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Primary Belt drive by Bob Newby


minivin

Well Known and Active Website User
VOC Member
That is a good point Dag, I think you've swayed the argument for me, as I don't really fancy chopping down a very expensive Quaife main shaft!
 

dagriise@online.no

Well Known and Active Website User
Non-VOC Member
And i didnt want to spoil my Terry P. 5 speed internals either.. Think to remember that I (in my Egli build) worked out that it would be -Almost possible to clear out the internal clutch housing, and perhaps do some slight weld build up, to make the belt run inside a std cover, but again didnt want to spoil the main shaft.. Im running a fresh triplex chain with the usual D components, as shock absorber, and twin blade chain tensisoner.. ok..

Dag
 

grahamsharrock

Well Known and Active Website User
Non-VOC Member
HI All
I have just had a phone call from Terry Prince regarding the 40mm belt drive on my engine and the standard cover will NOT fit. The cover needs so much machining around the clutch bulge that it will be too thin for the dome cover to be bolted on to. He said it would need to be completely machined away and a large diameter piece of alloy pipe welded on as to clear the clutch drum. I think I'll be waiting to see what happens with the dutch member's cover, hope he will make a few to sell.
Just another drama in building a completely new engine:eek:

Graham
 

vibrac

Well Known and Active Website User
VOC Member
You never know till you try
it does look as if the clutch orifice does need to be machined away severely, however there is a ridge of approximately 1/4" that is proud of the drum edge and the 'pillars' could be left for that length, enough to hold the 1/8" cover securing screws to be certain I shall probably have a 1/4" water cut alloy 'gasket' or some counter boring of the clutch spline to sit the drum in (It is a 40mm belt drum so thats without touching the front pully which is 30mm). However the shaft is starting to protrude into the boss where the nut goes so again I could counter bore the nut. As I found with the Egli racer with a sheet flat primary about 1/2" the end of the shaft thread has to go and from my notes I made a 1/8" plate to fix inside the spring plate to grab a bit more thread obviously not an option here.
The 36 tooth front sprocket is free of any ESA cover dome interference and indeed that is with the flat side to the oil seal spacer and the belt will I think be clear (another vote for the 1/4" gasket) the bottom of the cover may get a bigger chamfer. we are racing it with a 30mm belt we would have preferred a 40mm but it needs to look fairly standard (Lightning) but its a mild tune and Bob Newby has given us a new sourced stronger spec belt
Its one of those jobs that is a cut and shut until it fits.
 

vibrac

Well Known and Active Website User
VOC Member
Lets hope I come up with less than 1" that clutch side touching down can be very disconcerting
If its in increments of 1/4" or 8mm I can get them shelled out by my tame water cutter he can use a gasket as a pattern. Generally his plate edges (say on a set of lightning footrest plates) do not reqire cleaning up as they are smooth
 

Glenliman

Well Known and Active Website User
VOC Member
Is the bike using standard Vincent UFM /RFM?
If so then this is a concern.
With my monoshock Egli type, it's not an issue. It would need to lean way past tire contact before the clutch cover would touch.

Glen
 

Glenliman

Well Known and Active Website User
VOC Member
This is the 40 mm belt. I recall Bob needed all of that width to get 7 friction plates in there instead of 5. He used special thin friction plates at that. I'm glad he did as I really had to crank the springs down to stop the slippage. Even with the slippery Venhills stainless/Teflon cable it's a fairly stiff clutch pull. It works really well though, no slippage at all. There's no drag, just a click when first gear is engaged.

I used the stock covers for appearance.
I never looked at it to see what would be required with a flat cover.
It seems the flat cover would reduce the overall width a lot, maybe solve that leaned over ground clearance problem.

Glen
 
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