Taper roller headstock conversion on the A10

[Gerry]

hI all, Just wondering if anyone can give me the i.d and o.d of the headstock bearings as I want to convert to taper roller bearings. My ball cup bottom unit is stuffed!! Can't do it up tight enough to get rid of the play in the forks without binding up the steering. Did the conversion on my C15FT Trials Pastoral with readily available bearings but had to machine up two sleeves to fit into the headstock for the cups to fit. Worked out well on that but can't remember the sizes. Should have recorded it in hindsight!! Cheers Gerry

[Jules]

Hi Gerry, I had a lot of problems with my headstock because it was badly worn and I couldn't centralise the standard cup and ball bearings. Greg fixed it for me at reasonable cost - he ended up using tapered rollers top and bottom with a sleeve at the top because of the wear conditions, but he offers a kit with a tapered roller lower and a normal bearing upper which may suit you. Dont forget the increased overall "length" with the tapered rollers, it affects the shrouds fitting....below is his contact details and also what he ended up doing to mine. I know you are in Adelaide but Greg was very helpful, give him a go....hope it helps, cheers
Greg Ditchfield, 120 Lalal St., Ballarat , Vic
manx classic spares [mailto:manxcs@ncable.net.au]
Lower tapered roller 32006, ground down to 21/8”, upper tapered roller 6006 2RS 55mm od,30mm id sleeved to headstock 13mm wide……

[Gerry]

Hi Jules, Thanks for that mate, much appreciated. Makes sense using a double sealed (2RS) top bearing which doesn't take the vertigal load which the lower bearing has. So a thin walled sleeve to take up the space between the 55mm outer cup and the lower headstock location If I use a smaller diameter taper cup which is what I did with the Ceefer, with a shoulder to stop the cup from rising up inside. The top deep grooved ball race has an inner sleeve to take up the clearance between the brg'. inner and the headstock shaft? If I remember correctly the lower brg inner location on the ceefer was slightly larger in diameter to allow the bearing to easily travel down the shaft before locating at the very bottom. I machined this down to allow the same size inner for top and bottom. The two taper cones were available to fit the top and the bottom after I machined the bottom end of the shaft. I have a feeling that most BSA's of the 50's and early 60's had the same size bearings, (different top and bottom though) correct me if I'm wrong. I had no trouble with the bearings being too proud and allowing the headlight ears to be too short though. Cheers and thanks again. Gerry

[a101960]

SRM do a taper roller head bearing conversion kit which goes straight on. I fitted one to my bike it was just a matter of removing the old bearings and fitting the new ones. No modifications of any kind were needed. I believe that George Prew does a similar kit.

[Greybeard]

SRM do a taper roller head bearing conversion kit which goes straight on. I fitted one to my bike it was just a matter of removing the old bearings and fitting the new ones. No modifications of any kind were needed. I believe that George Prew does a similar kit.

Me too

[bsa-bill]

and me, Mr Prew went to lentgh to ensure it was an A10 as Goldie ones are just a little different in size somewhere

[Jules]

Just thought I'd update people on another issue with the taper roller change - the steering lock doesn't throw out far enough! I've been trying to source an alternate to the standard lock without success - I realise that the lock isn't that effective, however it seems pointless having it there if its not usable, and an open hole doesn't make any sense at all.....
So today, in desparation, I decided to see if I could pull apart the standard lock unit and make up an extension to the plunger pin. It actually came apart quite readily by pulling out the drive pin, then turning up a 6mm longer plunger, carefully drilling a new drive pin hole and it works! 

[Gerry]

Hi Jules, fellas, OK found a bottom taper roller bearing on an old set of Yamahahaha forks kicking around in the shed. Had a bugger of a time getting the inner off the shaft of the bottom yoke though!! Found my A10 bottom yoke shaft had been reduced to 30mm where the bearing fits and the bearing I found is 30mm I.D. so that will go on no problem. Outer cup was too large 55mm (2.165") and head stock is 2.125" I.D. So out with the dremel and fixed it to the compound slide tool holder on the lathe with a G clamp and ground it down to 2.125" took a while though. Woohoo!! bottom bearing fixed. Top cup and cone refitted as they were ok. Must check the steering lock fits in the hole ok. Thanks Jules I didn't think of that.... Just checked it and it still goes in ok. Cheers. Gerry