heavy clutch/ stack height (2015)

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DogT said:
If the gasket you're talking about is the large O-ring, I silicone it into the inner case and put a smear of silicone on the O-ring just before I install the outer cover. Seems to work for me leak free.
Click to expand...

I believe it is an 850 MkIII, so it would have a conventional gasket instead of the large rubber sealing band between the inner and outer primary covers.
 
hi l.a.b, the 4 to 5mm I tried to measure was as Needing suggested on page 1. I have not measured clutch lift, not sure how to do this, I imagine once my new cable is fitted that I pull in lever and measure the difference of movement at spring plate.? it has paper gaskets so I will re new. the only difference I encountered with measurements was that my plates appear slightly thinner than the measurement given by Andover Norton. these brass? plates are a bit strange, they are same thickness as sintered plates but have a spiral cut into them that certainly looks like an oil way which I assumed was for cooling/lubricating clutch etc, looking in the parts manual (page 9 in mine)at the diagram it appears to just show them. first in the basket and then middle of the 5. I have nothing to go on as this is first time in for me. I really appreciate the info and help, and am learning loads as well as enjoying doing the work. cheers again Neil
 
D/t luck of the draw a complete new stack or old one by itselt may not ever stack up well - unless 2 sets of plates on hand & or several thickness of pressure plate, which is why various to custom pressure plates available for decades. The plate spiral or plate slots segments is to help intruding oil a sling out path. I found I needed a semi worn extra steel plate I put in first against basket back to get perfect function easy clutch on my 2 clutches us ing the stock pressure plate. Lucked out I guess w/o measuring by numbers. Over filled gearbox over oils as much or more than over filled primary but if your Cdo is Not a MKIII, ATF may please you in these areas.
 
mudplugger said:
hi l.a.b, the 4 to 5mm I tried to measure was as Needing suggested on page 1.
Click to expand...

OK, as that sounds a bit excessive to me?

mudplugger said:
I have not measured clutch lift, not sure how to do this,
Click to expand...

This is how I did it. I was just curious to know if yours was about the same?
heavy clutch/ stack height (2015)



mudplugger said:
these brass? plates are a bit strange, they are same thickness as sintered plates but have a spiral cut into them that certainly looks like an oil way which I assumed was for cooling/lubricating clutch etc, looking in the parts manual (page 9 in mine)at the diagram it appears to just show them. first in the basket and then middle of the 5.
Click to expand...

Well, the standard "bronze" 06-3741 plates usually look like this (below)? The groove is there to remove oil from the plate surface.

concours said:
heavy clutch/ stack height (2015)
Click to expand...
 
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hi L.A.B. that is the same brass plates as mine. I will measure clutch as you said and will let you know.
 
hi L.A.B I have measured clutch as per your photo. I have about .083" movement. (first attempt was .116"). I haven't ridden it yet, (waiting on new fuel tap) but have renewed cable and I think that was where the problem was. it feels so different now. thanks again to all. keep it pinned. regards Neil
 
