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What to do about a pitted cone?

Old 03-18-15, 02:20 PM
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dantheobserver
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What to do about a pitted cone?

Hey everyone,

I've been road biking for the last 3 years using my dad's old Univega Supra Sport. The bike hasn't had an overhaul in probably 10 years, and when I went to get new tires last year, the guy at my LBS said the hubs should be repacked by this season. I took the front hub apart last night, and after cleaning everything, I found that one side of the hub was in great condition with no pitting or visible wear, but the other side had a fair bit of pitting on the cone (50-60% of its circumference), and out of the 10 ball bearings on that side, 3 of them were starting to form pits. I'm planning to replace all the ball bearings on general principle, but I'm not sure what to do about the cone. The pitting is barely wider than the smooth part of the track, but I don't know how quickly this sort of thing progresses.

I rode all of last season not knowing the hub was in this condition (maybe 300 miles total...didn't have much time last year but I'm planning to ride several hundred miles more this year). I never noticed any resistance or grinding noises from either hub, but this is also my first real bike and I don't think I'm experienced enough to be tuned into the signs of problems yet.

I brought the cone to my LBS and they suggested trying to scuff the pits with 320-grit sandpaper to take any burrs out of it and packing the hub with a lot of grease and hoping for the best. They didn't have a matching cone, and I couldn't find any definitive answers online about where to find a replacement cone without having to rebuild the wheel with a new hub since this one is so old (mid-80s). The hub is a Sansin (aka Sunshine) but I can't find a model number on it. It's the original hub that came with the bike.

If I do repack the hub with this cone, what will happen over time if the pitting gets worse and how can I tell if there's a problem with it when I'm riding? Or, does anyone know where I could find a replacement cone that will be compatible with the original hub and axle?

Here's a crappy cell phone pic of the cone. I can take a much higher quality pic with my camera when I'm home later if need be.
https://i.imgur.com/vV74Y9I.jpg

Thanks!
Dan
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Old 03-18-15, 02:29 PM
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The pitting indicates the metal is fatigued where the bearing balls roll.

If you keep riding on a pitted cone, you risk ruining the cup in the hub. The metal which comes out of the pits is harder than the base metal.

In order for sanding to save the cone you would have to sand away the fatigued layer or in other words sand the pits away completely and then some.
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Old 03-18-15, 02:33 PM
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Based on the photo, you seem to have worn through the hard surface layer of the cone to softer base metal. basically the cone is shot, but still usable until you can find a replacement. It'll obviously not run as smoothly as it should, but with decent grease and fresh balls won't be terrible.

One thing to be concerned about is the rotating hub tightening the cone as it turns, so mount this cone on the left side of the bike, and make sure it's locked down securely to it's locknut.

One trick that you might try is to use 4.5mm balls instead of 3/16". These are slightly smaller and will roll higher on the cone, hopefully on the unworn area. You'll need a washer or two to bring the overall width between the locknuts back to spec.
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Old 03-18-15, 03:27 PM
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get new ones . they're low cost.. . look at the bearing race in the hub too might be new wheel time if that's messed up.
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Old 03-18-15, 03:27 PM
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Wheels Mfg. may have a suitable replacement:

Taiwanese Hub Cones - Hub Cones & Kits - Products
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Old 03-18-15, 03:40 PM
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Originally Posted by garage sale GT View Post
The pitting indicates the metal is fatigued where the bearing balls roll.

If you keep riding on a pitted cone, you risk ruining the cup in the hub. The metal which comes out of the pits is harder than the base metal.

In order for sanding to save the cone you would have to sand away the fatigued layer or in other words sand the pits away completely and then some.
Ah I see. So if I sanded the pits out completely, would there be any of the tempered metal left or would it be down to just the softer metal at that point?


Originally Posted by FBinNY View Post
Based on the photo, you seem to have worn through the hard surface layer of the cone to softer base metal. basically the cone is shot, but still usable until you can find a replacement. It'll obviously not run as smoothly as it should, but with decent grease and fresh balls won't be terrible.

One thing to be concerned about is the rotating hub tightening the cone as it turns, so mount this cone on the left side of the bike, and make sure it's locked down securely to it's locknut.

One trick that you might try is to use 4.5mm balls instead of 3/16". These are slightly smaller and will roll higher on the cone, hopefully on the unworn area. You'll need a washer or two to bring the overall width between the locknuts back to spec.
Thanks for the advice about mounting on the left side, I definitely wouldn't have thought of that. I'll look into the 4.5mm bearings. How long does it take for this level of damage to happen with moderate use? Just trying to gauge how long I might be able to stretch this until it's unusable.

Do you have any ideas as to how I could find a replacement cone or even a complete hub to use for parts? I'd rather not have to rebuild the wheel with a new hub if I can avoid it but I don't know if it will be possible to find the proper cone replacement for this one.
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Old 03-18-15, 03:44 PM
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Originally Posted by garage sale GT View Post
The pitting indicates the metal is fatigued where the bearing balls roll.

If you keep riding on a pitted cone, you risk ruining the cup in the hub. The metal which comes out of the pits is harder than the base metal.

