Originally Posted by minastirith
My LBS just replaced my old BB to a new one and I got back my old-worn out BB. I have never fixed a bottom bracket before so I am new at this. How come the removable ring on the non-drive side just rotates and doesn't get detached from the BB body? According to Park Tool website, removable ring is either on the driver or non-drive side. If the removable ring doesn't detach, how are you supposed to install it onto your BB shell?
In most cases, the removable ring (which in the case of a UN-53 is plastic) will be on the non-drive side for an English BB. This type of cartridge BB is basically in two pieces - one being the BB cartridge body with the fixed flange being part of it's body, and, the second being the removable ring. Both of these two pieces install and are removed with the same tool (for this example - a UN-53), the 20-splined BBT-2. When you install the BB you take the fixed_flange/cartridge body assembly and screw it into the BB tube on the frame. After it is installed (remember - left hand threads on the drive side of an English BB tube) you then screw in the removable ring (regular right hand threads on the non-drive side). Aside from proper torquing both sides, that's it. The removable ring is pretty much there to keep the non-drive side of the spindle centered with the BB tube on the frame, and provide rigidity to the whole assembly. It does nothing as far as the bearings in the cartridge are concerned. The reason they can get away with using a plastic removable ring is because it's just a centering spacer. One thing they don't tell you on the Park site is that plastic removable rings don't require as much torque. If you put 360ft/lbs on them, often they will crack. I have started using 300 ft/lbs. This works fine and I have seen no problems with them backing out. Even if they do crack they will still do their intended job - keeping the spindle centered in the BB tube. I just don't like hearing that noise (the "crack") when I am installing a new BB.
I agree with just about everything they say on the Park site as pretty much gospel, but it's my experience that 350-360 ft/lbs will crack those rings at times. As they say, your mileage may vary.
I hope this answers your question ;-)
Last edited by cascade168; 04-05-06 at 03:24 AM.