Unread postby ginekolog » Tue Oct 11, 2016 5:08 am
My BBS02 750w is 1,5 years old and have 5000 km, mostly riding in mountain grasslands and woods under full power. I love my e-bike but had 3 major failures on BBS02:
1. Small metal pinion gear was made of peanutbutter steel - it got deformed after 2000 km. Dealer replaced it, no problems since.
2. At 2500 km motor shaft o-ring fell of shaft, shaft wore down to 7,94 mm (should be 8mm). Grinding sound was produced. I took unit apart, put blue loctitet 248 on shaf and it works well since.
3. At 2700 km big metal gear tightend to clutch with 5 M4 screws. They untigtened from vibrations, i heard grinding sound. . I retightened them with loctite 248 (but i did no degrease, this might have been mistake). Was good for 1000 km, then again i had to retighten, but one screw was broken - it snapped. I retightened with 4 screws, used load of loctite 248 (again no degrease). Grinding came back after 500 km, now 3 screws were broken.
I was looking for solution. I knew it was near impossible to remove snaped screws, so I decided to drill M5 holes. Material is very hard, I broke 3 drills. I managed to drill trough and made new M5 treads. This time I didn't use locitet but bullet proof method: making dent on screws. See pics. I am sure I fixed this issue for good. 8)
I think this is very bad design from Bafang. They should use longer M5 screws + use loctite in factory.

I hope this post helps fellow e-bikers in case of similar problems.