What happened to these?
 

https://cimg9.ibsrv.net/gimg/bikefor...3847071baa.jpgOK Folks,
I got a repair in today for a hub overhaul. These are the bearings that came out of the Shimano 600 Arabesque front hub. Hub was overloaded with white lithium grease, which is a pita to remove, but the bearings seem to be problematic. Any guesses? Maybe they were trying to make them look like ceramic bearings? Or just heat treated chrome? fire away at me with opinions... Smiles, MH

I call them "burned balls" to my customers. But I suspect they have been worn enough to better allow a surface of corrosion to happen. I wonder if the previous owner/service guy was thinking they needed more grease when they were last cleaned and lubed.

Replace with fresh and take a look at the ball tracks on the cups and cones. Andy

Lube failure, probably from to much and maybe not the right kind of grease. It leads to friction, which leads to heat, which leads to blue balls. I do it on purpose on small steel parts (especially screw heads) often with fire bluing.

custom anodized aluminum? :)

That's not the only thing that leads to blue balls...

/runs

If you didn't, I was going to attempt a lame joke. :lol:

What*******orry but never heard about too much lube (and lithium grease is a decade old acceptable bike bearing grease for most applications) being a cause of heat. Seriously, after 45 years of doing this stuff too much grease in a hub bearing... no. Andy

Any alternative suggestions for the OP then? Hot steel plus a petroleum product like grease or oil turns the steel blue or black. If the heat was from the bearing being tight the cones and/or the hub would be trash as well. It is not a problem in this case anyway. If the cones and hub are fine, it shouldn't be a problem in the future.

I alluded to an alternative story line. Lithium grease isn't the norm for a Shimano factory lube. I suspect these hubs have been serviced before and the balls were burned/blued before the mentioned lithium greasing.

I have seen many examples of this, sometimes with pitted or cracked hub shell cups, many times without visible damage otherwise. But I don't remember lot's of lube. Andy

Too many hours on the wrong saddle? :innocent:

:thumb: Especially on old hubs like those, any "excess" will just push past the seals.

I would've thought not enough hours in the saddle...

If I saw that I'd suspect a previous owner had experimented with DIY heat treating. It's not difficult, especially if you have a workshop or big back yard. When I lived in a rural area our garden had a burn pile. I used it for old fashioned metal working projects using scrap files that had rusted out, to heat treat a flat spring on my great-granddad's old .32 rimfire Marlin lever action, etc. You can get some interesting colors depending on the materials used.

Just checking back in on this one... Lots of interesting thoughts. I remember when custom grinding golf heads we would sometimes use a heat firing to achieve a special look on the outer surface of the club head. So I think heat is a likely problem here. I'm gonna let this one ride for a few days and see what else comes up. Smiles, MH

I notice the balls on the left appear to be a different color than the ones on the right. Did they come out of the hub like that (all the blacker ones from one side of the hub, the colored ones from the other) , or is that just a trick of the lighting?



At least with firearms, this is a heat treatment called, "case coloring", and is often seen on high-end hunting shotguns, and Western-type guns like single action revolvers and lever rifles. It results in a distinctive rainbow, "oil on water" kind of look. The balls on the right look a little like that ( but tough to tell how much with the blurry pic). But I would agree, it does look like they may have seen some sort of heat treating. I don;t see that being corrosion, or mere abrasion. It's also tough to imagine this taking place inside a bike hub, without doing some very visible damage.
I dunno.

I'm pretty sure there's no way that bluing happened inside the hub, unless the wheels have somehow been spun up to like 50,000rpm.

There are all kinds of ball bearings, for bikes it's as you well now usually stainless steel (alloys with chrome, nickle, molybdenium?). I have seen titanium bearings but it's not very common. I remember having drive chains with all or every other link in a bluish color, it lasted as long as the chain did. This type of surface treatment can wear off, and I don't see how it can be an advantage in a bearing? Some alloys have a color all through the metal.

