute this morning the bearings are holding up it all works. However I think the bearing that holds the cage on (Rotates to spin the gears etc) is rough. Its meant to spin with no notches and unfortuantly its a little notchy. This resonates a sound to which is amplified in the hub.

It may last if I can cope with the noise. THe better option would be to pull it apart and replace the bearing.


Does anyone know how to take the motor apart further?

 

[GrayKard]

Don't the three planetary gears have bearings too?

Gary

 

[Scottyf]

Yes but they are ok. One is a little harder to free wheel but by no means a problem.
They where caked in so much grease I doubt they suffered.

 

[ohzee]

At least she looks a lot cleaner.

Thanks for sharing.

 

[Alan B]

Waterproof grease might be a good idea. Regular grease does poorly when water gets in - emulsifies into a mess that isn't really a lubricant, as was shown in this thread. It was mentioned earlier in the thread - Use grease designed for boat trailer axles. They get dunked when hot. The waterproof axle grease handles water better and still lubricates.

Sealing any electric motor against water entry is more difficult than it sounds. Biggest problem is most likely when it cools off. They will suck in whatever's around them. If you park a warm motor in a dry place it will do better by drying off and sucking in dry air. Seals keep splashes out but won't stop the pumping due to thermal cycling.

Covering the bike while still warm might also help if you can't get it indoors for the cooling cycle. Worst thing is to let it cool off in a wet environment.

 

[fechter]

That was one of the nastiest motors I've ever seen. Amazing that it still ran.

Nice job on restoring it.

My observation is water typically follows the wires into the housing. It's very hard to seal around multiple wires where they enter. A 'drip loop' or low spot in the cable just before it enters tends to help keep water from getting in, as water doesn't follow the wires uphill. Silicone grease might help seal around the wires, or perhaps silicone glue. The trick is to get the stuff between all the wires.

A drain hole in the low spot is also a good idea to give any water a path to escape. Since the low spot depends on where the wheel is turned, I guess several small holes may be needed around the edge.

 

[Alan B]

Would drain holes let grease out?

 

[Scottyf]

I don't think there is anyway to avoid it completly.
Maybe just periodically checking and regreasing is the only way forward.

Its not particuly hard, and I did get 4000 miles out of it.

It also still works. The bearings are much nicer but the clutch is dead and who knows how long the cage bearings will last. I'll continue to use it untill it fails completly anyway.

 

[jateureka]

There are two more bearings inside the motor, so 4 in total excluding the planetary clutch.

 

[jateureka]

Here are the bearings.
When you insert the larger 6810 bearing you should apply bearing retainer compound to the outer race where it sits in the alloy casing.

 

[maca55]

Received my Bafang BPM kit last week and popped the cover open for a squiz.

Straight from the factory and guess what - missing the O-ring seal on the cover plate!
I have a feeling this may not be the first one to leave the factory without the o-ring.

full-throttle kindly came to my rescue, offering me a couple of spare o-rings.

I met him this morning on his daily commute (which it turns out is pretty much past my door step!) - nice guy who refused to accept any money for the o-rings!

full-throttle maybe you'll accept a beer instead?

 

[jateureka]

Can you measure what size the O-ring is diameter and thickness?

 

[full-throttle]

@ jateureka:
BPM will take a 2mm thick o-ring with an OD of ~150mm. The ones I found are 2mm x 120mm. They are soft and stretch just fine.
BPM CST will take 2 x ~145mm, so slightly smaller.

@ maca55:
How did you go fitting it? Got the bike up and running?

@ Scottyf:
Seems like all the new BPMs incl. CST come without o-rings..
Cost savings??

 

[maca55]

@ maca55:
How did you go fitting it? Got the bike up and running?

Sorry somehow I totally missed this post - Yep sure did get it up and running - the BPM 500 Code 10, 12S LiPo, 700x38c hybrid frame bike was up and running on 13th June 2013 and it has been my daily commute every since!!
I clocked up 10,000 km on it 1 year and 1 day later! The novelty of riding my ebike never seems to wear off. Even today after 600 rides, 350 hrs, and nearly 13,000 km, I still get that uncontrollable grin on my face as I fly past traffic jams or riders battling into head winds.

Unfortunately however today, the grin wore off rather quickly when the motor developed a very ugly sounding bearing noise.
Hopefully this video of will provide some clues for you all as to what the problem might be:

[youtube]fSgnaUGw2Ls[/youtube]

The noise is worst when the motor is coasting down or unloaded. Riding with no throttle there is no noise at all. I suspect it might be the inner most bearings?

I am a little depressed right now (to say the least) at the thought of having to drive a car to work, for the first time in 16 months! I am hoping with some help from you all I might be able to have this repaired quick and be back in the saddle before I go completely insane sitting in traffic jams?

Maca

 

[maca55]

I was thinking of buying the bearings kindly listed by jateureka, but then I check some pics I had of the internals of my BPM motor (taken in May 2014 when I disassembled to replace a cracked planetary gear) and it appears to differ majorly to the jateureka's and scottyf's motor internals posted earlier in this thread.




I can't see that large RHS bearing replaced? Instead it has a smaller bearing in the cover plate.

My motor internals seem to match up with spinningmagnets teardown:
http://endless-sphere.com/forums/viewtopic.php?f=16&t=51237#p758154

Now I'm concerned that the small internal bearings might differ also?

 

[d8veh]

It's behind that cover plate, which is held on with those three screws near the axle.

 

[maca55]

It's behind that cover plate, which is held on with those three screws near the axle.

Thanks for you help d8veh, but there is definitely no bearing there on mine. My BPM supports the RHS axle with a 6002RS mounted in the cover plate. So it looks like Scottyf and I have different design BPM motors!

 

[t3sla]

I'll email FT for you he doesn't check forums anymore.

As for the BPM I know people in Melbourne with Japanese replacement bearings for the outer two, PM u

 

[maca55]

I'll email FT for you he doesn't check forums anymore.

As for the BPM I know people in Melbourne with Japanese replacement bearings for the outer two, PM u

Thanks t3sla. FT still checks his PM's! He suggested I check the hall sensors but they all look good (multimeter check).

Last night I opened the hub to find a hub gear with a missing tooth, plus a few cracks here and there on the others. I replaced the clutch and gear set about [strike]6000km[/strike] 4000km ago. The first set of gears got me 9000km, so damaged gears this soon were unexpected. Also the noise this time was very different to before, which is why I suspected a bearing failure.

I'll post pics up soon, but right now I need to go get some grease to repack with. Recommended grease for these hub gears varies widely. I think I'll go for some with moly as that is what appeared to be in it from factory.

Thanks for help guys. I'll report back later once I'm back in service.

 

[d8veh]

I think some of the previous replacement gears are not up to the latest standard. Make sure you get the new blue type.
http://www.bmsbattery.com/accessory/634-gear-set-for-bpm-bpm-cst-motor.html