Author Topic: BSA B31 Head bearings  (Read 3809 times)

Offline tallon

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BSA B31 Head bearings
« on: March 26, 2017, 10:11:28 PM »
Greetings to all,
I am in the process of restoring a 1952 BSA B31 Rigid. I am however having a problem getting hold of a new set of steering head bearings. It would appear that the frame on my bike is a bit of an odd ball in that it has smaller bearings than any common B31 of any flavor.
I am told that certain models of this bike had bearings the same as the D1 Bantam but I am unable to find any reference to the actual sizes on that bike.
My old set of cups measure 1 7/8 inch on the outside diameter and the cones have an internal diameter of 1 1/16 inch for the stem. Can any of you fine people confirm for me that this is a Bantam set-up or indeed any other BSA variant? Any help or advice would be much appreciated as this problem is holding things up at the moment. I have emailed  some "British Bike specialists" but not one has had the kindness to send me a reply.

Many thanks.

Offline iansoady

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Re: BSA B31 Head bearings
« Reply #1 on: March 27, 2017, 10:16:14 AM »
I would try giving C&D a ring. They're pretty knowledgeable about all things BSA.

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Ian
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Offline mini-me

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Re: BSA B31 Head bearings
« Reply #2 on: March 27, 2017, 05:07:19 PM »
Try BSA C11/12 it was a common mod years ago to fit C11 forks to trials bantams so maybe thats the secret of the share?

Offline tallon

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Re: BSA B31 Head bearings
« Reply #3 on: March 27, 2017, 06:12:34 PM »
Cheers guys; I'll give C & D a call.

Offline Rex

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Re: BSA B31 Head bearings
« Reply #4 on: March 27, 2017, 09:09:04 PM »
Or Draganfly. They have good on-line parts diagrams too.

Offline tallon

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Re: BSA B31 Head bearings
« Reply #5 on: March 31, 2017, 05:02:56 PM »
OK Good news the problem is solved .....well almost !

BSA B31's of 1946 - 1948 vintage used the same cups and cones as the early D1 Bantams. So my frame is obviously from an earlier time than the rest of the bike.

Top and Bottom cones : Part Number 65-5319
Top and bottom cups   : Part Number 65-4465

Now just got to find someone who has then in stock.

Thank you all for your help and advice.
Cheers
Tony.

Offline Rex

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Re: BSA B31 Head bearings
« Reply #6 on: March 31, 2017, 06:37:29 PM »
It may actually be the same age. BSA, like any business, didn't want to get stuck with redundant immovable spare parts, and when some storeman pointed out in 1952 that he still had two gross of the older and smaller headset bearings left, the foreman told the frame shop that he wanted the smaller-sized headstock for the next two hundred frames. Problem solved.
This assumes that the numbers stamped on the frame are consistent with 1952, obviously.

Offline tallon

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Re: BSA B31 Head bearings
« Reply #7 on: April 10, 2017, 07:11:56 PM »
Well the problem has been well and truly sorted thanks to Rex at Rex Caunt Racing:  01455 846 963.
Rex identified the bearings, had a set in stock and sent them to me to try out on a pay me later basis: top man!

It would appear the frame on the bike is a mid 1940's when the B31 used the old Bantam sized bearings; hope this may be
of use to someone if they come across a similar problem.

Once again my thanks to Rex for his invaluable help and first class service. Just detailing to do now.........where's that 4lb club hammer  :)