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Belt Drive Conversion on MKIII Commando #72765
01/02/08 8:35 pm
01/02/08 8:35 pm
Joined: May 2007
Posts: 358
Regina Sk, Canada
Coco Offline OP
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Coco  Offline OP
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Joined: May 2007
Posts: 358
Regina Sk, Canada
I am seriously thinking about doing a belt drive conversion on my MKIII since the whole thing is apart at the moment. Electric starter will be retained so frequent greasing of the sprag needle bearings will be in order. I was told every 1500 miles would be sufficient.

Just wondering a few things. Any brand or manufacturer better than others? RGM, Norvil Clubman Racing (possibly an RGM unit?)and MAP Cycle seem to be selling them.

What kind of venting will have to be done to my primary? Inner primary venting holes on front?

What about the MKIII lack of gear box tension adjustment?

I did a search and didn't come up with much info.


Colin
--------------------------
1975 MKIII Norton Commando
'73/'70 Triumph 750 chop in the works
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Re: Belt Drive Conversion on MKIII Commando #72766
01/02/08 9:04 pm
01/02/08 9:04 pm
Joined: Jul 2001
Posts: 12,320
Central Virginia
Lannis Online content

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Lannis  Online Content

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Central Virginia
Coco -

When you say "did a search", did you search the messages on this site? There are hundreds of posts relating to "belt drive" on the Norton forum alone - it's not only been discussed but hammered into the pavement, squeezed of all juice, lightly killed, and packed in spring water.

Still and all, you'll find only opinions - there's no definitive answer as to which one's the best.

Personally, although I'm in favor of ModCons whenever appropriate on BritBikes, I wouldn't pay two cents to replace my oil-bath primary chain with a belt drive. It's the longest-lasting, most trouble-free part of my whole bike, and I'm not giving it up so I can discuss shredding fabric, oil on the belt/oil on the clutch, alternator cooling, etc for no discernable gain ....!

Lannis


We're approaching the tipping point ... where those who vote for a living will outnumber those who work for a living .....
Re: Belt Drive Conversion on MKIII Commando #72767
01/02/08 10:00 pm
01/02/08 10:00 pm
Joined: May 2007
Posts: 358
Regina Sk, Canada
Coco Offline OP
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Coco  Offline OP
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Posts: 358
Regina Sk, Canada
I typed "belt drive MKIII" for a search and came up with one hit which was referenced in a swing arm thread.

I'm kind of torn which way to go and figured now would be the time to do a conversion since everything is apart. I'm kind of leaning toward keeping everything stock just so I can put the cash toward something else.

If I stick with the stock chains, is it a good idea to install new ones? The ones I have are still original as far as I can tell.


Colin
--------------------------
1975 MKIII Norton Commando
'73/'70 Triumph 750 chop in the works
Re: Belt Drive Conversion on MKIII Commando #72768
01/02/08 11:04 pm
01/02/08 11:04 pm
Joined: Oct 2001
Posts: 627
Chesapeake Virginia
aprophet Offline
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aprophet  Offline
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Chesapeake Virginia
hello Coco try searching norton belt drive under the motor cycles specific brands i found at least 2 pages worth hth pal aprophet aka david


1964 A65C Rocket (Jeanie)
1971 T25SS
1971 A65T BSA (Lucile)
1965 A65D Lightning Rocket
Re: Belt Drive Conversion on MKIII Commando #72769
01/03/08 2:13 am
01/03/08 2:13 am
Joined: Aug 2001
Posts: 2,509
Springfield Nebraska
Richrd Online content
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Richrd  Online Content
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Springfield Nebraska
Lannis, Coco's quest is find info on putting a belt on a mkIII. I have only seen mention of one such setup on the market. Now watch everyone prove me wrong.

BTW. When do I get to build you a Norton?


