Originally Posted by
Panthers007
For swapping to a 3-piece BB, you need to get the old one out of there first. Measure the width of the shell on your bike (look it up). And make sure the pitch of the threads in the BB-shell match those you wish to install.
Viscount BB shells are unthreaded, with press-fitted cartridge bearings. The old bearings can simply be punched out. There's a circlip on each side of the spindle holding it in place. Pop those off and hammer away. I've heard that the shells can be tapped to accept a threaded bottom bracket, but it may be cheaper and easier just to use a threadless cartridge bottom bracket.