Question: Steering head races

C

chris78jota

Senior member
Location
England
I'm restoring a 1953 75 Sport and a 100 Sport; they share common frames and steering head races.

Unlike the big bikes, the tiddlers have old fashioned loose ball bearings and machined races on uppers and lowers.

For my 1954 75 Sport, I was lucky to get a new set from Cor Dees, who I think was making them (a small challenge for his genius) at the time, but it doesn't seem that new ones are available anymore.

My question is; is it possible to have the tracks re-machined or re-ground? If so, does anyone know of a firm that can do it?

Cheers
Chris
 
Last edited:
Hi Chris,
there were many old bikes which have such a bicycle system, i. e. Benelli I know.

http://www.benelli-bauer.com/Klassiker/250-2C/Rahmen

But you should know the exact dimensions and then you will find some which fit or may be modified to fit.

Good luck
Andre
 
Hi Chris,

I reckon with a bit of imagination, they might be able to be salvaged by grinding with a ball-shaped stone, depending of course how badly damaged they are.  Finding new balls shouldn't be a problem, lots of sizes to choose from at your local bearing supplier.

Would certainly be stroke of luck to find NOS items.

piet
 
Are the races part of the actual frame or a removable and replaceable like bicycle ones? If you have measurements, you can investigate other options (like bicycles). Another trick if top and bottom races are the same and they are removable) is to swap top to bottom. The indents from balls are nearly always confined to the bottom, which takes all the road stress. I've done it to bicycles with success.
 
They're removable and seperate from the frame Quentin.  Shouldn't be too hard to replicate.  Laser welding and a re-grind might well do the trick too.  Filler rod up to HRC75 is available!  I've rescued 4-cyl. MV crank main bearing (rollers) journals in this manner, steering head bearings should be a doddle. 

Easier still to fit an original part, though.

piet
 
When I fitted the Ducati parallel twin-disc brake frontend to my 64 Bonnie I managed to find a tapered roller to replace the cups and balls. The outer bit was undersized so I had it Hard Chromed and ground to an interference fit.I just couldn't go bicycle bearings. It took some trowling at the bearing shop. Is it worth a look?
 
Thanks, some good wisdom there for me to follow up on.

I think from memory they're common 1/4 inch loose balls.

I'd thought of trying to adapt bicycle headset bearings in the past - I think larger sizes are more available and common nowadays so maybe a Downhill Mountain Bike or similar will do, as they're the size of motocrossers these days.

For some reason I had imagined that someone would be doing what Piet suggests, for vintage bikes and similar, but I can't find anything on t'interweb.
Chris
 
Years ago I had a mate who couldn't find steering head bearings for a bike. I forget what sort of bike it was. Anyway, he cut the bearing housings off the top and bottom of the steering head tube, turned up a new pair to suit readily available bearings and welded them on. He used a crappy looking home made jig to keep them aligned while he tacked them in place. I thought he was being a bit ambitious, and it would be a complete cock-up. But to my surprise it all worked perfectly.
 
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