Rich (member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

69 bonney
72 commando
75 commando interstate
06 Suzu..Suzu.. uh appliance
couple of beesas a ducati
and the Snake Bike
Re: Belt Drive Conversion on MKIII Commando #72770
01/03/08 3:09 am
01/03/08 3:09 am
Joined: Oct 2006
Posts: 95
Colorado
kiwiinusa Offline
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Colorado
I did one on my MK111 It was from Clubman Racing and i was told it was the one for the Electric start model ,well on assembly i noticed it didn't clear the starter gears and the belt was going to wear out very quickly.
My answer was to take the front pulley to my machine shop and have them take a little off it so it would clear and keep the belt well away from the gears.
I slotted the top gearbox mounting plate and added an adjuster so i had a little adjustment in order to get the shafts aligned,this worked well and i have done quiet a few 1000 miles with no problems ,it is very quiet and smooth but if asked if i would do it again i would probably say no.

Re: Belt Drive Conversion on MKIII Commando #72771
01/03/08 2:29 pm
01/03/08 2:29 pm
Joined: May 2007
Posts: 358
Regina Sk, Canada
Coco Offline OP
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Coco  Offline OP
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Joined: May 2007
Posts: 358
Regina Sk, Canada
Kiwi, thanks for the info. Did you do any venting on your inner primary? Seems like your answer is what I suspected that the upgrade is good but not amazingly better than chains. The Clubman kits are RGM.

Aprophet, thanks for the search tips. I'll try your suggestion with using "Norton" in the search text.


Colin
--------------------------
1975 MKIII Norton Commando
'73/'70 Triumph 750 chop in the works
Re: Belt Drive Conversion on MKIII Commando #72772
01/03/08 3:26 pm
01/03/08 3:26 pm
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
D
Dave Comeau Offline

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Dave Comeau  Offline

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D
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
Besides the RGM (AT10) supplied by Clubman, Norvil makes one in HTD.
Obviously they have the sprag type front sprocket/pulley.
I have the RGM MKIII system, but have not installed it yet.
I have used my preMKIII belt drive from norvil since 1989 (faire spares at the time) without venting. I will leave my MKIII unvented also.


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: Belt Drive Conversion on MKIII Commando #72773
01/03/08 3:52 pm
01/03/08 3:52 pm
Joined: Jul 2001
Posts: 12,320
Central Virginia
Lannis Online content

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Lannis  Online Content

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Central Virginia
Quote:
Originally posted by Richrd:

BTW. When do I get to build you a Norton?
Richrd -

Don't torture me like that. It's one of the great conflicts in my life that:

1) I've ridden Nortons and love the way they run, handle, look, and pull like a train.

2) A Norton enthusiast who builds beautiful, durable touring Nortons is standing by, ready to build one to my specification, have me fly out to get it, and ride with me back to Blowing Rock ....

and YET I keep making excuses why I don't do it. The Excuse Book is FULL - last year it was "I don't have a job and I've got no money". Well, I've got a job and a paycheck now so that excuse is gone.

Then it was "I have to get a touring BSA so Fay and I can ride two-up in the next BSA International Rallies", so I spent money on that.

NOW we're flying to England/IOM in August ($3000 with the ferry) and I've just written the last college tuition check ($4000) and my little car just seized its engine ($3000 for another car) and... and ....

I'm like an alcoholic that knows he should quit drinking and spend his money on his family but just can't make himself do it.

It WILL happen someday.

Lannis


We're approaching the tipping point ... where those who vote for a living will outnumber those who work for a living .....
Re: Belt Drive Conversion on MKIII Commando #72774
01/03/08 3:58 pm
01/03/08 3:58 pm
Joined: Jan 2006
Posts: 233
United States
Gee Offline
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Gee  Offline
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United States
Cue "Beltdriveman"...once yo get him ging you may never get him stopped laugh

He should be chiming in any second now..then sit back with a cup of joe an read for a few hours.