In order for sanding to save the cone you would have to sand away the fatigued layer or in other words sand the pits away completely and then some.
Which would leave the non-case-hardened base metal exposed, which will wear quickly.
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Old 03-18-15, 03:45 PM
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Originally Posted by dantheobserver View Post
Ah I see. So if I sanded the pits out completely, would there be any of the tempered metal left or would it be down to just the softer metal at that point?
Some parts are through-hardened. I don't actually know about cones.

I wonder if you could do a concentric enough job.

Cones for older hub models are sometimes available if you look. Try wheels mfg. You might even be able to make a cone from another type of hub work.

I am not advocating sanding cones because I do not know how well it works.

I mostly posted just to say not to ride the ruined cones if you can avoid it because the material crumbling out of the pits can ruin the cup.

And if you do sand it, all the fatigued metal must be sanded away if you don't want to get hard metal bits in your grease. Whether that will cut through the hardening or not is something I don't know. Cones could be through-hardened.

Last edited by garage sale GT; 03-21-15 at 01:57 PM.
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Old 03-18-15, 03:46 PM
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Originally Posted by dsbrantjr View Post
Which would leave the non-case-hardened base metal exposed, which will wear quickly.
Sanding cones is something people used to do, and maybe they got some kind of service out of it in some cases.
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Old 03-18-15, 03:47 PM
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You could probably score a new, reasonable quality wheelset for under 150. A new front wheel would be a good deal less than that but it might not match the back rim.
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Old 03-18-15, 03:50 PM
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With good lubricant, you can buy yourself a decent amount of time, and if the undersized balls move the track far enough, they'll be like new. New cones ae available, from a number of sources, and there's often enough interchangeability, that you can use cones scavenged out of a used hub sourced at a bike co-op.

So, it's up to you, ride it a very short while until you find a replacement cone, or give 4.5mm balls a shot (only if you can't find a cone). BTW- sometimes you can buy a brand new hub for lower cost than a single or pair of cones, so consider that option.
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Old 03-19-15, 12:11 PM
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Originally Posted by fietsbob View Post
get new ones . they're low cost.. . look at the bearing race in the hub too might be new wheel time if that's messed up.
The hub seems fine, it definitely doesn't have any pitting and seems pretty smooth as far as I can tell.

Originally Posted by JohnDThompson View Post
Wheels Mfg. may have a suitable replacement:

Taiwanese Hub Cones - Hub Cones & Kits - Products
How would I know if the races on those cones would be the right curvature for 3/16" bearings in my hub? Or do I pretty much have to order something that looks right and find out by trial and error?

Originally Posted by FBinNY View Post
With good lubricant, you can buy yourself a decent amount of time, and if the undersized balls move the track far enough, they'll be like new. New cones ae available, from a number of sources, and there's often enough interchangeability, that you can use cones scavenged out of a used hub sourced at a bike co-op.

So, it's up to you, ride it a very short while until you find a replacement cone, or give 4.5mm balls a shot (only if you can't find a cone). BTW- sometimes you can buy a brand new hub for lower cost than a single or pair of cones, so consider that option.
That's what I figured, but I wasn't sure how to find the right cone online. The closest LBS to me doesn't have a replacement that would fit but I'll be going to another (better-stocked) LBS on Monday. So unless I can figure out how to find the right replacement cone online, I'm gonna see if the other LBS has a cone or any suggestions for what to get.

I thought about getting a hub but ran into the same issue with cone size and fit and not knowing quite where to turn. Like I said, I'd prefer not to have to rebuild the wheel if I can help it but I'll do that if there's no other long-term option.
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Old 03-19-15, 12:20 PM
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EZ you go thru a Bike Shop ... Wheels of Boulder *wont sell direct anyhow,
if not in stock

NB things are getting restocked at a rapid rate, in shops, for summer sales , ask your needed pieces be added.

* Update (know what you need?), they will sell at full retail + shipping,
& perhaps, Sales tax, online by now..
buying at LBS shipping is part of the margin , so included..






...

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Old 03-19-15, 12:33 PM
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Originally Posted by dantheobserver View Post
How would I know if the races on those [Wheels Mfg] cones would be the right curvature for 3/16" bearings in my hub? Or do I pretty much have to order something that looks right and find out by trial and error?
Ask them?
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Old 03-19-15, 03:47 PM
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The curvature of the race area doesn't matter, as long as the small and large diameters span the actual track width (they all will). The balls are smart and find the right diameter tracks in the cup and cone, because that's where the gap will be widest as you bring the cine into the cup. Kind of like making snowballs.

