Clutch slipping

RGM do a very good clutch kit which should eliminate slippage. Correct adjustment is also crucial. You should be able to pull the clutch with two fingers.

As far as oil goes, for my money, TQF or ATF is the best, at 200cc. Its only the chain that needs lubing, the clutch was designed to run dry apparently.

Big topic this one! Suggest you read through the technical notes here and have a look at the access Norton forum.

You won’t know whether to keep your plates or replace them until you have seen them and measured thickness against spec.

I have recently done this job to reduce clutch pull.

My suggestions would be to put in new friction plates and replace one of the 2mm pressure plates with an RGM 3mm one. There are loads of threads discussing clutch stack height relative to the heaviness of the clutch pull.

The Commando clutch is supposed to be dry, but oil migrates from the gearbox through the pushrod tunnel. Norvil sell a nifty oil seal to stop this, which comes from Atlanticgreen in USA (their website is worth a look)

I also use TQF oil (castrol is easy to obtain), best to only put in 170ml, this is sufficient to lube the chain. I read somewhere on the forum that the oil level hole is too high and allows more oil than is necessary, causing clutch wetting.

"... oil [CAN SOMETIMES] migrate from the gearbox through the pushrod tunnel".

Mine (& many others) do not have this problem, if gearbox oil is making its way along the shaft you should be able to see/smell it. Iirc, the Dave Comeau seal requires a little machining of the clutch pushrod to obtain the clearance required to fit. I have one in the spares drawer somewhere as a 'just in case'.

I run Castrol Classic XL 20/50 in my primary without any problems using the standard MK3 clutch pack (steel/bronze), just don't overfill it.

You can try ATF, somebody else mentioned in an earlier thread that it responds to gravity a little faster than 20/50 ;-)

I would clean the plates & reinstall; replace if worn, I replaced mine (together with the clutch hub) last November, they have covered just over 93k miles which I consider to be pretty reasonable performance :-)

The Commando clutch can be run in oil or without. However when dry it can squeal a bit and also the plates can be heard chattering when the clutch lever is pulled in.

What must be considered is the clutch basket bearing. This needs a supply of oil or replacing with a sealed version.

A BIG mistake, often made by owners, is to pull all of the plates out of the clutch basket and give them a cleaning. Then they mix them all up before replacing back in the basket. This will almost certainly lead to the clutch slipping while respective driver and driven plates bed back in with each other.  This applies to both Commando and AMC clutches and will also happen if old and new plates are mixed.  See Dominator clutch diagram for explanation.

Dave Comeau seal requires a little machining of the clutch pushrod to obtain the clearance required to fit.

ABSOLUTELY NOT!!!!!

As the original rod was 6mm...only bogus aftermarket 1/4" rods have a problem

My instruction sheet even warns you of this.

Occasionally the clutch center nut needs a few thou removed.

After over 6000 sold if there actually was a problem you think I would have been made aware of it in 1988 when I started these.

Now that one american company has stolen my design and makes them I have no control or responsablity for those counterfeit ones...and they charge more than mine

Dave Comeau/Atlantic Green Tech Svc

I can attest to Dave’s comments - fitting his clutch rod seal is a doddle. A few passes on the glass plate with some 320 silicone carbide paper taped to it is all the center nut needed . Never a problem with clutch slipping .

I bow to Dave's comment & apologise, in my defence, I said,'...if I remember correctly...'  I obviously didn't  (I haven't looked at the instructions in over 15 years as I've not needed to fit).

I remembered that something needed a little reduction. thought it was the rod. .

Whatever Dave says, is correct regarding his kit - I stand by my other comments.

For backing down a bit....I have never done a hard sell for my seal as I know some folks run a lower gearbox and/or primary lube level that helps.  My seal, which was offered to NOC decades ago to sell them, but I got a non response? No problem for me either I don't "need the money".  I originally did the first 75 or so by single point turning on a lathe for my local club members because they wanted them...

Having reviewed the 9+ NOC tech articles I have a significant amount of disagreements with portions of many of them. like:

The concept that gearboxes "pressurize to push 90W into the clutch is laughable to me...

START ARTICLE

Spring  2012

Gearbox pressure myth

Any gearbox breather discussion is a WAY over sold mod, even to the point of being ridiculous and should not be a real concern. Internet articles and forum postings on this subject are in my opinion of very low credibility. This is why.

I built a pressure test rig using a very low-pressure high-resolution gauge(3psi full scale), regulator and ball valve  I did a series of pressure tests of the AMC gearbox on my 72 combat. While the test included the demonstration of my clutch rod seals ability to restrain oil leakage, I was actually trying to debunk what I believed to be an unsubstantiated  old wives tail about gearbox breathing/venting deficiency and the need for further breathing mods. This test was demonstrated at a few of the INOA national rally tech sessions, and remained installed for an extended period of time to be able to redemonstrate the test at local tech sessions.

The first main leakage path is the path in the main shaft... this is what my CCRS fixes.

A close second leakage path would be the normal early vent in the little round access cover or the 850&MKIII brass tube style vent.

The third path is the clutch cable entrance. This can NOT hold pressure, even if you seal around the cable with RTV, the leakage also goes up the cable itself up to the handle bar.

A minor but variable fourth leakage path is the between the main shaft and sleeve gear bush.

In the final test the cable exit was totally plugged with a small rubber stopper and tested with soapy water for no leakage. Even with all the passages sealed, try as I might to actively pressurize the gearbox after totally sealing leakage paths one, two and three, there was no ability to view any residual pressure once the ball valve was shut to stop the regulated compressed air source. All remaining air pressure vented through the sleeve gear. The very high resolution...low pressure gauge went to zero quite quickly, soapy water bubbles showed the air leaving. The results were as I expected, and the normal gearbox is absolutely NOT able to hold pressure, especially once the clutch cable is reinstalled.

I would have no problem using an undrilled MKIII access cover or without the MKIII brass vent on AMC gearboxes. The results of the test show that any theoretical air expansion causing a pressurization of the gearbox due to heat from operation is in my opinion totally bogus and without any merit what so ever.

END ARTICLE

Dave