'60 Norton Dominator
'73 Norton Commando Prod Racer
'00 Guzzi V11
'79 Guzzi Cafe
'73 Guzzi Eldorado
'73 Husqvarna 400W
'05 Triumph Rocket III
Re: Belt Drive Conversion on MKIII Commando #72775
01/03/08 7:43 pm
01/03/08 7:43 pm
Joined: Jun 2007
Posts: 211
California U.S.
Hortons Norton Offline
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Hortons Norton  Offline
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Posts: 211
California U.S.
GEE WIZ GEE, Lets be nice!! beerchug :rolleyes:

Re: Belt Drive Conversion on MKIII Commando #72776
01/03/08 11:29 pm
01/03/08 11:29 pm
Joined: Jan 2004
Posts: 1,106
McKellar,Ontario
Kommandokenny Offline
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McKellar,Ontario
Oh goody!!! more Isle a Man racing stories laugh


If Norton made an airplane,would you fly in it?
Re: Belt Drive Conversion on MKIII Commando #72777
01/04/08 12:01 am
01/04/08 12:01 am
Joined: Aug 2001
Posts: 2,509
Springfield Nebraska
Richrd Online content
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Richrd  Online Content
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Springfield Nebraska
Dave, how is the belt tensioned on the MkIII?

Rich


Rich (member ThreeMustGetBeers)
"It's not always about going fast. Sometimes it's nice to slow down" (Wendy E.2016)

69 bonney
72 commando
75 commando interstate
06 Suzu..Suzu.. uh appliance
couple of beesas a ducati
and the Snake Bike
Re: Belt Drive Conversion on MKIII Commando #72778
01/04/08 1:12 am
01/04/08 1:12 am
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
D
Dave Comeau Offline

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Dave Comeau  Offline

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D
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
Richrd
On my RGM kit...The top straight bolt is replaced by a supplied ecentric bolt/cam. Basically they removed a bit of metal where it is in line with the engine cradle.

It is still a minor adjustment, since it is within the flex range of the back seal.


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: Belt Drive Conversion on MKIII Commando #72779
01/04/08 2:54 pm
01/04/08 2:54 pm
Joined: May 2007
Posts: 358
Regina Sk, Canada
Coco Offline OP
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Coco  Offline OP
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Posts: 358
Regina Sk, Canada
Thanks for all the replies so far and sorry to reopen a can of belt driven worms.

I am wanting to get the easy pull clutch from CNW simply because carpal tunnel has weakened my wrists. Any negative comments about fibre clutch plates in the wet, standard set up with triplex chains? I want to go this route wheteher I go belt drive or stick with the stock arrangement.

I also see some vendors selling tensioning devices to assist in alignment. Norvil belt drives don't seem to offer such a thing and I see it only with the RGM system and they as well as Clubman recommend going with at least a one sided tensioner. Am I in for some heavy modifications going with a tensioning device?


Colin
--------------------------
1975 MKIII Norton Commando
'73/'70 Triumph 750 chop in the works
Re: Belt Drive Conversion on MKIII Commando #72780
01/04/08 4:01 pm
01/04/08 4:01 pm
Joined: Jan 2006
Posts: 6,751
Laredo (South) Texas, USA
GrandPaul Online content
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GrandPaul  Online Content
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Laredo (South) Texas, USA
The easy clutch pull is achieved by acquiring the optimal clutch stack height (See the Old Britts website).

You can do this with a custom thickness pressure plate, or a custom steel plate to replace one of the OE plates, or a single additional (thin) plate added to the stack. The thin plate option is not adviseable, as it is likely to disintigrate under heavy load.

It is also possible to replace the entire clutch stack with all new plates of a certain construction (manufacture) that arrive at the optimum stack height right out of the box.


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, some BSA & European
"The Iron in your blood should be Vintage"
Re: Belt Drive Conversion on MKIII Commando #72781
01/04/08 5:46 pm
01/04/08 5:46 pm
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
D
Dave Comeau Offline

Crew Chief
Dave Comeau  Offline

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D
Joined: Aug 2001
Posts: 1,255
Hamilton, Mass. USA
Quote:
Originally posted by GrandPaul:
The easy clutch pull is achieved by acquiring the optimal clutch stack height (See the Old Britts website).

