Has anyone measured the force needed to pull the handlebar clutch lever to open the clutch?
If someone has what force was needed.
If not could someone measure it please? A spring balance that can read up to approx. 20 kg (40lb) will be needed. A loop of rope around the lever and the hook on the balance, pull the balance and see what the peak force is. Not looking for high accuracy, just a reasonably close number, the average of a few pulls should do it.
Thanks in anticipation.
Just checked my 99 which has…
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Clutch pull force
Hi John,
Which clutch actuation are you interested in? Early gearbox with swinging arm and single ball?
Later gearbox with three balls and scissor type action?
I can help with the latter.
Peter
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clutch actuation
Peter, either type. It would be interesting to know which is lighter/better.
The reason I am asking is that I have some ideas to improve clutch operation but need some numbers to see if its worth the effort.
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I can pull the clutch in on…
I can pull the clutch in on the 99/650/Atlas with one finger ,(after much fetling and regular use of a grip exerciser !. ) , But i'm still a relative youngster at only 78 . Both my lads grumble at the effort though . What have we made them into with modern life.?.
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Thats probably heredetary ,…
Thats probably heredetary , I am all fingers and thumbs !!
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Clutch pull force
Hi John - you confused the issue by asking for lightweigh/heavyweight clutch pull force. Which are you after?
Sadly, I have found the force on my Navi clutch to be quite heavy, versus friends with Dommi & Commando. A person with initials CJD, who shall remain nameless, mocks my clutch pull - which I have no trouble with. But I do admit, that a properly set-up Dommi clutch can be sweet. But if you look at the leverages involved, the Dommi has more leverage than a Lightweight - yet the clutches on both are similar.Likewise, a well set-up Commando clutch with its diaphragm pressure plate can be sweet.
A good quality, nylon lined, or a well-lubed steel cable helps, as does a smooth line from handlebar to gearbox.
I do not have a way to measure at present, apologies.
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Confused
Andy, I probably have confused things slightly.. Heavy and lightweights used the same springs at one point, if my deductions from various parts lists and suppliers are correct. The operating mechanisms are different. Therefore the forces measured may be different but not by much, the springs will have a far greater affect.
Had I thought about the clutch a bit more when I dismantled the engine some 2 years ago I would have made the measurements then, kicking myself for not doing it!
My bike has the early type gearbox, previously with the clutch mech associated with that type of box. It now has a 3 balls mech like the late type box.
The big change is the springs, short springs are the standard ones, see attached photo. These have made the clutch much lighter, need to check again, not sure I believe the numbers.
Hoping to have the bike on the road around easter time (said that this time last year!). Will be interesting to see how the clutch performs.
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Tried the new springs
I've assembled the clutch, firstly with the standard springs. Results very similar to Bob M's, 8.5kg maximum to open, 5.5kg to hold.
With the new springs 5.8kg maximum to open, 2kg to hold.
Definitely worth fitting the the lower rate springs. These springs still give the same clamping force as the standard springs, 14.5kg.
Not so easy to to quantify the operating mechanism, the 3 ball mech will have less friction than the other methods Norton have used, by how much I don't know. I've modified a Royal Enfield 3 ball mech from their 5-speed gearbox. Its identical to the Triumph (Meriden) mech except for the cable attachment and a built in adjuster.
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Just checked my 99 which has a light clutch operation - I modified the actuating cam and set the springs as light as I could without clutch slip.
I used the digital kitchen scales and it takes approximately 8.5 kilos to release the clutch over centre and then 6.3 - 6.5 kilos to hold it in. Tried this several times to get an average. Hope this helps.