The curious case of the Maxi-Car Front hubThis has given me a bit of strife since I picked up the bike, as there was always a telltale grumble and bump, it took me a little while to realise that it was from the front hub. The front hub is a bit of a special case, it is a Maxi-Car unit which have a nearly cult status amongst retro-grouches and Francophile cyclists. Their high quality and idiosyncratic construction has created a bit of a following, however they have been out of production for a little while so spare parts are a little thin on the ground.
Since I discovered the utter and total failure of the seals in the front hub, which allowed the insides to get completely corroded, I have managed to disassemble the hub and assess its condition. The bearings are totally shot with severe pitting, one of the cups is badly pitted and the other one is not too bad.
The technique involves using the axle and the old bearings fixed into the chuck of a drill. This is then used with some of the grinding paste and then spun around for a while until most of the pitting is removed. The first step involves grinding it with the coarse paste, the side which was more heavily pitted took quite a while to grind through. One of my concerns was that the cups were only case hardened on the top surface and once you cut through that it would be relatively soft metal which wouldn't last as a bearing surface. However despite this, even if the hub spun more smoothly for a little while it'd be better than it was currently, I had nothing to lose really.
After a fair bit of grinding I managed to grind away most of the pitting on the bad side, although there was still a bit of roughness. The old bearings I was using to grind were starting to give way so I wasn't really able to use them to grind properly. Ideally it would be better to use a lathe or some other more proper cutting tool to grind away at the bearings. A spin with the fine paste after to smooth things out was the next step.
Now I had a final go with some toothpaste
I popped in the new bearings that I bought online and tightened her up. The hub is slightly unusual in the way the bearings are installed and adjusted, however it allows you to set the tightness of the bearings instead of pre-loading them like most cartridge bearing hubs. Once it was greased up and assembled I gave the wheel a spin, it was a lot smoother than before and I had got rid of the loud rumble. While still not perfectly smooth, this should give the front hub a little bit more life.