DD: somewhat disagree here...unless Fred he has corrected his article since I last saw it.
http://www.britbike.com/ubb/noncgi/ultimatebb.php?/ubb/get_topic/f/12/t/000540.html#000011

GP: You can do this with a custom thickness pressure plate, or a custom steel plate to replace one of the OE plates, or a single additional (thin) plate added to the stack. The thin plate option is not adviseable, as it is likely to disintigrate under heavy load.

DD:
Which plate are you refering to clutch/steel or friction...tend to disagree here also, have you actually seen one disintegrate?


GP: It is also possible to replace the entire clutch stack with all new plates of a certain construction (manufacture) that arrive at the optimum stack height right out of the box.
DD: Who sells these? obviously it must be custom and not available through the norton parts distribution network.

COCO
I don't understand this tensioning device you refer to. I've seen/worked on many belt drives and have no clue exactically what you are refering to....

Installing, and using belt drives in commando since 1989.


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: Belt Drive Conversion on MKIII Commando #72782
01/04/08 11:07 pm
01/04/08 11:07 pm
Joined: Jan 2004
Posts: 1,106
McKellar,Ontario
Kommandokenny Offline
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Kommandokenny  Offline
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McKellar,Ontario
I think the tensioner in question is the lolipop that is used to square up the tranny with the crank shaft.[see Clubman's site]http://www.clubmanracing.com/index.html
I don't know anything about the MKIII but thats what I use on my MKII
As far as the fibre clutch plates go they were replaced with the sintered bronze 850 style because the later didn't absorb oil.
Thats not to say that the 850 style don't come with their own problems. IE heavier and hack up the clutch centre
I think the fibre plates may be a little easier on the wrists for a while, but in the long run, if your running a chain, in oil, the sintered bronze is a better bet?????????? 2c


If Norton made an airplane,would you fly in it?
Re: Belt Drive Conversion on MKIII Commando #72783
01/07/08 3:03 pm
01/07/08 3:03 pm
Joined: May 2007
Posts: 358
Regina Sk, Canada
Coco Offline OP
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Coco  Offline OP
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Posts: 358
Regina Sk, Canada
COCO
I don't understand this tensioning device you refer to. I've seen/worked on many belt drives and have no clue exactically what you are refering to....

Installing, and using belt drives in commando since 1989. [/QB][/QUOTE]

Dave, my description was a bit off and komandokenny has it right. The lollipop looking tensioner sold as an aftermarket item to square up the transmission is what I'm speaking of.


Colin
--------------------------
1975 MKIII Norton Commando
'73/'70 Triumph 750 chop in the works
Re: Belt Drive Conversion on MKIII Commando #72784
01/07/08 7:31 pm
01/07/08 7:31 pm
Joined: Dec 2002
Posts: 706
B
beltdriveman Offline
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DSear coco, Its amazing at the number of Norton exspurts there are in this World all so eager to give advice.
I note NONE of them has told you that if you do ANYTHING to reduce the release load of your clutch to make clutch lever action lighter you also reduce the clamp load the diaohragm spring is applying to the clutch plates and thus the amount of torque your clutch when fully engaged will transmit before slip occurs and with a clutch already prone to slip that is as clever as shooting ones self in the arse.
EXSPORTS............
Suggest you e mail me your e mail address and i will e mail you a long epistle explaining exactly how the Commando clutch works.
I might add I have for example the Laycock Enginering drawing showing all FOUR different versions of the Spring employed during Commando production that non of the exspurts will have!!!

Re: Belt Drive Conversion on MKIII Commando #72785
01/07/08 7:40 pm
01/07/08 7:40 pm
Joined: Dec 2002
Posts: 706
B
beltdriveman Offline
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Posts: 706
I would also add that the Gentleman whose brains I have been picking at for a few years now to learn about clutches , diaphragm spring design and manufacture etc etc is the retired Chief Clutch Designer and Engineering Director of Laycock Engineering
Laycock Enginering of course manufactuered the earlier Villiers Starmaker diaphragm Spring clutches and my friendly Gent still has his design note book for them. They also manufactured all the 4 different diaphragm springs employed for Commando production.

