approx jan 2003
 

Re the Commando vastly overweight unbalanced gearbox flywheels they jokingly called clutches.Well at least you got the load deflection curve a tad more accurate than the one shown in the NOC Commando notes booklet but it still does not show the results that the testing of them I have had done. However, minor point....Maybe its my olde eyesight but I dont think you even mentioned the real cause of the clutch slip and drag problem which is that Commando clutches are DRY clutches that were NOT designed to be employed with any oil on the friction interfaces and most of it that does get there is of course the iil held within the chain case oil bath. BSA also shoved dry clutches within such lumps and once actually blurted out the truth in the B32 publicity sheet for the B32 when calling the it  'BSA multi-dry plate with oil resisting inserts'. Later of course the DB models employed Ferodo MZ41 friction material throughout the clutch and the MZ41 data sheet states that it must NOT be used with oil. If you look at Mr Reynolds book'The racing legend..Norton' you will note that he correctly describes the clutches as being DRY.And so they are as simple clutch torque requirement capacity and actual in thoeory torque capacity calculations will show you. That of course is why my manuals for Atlas.99.88 etc state on the problems page that one cause of slip is 'oil on plates' and the remedy as'strip clutch wash plates in petrol reassemble using a smear og anti centrifuge grease on the rollers...............(Ah that ancient  clutch strip ritual)As for moving the cluch fully engaged position of the diaphragm spring did you remember to state that any movement caused by, for example,one of those silly RGM thicker than std pressure plates will not only make clutch action lighter( 0.050 inch =a 25 ish % reduction) but it will also reduce by the same amount the clamp load and thus reduce the amount of torque the clutch will carry before slip occures also by approx 25%...................which is a bloody stupid thing to do..Oh and you have not found the real reason for early &50 Commando clutches being easily operated with one finger whist NEVER suffering from slip problems...till oil got into them...... and the later 850 ones being harder to operate than T140 ones (Actually they were harder requiring a greater release load than even the T140 overweight unbalanced gearbox flywheels...............)Of course you will never find it even if I tell you that the changes that resulted init were NOT put on the drawings NOR were the componant part numbers changed. ...... Happy researching.....

A second unsolicited email

Subject: Commando diaphragm spring test results
   Date: Sat, 25 Jan 2003 20:31:53 -0000
   From: "J M Leadbeater" <jl006a5245@blueyonder.co.uk>
     To: <dynodave@gis.net>
Sir, Your test results shown are incorrect. I suspect that someone measured load at the release ring in the
center of the clutch and NOT at the pressure plate. Your readings are approx half that obtained at the pressure
line. I also suspect you tested a spring from a late 850 clutch. If you send me your mail address i will send you
the set of test results Norton supplied to me in 1990.
These are correct as testing I have had done shows........by a friendly motorcyclist who happens to be the
Senior Technician in the Mechanical Eng Lab of a rather large University 'somewhere' in England . Somewhere
because it gets done for free and the test machine is expensive to run!!!!!!
Your testing of cams was interesting....something I did 20 odd years ago..somewhere I still have the new
'GENUINE NORTON' cam with its 'GENUINE NORTON ' (YOU CAN TRUST GENUINE NORTON
SPARES)wrapping that is as soft as the stuff Texas exports in lumps of glass!................350 Vickers.  Of course
there is always the camshaft oil bath that Mr Hopwood so carefully designed INTO his Dominator design to
ensure the cam was correctly lubricated at the front of the motor. (FACT Before TRIUMPH listened to one gent I
consult and nitrided the cams to give 900-1000 Vickers surface hardness ONE IN THREE Bonnys had the
exhaust cam changed under warranty!!!!!!) Guess why Mr Hopwoods BSA Twin design also had a camshaft oil
bath designed into the crankcases.... Nortons of course then proceeded to design the Dominator cam shaft oil
bath out.........till it had TOTALLY gone with the Combat cases...NOT helped by ignorant owners following the
tuning books advice and attacking the camshaft tunnel to get the 'go slower' high lift cam in and removing the oil
bath as they did so......... Say please and I will send a copy of Mr Hopwoods letter on the subject.!!!!
I should add that the gentleman whose brains I pick at for free on the subjects of clutch, diaphragm
spring,gearbox, overdrive units etcetc design and manufacture was, when I first started to pick at his brains, for
free of course, the Engineering Director of the Company that made the Diaphragm springs for Nortons. He is
now retired. GKN bought them out and being managed as incompetently as GEC / Marconi / BAe etc closed
them down.......J M Leadbeater.
 

