BSA Owners' Club Workshop Discussions

The BSA Workshop => Pre War => Topic started by: LES on 26 Sep, 2018, 15:46

Title: Help
Post by: LES on 26 Sep, 2018, 15:46
I need a brake drum/sprocket  part# 15-7081 for a 1935 Blue star wheel,. I doubt I am going to find one, I have contacted Cornucopia. Part# 66-6107 for an M20 is still available from Russells, Does anyone know if it can be made to fit, and  what is the difference.

Les
Title: Re: Help
Post by: David Samways on 26 Sep, 2018, 16:26
This may be out of date, but John Hemming Engineering used to re-tooth sprockets Tel: 01547 530759

In the past I've turned off the old teeth from gearbox sprockets, bought a sprocket of the right size, bored it out and welded it to the hub, I would think this is how the firm above does it.

I take it you've tried Draganfly?

David
Title: Re: Help
Post by: LES on 26 Sep, 2018, 18:35
I don't have a worn brake drum to repair unfortunately, All I have is a collection of bits that I am trying to turn into a viable project. Drags and Cornucopia can't help, but the M20 looks same design, but I'd like to be sure it's adaptable before I spring for a new one.

Les
Title: Re: Help
Post by: David Samways on 26 Sep, 2018, 19:12
Hi Les

My '34 BS uses the same drum/sprocket as your '35 machine. I had the whole thing apart a couple of days ago and the 66-6107 sprocket certainly looks identical. If you want me to provide any measurements let me know.

Best regards

David
Title: Re: Help
Post by: LES on 26 Sep, 2018, 19:26
Knowing it looks the same, compared to your original, leads me to think that buying one with the possibility of having to modifying it is probably my only option. If  no-one
has actually done it, and can advise, that is probably the route I will take.

Thanks, Les
Title: Re: Help
Post by: David Samways on 26 Sep, 2018, 19:30
Mine looks to be a modern replacement. I've only owned the machine for a month or so. I'll ask the seller if he can remember where he got it and get back to you.

David
Title: Re: Help
Post by: David Samways on 27 Sep, 2018, 12:29
Hi Les, here's the response from the previous owner of my bike:

"if I remember rightly i think rear sprocket is the same as a wm20 if you ring Russell's with part numbers they should help you out" - http://www.russellmotors.co.uk

Best regards

David
Title: Re: Help
Post by: Dean Southall on 27 Sep, 2018, 12:36
I have a spare M20 drum with worn sproket you are welcome to borrow to se of it would work.
Title: Re: Help
Post by: LES on 27 Sep, 2018, 16:28
I'm over the pond, so can't take advantage of Deans offer. I am going to go with David's message from his previous owner, I can't imagine there is such a great difference that I can't modify it if necessary.
Thanks to all, Les
Title: Re: Help
Post by: David Samways on 29 Sep, 2018, 13:30
Don't forget to post back here with your conclusions Les.
Title: Re: Help
Post by: Hoppe30 on 05 Oct, 2018, 15:59
David,

Is your sprocket the one with a circular ridge with 5 slots. if so the WD M20 drum won't fit. But it can be adapted it you machine the slotted ring and weld it on to that drum. The other alternative is to buy a industrial sprocket to of the correct size machine it until only the outer rim remains. Machine the teeth of the worn drum and weld (and pin) the new sprocket ring on to the old drum. If you have this QD hub please note that it is a terrible solution and a lot of play will develop over the years which means that the drum will be knocked about everytime you throttle up or brake opening up the worn slots further. Welding and machining the hub to fit the reamed slots is a horrible job.

Good luck.

regards,
Leon