Re: Belt Drive Conversion on MKIII Commando #72786
01/07/08 7:48 pm
01/07/08 7:48 pm
Joined: Sep 2006
Posts: 609
Mexico City, Mexico
MexicoMike Offline
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Mexico City, Mexico
I don't know anything about the various clutch discs or springs available for the Commando but I can verify that following the instructions on the Old Britts site produced an easy two finger pull with no clutch slippage on my stock 850. Obviously, adding engine upgrades to produce more power might require some clutch revisions.

Re: Belt Drive Conversion on MKIII Commando #72787
01/09/08 2:46 pm
01/09/08 2:46 pm
Joined: Jan 2006
Posts: 6,751
Laredo (South) Texas, USA
GrandPaul Online content
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GrandPaul  Online Content
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The key word here is "optimal". Outside of that fine range there be slippage.

For those who are interested, I believe this forum is a fellowship of ENTHUSIASTS. I have never seen any bb.com forum promotional information describing it as a collection of EXPERTS and/or know-it-alls.


GrandPaul (does not use emoticons)
Author of the book "Old Bikes"
Too many bikes to list, mostly Triumph & Norton, some BSA & European
"The Iron in your blood should be Vintage"
Re: Belt Drive Conversion on MKIII Commando #72788
01/10/08 8:58 pm
01/10/08 8:58 pm
Joined: Dec 2002
Posts: 706
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beltdriveman Offline
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DEAR COCO.
You are totally missing the point. The fact that your Mk3 clutch dies not suffer from slip means that you are not putting enough of the motors available grunt through it to induce it to do so. Even the Norton Owners Club Commando Service notes mention the problem of ‘gunge’ forming on the friction interfaces of bronze plate clutches resulting in drag problems…..’gunge’ that has owners performing the wash the plates in petrol ritual to cure the drag and slip problem and recommended as a cure for clutch slip in my Norton Instruction for models 50-ES2-88-99-Atlas book on the problems page as a cure for a slip problem!! Norton employed a DRY clutch within the oil bath chain case (OBCC) in 1934 when they finally introduced it and it never changed. That’s why the oil level plug set the oil level so it only just touched the chain at its lowest point and shoved an ‘oil excluding band ‘around the basket. Other manufacturers did exactly the same.
A motor cycle multi plate friction clutch correctly designed, will possess, if set up correctly, the quality that it will NOT slip when fully engaged. Does your car clutch slip going up a steep hill with the throttle to the floor when loaded to the gunnels with the family and a caravan stuck on the rear as you use every last dollop of torque the motor can produce? Of course it doesn’t and if it does you know you have a clutch problem.
The ‘gunge’ the Service manual talks about in the bronze plated clutches is burnt oil, the result of clutch slip generating, very quickly, vast amounts of heat within the clutch which burns off the oil causing the slip in the first place. Several ex Norton/NVT gents have told me it was a very last attempt by Norton to cure the problem of clutch slip die to oil. This being the result of Norton employing a dry clutch within the oil bath chain case in 1934 and continuing to do so to the very end.


The Service book also talks of the early Commando clutch problem which was that the postage stamp sized lumps of Ferodo MS6 friction material would come adrift from the steel backing plate and jam up the clutch causing serious drag problems The problem being caused by the slip due to oil entering the DRY clutch which resulted in the heat which damaged the adhesive bond. To cure that problem they changed to employing solid asbestos containing fibre Don International Don 112 material friction plate. The new ones still in my stock being marked 061339. The Service manual states that these became impregnated with oil and suffered from glazing, the glazing of course being the result of the heat due to slip which was due to oil entering the DRY clutch…….
You want a wet clutch for your MK3? OK lets PLAY, very simply, at clutch designer.

