74 Mk2 - clutch -- need food for thought...

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joe czech

joe czech

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i'm assuming the clutch on my 74 is sticking from the bike sitting 6 or 7 years. seems I need an excessive amount of pull to dis-engage the clutch. in a nutshell, i'll have to disassemble everything to clean and inspect - not sure what to even look for during an inspection. worst case, i'll have to replace the clutch assembly. first step - my "new to me" clutch removal tool in in the mail as we speak.

on the low end, i'm seeing a Barnett kit for around $75 - i'm assuming it just the friction plates, whereas on the other end, i'm seeing a cNw "easy pull" kit for just north of $200. the cNw kit seems to be the Barnett kit plus measured plain or spacer plates and a custom sized pressure plate. i'm guessing the cWw kit is sized to get that perfect stacked height - am I correct in my thinking? while I have things apart, should i bite the bullet, and just throw in a new set of friction plates? new to this - never done a clutch on a bike. do I have any other options - old brits, AN, others? ???? food for thought comments. TIA....
 
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To me, on a Norton, the clutch is one of the easier things to work on. I suspect that simply removing the plates and cleaning them will be all you need if it was working before being parked.
 
Your stock plates would have been the 850 sintered bronze 5 plate stack. They are very long lived and work very well. Mine wore less than .002" after 45 years and multiple "cleanings". The key to keeping them unstuck is to use ATF instead of motor oil.

As for clutch pull, the "stack up" of the plates can (should) be shimmed to put the spring at its sweet spot. This is done by adding an extra steel plate in the stack. Old Britts used to offer steel plates of different thicknesses for that but last I looked they only had a few left. Mine ended up needing a .070" plate to be perfect.

see this - http://atlanticgreen.com/ndnsclutch.htm
 
marshg246 said:
To me, on a Norton, the clutch is one of the easier things to work on. I suspect that simply removing the plates and cleaning them will be all you need if it was working before being parked.
Click to expand...
thanks! anything I should be looking for while things are apart? the service manual is, at least to me, rather vague. i'm assuming I can use a standard prep-sol for cleaning, maybe a scotch-brite, ???? any do's and don'ts?
 
joe czech said:
i'm assuming the clutch on my 74 is sticking from the bike sitting 6 or 7 years.
Click to expand...

Unlike fibre plates, I've never known the bronze friction plates (if standard as they should be for a '74'?) to stick although they can cause drag if they need cleaning.

joe czech said:
seems I need an excessive amount of pull to disengage the clutch.
Click to expand...

That's normally due to (low) stack height, not sticking plates regardless of which type they are.

http://atlanticgreen.com/ndnsclutch.htm
https://www.oldbritts.com/ob_clutch_info.html
 
Scotch brite and spray carb cleaner are my cleaners of choice.

When replacing the clutch nut disregard the books and use 40 ft lb with blue locktite.
 
L.A.B. said:
Unlike fibre plates, I've never known the bronze friction plates (if standard as they should be for a '74'?) to stick although they can cause drag if they need cleaning.
Click to expand...

This is true - mine tended to slip under load when they needed attention.
 
maylar said:
This is true - mine tended to slip under load when they needed attention.
Click to expand...

Yes, although fitting the dynodave clutch pushrod seal mod cured mine of that.

Now using Surflex (fibre) friction plates. No sticking, slip or drag problems so far.
 
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maylar said:
Your stock plates would have been the 850 sintered bronze 5 plate stack. They are very long lived and work very well. Mine wore less than .002" after 45 years and multiple "cleanings". The key to keeping them unstuck is to use ATF instead of motor oil.

As for clutch pull, the "stack up" of the plates can (should) be shimmed to put the spring at its sweet spot. This is done by adding an extra steel plate in the stack. Old Britts used to offer steel plates of different thicknesses for that but last I looked they only had a few left. Mine ended up needing a .070" plate to be perfect.

see this - http://atlanticgreen.com/ndnsclutch.htm
Click to expand...
thanks for the reply. a bit confused - when you say, "adding an extra plate," do you mean adding a 5th plate OR replacing one of the 4 existing plates with a different thickness to find that sweet spot. to find the stacked height, is it just the 4 friction plates and 5 plain or spacer plates. or what? what is the sweet spot, and what should I be looking for - plus and minus value....

again, new to all this.
 
joe czech said:
thanks for the reply. a bit confused - when you say, "adding an extra plate," do you mean adding a 5th plate OR replacing one of the 4 existing plates with a different thickness to find that sweet spot. to find the stacked height, is it just the 4 friction plates and 5 plain or spacer plates. or what? what is the sweet spot, and what should I be looking for - plus and minus value....
Click to expand...


http://atlanticgreen.com/ndnsclutch.htm
https://www.oldbritts.com/ob_clutch_info.html
 
L.A.B. said:
Yes, although fitting the dynodave clutch pushrod seal mod cured mine of that.

