Aluminium Specs

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vibrac

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I am making a sprocket carrier for our twin racer I am making it out of 6082T6 this seems suitable and available in the large size i need commensurate with cost
I am thinking perhaps I should harden it after machining, as I have had some wear in bolt holes on previous items (OK they may have come loose :eek:)
comments welcome
 

Comet Rider

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I'll dig out my dad's "Fletchers" book later
It lists all Aircraft alloy spec's as well as treatment methods
 

litnman

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This sprocket carrier was made for a drag bike from 6061T6 in 1957. It's still in good shape. I don't find much difference between 6061T6 and 6082T6.
Sprocket carrier.JPG
 

greg brillus

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As tempting it might seem to machine lightning ribs or spokes in the carrier, i recommend you don't. The power pulses from the engine will cause cracks to appear, especially if running a belt primary that offers no shock absorbing from these pulses. I found this within a years use on the racer.........
 

davidd

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Crack 02.PNG

This is Greg's sprocket a year or so after it was put into use. Greg change the design to one without spokes, which was very similar to the design I was using.
100_0035.jpg

Mine, which is above, is 6061, but it has never cracked. Bob Lamour made a batch of these based on my drawing. It replaces the drum, but it is for a 1/4" chain. This design takes the Suzuki RM sprocket, which is an off the shelf item. I use a 7075 sprocket from Sprocket Specialtist. It was a real help getting rid of the Vincent sprocket.

David
 

Bill Thomas

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Maybe small holes will be OK, A friend did this for me in 1980, For my L/ning.
 

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vibrac

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Great minds think alike David :cool: except I am going to use Honda 450 sprockets with the small belt you need 45 teeth or less sprockets on 520 (1/4) chain
I think we are going to use. Composite steel/alloy sprockets they are cheap enough
 

greg brillus

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With the 1000 cc engine I found that with the 1.66:1 Bob Newby primary ratio and a 21 tooth front sprocket, the rear I ran a 44 tooth sprocket on pretty much all the tracks. I originally ran a 41 tooth, but this seemed to bog the bike down too much, and the drive out of corners was poor. I use to shift at around 5800 and max rev's down long straights would hit 6200 but only for a second or so. These were at Philip Island and Eastern Creek in Sydney..........
 
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vibrac

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The spares company have a 22 teeth 1/4" gearbox sprocket which will just pass through the G50 plate. One of the first meetings hopefully we will do in 2020 will be Silverstone. I was a young guy the last time I rode a Vincent there so we shall need a good range of sprockets to chose from. luckily scramble guys ( sorry MX) get through a lot of rear sprockets so they are cheap to buy.
The other thing I have never resolved is the 10 hole 5 hole hub quandary they must have had good reason back then to have two types but I can't believe that 5 well fitting cap screws nowadays is not enough or that 10 loose standard hex bolts is insufficent
 
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greg brillus

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Tim are you and Ben running a 4 or 5 speed box.......I found with the 5 speed I never needed to change sprockets, the bike had enough torque and flexibility to cope with small and larger tracks. I know on the smaller capacity singles and the like that you have to change them more to suit the tracks.
 
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