Originally Posted by andy_is_me
i finally got those elusive and expensive phil wood bb cups today. i went to install the old un72 bb and even when the cups were tightened down as far as they would go, there was still play. does anyone know if there are different shell sizes used with the un72? mine measures about 57mm. i saw one on ebay just now with a 73mm shell. i assume that's what i need. can someone tell me if that one (the 73mm shell) is the one i want?
Sorry to hear that you're having trouble. I could be wrong about this but I think that all UN72 shells are 57 mm long. What is different between a 68 mm and a 73 mm UN72 is the cups which are not used when installing the Phil Wood rings. The Phil rings have to screw in farther than the normal bb cups to clamp the bearing. The problem may be that the threads in the shell don't go in far enough or that there is schmutz from the chainstay welds in the threads that is preventing the cups from going in. On one of my 20's it took excessive force to get the rings installed, enough to oval the installation tool. If you can find a Raleigh dealer that has been in business for 20 years or more they should have the correct tap to chase the threads. Otherwise a shop may be able to make a tap from one of the original bb cups and run it in far enough to reach. Hope this helps.