Author Topic: Pitted hub bearings  (Read 446 times)

Pitted hub bearings
« on: January 27, 2019, 11:52:20 am »
It's uneconomic to replace the cones and cups - £30 per wheel, and that's shopping around.  If the balls are replaced at frequent intervals, do they improve?  I know this is contrary to theory and best practice, but has anyone tried it?  These are 27" wheels and new hubs would also mean new 700c rims and new spokes, and it's not my bike.

The hubs are Campag, not Record, and they adjust and run very well despite a bit of rumble.
Never tell me the odds.

Re: Pitted hub bearings
« Reply #1 on: January 27, 2019, 12:36:12 pm »
if you are careful about adjustment  (a little free play that just disappears as the QR is used to tighten the wheel in the frame is correct; no free play with the wheel out of the frame means you are destroying the bearings) and you use a grease that is heavily loaded with solid lubricants, the cones will usually either not get much worse or may even improve slightly.

You can gauge what is happening by examining the cones carefully under a strong magnifying glass or a low power microscope. Rounded edges to any marks in the cone surface mean that the marks have been there for many miles and may have stabilised. Jaggy edges to marks and/or bits of metal in the grease  mean that the damage is ongoing.

To check for debris, wash the balls down in solvent over a wad of tissues and fish around the residue  using a strong magnet. You will soon find any debris that has been freshly generated.

There are some things to watch out for; campag cones vary in profile with the hub model; if you have the wrong cones they will carry on breaking up for ever. If you trash the hub inserts you will feel pretty annoyed with yourself.

The method of manufacture of cones also varies with hub model; Record quality cones appear to be hardened differently from some others. This is important because the better quality cones seem to have a thicker hard layer on the surface and this means they are more resistant to subsurface fatigue damage (very likely if the hubs are adjusted too tightly, i.e. with no free play).  Once cheaper cones start to crack up through subsurface fatigue, sometimes they are irrevocably damaged and they just carry on breaking up no matter what you do.


If you take a cone, mount it in an electric drill, and polish it lightly with emery cloth, you will cause any marks on the cone's surface to have a slight radius to the edges. This not only means that you can see whether this is old or new damage the next time you inspect, but it also lessens the chance of further damage arising.

Record quality cones will (IME) take a light grind and this  will still leave a hard layer that is thick enough to work OK if you are careful about adjustment. If you have the bearings set too tight (i.e. no free play with the wheel out of the bike) then the reduced hard layer  thickness won't be enough for the loads imposed and the cone will break up.

If there is just one damaged area on a cone, you can mark the outside of the cone to show where the damaged area is, and then install the wheel so that the mark (and damage) is uppermost.  Any service loading won't pass though the damaged part of the cone surface so it should not cause further wear. However if the bearings are not correctly adjusted, you can still get further wear occurring.

cheers

Re: Pitted hub bearings
« Reply #2 on: January 27, 2019, 06:05:45 pm »
Thanks.  The sealing on Campag hubs of this age is non-existent so they are often rust-pitted.  I did replace the cones on my Record l/f front hub but they were a reasonable NOS price and the cups were thankfully fine.
Never tell me the odds.

Re: Pitted hub bearings
« Reply #3 on: January 27, 2019, 08:28:37 pm »
I've got some Ultegra 6500 hubs on which the front has significant pitting. I put it back for the reasons you say, and it's been fine to date. I have since managed to pick up a spare NOS hub just in case.

In the good old days, you could get the bearing surfaces in Campagnolo hubs replaced.

Maybe an argument for sealed bearings, where you replace the whole unit.

Re: Pitted hub bearings
« Reply #4 on: January 27, 2019, 08:49:37 pm »
You can replace all bearing surfaces on all traditional Campag hubs.  Getting the cups out involves heating up the shell a bit and then tapping them out with a bearing puller and either slide hammer or drift.  It is, apparently, not easy.  The shell also has to be heated up before the new cups are fitted.

Cups are about £5 each and cones are about £10 each.
Never tell me the odds.

LittleWheelsandBig

  • Whimsy Rider
Re: Pitted hub bearings
« Reply #5 on: January 27, 2019, 09:03:02 pm »
We replaced cups in quite a few old Campag hubs (pro tip: Nuovo Tipo are different) and never needed to do more than pour some hot water over the hub beforehand, along with decent pullers and setting tools.
Wheel meet again, don't know where, don't know when...

Re: Pitted hub bearings
« Reply #6 on: January 27, 2019, 10:28:34 pm »
You can replace all bearing surfaces on all traditional Campag hubs.
By traditional do you mean freewheel (as opposed to freehub) generation, or more? Baker's Bikes in Bishop's Stortford used to supply and fit replacements, but that was decades ago. I believe they had replacements for obsolete ones made to order.

Re: Pitted hub bearings
« Reply #7 on: January 28, 2019, 12:04:55 am »
its not difficult to replace inserts in old campag hubs (Nuovo record, Nuovo tipo etc).  Nuovo tipo cups are pressed steel and the cones have a different profile. However whilst the rear cups are a different diameter, the fronts are not; I have rebuilt a Nuovo tipo front hubshell with all Nuovo record internals.

 I have also used various campag cups and dustcaps in Zeus hubs; IIRC the rear zeus hubs use Nuovo tipo sized cups and dustcaps. The Zeus cones and axles are 1mm pitch though.

If done in the right way, cup and cone hubs are still (IMHO) better than cartridge bearing ones;  it is practically impossible to maintain the required tolerances in a cartridge bearing hub; amongst other things when the wheel is built the flange moves enough that the interference between the bearing and the hubshell (and therefore the running clearance of the bearing) is changed.  Its probably easier to build a hub for  disc brake with cartridge bearings though.

With a cup and cone hub one degree of cone movement is 'worth' about 3um of clearance. Realistically you are never going to achieve that accuracy inside a cartridge bearing hub, which is presumably why campag and shimano still use cup and cone bearings for their best hubs.

cheers

Re: Pitted hub bearings
« Reply #8 on: January 28, 2019, 08:48:16 am »
You can replace all bearing surfaces on all traditional Campag hubs.
By traditional do you mean freewheel (as opposed to freehub) generation, or more? Baker's Bikes in Bishop's Stortford used to supply and fit replacements, but that was decades ago. I believe they had replacements for obsolete ones made to order.
Yes, these are from the generation of screw-on freewheels.
Never tell me the odds.

Re: Pitted hub bearings
« Reply #9 on: January 28, 2019, 07:20:50 pm »
Actually, re-reading your original post, it's obvious they'd be screw-thread in 27" wheels :)

Re: Pitted hub bearings
« Reply #10 on: January 28, 2019, 08:57:02 pm »
Actually, re-reading your original post, it's obvious they'd be screw-thread in 27" wheels :)
I bet someone's built 27" rims onto Dura-Ace 11 speed somewhere.  And then been taken away to a cell with rubber wallpaper.
Never tell me the odds.