Heavy griffon clutch

[dave higgins]

Here`s a quick, cheap way, to make a heavy two handed griffon clutch, a two fingered walkover...
If you cut & shut the clutch arm as in the pic, ( originaly straight ) this will allow the hardened face in the arm to contact onto the push rod in a much more agreeable position, giving a very easy action.
The arm has to be cut, cranked & rewelded, to fit inside the casing.....

[Kim275]

Good Mod !

Dave looks a smart and easy mod thanks for sharing

Was your arm one of the first - as they did change the design in the second season of production?.........Geoff nunn got me a later ar for my 69 griffon and that made a big difference as well. I am assuming that as you are improving the angle @ the cable this would improve on either version...
Cheers Kim

[dave higgins]

Hi kim, i don`t know which arm it is, but its off the qub, this really does work, i`ve done the t/port as well.
If you dissconnect the cable & wind the clutch adjuster in, on the clutch itself & keep checking the pressure of the clutch arm with your hand, by pressing it in, when it gets to a certain point it gets incredibly easy to operate, thats the angle you want & then its a case of cranking the arm to fit inside the casing.
It works with a cam action, i think greeves got the angle wrong & its a lot cheaper than an neb......

[Brian Thompson]

Griffon Clutch Mod.

Cool tip Dave, thanks for posting.

Brian.

[Kim275]

Agree Top Tip !!

If it improves your QUB and twinport action - they no doubt have the later clutch arm - so that really is worth doing !

[druid]

Griffon clutch action

I'm intrigued by Dave's mod to his clutch lever but can't see how it reduces the force required to operate the clutch.
Altering the angle of the lever doesn't alter the leverage ratio which is what determines how light or heavy the action is.
My Clutch only requires a normal hand for operation. I just make sure that the cable run is smooth and friction free, a couple of things to watch for are the diameter of the push rod, I think it's 7/32" NOT 1/4" and if the shaft is slightly bent this will cause a problem, also if you've fitted aftermarket levers with a reduced ratio this will again give a heavy clutch.

Druid

[dave higgins]

Altering the angle of the lever does effect the leverage required, its the same principle as a rear brake arm set up, imagine your brake plate as a clock face, the optimun postion for the brake arm is 5 o clock, move it over the centre of the anchor/pivot point to say 7 o clock & the brake performance will be less with the same amount of effort used.
But should anyone need proof, then send me your arm & I'll alter it for you free...

[Brian Catt]

I can see a vast new industrial concern here, modding clutch arms! I could buy and arm extender for my Honda, but it's only useful for those people who ride trial sections so tight that they disappear up their own fulcrum.

[dave higgins]

This bsa factory bulletin proves my point that the angle of the clutch arm position is crucial, this bulletin is saying that when wear occurs in the clutch, simply adjusting at the cable will not do, as wear has allowed the clutch arm to move out of its designed postion.
Adjusting it correctly using the pushrod to push the arm back into its correct place gives a free & light clutch.
As i said before i found the clutch arms optimum postition & used that, i think greeves got there angles wrong.

[griffon380]

Sounds like a good mod Dave, I am going to try one and see if I can work it out. Then I have three more to do.
Craig

[dave higgins]

Craig, if you dissconnect your cable, slacken off your pushrod adjustment nut & wind your pushrod through so that the top of the clutch arm is approx 45mm from the top outer edge of the gearbox casing, then you are in the right area.
I you to push the clutch arm there, then wind it back in to its original postition, the you will find a considerable difference.
Obviously, when its out that far, then the outer casing will not go back on, hence the dog leg, defo worth playing around with, post your results up, with what you find though craig...
Copy this & you will have a lighter clutch.