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Heavy Clutch

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Te 650SS I bought recently has a clutch operation force that would have defeated Superman. I read in this website 7/8" is the correct distance between fulcrum and the centre of the cable nipple. Mine has a distance of just over 1.1". I asked at ANIL who say 1.1" is correct, technical at ANIL also measured another 650SS and an early dominator. I would think the greater the distance between fulcrum and nipple centre would result in needing less force not more.

So any ideas, something odd with my bike?

Many thanks Roger

 

 

 

 

 

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Hi Roger,

The bigger the distance from fulcrum to nipple the greater force required to pull the cable. It is down to the ratio of lever movement to cable movement.  

That is why 7/8" is better. It will require just 70% of the effort of a 1 1/4" lever.

Regards, George. 

In reply to by george_farenden

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Hi George, yes my mistake - I was looking at the end of the lever where the load is lifted rather than the end where the force is applied. I must think twice and write once!

Actually I was wondering how long it would take to spot my mistake.

 

Regards Roger

 

In reply to by george_farenden

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Hi George, I've found a drawing that may help to explain the difference between the levers.

Not that professional, just a basic view...

Best regards, Harry

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Definately a wrong lever .  But that is only  part of the issue.  You also need a good quality nylon lined cable lubed with thin silicone  ,regularly.  A correctly positioned  modified lever in the box, 20 w oil  or thinner in the primary, Some bar raisers to get the cables to clear the fork nuts, Levers in line with  your forearms, the correct temper and gauge springs, not overtightened, flat clutch plates finely set to clear well, a clutch center and drum without notches, spring boxes without wear steps , Enough primary chain slack and if really fussy a set of oversize rollers in the race to reduce rock to the minimum. Result : a 2 finger Atlas clutch.   

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As Robert said plus that some grease so that the nipple on the lever end of the wire can rotate easily in the lever. Also check so that a previous owner had not put a clutch operating lever from a Commando in the gearbox. They are different from the ones used in the 650SS. The Commando type clutch needs a longer stroke and less force to work as intended. The reduction in force needed with a shorter fulcrum to nipple distance of course also means lesser lift. So the things mentioned by Robert will reduce risk of a dragging clutch. And as usual, routing of the clutch cable can make a huge difference.

Edit: I don't trust all info from Andover. Got way to strong clutch springs for my Manx from them. Which they swear was correct.

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I just measured mine with a luggage scale on the clutch lever and it requires around 9-10 lbs to pull it in, and 6.5lbs to hold it there. My lever is a 7/8" one, 5.5" long to the ball end. Feels ok and normal when I ride it. Maybe I have a strong grip?

As Robert says, a 'featherlight' cable carefully routed and careful alignment of the actuator inside the gearbox is a big help.

Have no idea how that compares with other Nortons, but as a contrast it is 50% greater than my Morini needs and over 100% greater than the modern 650 Enfield. 

Regards,

George 

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Spotted it instantly , but the overiding thought was   what the heck does ANIL  know about real Nortons ?. And should I be worried about  what  I may buy in the future ?. I could offer my services  but I have just refused one  job offer , at  75  my time is too precious. and  half my brain cells have gone already.

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A lever 7/8" pivot distance and a cable from Venhill Ltd, carefully routed on my 99 transformed the pull necessary, plus all the above.

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After boasting about a 2 finger Atlas clutch  ,I tested the boys Atlas and  I can pull it in with one finger.  Keep working at it ,  it will be worth it.

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Has anyone ever bothered to properly grease the lever rolling and bearing surfaces? I don't believe I have...moly grease this evening. It can't get much splash lubrication in there.

 



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