I have an oldschool set of 401's with sealed BB. there is a 3" or so shim - does this go within between the two bearing cups when it is in installed or is it used to put the last bearing in as a sort of hammering tube?
If it is to be fitted in the bike...how the tell will you ever get the bearings out if you need to?
First build.......probably a silly question...
Cheers