BBS02 Thrust Bearing failure

[Tmiller48111]

I took apart the Secondary reduction gear to regrease and removed the entire shaft and gear to clean and inspect. The retainer ring on the gear side thrust bearing had failed and was basically non existent. The bearing balls just came out everywhere. I have ordered a new bearing but wanted to know if this is a common failure. There doesn’t seem to be much discussion on this. I do a lot of gravel riding and there was evidence of some dust penetration on the bottom of the plastic cover close to the pinion. Thoughts?

 

[Gionnirocket]

I took apart the Secondary reduction gear to regrease and removed the entire shaft and gear to clean and inspect. The retainer ring on the gear side thrust bearing had failed and was basically non existent. The bearing balls just came out everywhere. I have ordered a new bearing but wanted to know if this is a common failure. There doesn’t seem to be much discussion on this. I do a lot of gravel riding and there was evidence of some dust penetration on the bottom of the plastic cover close to the pinion. Thoughts?

I don't think it a common issue as you say, not much discussion on it. Were you experiencing any noise?
I noticed the dust as well when re_greasing but don't think it gets past the rubber seal on the plastic cover.
That said I did put some easily removable sealant around the cover filling the gap to the motor as I found it hard to remove without the dust falling inside.

 

[Tmiller48111]

No noise. I think all the ball bearings were in place while together. There was dust on the inside of the cover. The grease seemed fine. It was obvious where the pinion and ring gear were meshing *shiny looking) but there didn’t seem to be any abnormal wear on the gear set. There was no slop in the meshing. The grease on the bearing might have had a little gritty quality but that could have been due to metal contamination from the disintegrated retainer ring. The race seemed fine. The shaft nuts came off with nominal torque so I don’t think it was running loose. Perhaps a bad part?

 

[tomjasz]

Hard use no maintenance and high miles? I's not a big selling part. I've never replaced one in a dozen brutally treated motors but they were always kept well greased and moisture free.

I'm away from a shop for almost 18 months now and don't know how Bafang is sealing the axel. I have the sets of bearing I purchased with my first two BBS01 250W in 2014. Several axels as well. And a plastic gear for each version.

How old of a motor? B version?

How many miles?

Bafang was notorious for being careless with factory lubrication. I'm told that's been solved. But sadly Bafang can be sloppy. That bearing is the only proprietary bearing. I wouldn't be surprised by a bum bearing getting past inspection, Some of the PCB are absolutely crap. Yeah the motor I love and love to hate. I'm still in the open it up when you get and lubricate if necessary. AND get some RTV, Boeshield/ACF50, and some labor further water proofing.

The best news is we can get parts and repair!

 

[Tmiller48111]

3300 miles. First lubrication. Road and Gravel miles only, motor usually runs at around 100 - 150 watts steady. Purchased in Nov. 2021, B version. This bearing was on the reduction gear side, so it has some protection from dust and dirt? The other bearing was gritty so I ordered 2 and will replace Both.

While we’re on the topic. Since I have it opened up, should I go ahead and check the primary nylon gear? I have Mobil 28 and have been cleaning out the factory grease so as not to have compatibility issues. Should the Nylon gear be inspected?

 

[tomjasz]

3300 miles. First lubrication. Road and Gravel miles only, motor usually runs at around 100 - 150 watts steady. Purchased in Nov. 2021, B version. This bearing was on the reduction gear side, so it has some protection from dust and dirt? The other bearing was gritty so I ordered 2 and will replace Both.

While we’re on the topic. Since I have it opened up, should I go ahead and check the primary nylon gear? I have Mobil 28 and have been cleaning out the factory grease so as not to have compatibility issues. Should the Nylon gear be inspected?

The noise about the nylon gear all started with the Luna(tic) supporter Karl. A good fella but the failures are overplayed IMO. I worked for a reseller for most of a decade and the nylon gear is another replacement part that had very low sales. Sure, inspect it, but sensible shifting will likely never need replacing. Me? I keep all the parts that COULD be needed only because I don't want to wait should anything go bad. I've yet to need to replace the nylon gear. I'm not saying they don't fail. It's just not as common as the blather in forums. SCH100 IMO is a better choice but scores of riders like mobile 28.

3300 miles and no lubrication check until now, the likely culprit IME is Bafangs poor quality control and poor lubrication.

IMO if you want a beast that'll take all the s*it you can through at it consider a BBSHD. I had 3 and decided to slow down, but a recent build was week with a BBS01B 500W. A new BBSHD completely changed the ride. My 500W will serve me well on a 2 wheel step through. But for sheer power and torque, BBSHD. All those pedicabs have shown what a reliable beast it is.