Last minute repairs
Despite the tweaking I did on tuesday, all it took was a short 1000' climb (from downtown to the Zoo) to bring out the chorus of clattering noises that were bedeviling me. So off I went to the LBS to buy another bottom bracket, and this time I splurged and spent $16 for a Truvativ unit because it didn’t come with a plastic non-drive-side cup.
This may have been the right choice™, because when I pulled the Shimano unit that was in there I discovered first that the threads were positively infested with grit, and, secondly, after I put in the new bottom bracket and started cleaning up the old one so I could save it as a spare if it turned out that I could service the bearings, that said plastic non-drive-side cup was actually shattered and only holding itself together by a couple of fragments of plastic.
I’m not going to bless the sealed bearings in the rest of the Shimano bottom bracket yet, but I could certainly see how a broken cup could act as a very nice pump to inject fine Oregon grime into the threading, as well as make lovely creaking and clattering noises as the bottom bracket slowly pushes the grime into places where it’s not supposed to be.
If it doesn’t rain tomorrow, I’ll have to take it out for a fairly long loop to verify that this was not a horrible mistake on my part. And then sometime next week I’ll need to figure out whether the non-plastic parts of the old Shimano bottom bracket are still functional.