MY ONLY CORRESPONDENCE TO JML....ever

From: "David Comeau" <dynodave@gis.net>
To: "J M Leadbeater" <jl006a5245@blueyonder.co.uk>
Sent: Saturday, January 25, 2003 11:31 PM
Subject: Re: Commando diaphragm spring test results
Sir
 What is the point of your emails? You've emailed me twice in the last  month. I'm sorry if any of my work offends you personally or lacks the
 detail you desire. If you have better data and want to write and  publish your own work, it's your life, and your time, feel free to do
 so. If I am satisfied yours  is better and freely accessible to the NOC  and INOA members, I'll be glad to take mine off the server. In the mean
 time I will work on things that are more important to me, since, I do  have more interests than norton motorcycles.
 

"Subject:  Re: Commando diaphragm spring test results
Date:  Sun, 26 Jan 2003 02:16:19 -0000
From: "J M Leadbeater" <jl006a5245@blueyonder.co.uk>
To: "David Comeau" <dynodave@gis.net>
 References:
            1 , 2
OOPS  Sorry, I just thought you mignt like to correct your web site. However I do not mind quoting your web site as yet another example of
misinformation along with the curves shown in the N.O.C Commando Service Notes booklet in the letter I am sending in to the NOC for publication regarding the Commando diaphragm spring clutch and how it really works (Along with correct clamp load and release load deflection curves). We have enough  people giving Norton Owners misinformation as it is without further ones joining them "
 

To my knowledge this has not been published as of this date Dec 2005
Angry due to lack of response, he continues....

Subject:  NORTON COMMANDO Clutches
Date:  Sun, 16 Feb 2003 15:35:19 -0000
From: "J M Leadbeater" <jl006a5245@blueyonder.co.uk>
To: "David Comeau" <dynodave@gis.net>

Are all you Yanks total PRATTS????You certainly are because you are not even capable of the simplest clutch
calculations. You sir are whar is known as an  EXSPURT  and likes to demonstate it to the World
A few 1st year mechanical engineering calculations, as you are CLEARLY incapable of performing them.
750 Commando.
REQUIRED CLUTCH TORQUE CAPACITY. The max torque claimed at the crank is 48ft lb.
Assuming(incorrectly) no power losses in the chain and std 26t-57t sprockets then the max toque at the clutch
is 48 x 57/26 =105 ftlb
To this a designer will add a safety factor of between 1.6 to 2.4 depending upon the application and the ancient
rule of thumb one for clutches is X2. Thus the required clutch torque capacity is 105 X 2 = 210 ft lb.
THE IN THEORY CLUTCH TORQUE CAPACITY. The vastly overweight  unbalanced gearbox flywheel employs
4 friction plates giving 8 interfaces. The effective radius of the friction interfaces is 0.205ft. The clamp load
applied by a correctly set up 750 spring is, according toNorton s own test results supplied to me in 1990 and
the testing I have had done at *********Universitys' Mech Eng Dept would be 380 lb. As for the coefficient of
friction of the original friction material I have no idea nor care but for the later used SOLID fibre Don112 friction
plates the data sheet gives a DRY value ONLY of 0.34. Now a friction material specifically designed for oil mist
motorcycle clutches was Ferodo MS6 and it gives typical C of F values for design purposes of  DRY 0.34. OIL
MIST 0.12. IN OIL 0.09.
Thus using thes typical values the in theory torque capacity of the lump would be
DRY....................8 x 0.205 x 380 x 0.34 = 212 ft lb
OIL MIST ,..........8 x 0.205 x 380 x 0.12 = 75 ft lb
IN OIL ................ 8 x 0.205 x 380 x 0.09 = 64 ft lb.
 
