BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: RobinG on 24 April, 2018, 09:56:12

Title: C15 cam and gearbox bushes
Post by: RobinG on 24 April, 2018, 09:56:12
Hi, I’m rebuilding a C15 engine. The gearbox and cam bushes in the engine cases are all pretty shot, so am replacing with new ones from Draganfly. Can anyone point me to info about reaming clearances please? Or do people just ream them for a fit that “feels right”?  Any advice gratefully received.  Robin
Title: Re: C15 cam and gearbox bushes
Post by: Dabbist on 24 April, 2018, 10:20:52
For the camshaft bushes, Rupert Ratio suggests using an expanding reamer for a "good fit". They also need to align properly, so fit the timing case and do both at the same time.
He suggest that there should be some free play but that the other end of the camshaft should not be able to rock by more than 1/16" each way. Alas he doesn't give a figure to aim for.
I'm not sure about the layshaft one, but I do have vague memories of reading some generic information for bronze bushes on line, so it may be worth a search.
Title: Re: C15 cam and gearbox bushes
Post by: AWJDThumper on 24 April, 2018, 17:39:22
The camshaft bushes need to be line reamed to give a clearance of about 1 thou in both bushes. I haven't looked up the clearance for the layshaft bush but it's probably 1-2 thou. I would recommend get the bushes reamed in a proper engineering shop.
Title: Re: C15 cam and gearbox bushes
Post by: RobinG on 24 April, 2018, 18:33:07
Thanks all for the advice. Much appreciated

Robin
Title: Re: C15 cam and gearbox bushes
Post by: JulianS on 24 April, 2018, 18:50:35
If the bike is distributor model than the gear shaft bushes are quite difficult - the clutch end bush is blind as is the bush in the kickstart quadrant on the other end so you cannot line ream. You may find that the clutch end bush is the right size when fitted.

The mainshaft sleeve gear bush is, if I remember correctly, larger diameter than the inner cover bush, making line reaming difficult.

So the advice to take to a proper engineering shop is good advice.
Title: Re: C15 cam and gearbox bushes
Post by: AWJDThumper on 24 April, 2018, 23:13:48
A good engineering shop will know how to ream out the bushes whatever their configuration.
Title: Re: C15 cam and gearbox bushes
Post by: TDub62 on 01 May, 2018, 20:49:01
I've just bought a new camshaft bush for my distributor 1959 engine which came as a non runner loosely assembled project. The bush I received is a straight tube, the one on the bike has a lip on it with a peg. Is it possible someone has put the wrong bush in previously?
Title: Re: C15 cam and gearbox bushes
Post by: TDub62 on 01 May, 2018, 20:50:30
Sorry picture missed off previous
Title: Re: C15 cam and gearbox bushes
Post by: JulianS on 01 May, 2018, 22:33:05
I think it was non flanged for the inner bush for distributor model and flanged for side points models.

The very early ones could have been different.

Title: Re: C15 cam and gearbox bushes
Post by: GUY HUTCHINSON on 02 May, 2018, 13:35:59
I assumed that they would send me an outer one but its probably the inner one they have sent. I'll have a better look tonight, thanks.