Either way, with a quick web search, all kinds of odd tings turn up.

Those blued bearing balls do look like they'd been in a fire.

Usually the only time I personally see blued metal from friction is from using a grinder without letting the object being ground cool properly between grinds.

One time I saw blued metal from heat was the head bolts in my step-daughters first Honda, which she drove without coolant until the engine seized.

Yet another time was a front axle spindle on my old 1972 Dodge Charger because all the grease turned to oil and ran out of the bearings. That got so hot from friction it tore the bearing cages apart and bent the spindle, and that spindle had turned blue.

So, I can't really imagine friction heat from a bicycle being ridden turning bearings blue without some real damage to the bearing cups, and you'd think the cyclist would have stopped pedaling due to increased resistance long before the bearings would have a chance to go blue.

However, I could see it being done with a bicycle with a gas engine mounted to it. Or by a cyclist that can pedal like a gas engine. :D

Interesting, I've never seen that before. I like the thought of a gas/ebike being able to consistently cause enough heat to cause this, but I do know from experience that that amount of heat would have caused that lube to smoke. It would interesting to see a bike front wheel smoking down the road. Possibly a bike owned by that "Ghost Rider" guy.

I have "blued" various metals before but not something that was already properly heat-tempered and/or load bearing. There is a chemical "wash" that will give a similar appearance.

The only way too much lube gets enough heat to oxidize steel, or to change it's temper, is if the bearings are driven at high speed. Nothing on a bike approaches that speed (except the old friction dynamos). Even the dynamos aren't that fast.

I suspect that someone put these together with too little grease, or with oil, or without lube,and the resulting low- or no-lube condition caused heating.

No lube would cause damage like a crushed ball, excessive wear, hault... pretty fast.

I really attribute this bearing condition to a wear issue, not a heat one. My suggestion of the term "burned" is more for customer acceptance then actual causation. I've never thought that a bike component can get hot enough to chemically change the surface. I do see the effects of work hardening all the time. Common pits of ball tracks being the usual but in the extreme the hub shell will crack through when there's no pressed in, and thus separate piece, ball cup.

But I'm no bearing engineer so... Andy

Andy,
I figured you would have picked it up right away. Brocephus is on the right track about the balls coming from either side of the hub.
A little back history on these hubs; I picked a Reynolds 531 bike complete out of the crush pile at a local scrap yard and paid six bucks for it. Group was a 600 arabesque, with touring tires and fenders. I kept the frame and sold the groupo to a young mechanic who wanted it for a project he was working on for $60. The wheels showed up in the local co-op last week so I bought them back. I think the white Li came from the young fella who probably overhauled the hubs. And I also think he put the same bearings back into the hubs in the same place.
Kimmo, I don't think the high speeds are a problem with these.
It is however my opinion that pressure was the culprit. And I think the damage was done long before my young mechanic got to these hubs. If you all will go look again at the picture again you may see it. The extremely damaged bearings are all the dark ones on the left side and were caused by too much pressure in the hub. The right side bearings show secondary damage due to temperature build up from the extreme pressure of the ones on the left. Some mechanic in the past made a rookie move and "count em" put twenty-one bearings into that hub. Riding it may have been difficult because the front wheel would roll ok, then tighten up, (and lather, rinse, repeat) for the duration of a ride. Maybe why it would up in the junkyard in the first place. It is possible to make a wheel feel like it is correctly set for bearing tolerances with too many bearings in the shell, but it will alternately loosen and tighten making truing impossible. I hope you all had some fun speculating, Smiles, MH

So this was a test? :foo:

Shelbyfv,
Your only submission was about excess lube being pushed out. and nothing very creative in your answers so maybe a C-.
It wasn't as much a test as we collectively could see the obvious problem before the speculation begins. Nobody heat treats bearings, they do it themselves from use. For me just another day in the mechanic room to see what will come in next. Smiles, MH