Are all balls created equal?

[rogerzilla]

The quick fix is to fit loose balls, then you get a slightly rough, but not actually indexed, headset: the balls can't all line up with the pits in the races.

The worst headsets I've used were Shimano 1055 in 1" threaded: I had a couple and they were both indexed within 500 miles.  Still rideable, but annoying.  The very low stack height meant not much else would fit.  In the end I got a new fork.

The Cane Creek S6 on my commuter has been in place for 8 years with no attention whatsoever, and is still index-free although the outside looks awful due to road salt and (ahem) abrasion from the front brake cable housing.  I think it might deserve new cartridges this year - I have them in my spares box.

[quixoticgeek]

We swapped out the ball bearings on the headset of my friends bike on Saturday.

Having extracted the old ones, I took some photos.






I'm not sure exactly how, but I'm pretty certain they aren't supposed to be that shape...

J

[Brucey]

almost anything will be an improvement over those!

BTW some folk describe those balls as having 'shelled' because it looks as if a layer or shell has flaked off the outside of the balls.  I have seen balls from a number of different manufacturer's hubs and BBs fail in a similar way.

It may reflect a certain method of manufacture or a failing therein (eg case-hardened balls with excessive residual stresses in them) or it could be pot luck if they fail like that.

cheers

[rogerzilla]

Once rust has eaten away the outer hardened layer (assuming they're only case hardened), the balls can spall quite easily.  Rust is no respecter of hardened steel - it ruins it just as happily as if it were mild steel.  Only the chromium content slows it down.

[Brucey]

there is no sign of any corrosion on QG's balls.

cheers

[quixoticgeek]

Excuse the thread necromancy, does anyone know what grade of balls are used by Shimano?

I've just done an order of stock as I realised I was out of some sizes. I couldn't find 3/32" in other than grade 100.

Is there any issue with using higher grade balls than originally intended? I went for grade 10 for everything else.

J

[Brucey]

IIRC you should be using Gr25 Chrome steel bearings if you want like-for-like replacements.  You can buy these on e-bay in 3/32" size, but tbh you may as well buy a bag from shimano.

FWIW I would under no circumstances

a) mix balls in SPD pedal bearings i.e. used ones from one bearing with another and/or

b) mix balls from one bag of new ones with another

If the balls don't look marked in any way, I'd vote for keeping the original ones in fact.

FWIW one of the kinds of  horrible experiment I have carried out is to see what happens if I try to 'recover' knackered SPD pedal bearings.  The first set I tried had oval cones and after a period of use with better quality grease (full of solid lubricants / EP additives) and better adjustment, they 'wore back' so that they were actually pretty good. In the end I used them for a further year or so and they didn't need adjusting again in that time. A good result.

 Obviously those pedals weren't quite knackered enough; second experiment was to take a set of  PD-M324s where the balls had run over one another in one pedal and had mangled both the cone and the raceway.  These pedals were so bad that I wasn't sure if I could assemble them so they would work at all, leave alone be usable or improve with further use. That experiment is ongoing.  No point in using new balls in the course of this experiment, so old balls went back in. Interestingly some of the balls that went back in were already marked. After a thousand miles or so I cleaned the grease out and sure enough there was plenty of sharpnel in the grease. However examination of the marked balls showed that there were no sharp edges on the marks; this suggested that the conditions in the bearing were stabilising.  Currently the bearing is still a bit rumbly but it is a fair bit smoother than it was doesn't seem to be wearing too quickly,  and it also adjusts without bad loose/tight spots.  I guess the bearing is due for another examination any time soon.  If the bearing surfaces are good enough I will put better ball bearings in this time.

Needless to say these bearings only work properly if the balls are able to share the load. This only happens if two conditions are met

1) that all the balls are exactly the same size and
2) there is no slack in the bearing.

IME the slightest free play in SPD pedal bearings normally causes greatly accelerated (ot to mention uneven) wear.

cheers