Black Flash

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I used a belt conversion from norvil on my comet. The front "sprocket" I machined in my mill to accept the pd4 with the help of a 25 ton press. If using this arrangement I had to widen the clutch cover with a welded on strip of alloy all way round.
If you do so please don't forget to use the commando type clutch lever in your gearbox, the atlas type has not enough lift for the diaphragm spring.
While it worked okay I changed back to chain with a self fabricated clutch conversion [yam clutch] with Peter Barker making the cush rubbers for me.
I simply changed as I found the cover to wide to look beautiful, so purely cosmetic reasons.
Bernd
 

Jez Nemeth

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The back road from Rhayader to Devil's Bridge is a ripper, but mind the sheep!
That's one is defo on the plan. Miss the roads of NSW, but when the sun shines, Wales has some amazing roads, spaces and places - mostly empty too...bar sheep!

Weighed up all advice, really appreciate all the help and information.
So bit the bullet. 54 tooth AT10 Clutch Basket fitted with sealed bearing, 30 Tooth front pulley 32mm belt width- Retaining stock 1.8 standard ratio, and with a smaller diameter drive pulley at 3" 6/8 (96mm) than the 106mm I had in mind. New AT10 (Red Gen3) Belts available in every possible length/width, and relatively inexpensive too, they'll be around for years -have no wish to build in obsolescence. I'll fit the pulley before ordering correct belt. Basket is slightly smaller than the standard Norton Commando one, so gearbox won't need to be jammed tightly to the back of the engine casing to clear some of the fixing bolt flanges for fitting the Primary cover, it will just fit better, and should be able to use the range of the tension adjusters fully (1 1/2") Moved the clutch cable boss yesterday accordingly, and alu welded up the hole in the gearbox cover, tap a new hole later after work for the cable adjuster and that should all be good - I'd love a Newbie system...but had complete clutch internals already, so it just made sense to do it this way than buy a whole new system. If all goes pear shape, be the first to be knocking at Bob's door...
 

Jez Nemeth

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I used a belt conversion from norvil on my comet. The front "sprocket" I machined in my mill to accept the pd4 with the help of a 25 ton press. If using this arrangement I had to widen the clutch cover with a welded on strip of alloy all way round.
If you do so please don't forget to use the commando type clutch lever in your gearbox, the atlas type has not enough lift for the diaphragm spring.
While it worked okay I changed back to chain with a self fabricated clutch conversion [yam clutch] with Peter Barker making the cush rubbers for me.
I simply changed as I found the cover to wide to look beautiful, so purely cosmetic reasons.
Bernd
Thought of that one Bernd -but good point ..a mate mentioned to me there might not be enough 'pull', checked it against a commando one -bit of luck, had a Commando lever in place! Might it be a Norton owner's mod? (even thought about lengthening it a bit too, cut, weld, temper...). Think the Clutch should be ok, its just that cush system, or rather lack of one which is having me scratch the rain detector. Can't think of what I've got close to 25 tons hanging round the house to do what you've done there :) . Looked at Yammies, Hondas and Suzie clutches, there seemed some possibilities -Ben and Steve over at Conways/Godden do a loverly one with their Honda kit.
Trying to keep standard case if possible, if everything works out it should all fit, otherwise its an 8mm thick 6082 'gasket' Vibrac mentioned.

Ordered a mild steel pulley for 32mm Belt (it was a choice between 25,27,32), AT10mm pitch, 37mm (Outer flange to Flange width) - 93mm OD (bonus meant I could go wider with belt, stated 96mm on web, but actually 93mm?), and has a boss of 50mm OD -13mm depth that I can turn down. Be here in 10 days. Only real issue is if my old 1920's Drummond lathe will cope with turning down the bits, or do it at work, when I have the time...

Question though, did you find it harsh in use when you had the belt on it? Don't remember Commando Clutches being discussed as exemplary examples of clutch technology, but they can be refined...that Comet Mongrel post is good for that.. Commando Lever + Alloy Boss, be fettled drilled and tapped later...Friday night,
my wheelie bin goes out more than I do...
27413
 

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Jez Nemeth

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Belt Clutch basket arrived -cheap, much lighter and fits with a little more room as hoped -full 1 1/2" adjustment, mild grinding of one bolt flange at top of full range, not absolutely necessary but just to be safe, but all good. 1st fitted, 2nd at full outward adjustment. Anybody looking for a standard Norton Clutch basket pm me...
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Jez Nemeth

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Update on where we were last summer, just starting to get some bike time again - Belt drive fitted -kept the standard Comet ratio, 30mm AT10 belt, Lightened Commando basket with sealed bearing - seen here without plates and spring fitted -seems smooth in rotation, shafts parallel -as yet engine hasn't been started, which will be the true test. Cover fits fine, with room, had made a 10mm 'spacer' in case there had been problems -but none. Just had to use grinder very lightly in a few places just to be sure. Local shop welded a pulley onto the ESA shaft (as Chris suggested -thanks mate) Really appreciate all the great advice, and collective knowledge -have no doubts it will do the trick perfectly.
 

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vibrac

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Summary
I have had the belt drive on the flash with standard cover for years newby clutch with center for Albion clutch
And the racing comet for many seasons before that with sheet cover did change belt every season newby clutch
My egli comet has a belt drive as well but I included a vent at front of cover ( picture on here above) all have just standard nut on front pully
Only comet with chain is electric start now being completed
You can't have to many comets(. ❛ ᴗ ❛.) But nobody else wanted them back in the day. there is a lesson there!
 
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Chris Launders

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You need to be careful setting up the Commando clutch, there are different pressure plates to do this, the spring wants to be flat when installed, if it's dished IN the action will be much heavier. You may be able to do it without buying another pressure plate by fitting an extra plain plate (that's what's in my Atlas)
 

Jez Nemeth

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Good advice, thanx Chris, did measure and fit the plates and spring a time ago, seems good, fingers crossed -got another question though, if ever I would want to fit a Burman BAP instead of my amc/Norton Box, can the mainshafts be swopped about to fit Commando clutch, or is it back to the machine shop. Seem to have read someone had a setup like this?
Having had a good look again, I can see how it could be done without too much effort using the Burman Comet Mainshaft and some fettling of the Norton Clutch parts. Not planning to swop out the Norton box, which I'm assuming has several evolutionary advantages over the BAP being later, was just a little curious.

There's also the future possibility of fitting an electric starter setup down the line. Found that sprag clutch, cogs + mounts from an early GSX 750 all fit fine under the casing (its a no chain set up), but being a Norton Box, top mount stopping the fitting of the starter motor without cutting the casing about and re-welding the mounts (a la BAP). A conversation for another time perhaps...
 
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vibrac

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Yes I can confirm that an Alton electric start would pose a problem with a Norton box. My contention is now we have an electric start perhaps the next Comet up grade should be a nova transmission and conversion to oil
 
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