Headstock Ball bearing size

buwgafa · Oct 11, 2014

I removed the yokes on my 1970/1 Roadster and the top head bearing felt rough so decided to pull it out to clean and grease it. I was expecting a roller bearing but instead it was cup and cone so typically the balls shot all over the floor. Question is, what size should they be, I have measured them at 0.3110 in, but I am wondering should they be 0.3125 in (5/8ths). This seems to be the only size available. Also how many should there be ?

lcrken · Oct 11, 2014

Don't know about the size, but the parts book says there should be 36 balls. I'm assuming that's 18 top and 18 bottom.

Ken

buwgafa · Oct 11, 2014

Looking on the Norvil site they only list 5/16ths for earlier Norton's but with a set of 17 balls. Got my imperials in a twist on my first post !

lcrken · Oct 11, 2014

I checked three different parts lists for '68 -'71 Commandos, and all show a total of 36 balls. There are a couple different part numbers for the races, depending on the year, but no change to the number of balls. A later '71 parts list shows the switch to the sealed ball bearings used from then on. I'd just buy 36 of the 5/16" balls from my local industrial supply house, and see how many will fit. They are quite inexpensive. Even my local hardware store has them.

Ken

lcrken · Oct 11, 2014

Earlier parts list for '66 - '68 Atlas also shows the same part number for balls, and also shows the quantity at 36. Only the P11 is different, with 56 balls.

Ken

buwgafa · Oct 11, 2014

Thanks Ken, sounds like good advice. I will buy some and give it a go.

Tintin · Oct 13, 2014

buwgafa said:
I was expecting a roller bearing ...

7205 angular contact ball bearings are a direct replacement and have the option of lip seals, usually indicated by "2RS".

Tim

B+Bogus · Oct 14, 2014

Tintin said:
7205 angular contact ball bearings are a direct replacement and have the option of lip seals, usually indicated by "2RS".

Tim

A useful upgrade, but don't forget the spacer tube.

DogT · Oct 14, 2014

I don't know why but mine had annular bearings and no spacer. Don't know if it came like that or not, but put them back since they felt fine.

Dave
69S

Tintin · Oct 14, 2014

B+Bogus said:
A useful upgrade, but don't forget the spacer tube.

On a 1970 you don't need one as that's the old style set-up where you dial in the bearing preload with the lower nut, then put on the upper yoke and tighten everything down with the upper nut.

Tim

DogT · Oct 14, 2014

That helps clear it up. Thanks Tim.

Dave

Headstock Ball bearing size

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