It is totally clear that the people posting on this subject know very littl;e about the Commando diaphragm spring clutch. Some history based on FACTS.
The Commando clutch was originally designed by a Mr Peter Senior (Senior Clutch Designer and Engineering Director) of Laycock Engineering of Sheffield for the early 1960s Villiers Starmaker 250cc trials, scrambles and road race motors. For the different engine configurations producing different torque outputs he designed single and a twin friction plate diaphragm spring clutches each clutch having slightly different thickness diaphragm springs (0.073 inch and 0.077 inch thick) each giving different clamp loads when CORRECTLY set up as the clutch was DESIGNED to do when fitted with new friction and inter plates.
The original Atlas Mk3 or Commando as it was later named diaphragm spring clutch was simply a BODGED version of the Starmaker clutch but was, torque capacity wise, correctly designed. I.E. the required clutch torque capacity was equal to the in theory torque capacity within the clutch I.E. the clutch would NOT slip when fully engaged when the engine was putting through it every last gasp of torque it could produce !!
UNFORTUNATELY Nortons had since introducing the Norton pressed steel oil bath chain case in 1934 ish enclosed within it a designed to be employed DRY clutch so when oil eventually works its way into the clutch the Coefficient of Friction acting between the friction interfaces reduces to roughly 1/3 of its DRY value reducing the torque capacity of the clutch to roughly 1/3 of its dry value and IF an owner shoved a bit of grunt through the clutch it SLIPPED and a multi plate gearbox mounted friction clutch should possess a few basic qualities one of which is that it will NOT slip when fully engaged even when hot.
The original Commando diaphragm spring (0.075 inch thick) when correctly set up applied approx 380lbf clamp load to the friction interfaces giving an initial release load of approx 210 lbf and with the clutch lever back to the bar approx 150 lbf giving a clutch lever EASILY operated with no more than two fingers. Or as one road test reported, from memory so probably not word perfect ' I find it incredible that such a delightfully light and positive clutch could of been ignored by motor cycle manufacturers for so long before being introduced on the Commando'. The first time I pulled an early 750 Commando clutch lever I turned to the bike owner and said 'OK so who is the clever ******* who disconnected the ******* clutch!!!!' The owner replied 'Funny but most people ask that question'.
To overcome the clutch slip problem the manufacturer (AMC / NVT) had Laycock Engineering manufacture a slightly thicker spring to increase the clamp load and thus increase the torque capacity within the clutch. This did NOT cure the slip problem so they did this trick several more times increasing the clamp load with the last spring produced (0.084 inch thick) and used in the late 750 and all 820 lumps to approx 550lbf requiring an initial release load of approx 300lbf and with the clutch lever back to the bar approx 250 lbf making the clutch lever action a BASTARD to use.
Even this did not cure the clutch slip problem.
Now when Villiers asked Laycock Engineering to design the clutches for the Starmakers NO ONE at Villiers bothered to tell Laycock Engineering that the clutch was to be shoved within the oil bath chain case!!(The idea of enclosing a clutch within an oil bath chain case being VERY POLITELY described by the Staff of The Motor Cycle in their book 'Speed and How to Obtain it' as and I quote 'FRANKLY A COMPROMISE'. Thus Villiers were in deep doggy doo with a clutch slip problem. The quick and very cheap bodge that someone came up with was to replace the original 'suitable for DRY use only' friction material (I believe Ferodo VG material) with sintered bronze material the theory being that when oil eventually entered the dry clutch reducing the Coefficient of Friction acting between the friction interfaces from, rule of thumb for sintered bronze, 0.3 to 0.06-0.08 and thus reducing the torque capacity within the clutch to damn nigh sweet nothing the resulting slip would generate very high temperatures within the friction interfaces burning off the oil causing the slip leaving the clutch once again slip free...for a while!! Clearly someone at NVT was an ex Villiers person and remembered the Starmaker bodge and it was applied to the Commando clutch but to offset the lower DRY C of F of sintered bronze compared to the Ferodo MS6 friction material used previously (and the later DON 112 solid fibre material) they added yet another friction plate.
I am NOT going to explain here how the diaphragm spring clutch 'works' but I would suggest all owners try to learn by sitting down for a few hours and reading the web pages http://a20b767e.magix.net/#xl_xr_page_1.
I actually wrote the document many years ago intending to put it on the web for the benefit of Norton Owners Club members but it never happened as I and a few older Norton owning friends left the club muttering nasty things about owners who knew bugger all about Engineering and the bikes they owned. Later a fiend had m finish it and he put it on the web on a free site which finished a while ago but He has had a go at putting it on this site but unfortunately he is waiting for me to proof read / fault find it...at least one section is totally missing. IF i live long enough AND manage to find the enthusiasm I might correct it and even pay to put it on a site in the hope that at least one Commando owner will learn......
I should add that I do have a copy of the Laycock Engineering drawing that shows all 8 of the slightly different springs produced for the Starmaker, Commando and rotary Norton clutches and that I have spent 25 years trying to learn just a little bit about the subject, along with a few other subjects.
 