Max motor grunt 55 ft lb. Primary ratio 26-57. Max torque at clutch 105 ft lb (NOT allowing for losses in chain) Apply rule of thumb clutch safety/service factor of x2. giving a REQUIRED clutch torque capacity of 210ft lb

There are 10 friction interfaces with an effective radius of approx 0.21 ft. The rule of thumb Coefficient of friction values for sintered bronze are DRY 0.34. WET 0.06-0.08.


The ORIGINAL 750 Commando diaphragm spring applied approx 380 lbf clamp load and gave EASY worst case two finger back to the bar freeing off operation YOU will have the 4the edition of the diaphragm spring fitted to Commandos in an attempt to cure the slip problem, each new edition giving an approx 10% increase in the clamp load and grunt required to operate the clutch lever over the last edition!! Your spring applies approx 550 lbf and requires a ridiculous amount of grunt to operate the clutch lever. IN FACT initially it is GREATER than that required for a poxy T140 clutch and owners often fit hydraulic clutch operation to them! Thus the in theory clutch torque capacity will be……………

1. Using early 750 spring DRY………..10 x 0.21 x 0.3 x 380 = 239.4 ft lb
2. ………………………. WET……….10 x 0,21 x 0.08 x 380 = 64 ft lb
3. Using the 550 lbf spring DRY …… ..10 x 0.21 x 0.3 x 550 = 346 ft lb
4. ………………………….WET………..10 x 0.21 x 0.08 x 550 = 92.4 ft l
Now for your correctly designed wet clutch and the RAMIFICATION ……!!!!!
1 Lets increase the number of friction interfaces/plates
WET. Early spring Number of interfaces x 0.21 x 0.08 x 380 =240 ft lb.
Number of friction interfaces = 37.5 , 38 to nearest.
Number of clutch plates required =19.
So explain to me how the hell you will get the lift required from a diaphragm spring to give the lift required per interface if the clutch is to free off correctly. It would also require a MAJOR redesign of the lift mechanism and I dread to think what the static weight would be let alone the rotating weight and a motor cycle multi plate clutch is supposed to posses the LIGHTEST rotating weight reasonably possible not the **** heaviest.
WET. Late spring. It works out to 13 friction plates. The same ramifications apply

2………Lets simply increase the clamp load, Just for a laugh…..
WET. 10 x 0.21 x 0.08 x clamp load = 240 ft lb.
Clamp load = 1429 lbf
So explain to me how you are going to free off the clutch without some SERIOUS hydraulics!!

3……… Lets increase the effective radius of the friction interfaces for another laugh.
WET. Early spring 10 x effective radius x 0.08 x 380 =240 ft lb
Effective radius = 0.789 ft or approx 9.5 inches giving an effective radius of 19 inches which would probably result in a 24 inch in diameter clutch. Ye gods imaging the flywheel effect of that rotating at around half engine speed!! Where would you run the chain? Not around that!! Hell at tick over speed it would probably fail big time taking your leg off after coming through the freshly polished OBCC!!!!

4 ………A combination /compromise.
WET. 20 x 0.3 x 0.08 x 500 =240 ft lb
Sorry but with 20 interfaces you still need to find a lot more lift requiring a major redesign. The rotating weight has been GREATLY increased with double the number of friction and steel interpolates and the lump will have an effective diameter of 7.2 inches giving an OD to the lump of probably 12 inches and running at half engine rpm you could not run the chain around the outside of it….not without it failing big time very quickly.

I now invite you to guess why the Staff of The Motor Cycle in their book ‘Speed and How to Obtain it’ refer to the idea of shoving a clutch within an OBC C as ‘Frankly a Compromise’ and the Ariel system of running the chain within the OBCC with lots of nice thin lubricating oil to keep chain efficiency as high as possible but with the clutch running dry EXTERNALLY beneath a cover as ’A much better idea’. Something Mr Williams did on the Works Commando race bikes ……..

