Shimano BB-CS20 bottom bracket unable to assemble

marcinkrk

Retro Newbie
Hi,
I've serviced couple of Shimano's bottom brackets but that one seems strange. As in RJ's the bike guy tutorial I removed rubber seal from the one side where the flange is and undone the locknut, then undone the cone nut, cleaned, regressed and tried to reassemble. The problem starts when I want to torque the locknut because it drives in the cone nut with it because there's no washer in between with a tooth that stops it from rotating I end up with overtighten bearings. There's also no slit in the axel where the washer's tooth would fit. I can't also imagine how did they assemble it and torque it rather strong in the factory. There's no way to hold the cone nut properly and do the locknut because there's socket on the way. Do you guys have any idea what kind of sorcery did they use to tighten it down?
 

Attachments

  • IMG_20210923_235112.jpg
    IMG_20210923_235112.jpg
    355.9 KB · Views: 11
  • IMG_20210923_235004.jpg
    IMG_20210923_235004.jpg
    207.1 KB · Views: 11
  • IMG_20210923_235151.jpg
    IMG_20210923_235151.jpg
    308.4 KB · Views: 11
What I do normally is:

1) put old sealed BB in the metals scrap bin
2) buy another

Sorry I can't be of help but is it worth the faff? Maybe on a un7* at a push, but a cheapo one?
 
I see. Out of curiosity how do they tighten it? Does involve some thin octagonal pipe socket which fits the cone nut to hold it and allows socket to go through it to tighten the lock nut? I've never encountered pipe socket which is octagonal in shape, only hexagonal and they will not fit that particular cone nut.
 
Back
Top