the above is all very interesting and I will try and find time to sit and read the suggested material. unfortunately not every rider of what ever bike they choose is lucky enough to be engineering minded, do you know the ins and outs of every vehicle you have ever rode, driven or pedalled. I for one am interested and come from an engineering background, but not bikes and am more than happy to ask, learn and try. hence the reason I read and listen to the other members of this forum. some of them have an immence knowledge of the bikes. if you are such an expert surely you would make the time to share this valuable info with us instead of tramping over those who don't know.
 
mudplugger said:
the above is all very interesting and I will try and find time to sit and read the suggested material. unfortunately not every rider of what ever bike they choose is lucky enough to be engineering minded, do you know the ins and outs of every vehicle you have ever rode, driven or pedalled. I for one am interested and come from an engineering background, but not bikes and am more than happy to ask, learn and try. hence the reason I read and listen to the other members of this forum. some of them have an immence knowledge of the bikes. if you are such an expert surely you would make the time to share this valuable info with us instead of tramping over those who don't know.
Click to expand...

I wouldn't take it too personally if I were you-as BDM/J.M.L is like that with everyone. :roll:
 
Dear Mr Leadbeater.
Re your "...I should add that I do have a copy of the Laycock Engineering drawing that shows all 8 of the slightly different springs produced for the Starmaker, Commando and rotary Norton clutches...".
This sounds like a most interesting document. Is it practicable for you to have it digitised and the file posted or linked to this forum so we may analyse it and interprete it for Norton specific and perhaps other applications?
Ta in advance.
 
I wouldn't take it too personally if I were you-as BDM/J.M.L is like that with everyone.
Click to expand...

cheers for that. were my measurements for clutch movement in the right ball park. they were a bit less than yours. Neil
 
mudplugger said:
were my measurements for clutch movement in the right ball park. they were a bit less than yours.
Click to expand...

If your .023" measurement is reasonably accurate, then the clutch stack does not seem "low" as I think mine was around .055" when last measured and I don't consider my Commando's clutch pull to be particularly heavy.

Although your lift measurement figure is somewhat less than mine I'm not sure there's a problem-but how much are you backing off the pushrod adjuster? The manuals say to back the adjuster off by "one full turn" when setting the pushrod clearance, however, I think many of us would say that is too much, and backing off by about one third is usually enough.
 
mine was .083 not .023. will ride it soon. put new petrol tap on and the juice poured out of the new fitting. sent it back to Andover and am waiting for a BAP replacement.
 
