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Clutch Pushrod Commando

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Clutch Pushrod Commando

Posted by john_hall1 at November 11. 2017

Hi,

Bought a Clutch push Rod from a known supplier consisting of three letters and up in the Northern wastelands, only to find that it has a diameter, having been checked by Micrometer, is Metric and six mm rather than the 1/4 inch Imperial measurement originally fitted in the glorious earlier days of the Empire!

So I am not happy about this, because there are numerous stories of Norton clutch plates getting oiled

6mm is not and never will be 1/4 of an inch, it is smaller in diameter, possibly making it less strong and possibly gives an easier path for a molecular film of oil to migrate from the Gearbox to  the clutch plates

So I am on the phone to them to day to ask them what the hell, going on!

 

Disillusioned and Disgruntled!

Oh! and I have gone to the expense of a Barnett clutch too!

 

Cheers

 

 

John

Re: Clutch Pushrod Commando

Posted by richard_woolnough at November 11. 2017

whassa Barnet clutch please? kind regards

Re: Clutch Pushrod Commando

Posted by john_hall1 at November 11. 2017

Hi, Richard,

Barnett clutches ,are friction plate and steel inserts manufactured in the "good ole USA" and reputed to be superior than other options when set up and run in ATF. My mate has a Royal Enfield Constellation Road bike with a 998cc Imp engine in it, running a Commando clutch and he reckons it is the best money he has ever spent, no trouble for 10 years!

 

http://www.barnettclutches.com/

 

Cheers

 

 

John H

Re: Clutch Pushrod Commando

Posted by david_evans at November 11. 2017

The original Commando clutch push rod is 6mm not 1/4" before you go off on one to RGM.

Re: Clutch Pushrod Commando

Posted by david_evans at November 11. 2017

There are several soloutions to preventing clutch oiling. you can get a seal to go on the end of the sleeve gear, you can grind a small groove in the push rod and fit a small O ring. (amal carb air screw or throttle stop screw o ring comes to mind)  pack the hole through the main shaft with grease or dare I say it, silicon bath sealant.

Re: Clutch Pushrod Commando

Posted by john_hall1 at Sunday 10:24

Hi David,

I stand corrected, but was told this was a common fabrication mistake on asking around  the use of the nearest metric equivalent in fabricating parts rather than an exact Imperial measurement. How come Norton/AMC ended working in millimetres ? Am I being naive?

Would it not have been initially designed for  Imperial 1/4 bar?

Cheers for the sealing tips

Are there other instances of metric measurements for component parts?

Clutch plate contamination from oil migrating (and oiling the friction plates), from the gearbox, seems to be a common gripe from  Norton Commando Owners, a guy who races stuff intimated to me that  there is too much clearance with 6mm Clutch pushrods with the  access gap being left too large!

I can easily have a Silver steel, 1/4 bar clutch push rod made, has anyone done this and tried this?

Does the AMC/Norton gearbox pressurise in non-Racing use?

Many mysteries are out there!

 

 

Cheers

 

 

John H

 

 

Re: Clutch Pushrod Commando

Posted by david_evans at Sunday 13:48

I guess that 6mm gives a satisfactory clearance through what was probably a 1/4" hole. The NOC service notes suggested cutting the rod in two, hardening the two new ends and fitting a 1/4" ball bearing between the two halves to remove the issue of the rod bowing under pressure. I did this mod about 35years ago but to be honest, the chance of the rod bowing under the pressure of a cable operated lever is probably nil. Also, any oil has to find its way up into the RH end of the main shaft then migrate through the hole and end up in the centre of the clutch. I recently did the groove and rubber ring thing in one end of each of my two bits of push rod. The clutch action is now notchy. So me being a smart arse has not payed off. Probably only needed one rubber o ring. If you have 1/4" silver steel make one and see if it works. (harden and temper the ends)    the hole through the main shaft is rough.

Re: Clutch Pushrod Commando

Posted by David Comeau at Sunday 19:15

Previously john_hall1 wrote:

Hi,

Bought a Clutch push Rod from a known supplier consisting of three letters and up in the Northern wastelands, only to find that it has a diameter, having been checked by Micrometer, is Metric and six mm rather than the 1/4 inch Imperial measurement originally fitted in the glorious earlier days of the Empire!

SNIP

 

The commando, featherbed twins and garden gate twins back to 1949 used 6mm push rods.

Around 1988 I saw an article where someone in England made a clutch rod seal. I could not buy one anywhere and only heard someone in australia made some. I could never find them...

I designed and made my own, based on 6mm rods and had some guys that wanted one also...

Well to date I have sold just under 6000 for commando. Norvil sell my seals, while RGM refused to talk to me about them??? I got the same nonresponse from NOC parts scheme?

Singles by mail to england is stupid expensive. I just sent 5 @ club/shop price to a private sale to England the other day.

IMO the cut shaft and ball bearing or o-ring groove is pathetic.

