Originally Posted by
pgoat
Can someone tell me what the typical cost is to re-chase one side of a shell? And is that something most shops can do? Or do I need to find a frame builder?
I just found I broke my fixed cup (Drive side) - it sheared along the outer cup threads. I tried threading the cup back in and it feels a bit rough...I think it looks like it's screwing in cock-eyed, but hard to tell. A new cup might work fine, or I may have stripped the shell threads a bit (I rode it a few days with the fixed cup working its way out a couple of turns).
It's an old 501 reynolds steel frame, I was going to look for a bargain parts bin cup at the shop and failing that just pick up a cheap sealed Shimano BB. This is just an old 80s bike I use for commuting and street lock up so I want to keep costs down...
Loose ball cups can crack around the ball track after many miles of abuse, and an incorrectly adjusted Bb is abuse. The ones I usually see can be unthreaded from the shell with standard cup tools. Rarely the cup's end will completely separate from the threaded portion. The shell's threads are usually not badly harmed.
The cup will become distorted after cracking, the end will look cocked WRT the threaded portion. Trying to reuse or even reinstall a cracked cup is bad decision making.
When chasing a BB shell threads it is very important to maintain the shell's sides' coaxialness. So only chasing one side without the other side's tap in place, and support the pilot shaft, is another example of poor decision making. If a shop or builder is willing to only run one side's tap through the shell then question their experience. It is very easy with such a large diameter but fine pitch tap to miss align the threads and cut across the OEM threads. Andy.