Narhay

Barring a precision lathe and grinding new cup and cone surfaces can a slightly pitted cone ever improve with usage with new balls, clean races and new grease?

noglider 

I'm not a machinist though I worked as a bike mechanic. I've done a lot of bearing overhauls. My semi-informed opinion is no.

Mr. 66

Mad Honk was doing just that with a headset in a thread just the other day.

merziac

IME they can, I've told this story before.

My first lesson in what is now C+V was way back in high school when after I got my first really good bike.

It was a unique to the PNW Mizutani Super Seraph, top of their line, a bit heavy and equipped with a Sugino Mighty Competition crankset.

I failed to realize when the pathetic factory grease got washed out of the BB early on from the deluge that was PDX, everything was compromised finish wise, no actual pitting but pretty rough.

Still wasn't smart enough to replace the bearings, but cleaned and scrubbed everything, loaded it up with thick auto wheel bearing grease and set it up a bit loose.

Cleaned and regreased everything monthly for about six months while tightening the adjustment each time.

It lived on just fine for 30 more years until it was stolen along with the Raleigh SC it was on.

I would bet money its still going, wherever it is.

I now use said grease on any BB, HS and hub that is headed in the wrong direction as many are now days that are more or less mid level to keep them going, seems to work just fine long or short hall.

Hobbiano 

Not if it's a Helicomatic.

grizzly59

Find a spare axle for the cone. Put the cone on with a lock nut, close to an end with enough axle sticking out to chuck it in a drill. Use some 3m autobody paper, maybe 340 grit, run the drill and polish the cone, use your finger to press the paper into the curve of the cone. Go up to 600, 800, 1500. The cone may be case hardened and you may sand off the hardened layer if you take off too much.

bark_eater 

Any one try re hardening a cone after grinding out the pits? If you get a piece of steel hot enough that a magnet wont stick and drop it in a cup of oil, its going to end up be pretty hard, like file skates hard. I'm not sure what the warpage tolerances are, but if you can still thread it on an axle, id assume your good.

iab

Same thing except put the axle/cone with sacrificial bearings into a sacrificial hub. Add grinding paste instead of grease. And Bob's yer uncle.

randyjawa 

And, out of pure kindness, he refurbished a lower headset cone for my Torpado. The cone race is better than perfect, appearance wise. Durability will be an issue worth keeping an eye on. Thanks so much Mad Honk. This is what Mad Honk's piece is replacing...

rhm

I tried that once. Totally ruined the cups.

iab

But how were your cones?

rhm

Honestly i don't remember. This was 1983, or possibly 1982.

It was a classic "well it seemed like a good idea at the time..." moment.

​​​​In retrospect I just didn't think about how bearings work. Consider what i found on the internet (link below):

"In conventional ball bearings, steel to steel contacts between the balls and the raceways are at the origin of microwelds which lead to material transfer, surface roughening, lubricant breakdown, and finally to a loss in the bearing performances. To minimize the microwelding tendencies of the contacting partners it is necessary to modify their surface materials; the solid to solid collisions themselves are difficult to avoid."


https://ntrs.nasa.gov/citations/19880012102

bark_eater 

So ceramic balls are the one true path?

rhm

Dunno!

My takeaway is: good lubrication!

If material is getting transferred from cone to ball to cup and vice versa, then smoothing the surfaces of the cone to remove the deposited material may be good, both short and long term. But i have my doubts about the pits that developed.