Hard to Pull Clutch - Ideas? (2011)

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dynodave = Hamilton Mass USA
USA has high school to 12th grade
Junior high or middle school 6-8 grade I was 12-13 in 8th grade

Yes, as I looked it up but shows how easy it is to assume everyone automatically knows what certain things mean.
12th grade = 17-18 years. I'd have been at work 1-2 years by then. It could have been getting on for 3 but I stayed on the extra year at my parents' insistence to get some qualifications (I might as well not have bothered for all the good they did)!


Lift comes from a magic external device some how connected to the handle bars.

Yes, I know, but it's the part about how the spring lift relates to clutch lift that deserves a little explanation.

(this is called sarcasm)

Glad you mentioned it. Didn't do so well in sarcasm class then?

Even BDM goes over it...in an unscientific way "NOT laboratory type" pg 30 of his article.

But at least he does get the point across about the difference between spring lift and clutch lift in an understandable way.


If you ask me how to make bread....am I supposed to tell you how to grow wheat and ferment yeast too?

Well, yes, as I'm neither a farmer nor a brewer. Doesn't matter anyway as I buy my bread from the shop opposite.
 
Yes, I know, but it's the part about how the spring lift relates to clutch lift that deserves a little explanation.
I believe it HAS been discussed many times on this forum and many other norton forums .

My article research was done about 5 years before being criticized by BDM. It took at least 10 years (I estimate 12) before he published his more comprehensive
anecdotal, but entertaining to some, ramblings.

My article was narrow in scope being focused on the shape of the pressure curve of the diaphragm spring mainly to differentiate it from a linear coil spring clutch.
Sorry if my old article fails to meet your current expanded expectation.
 
I believe it HAS been discussed many times on this forum and many other norton forums .

Yes, but I think you're missing my point.

My article research was done about 5 years before being criticized by BDM. It took at least 10 more years (I estimate 12) before he published his more comprehensive anecdotal, but entertaining to some, ramblings.

Yes, but nevertheless still useful ramblings.

My article was narrow in scope being focused on the shape of the pressure curve of the diaphragm spring mainly to differentiate it from a linear coil spring clutch.
Sorry if my old article fails to meet your current expanded expectation.

I think perhaps you are still missing my point that the difference between 'spring' and 'clutch' lift deserves a mention so spring lift is not misinterpreted as being clutch lift which often occurs in clutch discussions. That's all.
 
What shape is your clutch diaphragm spring? It needs to have a convex shape i.e. not flat. You can adjust it to the correct shape using the clutch spring compressor. If adjusted correctly, you will have a nice easy pull. Also, try putting an additional steel plate on top of the last plate in the stack so you can just fit the retaining circlip after you install the clutch pressure plate and clutch diaphragm spring.
 
What shape is your clutch diaphragm spring? It needs to have a convex shape i.e. not flat.

The spring would normally be concave when viewed from the outside.

Ideally, the stack height needs to be as 'high' as possible but not so great that it results in clutch slip as "clamping force" is reduced the closer the spring is to (and beyond) flat (approximate 'spring flat' position marked in red) at the "Fully home" position, therefore, stack height is a trade-off between the lightness of clutch lever action and 'grip'. The transition period where the spring moves through 'spring' flat should be felt at the handlebar lever when the action becomes lighter as the lever is pulled back to the grip so the closer this changeover point is to the start of lever movement the lighter the action will be. If it only occurs when the lever is almost back to the grip or if not felt at all, then the stack height probably is 'low'.

Moving the fully home position also changes the full lift position so there seems little to be gained by setting the fully home position much beyond 'flat' (in my opinion).

Diapragmchart.jpg

The diagram is a copy (of a copy) from the NOC Commando Service Notes, 1979)

You can adjust it to the correct shape using the clutch spring compressor.

If the spring is set 'flat' with the compressor and held in position (without releasing the compressor) then the distance the stack height is (usually) short of what would be the 'spring flat at the fully home' position can be determined by measuring the distance from the spring to the circlip groove (or circlip) as demonstrated in the OldBritts image, below and without the need for stack height-clutch drum depth calculations and also takes spring thickness into account.
clutch_info_a.jpg



If adjusted correctly, you will have a nice easy pull. Also, try putting an additional steel plate on top of the last plate in the stack so you can just fit the retaining circlip after you install the clutch pressure plate and clutch diaphragm spring.

An additional plate can often cure a heavy clutch lever action, but as the ring of the pressure plate is in contact with the spring at approximately half distance then any alteration to the stack height alters the spring's position by approximately double the change in stack height so in certain cases an extra plate could be too much.
 
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Nice summary by L.A.B.
I didn’t have room for an extra plate but replaced one of the 2mm plates with the 3mm one from RGM and that did the trick.
 
Nice summary by L.A.B.
I didn’t have room for an extra plate but replaced one of the 2mm plates with the 3mm one from RGM and that did the trick.

Thanks, and I also replaced a standard plain plate with the 3mm RGM item. It's a pity they don't offer a greater range of thicknesses to choose from, only 3mm and 4mm as the 4mm plate could have been too much.
 
It's a pity they don't offer a greater range of thicknesses to choose from, only 3mm and 4mm as the 4mm plate could have been too much.
Yes, I could probably have fitted a 3.5mm plate, or even a 2.5mm to replace another of the standard plates. You also need to be careful when you replace the 2mm plates. The originals are spot on 2mm whereas the replacements from RGM measured 1.85mm and can negate some of the stack increases.
 
Bringing an old one up. I currently have my bike disassembled. My clutch has the sintered and steel plates in the standard arrangement. I want to try to get an easier pull on the clutch. Does anyone stateside have the 3mm steel plates or is RGM the only supplier?
 
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