If you want this clutch to be correctly designed as an oil mist clutch then you must increase the number of friction
plates to 22.5 interfaces or 11 friction plates or increase the clamp load to 1067lbf or increase the effective
radius of the friction enterfaces to 0.576 ft giving a clutch well over one ft in diameter.
So how would you ever free off the lump with 22 interfaces when for correct freeing off you need , with fibre type
materials, 6 thou per interface and with 22
this would be 0.132 inches at the pressure line or a required lift at the release ring of 0.268 inch. So how would
you ever free off the clutch with a clamp load
of 1068 lbf which is 3 times greater than an early 750 Commando?So how with a clutch of over 1 ft in diameter
would you achieve correct gearing and keep chain speed down below 6000 ft per min , a speed at which
YOUR Supercycle Magazine of Sept 78 stated in thier Harley belt / chain dyno testing 'the chain at 6000 ft per
minute was stiff as a broom handle absorbing vaste amounts of power...........'
AS for that even heavier even more vastly overweight gearbox breaking unbalanced flywheel fitted to later '850'
 motors what a total abortion....I will leave you to play with your calculator....the required torque capacity is 240 ft
lb and the Coefficient of friction values for sintered bronze are, rule of thumb   DRY 0.3   WET 0.06 to 0.08 and
the gent I consult(the now retired Engineering Directorv of Laycock Engineering who designed many of the
clutches fitted to your gas guzzlers and who designed the clutches fitted to the Villiers Starmaker motors etc
and who is, according to the Eng Director of the Worlds Largest clutch manufacturer,and I quote  'He is one of
no more than 12 people in theis World with his experience of clutch , diaphragm spring, overdrive units etc
design and manufacture) said of using 0.08 as the wet C of F 'thats being a bit pessimistic I always used 0.06'.
Hell I even phone up your race car clutch designers for info AND ALWATS get it!!! I n fact one said to me as he
told me the C of f he uses for carbon fiber in his race cluch designs and I told him what a British race clutch
desinger used  'That could well explain why they suffer a greater percentage race clutch failures than we do do'
Commando clutches just like the earlier Atlas, Dommy etc clutches were DRY clutches shoved inside the oil
bath chaincases as were many others such as BSA Gold Stars, in fact the 1949 BSA B32 Gold Star brochure
states that it is 'BSA multu dry plateclutch with oil resisting fabric inserts'. Gold Starsfor years employed Ferodo
MZ41 friction material and the data sheet for it Sheet F20.
'It is suitable for use under dry conditions only9i.e. it is not suitable for use with oil)'The FACT that they soon
neglected to tell owners that the clutches were dry ones was because they would of had lots of clever people
who overfilled the lumps writing in moaning 'what idiot put a dry clutch in.....' Of course 99.9999% of owners are
totally unaware of the vaste differences between correctly designed dry and wet clutches....wet clutches for
example have mechanisms to ensure they free off instantly without drag........well correctly designed ones do
anyway.
Of course had you not of been such a pratt and asked me to explain further to my previous e mails you would
not of yet again provided me with a perfect example to use of total incompetence in my nearly finished letter to
the NOC mag........
 
Mr Phil Heath who was part of the original team that developed the rather clever Norton pressed steel oil bath
chaincase in1934 as Sunbeam were bust REMOVING thier non racer looking secondary oil bath chain
case.told me how he ensured his Norton clutches did not suffer from slip or drag due to oil.....it went as
follows..Strip clutch.and wash everything in petrol to remove all traces of oil. Reassemble CORRECTLY
applying a SMEAR of grease to the rollers as recommended in the books. Replace chaincase. Remove spark
plug or plugs, remove chain case inspection cover. Find wife or son. With them turning the motor over slowly fill
chaincase with SAE10 oil but as soon as you see oil is TOUCHING the chain as it goes past your nose STOP
filling.  He added the comment " It ensures a slip and drag free clutch but it does little for chain life"
Do it this way and any AMC/Norton clutch will possess all the qualities such devices are SUPPOSSED to
possess some of which are that it should........
1. NOT slip when fully engaged,even when hot.
2 free off INSTANTLY  without drag whenever required, even when hot.
£ be EASILY operated by the user.
4. possess the LIGHTEST rotating weight reasonably possible.
 
Of course you have a 73 year old gent over there who has been making such clutches for British Bikes (and
even American) for around 30 years. He even wasted his own money trying to help Triumph by visiting and
offering them his real electric start mechanism  his primary drive belt system and secondary belt drive
system....in 1978. I believe that pratt in Oregan who dreams Nortons has nicked his electric statrt system that
he developed . I told him NOT to touch the man with a barge pole but does he listen.......
Might I suggest that you go to your local library and find some books on clutches and learn from them. You might
even buy the book' by Mr J Reynolds..'A racing legend. Norton' and note how he describes the clutches as DRY
multiplate cluches in oil bath chain casesIf the rest of your web pages are as accurate as your norton
ones.....Oh, one last thing......Cam wear. Quote. Mr Hopwoods letter to me on the subject......'The camshaft
tunnel of the Dominator engine was designed to retain as much oil as possible..................' now look up that
prattEmery on his Norvil web pages and read the Piper Tiuning Notes  bits on cams he has plagerised. Or
better still get your copy off the shelf and read what they say about premature cam failure and REALISE why Mr
Hopwood included into his Norton and BSA  twin desugns a CAM SHAFT OIL BATH that RETAINED oil in it so
that EVERY time the motor was started the cam and tappets were CORRECTLY lubricated so that galling did
not take place. Of course if you lay out all the various editions of Norton twin crankcases you will see how the
unemployable brain deads designed OUT this design feature over the years......
HAVE A GOOD DAY AND BE A GOOD BOY AND TRY TO LEARN.
Incidentally the staff of Classic Bike or Classic Crap as some of us correctly call it also would not know the
difference between a wet and dry clutch so you are in good company and as for that Welsh ****** Haywood
telling Norton owners his belts were designed to be run in oil when I have letters from his belts manufacturers
stating that they were designed to be run dry and that NO testing with oil has been carried out....................Gosh
you could become known as the U.S.A. Haywood!!! I must inform Mr Oswald instantly