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Sprockets and Sprocket Carriers

davidd

Well Known and Active Website User
VOC Member
I think the 10-bolt hubs have performed really well over the years. The hub castings seem to have failed at a higher rate. I would follow the Flash TT bikes and used a billet hub if I were worried about the strength. Bob Larmour made a few for me about ten years ago.

David
 

vibrac

Well Known and Active Website User
VOC Member
When I bought a basket case D the rear drum was loose on the hub the holes in the drum had turned into slots about 3/8" long along the PCD circumference no sign of cracking I did replace it in the rebuild
 

Herman-Handlebars

Well Known and Active Website User
VOC Member
Yes, I have a drawing. There are a few things you should know. First, Bob Lamour in Canada can supply these to anyone who is interested. I am using one of his on the racer I am currently building. These are done to print, so if the print doesn't meet what your needs are, make your own.

Second, this adaptor was designed for Lightnings and Flashes, so it must use a 1/4" chain, which is generally stronger than the 5/8" chain. If you wish to make one for a different chain you would have to check the dimensions.

Third, you may want to use a different material, like 7075. The ones I have are made from 6061. These have worked well for high hp Comets but based on Greg Brillus having problems with his twin sprocket adaptors cracking I would take some care in choosing the material and the design. My adaptors are solid, which I think is a key to prevent cracking, so I would not machine any additional holes.

Finally, the adaptor can be machined to match the thread on the new sprocket bolts if you choose to. I have done this on mine.

I use AN bolts for the hub to adaptor and I have found for the Comet that 5 bolts are sufficient.

View attachment 38504

I have one or two done to print if someone has a need. Otherwise, the drawing is the best starting place.

Bob Larmour does a nice job. This is one that he anodized. The holes were threaded also for the Suzuki RM sprocket.

View attachment 38505

The part no. is at the top. It is 452 with the number of teeth (48) added.

View attachment 38506


The sprockets are 7075 and are available in tooth sizes from 30T to 74T. The part number is 452, which can be seen in the photo.

David

Thanks again for the info on the sprocket carrier's and putting me on touch with Bob. I'm really please with how well it fits the hub and the quality of machining. I could only dream of producing something like that. Next is building up the wheel Cheers
 

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vibrac

Well Known and Active Website User
VOC Member
Now you can buy aluminum round blanks of the almost exact size there is nothing quite as satisfying as turning up a sprocket carrier but the mountain of swarf has to be seen to be belived
 

Herman-Handlebars

Well Known and Active Website User
VOC Member
I enquired with my local stockist, but the sizes I can afford (less than 300mm length) were classed as offcuts to them. 7075t6 only seems to be available in large diameters and is a bit of a struggle for my Myford to machine without lots of cutting. Not so rewarding, but a lot more to get on with.
 

vibrac

Well Known and Active Website User
VOC Member
I just went on the net and found a supplier not off cuts I have searched my records but cant find who I used For the one before I used Mallard Metals he regrettably is deceased he could get anything.in small quantities
My Harrison has a big bed but a regrettably small throat but I turned up a jig with 5 holes to drive it all (holes first in blank turn and bore after)
 

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