Rear Drum Sprocket

phutton · June 16, 2020, 11:16:14 PM

These drums have been fitted with a sleeve that allows the use of a very common stock bearing. We have these now and they will appear on the shop. We also have some spare sleeves so members can fit the new bearing into their existing drums if necessary.

For those machines 1928 to 1931, members will need to purchase the BSF hub locking screws, part no 4950. We decided only to make the one version, rather than stock two different types.

singleminded · June 15, 2020, 10:04:48 PM

Paul Hutton and i came to the same conclusion that the onlt difference is the BSF or BSC threads.

shorrog · June 15, 2020, 05:14:51 PM

The part no is 6782 and it is the same as 4587 except the thread for the mounting bolts is BSF. The price is currently being set and they will appear in the shop very shortly.
It fits a wide range of models from 1928 to 1934. For full details consult the Spares List

Thomas · June 15, 2020, 12:54:39 PM

Ok, Graham! Just a suggestion for your internal discussions: It might be interesting not to only sell the hardware but also the software (with protected copyright). I mean, modern machining is available everywhere and it might be cheaper to buy the drawings. A pdf would help in any case, of course. Do you already have an idea about the price of the drum? I don't need it now but who knows the future...
Cheers and thanks for your great initiative, Thomas

shorrog · June 15, 2020, 10:15:10 AM

Hi Guys
Thomas I don't think we will be releasing the 3D cad model but I can produce a drawing in PDF format that will show the principle dimensions so folks can check if it will fit their bike. I need to get confirmation of which bikes it will fit and we will post the info shortly.

John
As part of the project we are getting some sleeves made so that a standard bearing will fit.

singleminded · June 15, 2020, 09:13:22 AM

Really nice to see this project coming to fruition..I guess the bearing housing will fit a modern bearing.

Thomas · June 15, 2020, 06:22:57 AM

Very great, indeed, Graham! For which years do these drums match? Will you share the CAD drawings?
Cheers, Thomas

shorrog · June 13, 2020, 02:44:25 PM

Some more photos.
The internal splines have been "Spark Eroded"

shorrog · June 13, 2020, 02:41:44 PM

Hi folks
I thought you might be interested to see some work the Spares Team have been doing.
The rear drum sprocket has been modeled in a 3D CAD package and then CNC machined from a solid billet.

Inspection has yet to be done but they are looking good so far.