Now using Surflex friction plates. No sticking, slip or drag problems so far.
Click to expand...
sureflex - brand name? dynodave clutch pushrod seal - ???? point me in a direction....
 
This what I would do.

1. Drain and clean Primary.
2. Disassemble Clutch. Clean, deglaze plates as necessary.
3. Reassemble, with clutch rod seal.
3. Remove Gear box inspectiion cover. Verify cable is in line with actuator. Correct as necessary.
4. Verify Clutch cable has smooth action. Correct or Replace if necessary. Venhill is good choice.

After all these are complete, then decide if further action is necessary..
 
Adding a shim between the clutch diaphragm spring and the 06-0751 spring retaining circlip can be an alternative to adjusting the plate stack height.
 
The hard clutch pull could also be related to mis-routing of the clutch cable and/or a cable that needs lubricating oil dripped through it.
The Venhill clutch cable has a teflon coating on the interior and doesn't need oil lubrication.
When clutch is apart, inspect the clutch hub. Specifically, look for notches within each groove where the steel plate tabs hammer against it.
If the notching is pronounced it keeps the clutch plates from separating causing clutch drag. cNw sells a properly hardened clutch hub.
I once had an A/N sourced clutch hub which had excessive notching within 1500 miles of installation.
I've found Krud Kutter. (https://www.homedepot.com/p/Krud-Kutter-32-oz-Original-Concentrate-Cleaner-Degreaser-KK326/203396788)
to be more effective in cleaning clutch plates than carb cleaner and is bio-degradable.
Use ATF Type F in the primary instead for the specified oil.

Commando clutches are quite simple and easy to work on.
 
joe czech said:
thanks for the reply. a bit confused - when you say, "adding an extra plate," do you mean adding a 5th plate OR replacing one of the 4 existing plates with a different thickness to find that sweet spot. to find the stacked height, is it just the 4 friction plates and 5 plain or spacer plates. or what? what is the sweet spot, and what should I be looking for - plus and minus value....

again, new to all this.
Click to expand...

Check the Atlanticgreen and OldBritts articles, they explain it well. What you end up with is that when you pull the lever you feel a "snap" when the spring toggles over its center point. Clutch pull is drastically reduced. The thickness of the extra plate determines where that happens. There's a compromise to be had, as too much shim leaves you with a clutch that slips. Fred Eaton used to sell a set of steel plates ground in .005 increments - you could buy the set and return the ones you didn't use.
 
+1 for Teflon cable. I recommend a new clutch actuator [pork chop]. Realign so there is a nice straight pull.
 
baldy said:
+1 for Teflon cable. I recommend a new clutch actuator [pork chop]. Realign so there is a nice straight pull.
Click to expand...
thanks for the reply. my new clutch cable is a Barnett assembly. looked at the specs, and don't see where it says Teflon lined. I do have a second cable I bought from old brits - pretty sure that cable is listed as Teflon lined. I routed the cable to what I perceived as factory. smooth transition from point A to point B w/ no sharp bends or kinks. I was pretty anal when a reassembled my clutch pull actuator in the gearbox, and as far as i'm concerned, it dead nuts on the money. not 100% sure what the "pork chop" is, but when I reassembled everything, all parts within the clutch pull mechanism seemed in good condition.

my clutch pull tool should be delivered today, hopefully within the next day or two I can pull the friction and spacer plates for cleaning and inspection. everything's coming together - getting a bit antsy for my first ride. ;)
 
All good advice so far. I'd change out the crank oil seal in primary and also replace the clutch location circlip that gets damaged by over torque (use oldBritts guidance on 40 ft-lbs with blue locktite instead of 70ft+lbs as per shop manual).


CLUTCH LOCATION CIRCLIP (MAINSHAFT)
part-no: 06.0752
 
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