650 SS commando clutch
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texasSlick
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The Commando clutch fits over the 650 transmission main shaft, but lacks a way to secure it. The recommended procedure is to replace the 650 main shaft with a Commando mainshaft. The 650 gearbox has to be snugged up closer to engine cases to use a Commando length belt or chain.
The stator and rotor must be moved outboard about 3/8 inch to allow for the added width of the Commando belt.
Note: the Commando clutch does not have a cushion drive. You would lose that in the AMC clutch, and unless you use a cush drive rear wheel, risk damage to the gearbox, but not if you are easy on it.
Slick
ashman
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I am going to run a Commando clutch on my 1960 Manxman cafe racer build, RGM sells the clutch centre to fit the 650 main shaft but I will be running an open belt and as Texas has said the Commando clutch has no cushion drive, I be taking it easy with clutch operation, but a later model rear hub be the go, I already have an alloy clutch basket and belt drive as well the clutch centre, just got to pull my finger out and get back into this project.
Ashley
Ashley
I have a 650 running a belt drive with commando clutch from RGM. I am quite pleased with it, no problems but only about 2000 miles on this one.
Previous one (c.2001) had an issue with (lack of) hard anodising, and failed after a few (five?) thousand (hard, loaded, luggage, pillion, and some Alpine!) miles.
I seem to remember the alternator was spaced off? Not sure what I did with the rotor...?
I did run the double sided adjuster on it When i put this one on 2 years ago And setting belt tension correctly (both hot and cold) is important and took me a while. No disasters tho...
Even without a cush...
Andy
Previous one (c.2001) had an issue with (lack of) hard anodising, and failed after a few (five?) thousand (hard, loaded, luggage, pillion, and some Alpine!) miles.
I seem to remember the alternator was spaced off? Not sure what I did with the rotor...?
I did run the double sided adjuster on it When i put this one on 2 years ago And setting belt tension correctly (both hot and cold) is important and took me a while. No disasters tho...
Even without a cush...
Andy
milfordite
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I used the belt drive set up on my Atlas based race bike from Norvil. Even though it was the street version, I never had a problem with it even though the bike was at 70HP at the rear wheel. Also used the double adjuster to align the belt.
baz
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I agree on the cush drive
Although the first commandos didn't have a cush drive
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If the lack of a cush drive disturbs you, use a Commando rear wheel hub with the plastic shock absorber inserts. Or much better is a Don Pender rear wheel hub with a proper rubber drive.
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Cush is not a necessity. The cush in the AMC 3 spring clutch was not all that great to begin with. You won't miss it.
I use the RGM pre-Commando with alternator belt clutch. Some minor trials and tribulations to make it work, but my Norton is not really supported, the 650SS is.
I use the RGM pre-Commando with alternator belt clutch. Some minor trials and tribulations to make it work, but my Norton is not really supported, the 650SS is.
Any gear cluster will suffer without a working cushion or spring system, especially when a single cylinder or parallel twin is at work.
I think early Commando transmissions are withnesses of that! ( :: Lots of gear wheels with pitting marks)
As for the cushion system in the AMC clutch, I beg to disagree. It was so good, that Triumph copied it !
- Knut
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Did all the early Commando gearboxes with pitting marks on the gears break?
Andy Molnar wouldn't agree with you regarding the "need" for cush in any Norton model. Ask him. I did. None of the TGA race bikes outfitted with belt clutches have cush rear hubs. A street bike that doesn't see near as much abuse should be OK. I'll take Andy's advice and not worry about it.
How can I know? This would be a question for John Hudson, former Service Manager with Norton Villiers.
I am sure many badly pitted gears have been discarded during transmission overhauls.
Furthermore, there are many examples of bent shafts and damaged bearings, which probably has its root cause in the same.
What is clear, is that once the nitrided layer is penetrated, wear increases rapidly, and ultimately the gear tooth will break.
For the record, I didn't comment on "need" for a cushion system in the transmission system. Since when has Andy become a Godlike person in technical matters? Would he reveal that the bikes he sell suffer from abnormal gear wheel wear by not having a cushion system in the drive chain? Probably not. Furthermore, your example is contradicted by NYC Norton and Steve Maney, who builds/built bikes with a cush drive.
In this case, the proof is not in the pudding, for the following reasons:
* The bikes TGA sell need to be historically correct. AMC/Norton/Seeley rear wheels did not feature a cushion system, because they relied on the AMC racing clutch hub originally.
* TGA offer these bikes (G50/Manx/G50 Seeley) with either Quife or TTi gearboxes, no standard AMC gearbox, thus no comparison whatsoever.
* There is a vast difference between a G50 / Manx, and the Norton twin (750/850), considering dynamics of torque.
* TGA developed and sell their belt drive system. Any functional deficit will be downplayed, of course.
* There is no comparison between a street bike which receives an overhaul every 30th year, and a race bike which receives an overhaul after every season.
* You claim a street bike sees "nearly as much abuse" as a race bike. Is this true? What's the mileage of a race bike after one season? The IOMTT race course is 38 miles long and there are 6 laps. Let's assume one season consists of 5 such race outings. The total mileage would be 1140 miles / 1835 km. What's the TBO of a road bike? No fixed figure, but I guess at least 20 000 miles or 32000 km, probably more. And what about mechanical loading? Race bikes run most of the time at high revs where power is maximum (to achieve maximum speed), but torque isn't, usually it drops significantly with higher revs. Maximum loading of the transmission occurs at the revs where torque has its maximum. For a standard Norton twin, this is between 4000 and 5000 rpm, i.e., in the rev band which is used frequently. (A race engine will produce max. torque at approx. 5500 rpm, but is run at 7000 rpm usually) Thus, there is no question that the severity of transmission loading in a street bike is significantly higher than in a comparable race bike.
Summing up, the relevance of TGA's equipped bikes can be dismissed.
- Knut
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