I've got a Schwinn Le Tour Luxe (from 1983, I think) and am overhauling it to set up as a commuter and semi-nice road bike, for a friend of mine. After stripping everything off the frame and apart (except for removing the headset cups and crown race), I noticed a crack in the crown race. It's a very fine crack, but goes all the way through the crown race. The crack was directly in line with the rear right edge of the fork's lug, so it seems the crack may have come from weight pressing down on the rear of the crown race.
For the time being, I've cleaned the crown race, and reinstalled it on the fork, with the crack lined up in the center of the right fork lug, so that the crown race is supported equally on both sides of the crack. It should work okay.
And I hope it does work okay, because it's a weird, possibly proprietary size. A JIS crown race (27.0mm inside diameter) is too large, and an ISO crown race (26.4mm inside diameter) is too small. It's possible the fork was milled to the obsolete Italian standard with a 26.5mm crown race diameter - the 26.4 won't go on, but it's close to fitting, and the 27.0mm crown race is noticeably too big for the fork.
So I've got three questions:
1) does anyone know offhand what the crown race size for this fork is supposed to be?
2) is it possible to get ahold of these crown races anymore, anywhere? I checked Loose Screws, but they didn't have anything along these lines.
3) will a fine crack in the crown race cause big problems for headset operation down the road? I'm guessing not much, except that the edges of the crack will be a prime spot for pitting, but since I've lined up the crack in a supported position, if I adjust the headset carefully things should work fine for the time being.
Useful reference from Sheldon Brown: