Primary Belt drive by Bob Newby

vibrac

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well the Comet racer was 600 plus for 3 seasons and all on belt smooth as silk
Its 500 now as you get more points for a 500
 

vincenttwin

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David
I git the 38/68 ,that is good to hear ,do you know if I will hae to shave anything of the outer cover on my Std B twin.
Thanks
Peter
 

davidd

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Peter,

From what I know, the 36 will fit with no modifications and one has been done on a Rapide. There have not been a lot of reports on the larger sizes. I would guess that the flange on the engine pulley is so large that it will impinge on the outer primary bump and you will have to make a thick gasket to gain the clearance.

David
 

johnmead

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Osman Malak of the, I think, Dutch section is in the process of making primary covers that will fit the 40mm Newby beltdrive setup. We have been emailing back and forth for the last year or so and he sent me pictures of a couple of CNC covers and the last email I got from him had a picture of the first cast cover.

I have emailed him a couple of times over the last 3 months and have not gotten a response. Maybe someone in the UK or Europe will know how to contact him.

I am putting a Newby drive in a 1200 twin with Quaife 5-speed and got nuts from Bob for both the crank and clutch. I only had to machine off some of the threads on the mainshaft to fit the clutch closer to the inside of the primary. I eliminated both spacer that came with the kit and that gave me enough without grinding the engine cases.

Bob said that a 1/2 inch thick spacer would be required to use a stock cover with the clutch chamber removed. I don't know if that was for the 39mm or 40mm unit.
John Mead
 

vibrac

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john's experience seems to mirror mine although I got that extra 1/8 th futher in by making the clutch pressure plate thicker but I was interested in getting below the joint face rather than a clutch dome since I did not have one
 

clevtrev

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RIMG0116.jpgRIMG0108.jpg
It`s all been done before, these pictures are ten years old !
 

vibrac

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"Its all been done before" after 60 odd years what a well oiled refrain and what a lot of reading there is
 

vincenttwin

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Trev
Since you are the guru on machining ,can I buy Bobs clutch set and rip my cover off and install it or do I need to machine a lot off the outer cover?
Thanks
Peter
 
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clevtrev

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Trev
Since you are the guru on machining ,can I buy Bobs clutch set and rip my cover off and install it or do I need to machine a lot off the outer cover?
Thanks
Peter
Have a look at the picture, and take note of the flange thickness, that abuts the case. You will find you do not need to machine anything, merely to add.
 
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