The length fo the cone matters a bit because it can affect the axle width, but most are close enough. So all that does really matter is the thread (duh!) and the OD, since that affects the gap in the seal, which is important if you ride in wet or dusty conditions. Most common cones are pretty similar, but you might measure th OD of the old cone and ask that of the replacement candidate.
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Old 03-19-15, 04:17 PM
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At least ask what replacement wheel(s) might cost. There are deals out there, especially if you can wait some. bk
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Old 03-19-15, 06:54 PM
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well its a pretty simple question. A 85cent cone vs a whole wheel ruined
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Old 03-20-15, 01:47 AM
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Originally Posted by dantheobserver View Post
I brought the cone to my LBS and they suggested trying to scuff the pits with 320-grit sandpaper to take any burrs out of it and packing the hub with a lot of grease and hoping for the best. They didn't have a matching cone, and I couldn't find any definitive answers online about where to find a replacement cone without having to rebuild the wheel with a new hub since this one is so old (mid-80s).
That cone looks pretty generic to me. Your LBS must be a pretty dinky little operation. I'd try another bike shop; almost any ordinary cone for a QR front axle (assuming that's what you have on your 80s road bike) should fit, I reckon.
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Old 03-20-15, 02:48 AM
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Originally Posted by dantheobserver View Post
I brought the cone to my LBS and they suggested trying to scuff the pits with 320-grit sandpaper to take any burrs out of it and packing the hub with a lot of grease and hoping for the best. They didn't have a matching cone, and I couldn't find any definitive answers online about where to find a replacement cone without having to rebuild the wheel with a new hub since this one is so old (mid-80s).
That looks like a pretty cheap, generic cone.
The light colored stuff on the surface is probably zinc, and not some magical hardening. The surface around the bearing track doesn't look particularly smooth, and likely has contributed to the wear on the cone.

There are some people who have re-cut the cones on a lathe with good luck. Perhaps you could work on it with a hand drill spinning it. You would not get an acceptable job smoothing it just by hand as it must be perfectly round when you finish.

I second the opinion to try another bike shop and see what they have. Then go online and hunt for the right cone which should be easy enough to find.
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Old 03-20-15, 09:44 AM
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Thanks for the advice everyone, I appreciate it! The shop I went to the other day is very small, and not well-equipped to service older bikes. I went there on my way to work since it was convenient, but the place I usually go has a far better selection of everything and their service department does a lot more business in terms of repairs and overhauls so I think I'll have better luck finding replacement cones there.

I took apart the rear hub last night and those cones are definitely higher quality metal. I see what you all mean about this one looking pretty cheap and generic. I'd thought the size and curvature had to be a lot more specific for a given hub, but I'm glad it isn't too important and that these cones aren't anything special. There are a couple from that Wheels Mfg. link that should be the right fit if the other shop doesn't carry them.
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Old 03-20-15, 09:59 AM
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If your replacement cones aren't an EXACT match, then best to replace them in pairs.
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Old 03-20-15, 10:52 AM
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Originally Posted by CliffordK View Post
If your replacement cones aren't an EXACT match, then best to replace them in pairs.
Yep, that's the plan. I thought the cone on the other side of the front hub was fine, but upon closer inspection, I noticed very small pits starting to form so I figured it would be best to go ahead and replace both.
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Old 03-21-15, 06:15 AM
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Just as a point of interest, you can restore case hardening of parts like this by simply glowing the part with a torch and quenching in water. Manufacturers use oil hardening steel so they can machine parts in a soft state then they are heated in a furnace and quenched in oil. Glowing with a torch and quenching in water isn't as accurate but still case hardens parts surprisingly well. So if you have an axle or cone that is difficult to replace, it would be possible to resurface it on a lathe with radius stones and lapping polish then re heat treat it to a reasonable case hardness.
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Old 03-21-15, 10:05 AM
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Originally Posted by BigChief View Post
Just as a point of interest, you can restore case hardening of parts like this by simply glowing the part with a torch and quenching in water. Manufacturers use oil hardening steel so they can machine parts in a soft state then they are heated in a furnace and quenched in oil. Glowing with a torch and quenching in water isn't as accurate but still case hardens parts surprisingly well. So if you have an axle or cone that is difficult to replace, it would be possible to resurface it on a lathe with radius stones and lapping polish then re heat treat it to a reasonable case hardness.
Good to know! I found a replacement (CN-R084 from Wheels Mfg.) that I think should be the proper size based on FBinNY's tips regarding curvature and cone size. I ordered a pair last night, but if those don't fit, I'll definitely try resurfacing the races.
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Old 03-21-15, 11:32 AM
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Originally Posted by BigChief View Post
Just as a point of interest, you can restore case hardening of parts like this by simply glowing the part with a torch and quenching in water. Manufacturers use oil hardening steel so they can machine parts in a soft state then they are heated in a furnace and quenched in oil. Glowing with a torch and quenching in water isn't as accurate but still case hardens parts surprisingly well. So if you have an axle or cone that is difficult to replace, it would be possible to resurface it on a lathe with radius stones and lapping polish then re heat treat it to a reasonable case hardness.
You have a poor understanding of case hardening.
It involves "baking" the steel part in a bed of carbon so that some carbon "transfers" to the steel. The CARBON is the key.
Since this is an extremely thin surface layer, any grinding penetrates through it.
The point of case hardening is to have a hard surface without the rest of the part being as brittle.
It's the CARBON in the steel that contributes to its "heat treatability".
Without any carbon, they call it IRON.
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