J. M. Leadbeater said:
It is totally clear that the people posting on this subject know very littl;e about the Commando diaphragm spring clutch. Some history based on FACTS.
The Commando clutch was originally designed by a Mr Peter Senior (Senior Clutch Designer and Engineering Director) of Laycock Engineering of Sheffield for the early 1960s Villiers Starmaker 250cc trials, scrambles and road race motors. For the different engine configurations producing different torque outputs he designed single and a twin friction plate diaphragm spring clutches each clutch having slightly different thickness diaphragm springs (0.073 inch and 0.077 inch thick) each giving different clamp loads when CORRECTLY set up as the clutch was DESIGNED to do when fitted with new friction and inter plates.
The original Atlas Mk3 or Commando as it was later named diaphragm spring clutch was simply a BODGED version of the Starmaker clutch but was, torque capacity wise, correctly designed. I.E. the required clutch torque capacity was equal to the in theory torque capacity within the clutch I.E. the clutch would NOT slip when fully engaged when the engine was putting through it every last gasp of torque it could produce !!
UNFORTUNATELY Nortons had since introducing the Norton pressed steel oil bath chain case in 1934 ish enclosed within it a designed to be employed DRY clutch so when oil eventually works its way into the clutch the Coefficient of Friction acting between the friction interfaces reduces to roughly 1/3 of its DRY value reducing the torque capacity of the clutch to roughly 1/3 of its dry value and IF an owner shoved a bit of grunt through the clutch it SLIPPED and a multi plate gearbox mounted friction clutch should possess a few basic qualities one of which is that it will NOT slip when fully engaged even when hot.
The original Commando diaphragm spring (0.075 inch thick) when correctly set up applied approx 380lbf clamp load to the friction interfaces giving an initial release load of approx 210 lbf and with the clutch lever back to the bar approx 150 lbf giving a clutch lever EASILY operated with no more than two fingers. Or as one road test reported, from memory so probably not word perfect ' I find it incredible that such a delightfully light and positive clutch could of been ignored by motor cycle manufacturers for so long before being introduced on the Commando'. The first time I pulled an early 750 Commando clutch lever I turned to the bike owner and said 'OK so who is the clever ******* who disconnected the ******* clutch!!!!' The owner replied 'Funny but most people ask that question'.
To overcome the clutch slip problem the manufacturer (AMC / NVT) had Laycock Engineering manufacture a slightly thicker spring to increase the clamp load and thus increase the torque capacity within the clutch. This did NOT cure the slip problem so they did this trick several more times increasing the clamp load with the last spring produced (0.084 inch thick) and used in the late 750 and all 820 lumps to approx 550lbf requiring an initial release load of approx 300lbf and with the clutch lever back to the bar approx 250 lbf making the clutch lever action a BASTARD to use.
Even this did not cure the clutch slip problem.
Now when Villiers asked Laycock Engineering to design the clutches for the Starmakers NO ONE at Villiers bothered to tell Laycock Engineering that the clutch was to be shoved within the oil bath chain case!!(The idea of enclosing a clutch within an oil bath chain case being VERY POLITELY described by the Staff of The Motor Cycle in their book 'Speed and How to Obtain it' as and I quote 'FRANKLY A COMPROMISE'. Thus Villiers were in deep doggy doo with a clutch slip problem. The quick and very cheap bodge that someone came up with was to replace the original 'suitable for DRY use only' friction material (I believe Ferodo VG material) with sintered bronze material the theory being that when oil eventually entered the dry clutch reducing the Coefficient of Friction acting between the friction interfaces from, rule of thumb for sintered bronze, 0.3 to 0.06-0.08 and thus reducing the torque capacity within the clutch to damn nigh sweet nothing the resulting slip would generate very high temperatures within the friction interfaces burning off the oil causing the slip leaving the clutch once again slip free...for a while!! Clearly someone at NVT was an ex Villiers person and remembered the Starmaker bodge and it was applied to the Commando clutch but to offset the lower DRY C of F of sintered bronze compared to the Ferodo MS6 friction material used previously (and the later DON 112 solid fibre material) they added yet another friction plate.
I am NOT going to explain here how the diaphragm spring clutch 'works' but I would suggest all owners try to learn by sitting down for a few hours and reading the web pages http://a20b767e.magix.net/#xl_xr_page_1.
I actually wrote the document many years ago intending to put it on the web for the benefit of Norton Owners Club members but it never happened as I and a few older Norton owning friends left the club muttering nasty things about owners who knew bugger all about Engineering and the bikes they owned. Later a fiend had m finish it and he put it on the web on a free site which finished a while ago but He has had a go at putting it on this site but unfortunately he is waiting for me to proof read / fault find it...at least one section is totally missing. IF i live long enough AND manage to find the enthusiasm I might correct it and even pay to put it on a site in the hope that at least one Commando owner will learn......
I should add that I do have a copy of the Laycock Engineering drawing that shows all 8 of the slightly different springs produced for the Starmaker, Commando and rotary Norton clutches and that I have spent 25 years trying to learn just a little bit about the subject, along with a few other subjects.
Click to expand...

very interesting as to how the design evolved. So what are your concise recommendations for typical owners to optimise components/ setup?
 
jan nelder said:
very interesting as to how the design evolved. So what are your concise recommendations for typical owners to optimise components/ setup?
Click to expand...
J M Leadbeater or "belt driven man" died a while back sadly
 
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