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Old 01-10-2018, 02:26 PM   #16
Dukedesmo
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Quote:
Originally Posted by Mr Gazza View Post
I suggest that your RCS master @16mm, is producing less mechanical advantage (but more clutch lift). Hence the slightly heavier pull than mine.
Interesting, there are 2 settings on the RCS: The cylinder is 16mm bore but there are both 16 and 18mm pivot/lever settings. On the other (lighter) setting it pulls around 5kg but you do need to pull it all the way in to get a good plate separation.

Also I'm finding it difficult to get a consistent reading with the digital gauge that I'm using and it could well read differently with another (yours?) so, like dyno readings they may not be directly comparable but there is a noticeable difference between the two settings which I suppose is one selling point of the RCS masters.
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Old 01-10-2018, 06:38 PM   #17
Mr Gazza
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That is interesting. since the leverage that the handlebar lever exerts upon the piston, has it's own mechanical advantage, which should be taken into account when calculating the overall Mech adv.
So by applying more leverage to your larger piston, a similar mech adv. to that of my 13/29 set up is achieved. A higher mech adv will always produce less lift by it's nature.

The mechanical advantage of most cable systems will always be fairly similar to hydraulic systems in terms of lever travel to clutch lift. Unfortunately cables suffer from huge amounts of friction within, which is compounded by curves and poor lubrication. This is why they need more effort to pull, not because of poor mechanical advantage.

BTW I used an old brass spring balance with a sliding scale. I simply pulled the lever to about half it's travel with the balance and then held to take a steady reading.

The Commando uses a somewhat unique (in motorcycles) steel diaphragm spring, cut into central "fingers". This has the bizarre property of exerting a varying pressure at different points of it's deflection. It creates an "S" shaped graph of it's pressure as it goes beyond the "flat and pops the other way.
The trick of setting them up for a light clutch operation is to get the sweet spot of the spring by tuning the stack height..... Different strokes eh?
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Old 02-10-2018, 09:46 AM   #18
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Sometimes 'old school' is better, I have an old brass engineering spring balance but it only goes to 5lb. The electronic one (designed for airline luggage weighing) sets and stores the weight after a couple of seconds but it's difficult to get a true reading that quickly due to the bars being in the way etc.

One useful way of reducing clutch pull though is to remove 2 (or even 3) springs from the clutch.

I ran my 916 with 4 springs only for several years and combined with the larger slave it was so light a small child could have operated it, never slipped either.
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