BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: sidewaysid on 04 March, 2018, 14:11:36

Title: B31 Rigid frame help needed
Post by: sidewaysid on 04 March, 2018, 14:11:36
Hi Guys

I still cannot post pictures, I am on other sites and it works perfect, but that is not my reason for being here, I have now purchased a 1946/47 rigid frame for my 1949 B31 motor, I got it home and up onto the bench, offered up my crankcases (I got engine plates too) the front plates fit good, all holes line up, but the rear plates the guy gave me don't look right at all, these are the long plates that also hold the gearbox in situ, if I marry up the plates to my cases, and then into the frame it leaves the far rear hole a mile out, it simply won't fit, so can anyone tell me are there different plates for years ??

Cheers Guys
Title: Re: B31 Rigid frame help needed
Post by: JulianS on 04 March, 2018, 14:54:02
The part numbers for 1946/47/48  frame and rear engine plates are the same but different numbers are shown for the 1949 parts.

These early parts books contain parts for the whole BSA range for the year. The B31 parts are arrowed.

First photo from 1948 book.

Second from 1949.

Maybe you have the wrong plates for your frame.

I think the change came when the gearbox changed for the ZB31 engined bikes for 1949 season.

1946 and 1947 season were  XB31.

1948 was YB31.
Title: Re: B31 Rigid frame help needed
Post by: sidewaysid on 04 March, 2018, 15:50:23
Hi julian

So it looks like i need XB31 plates, I bet these are the others, I was in a proper messed up state about 2 hrs ago, when i got the frame home and nothing seemed to fit, then I settled down and thought i can make my own plates anyway, but i still wouldn't rest until I sorted the truth, I think you may have nailed it, I'm going to see if Draganfly have any. Thanks mate

Phil
Title: Re: B31 Rigid frame help needed
Post by: sidewaysid on 04 March, 2018, 16:04:06
Julian

I couldn't by any chance trouble you for the same parts book pictures for the rear sub frame on 1949 model, and as a matter of interest, what book are they in, it looks bloody good.

Thanks
Title: Re: B31 Rigid frame help needed
Post by: JulianS on 04 March, 2018, 16:33:41
Will send you a PM check under "My messages"