Sprockets and Sprocket Carriers

vibrac

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Perhaps that pile of swarf to turn an alloy billet into a 5/8 X 1/4 Honda sprocket carrier to give a wider sprocket choice on a belt drive for the twin was worth while
Since it's been 40 odd years since I rode a twin at Silverstone and the bulldozers have been at work our choice of gearing needs to be wide
 

davidd

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David has one of my sprocket adaptors. He has had it for several years, but he thinks it adds too much weight to the rear wheel. I feel that the weight penalty is very small and the out-weighed by the range of sprockets (33T-78T). It is also much easier to change the sprocket because the 6 bolts are much easier to work with than the 10 small bolts on the stock drum.

100_2765.jpg


David
 

Herman-Handlebars

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Non-VOC Member
David has one of my sprocket adaptors. He has had it for several years, but he thinks it adds too much weight to the rear wheel. I feel that the weight penalty is very small and the out-weighed by the range of sprockets (33T-78T). It is also much easier to change the sprocket because the 6 bolts are much easier to work with than the 10 small bolts on the stock drum.

View attachment 32572

David
Hi David,
I don't suppose you would have a drawing for your sprocket carrier i could copy would you? Sorry if it comes across a bit rude butting in on your thread. I would like to have a go a making one for my racing twin as I have a few new fireblade 520 sprockets from racing my Honda.
Herman
 

vibrac

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One thing you need to be very careful with is the 5 or 10 holes in the carrier to fit to the hub they need to be a real good fit with no slop. The carrier we used for the big twin Egli racer was bought in and after two seasons there were a network of fine cracks from the bolt holes and the bolts continually worked loose, the alloy does not have the resistance of the cast iron brake plate. I made my own carrier for our new twin racer and reamed and locktighted the bolts into position make sure the plain shanks are precisely the correct length. On a twin there is a lot of power jerking through there.
 

Herman-Handlebars

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Non-VOC Member
One thing you need to be very careful with is the 5 or 10 holes in the carrier to fit to the hub they need to be a real good fit with no slop. The carrier we used for the big twin Egli racer was bought in and after two seasons there were a network of fine cracks from the bolt holes and the bolts continually worked loose, the alloy does not have the resistance of the cast iron brake plate. I made my own carrier for our new twin racer and reamed and locktighted the bolts into position make sure the plain shanks are precisely the correct length. On a twin there is a lot of power jerking through there.
Thanks Tim.
I haven't built my wheels yet as at the time i was reading the thread about 5 vs 10 hole hubs.. I put it on hold then recently bought a 10 hole hub. I have a chunk of 7075 alloy that hopefully is big enough, so was looking to get a design together to have a go at whittling it down.
Are you using Yamaha RM sprockets?
Was thinking about incorporating a cush drive or sleeves with polyurethane tubes to help with the engine pulses but that might be too adventurous for me..
Cheers
 

davidd

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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.

DSCN4595 (2).jpg


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.

DSCN4381 01.jpg


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

DSCN4382 01.jpg



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
 

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  • SprocketAdaptor.pdf
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vibrac

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VOC Member
Thanks Tim.
I haven't built my wheels yet as at the time i was reading the thread about 5 vs 10 hole hubs.. I put it on hold then recently bought a 10 hole hub. I have a chunk of 7075 alloy that hopefully is big enough, so was looking to get a design together to have a go at whittling it down.
Are you using Yamaha RM sprockets?
Was thinking about incorporating a cush drive or sleeves with polyurethane tubes to help with the engine pulses but that might be too adventurous for me..
Cheers
5/8 X 1/4 Honda Scrambles (oops nearly said Moto Cross :) ) see post #2 ( 5 bolt:eek:)
1604935199799.png
 

Herman-Handlebars

Well Known and Active Forum User
Non-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

Hi David,
They look fantastic thank you for sharing the differences and options for the carrier. I'll have a measure up with what I have, noting as Tim and yourself have said the importance of getting a good fit between the hub and carrier.
7075 doesn't seem very common in the uk, so hope my piece is a suitable size!. I may well contact Bob in the future depending on how I get on, so thanks for that option also.
I have 44, 45 and 46 teeth 2014 fireblade sprockets in 520 or 5/8x1/4 and the same 22 (i think) tooth 1/4 sprocket already on the gearbox. I probably will just use the RM sprockets like you have used, as the inner section of the sprocket is ideal for centering ro the carrier.
I have a 5 speed fitted but no belt drive unlike Tim's so will have to work out which final ratio will be best.
Thanks again
 

Comet Rider

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VOC Member
HH,
You can get 70756061 etc, in billet from Smith's Non Ferrous metals based in Biggleswade, Bedfordshire.
they will cut to size for a nominal charge. Get a slightly oversize billet and machine from there.

Neil
 
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