Replacement cones?
 

Howdy,

I was overhauling the rear Normandy hub of my Motobecane Grand Jubilé today and after cleaning, noticed an unusual mark in one of the cones. It appears to be either the result of brinnelling or corrosion. The mark is deep enough to catch a fingernail. Although over 30 years old, the grease was in good condition before cleaning. I've maintained proper adjustment of the cones over the years. Although a few of the rear spokes have been broken through fatigue in the past year, AFAIK there has never been a severe impact to the rear wheel; certainly nothing enough to damage the rim.


I have two questions:

1. What is the probable cause of this damage?
2. Any suggestions where I should look for a replacement cone? The ball bearing diameter is 1/4" and the cone minor diameter is 1/2". The axle diameter & thread pitch are 10mm x 1mm.

Pictures of the Normandy hub are included for reference. Thanks for any help!

Pitting happens with age. Can be due to grit getting into the grease, subtle ovalization of the bearings, work hardening of the cone surface or all of the above.
If I were you, I'd find the oldest bike shop in the area and take it in there to see if they have a replacement. The size and thread of yours is common, so it shouldn't be too big a deal. Get some fresh bearings too while you're at it.

I buy NOS hubs on Ebay.

I have a pair of old French hubs. PM me so I'll remember to tear them down and look at the cones.

Thanks for the replies. I was thinking the fallback position would be to purchase a new hub, but it would be a shame to retire a complete hub for one bad cone.

Thanks for the offer, sailorbenjamin; I'll do that.

Here's a similar picture of the pitted rear hub cones I found when overhauling a 1988 Bianchi with a Campy Chorus group (from left to right: NOS cone, used left side cone, used right side cone). I ought the bike on Craig's list, so I don't know what history of impacts there may have been on the rear wheel. Fortunately, Campy hubs were common enough that I was still able to find replacement parts on-line at loosescrews.com. Gave me new respect for the hidden problems and costs sometimes lurking in even high quality used bikes.

Sheldon/Harris Cyclery advice on replacement cones is here:
http://www.sheldonbrown.com/harris/hub-parts.html

Thanks for the info and the link. I'd say the cone on the right is badly fatigued. When a bearing surface wears out (due to fatigue, a result of repeated loading and unloading which is what happens to a bearing going round and round; fatigue is a cumulative effect of load magnitude and number of cycles), cracks occur first under the surface, then grow until an entire chunk of material flakes off, leaving a pit. The pits will increase in size and merge, the end result is more or less catastrophic, as far as the bearing function is concerned.

The good news is, I found a complete NOS axle with 2 cones on the 'bay, and I'm the first bidder. We'll see what happens. The Harris Cyclery link wasn't very encouraging for finding the correct cone; they seemed to focus on newer stuff.

I think that most Maillard and Normandy and some Schwinn approved hubs made by Normandy ar interchangeable. You should be able to find discarded wheels and use them as a source for replacements. Thirty years without repacking the bearings is a long time.

Thanks everyone for the tips! I'll post my solution when I have it...

Yeah, I'll take a close look at Shwinn approved if I can't find genuine Maillard/Normandy.

That's definitely an option, but I'm not too keen on collecting large amounts of bike parts that I'll probably never use and need to dispose of again. My modus operandi for parts I need is more "surgical".

Yes it is. I used the bike only sporadically between the early 80's and last year; and I've been working my way through the maintenance items as time permits. I actually bought a spare wheelset last year to take the original wheelset off the "front lines", so to speak I (not to mention two complete "spare" bikes - goint on 3!).