Originally Posted by
Duragrouch
...... I think I brinneled the cups. This was not deep into its life, circa '89 Shimano 105 headset. Perhaps it had fretting that only showed up after tightening, but like I said, not that many miles...... Usually, not that easy to damage a bearing, if the race has any reasonable thickness. But if a thin stamped race and balls or needles with small contact area, not that difficult to brinell......
Since you bought it used, you don't actually know how many miles. But think back, and if you remember, did it index straight ahead? I'll bet a night's bar tab it did, and if so what are the odds that it happened while tightening.
In any case, give some credit to the folks who make headsets. The parts aren't stamped. They're either forged or turned from bar stock. The alloys used and heat treatment produce excellent surface hardness and case to core ratios that preclude brinelling this way.
It
might be possible to brinnel the lower stack by riding loose long enough that the repeated pounding does it, but it's not likely. In my 50+ years of experience, I have never seen an "index" headset not caused by fretting, and doubt that I ever will.