You can read about them on my website atlanticgreen.com, but in reality if I never sell another one of my seals it's not a big deal to me.

Re: Clutch Pushrod Commando

Posted by Colin Peterson at Sunday 19:56

Hi David, I bought one of your clutch rod seals many years ago, maybe around 2000. It's still fitted and works fine, here in the UK. You might or might not recall that to begin with I had an issue, in that the clutch end of my mainshaft is countersunk into the pushrod hole, meaning that the o-ring couldn't make a seal – at the time we decided this was an oddity, and I got around it by making a shim out of a beer can to go between the end of the mainshaft and the o-ring, obviously with a hole for the pushrod to pass through, thereby holding the o-ring, perhaps even compressing it somewhat, into its seat in the cap that screws onto the end of the shaft. Anyway, the thing is it works, and I'm happy to vouch for your seal. My clutch used to get very sticky and slippy from time to time, but it hasn't since I fitted this seal, although I've replaced the o-ring once or twice – o-ring 04.0079 for the gearbox ratchet spindle does the job for me.

Why no-one other than N*rv*l wants to stock it in the UK is beyond me. I'd previously tried the o-ring-on-the-pushrod idea, but, while the inside of my mainshaft doesn't seem rough – the o-ring's still there undamaged, when I last looked this summer – it didn't stop gear oil getting onto my clutch. I know it's gear oil, because I run Norman White's dry belt drive.

Re: Clutch Pushrod Commando

Posted by David Comeau at Sunday 23:47

Hi Colin

The story of the extra deep chamfer on the main shaft does ring a bell. This seems to be quite rare, but I've only had maybe 3 like that in all these years.

The imperial sized oring...dash 010  (-010) oring is correct as you state for the gearbox shaft seal 04-0079 and my Commando CRS and Atlas CRS though the final design is for the 6mm rod.

I have not previously heard of a seal on the end of the sleeve gear (per David Evans) that would do any thing for the clutch plate oiling since it is outside of the clutch on the back side of the drum? Maybe he can explain.

Re: Clutch Pushrod Commando

Posted by David Comeau at Monday 00:30
Gearbox venting/ pressure? A persistent rumor I felt need investigating. Read my report below.
Attachments

Re: Clutch Pushrod Commando

Posted by john_hall1 at Monday 08:42

Interesting stuff!

Pre-49 was it a quarter inch bar fabrication then?

Many Thanks

 

John H

Re: Clutch Pushrod Commando

Posted by david_evans at Monday 09:47

My mistake, the clutch seal was fitted on the clutch end of the main shaft not the sleeve gear. I bought one from Norvil years ago and when I went to check it after about 10,000 miles it had been eaten by the inner face of the diaphram center.

Re: Clutch Pushrod Commando

Posted by David Comeau at Monday 13:38

Previously john_hall1 wrote:

Interesting stuff!

Pre-49 was it a quarter inch bar fabrication then?

Many Thanks

 

John H


I own 2 garden gate twins, so I have first hand experience back to the model 7 era, continuing with several featherbeds and many commandos. I can't speak to pre model 7 1949 push rods. After you find out what size rod is in early bikes let us know...though I will not be designing seals for them.

Re: Clutch Pushrod Commando

Posted by Colin Peterson at Monday 18:38

Previously David Comeau wrote:

Hi Colin

The story of the extra deep chamfer on the main shaft does ring a bell. This seems to be quite rare, but I've only had maybe 3 like that in all these years.


I wonder how this chamfer/countersink arose then, as it seems to be so rare – another bit of Norton trivia to ponder!

Re: Clutch Pushrod Commando

Posted by peter_hatfield at Tuesday 15:26

I have four of Dave Comeau's clutch push rod seals that are surplus to requirements, and I'll sell them on for a lot less than Norvil wants.

Tel: 01963 240010

Mob: 0790 353 2620

Email: peter_hatfield at yahoo.co.uk

Re: Clutch Pushrod Commando

Posted by john_hall1 at Tuesday 16:07

Peter,

Okay I will have two! Cheers

4 chat, all sorted!

Many thanks

 

John H

Re: Clutch Pushrod Commando

Posted by john_hall1 at Tuesday 16:08

Previously David Comeau wrote:

Previously john_hall1 wrote:

Interesting stuff!

Pre-49 was it a quarter inch bar fabrication then?

Many Thanks

 

John H


I own 2 garden gate twins, so I have first hand experience back to the model 7 era, continuing with several featherbeds and many commandos. I can't speak to pre model 7 1949 push rods. After you find out what size rod is in early bikes let us know...though I will not be designing seals for them.

I will!

 

Cheers

 

John H

Re: Clutch Pushrod Commando

Posted by peter_hatfield at Tuesday 16:20

I have sold two already! Therefore, I have only two left - price is £20 + £1 P&P.

Re: Clutch Pushrod Commando

Posted by peter_hatfield at Tuesday 20:56

Only one left now.

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