i have a '30s BSA spare engine with a camshaft with one tooth partially broken off (most likely because of rough treatment in the past)
It is not easy to find a replacement, but can it be repaired, maybe by welding ?
Anyone ever tried/done this before ?

Hi Michael...I've seen them welded, but it seems unlikely to me that the tooth form could be accurately reproduced afterwards and it would play havoc with the heat treatment...Also, if the tooth broke again in use the damage caused could be nasty....
I have stripped engines for rebuilding that I know have been running with a small section of a tooth missing...so that may be possible in your case if it's not too bad...
Alternatively you could talk to David Newman Camshafts in the UK...They may well be able to make you a new one complete...
They make Goldie and other cams...They made a very nice job of a cam for my friends 1948 rigid A7 which they made from a modified A65 cam blank, using the knackered A7 cam as a pattern for overall dimensions.....Ian

email (option): ian@wright52.plus.com

Ian,
I'd be interested how that modified A65 cam converted to A7 worked out, I have an early (1948) A7 also and a mittful of knackered cams too, seems to be the weakest point in the engine.
Does anybody know of a nitriding company??

Ian,
I'd be interested how that modified A65 cam converted to A7 worked out, I have an early (1948) A7 also and a mittful of knackered cams too, seems to be the weakest point in the engine.
Does anybody know of a nitriding company??

Hi Vincent...It was done about 4 years back and the bike is still running well..Ian

email (option): ian@wright52.plus.com

M20 cams are a dime a dozen. I throw them in the dumpster!Ebay is usually full of them?

Shame on you Douglas. Those are originals!

email (option): britool51@hotmail.com

Hi,
if it was a m20 camshaft it would be easy te exchange, but it isn't (it is an earlier 30's BSA).
Therefor the question about possible repair of a half broken tooth.
But I think Ian has got it right, the difficulty is to get the right shape of the tooth back.
And how does the gear react on welding ? (i really dont know)
Thats why i asked; has anyone tried this before ? With any luck ?

Hi Michael,a long shot if there is no other answer ,and the pinion is not hardened
is to drill and ream enough holes to remove the damage,in line with the broken tooth.then make tight fitting pins,and drive them in.These can be filed to suit
and a reasonable test for fit is to roll two pinions together.Not the best
repair but a get you going until you can source another.
If the pinion is hardened,all the teeth and more could be ground off on a cylindrical grinder. A stock gear pinion could be obtained from HPC gears and
machined to suit then shrunk on in position,This would require some accurate marking of the original for tooth centreline on both parts prior to machining.
hope you get sorted.
cheers Rick

email (option): richardholt@rocketmail.com

Michael,

What camshaft are you looking for? I have a box full of 1930's cams. I might have a spare one. Send me a PM. It might take some time to answer you since I am abroad right now.

Regards,
Leon

email (option): leonhop3@planet.nl

Hi Leon,
i'll get in touch with you. Thanks.

TO answer your original question, yes you can build up the missing tooth then get it machined to the correct profile then have the whole thing normalised then reheat treated, it is done all the time, to gear wheels the size of your front tyre.
It can be done on a BSA cam if you really want it to but the cost would be not much short of a grand.
A little cheaper would be to machine off all the teeth and fit either a plain band and recut all the gears or fit a band of good teeth cut off a donor cam. not too dissimilar to rebanding a buggered fly wheel on your tin top.

A little cheaper still is to cut off the cam & fit it into a solid gear of the correct size & profile.

Cheaper still would be to cut down an M or B series cam, recut the teeth then regrind the cam to suit your engine.
From memory the early cam gears were a lot smaller than the late ones.

email (option): wariron@tpg.com.au