As you will of probably noticed the in theory wet clutch torque capacity of Commando clutches is much lower than required if the clutch is not to slip when fully engaged ASSUMING the rider shoves enough of the torque available from the engine into the clutch. Of course with young Norton owners playing at being racers for decades and on a regular basis performing the ancient ritual of washing the plates in petrol most probably consider clutch slip to be perfectly normal as I once did the heavy clutch lever action of my Norton clutches due to using stronger springs in an effort to cure the slip problem that would test the valve gear to well over 7000 rpm . When I first pulled the clutch lever of the brand new early 750 Commando a friend had speared with in The Island I damn nigh screamed at him’ OK so who is the clever ******* who has disconnected the ******* clutch’ to which he replied ‘Funny but most people ask that question’ Even British road tests commented on it. It was a damn quick learning curve as to how a clutch lever should be operated. Later I read Mr Irvings listings of the qualities a motor cycle clutch should possess and again in the American book first published in 1914 ‘Early Motor- Cycles. Construction -Operation-Service.
IF you take a Commando clutch with the spring correctly set up with the clutch fully engaged and then fir a 0.050 inch thicker pressure plate to it you REDUCE both the load required to operate the lever AND the clamp load the spring is applying to the friction interfaces AND THUS the amount of torque the clutch when fully engaged will carry before, in theory, slip occurs by…………for the original 750 spring approx 25%, for the last 820 spring by approx 23% and for the NON Laycock Engineering spring now available for Commandos from Norton (Which gives a clamp load of approx 440lbf when correctly set up) it reduces by approx 18%.
To my way of thinking anyone running a Commando clutch within the OBCC with oil who already has a clutch somewhat prone to slip would be very silly to reduce clutch torque capacity further….. UNLESS they know EXACTLY what they are doing and I haven’t noticed anyone recommending one does just that tell anyone about the reduction in torque capacity…….
Thus I am informing anyone who bothers to read this so that IF they are considering following the advice of exspurts they are fully aware of some of the RAMIFICATIONS (There are others)
Years ago I phoned RGM asking what effect on clutch torque capacity fitting their 0.050 thicker pressure plate would have just to find out if they knew. They didn’t. They told me they didn’t think it did. Yet another reason I don’t use them.
Talking to the retired Laycock Engineering Chief Clutch Designer and Engineering Director this afternoon asking why when he designed the earlier Villiers Starmaker WET diaphragm spring clutches and employed sintered bronze as the friction material he replied something to the effect that it was the same reason Boeing used the same grade of sintered bronze to stop their planes from running out of runway…..it would take all the abuse any competition rider could ever subject it to and thrive on it UNLIKE the other friction materials available at that time.
AND for ANYONE telling tales of friction materials with as high a C of F value with oil as when dry will you PLEASE inform me INSTANTLY as to exactly what it is with a complete spec and INSTANTLY go on holiday so I can patent it and become one of if not the richest person in the World….as a Ferodo gent said to me at Chapel-en-le-Frith as he was giving me a little lecture on friction materials when I asked if he knew what the new grey coloured material a Ducati dealer told me about which did have the same C of F values wet and dry……Bull**** baffles brains….. the Gent gave me a funny sort of look and I said ‘I am talking bollocks aren’t I ‘to which he replied ‘Well let me put it to you this way, if ever you develop such a friction material will you please do two things….……….’

Re: Belt Drive Conversion on MKIII Commando #72789
01/11/08 12:46 am
01/11/08 12:46 am
Joined: Apr 2006
Posts: 1,397
New Zealand
J
johnm Offline
BritBike Forum member
johnm  Offline
BritBike Forum member
J
Joined: Apr 2006
Posts: 1,397
New Zealand
Well maybe but I would think the calculation is still correct.

Like the original poster on this thread my mind goes to beltdrive (and hence dry clutch) whenever I have to clean my otherwize acceptable clutch. (MK11 850 Commando used for very calm and sensible road riding)

What I saw was that Dave has had good results from a Norvil system unvented on a pre Mk111.

But does the money balance a bit of time every six months ?

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