So while I was rebuilding my hub (broken axle, worn freehub pawls), I figured I might as well put in new bearings (size 6902). I ordered a pair of NSK bearings, which are supposed to be excellent. I cleaned out the rat piss they use for OEM grease and lubed it up with Schaeffer's 221 #2. They were butter smooth. Then when I pressed them into the hub, they were not only high friction, but rough. I pressed them back out and they were butter smooth again. I went to the LBS and bought a set of generic 6902 bearings, same procedure, butter smooth when installed in the hub.
So apparently, the compression/squeeze forces of being installed in the hub caused NSK bearings to rub & stick? That's the only plausible explanation I can imagine. Maybe the hub bearing socket was not perfectly round, but seems unlikely since other bearings are butter smooth as installed.
Have any of you experienced a perfectly smooth new bearing becoming rough when installed? I mean properly installed with a good smooth press, not whacked into place.
So apparently, the compression/squeeze forces of being installed in the hub caused NSK bearings to rub & stick? That's the only plausible explanation I can imagine. Maybe the hub bearing socket was not perfectly round, but seems unlikely since other bearings are butter smooth as installed.
Have any of you experienced a perfectly smooth new bearing becoming rough when installed? I mean properly installed with a good smooth press, not whacked into place.