Clutch work on my N15CS, some interesting challenges

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Sep 15, 2020
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Well, one thing leads to another. My clutch was the original from '66 and all I did was clean it and it worked fine - for a while. I stupidly put oil in the chain case after reading the manual. Up to then it had ATF but I was out, so off I went like a fool and then it slipped. I drained it out, cleaned again but slipping continued after a bit.

I got new friction discs and Type F ATF and set about changing it, but as I did, I saw the primary case had a lot more oil vs ATF than it should, given my cleaning. My bike wet sumps badly, and I saw oil drooling down from the seal behind the main sprocket. I drained the oil from the sump and it stopped. All this stuff adds up. I never could get the centerstand to work worth a damn, and gave up on it, and the side stand is too short - it is correct but Norton didn't see fit to extend it for the N15's extra suspension travel I guess. So it leans way over and sumps badly, which seems to be dousing the clutch with engine oil, at least that's my current thought. It all adds up to a very precarious situation with the old (but quite 'pumpy') oil pump possibly being the start of the chain of events.

My clutch springs and its other parts besides the new friction plates are servicable, but with the new friction plates being .17" or so, vs my old oil soaked originals being .14", and yet again, it all adds up to a nuisance. The very last plate hardly engages the splines due to the added thickness. I have to screw in the adjuster so far to get the lever/cable to disengage that the nut won't bite on the adjuster screw. The last 'half' plate looks like it will just spin outside the splined basket, the stack is too fat for the basket. I am wondering if I should pull out a plate/disc or what. What a pain. Riding the Norton is fun but working on it is tough, taking 27 things apart to try to fix one problem.
 
Maybe try a couple of the old plates so it will engage, just clean them real good. Then once the plates have a little time on them (wear) you could put the new ones back in??
 
Random babble:

Aside from something aint right with your stack...

Should be 5 frictions and 5 steels, with a one-sided friction under the pressure plate, and they should all fit.

No plates should be spinning outside the clutch basket or the hub. I bought a brand new set for the AMC clutch last year or the year before and it came with an extra friction, which I thought was odd. It fit like the originals without the extra friction. I never reinstalled the clutch with the new plates. Lost my mind and installed a belt clutch.

For more bite at the adjuster nut, you could get a Commando length clutch push rod. They are 1/4" or so longer. You could also cut one to length out of 6mm drill rod and harden the ends with a propane torch. Get the end red hot from tip in about 1.5" and quench it in oil.

Engine oil in the primary: Replace the crank main seal and remove and thoroughly clean the 3 inner case screws and threads in the crank case. You might have to remove the little bolt in the big sump plug and let it drain while doing the work. Use a high temp silicon sealer just under the screw heads and on a couple of threads under the screw head. Don't put any sealer out toward the end of the screw. Excess sealer may end up in the crankcase. It does get trapped in the sump screen, but still it's not what ya want. Ask me how I know. I use a Permatex sealer product called Optimum Max Torque. It's good to 700F degrees. Permatex Optimum Max Grey is a little cheaper. Both need 24 hours cure time. You could also use Right Stuff if in a hurry on the cure time.

Gear oil can migrate out of the sleeve bush, but it is very slow unless the sleeve bush is shot. Also get a clutch rod seal and try just a little less gear oil in the gearbox.

Get a bike stand if you want to keep the bike parked level. It won't prevent wet sumping, but it might help a little with the drainage into the primary. A block of wood to set the side stand on is less expensive, but not as stable.
 
Random babble:

Aside from something aint right with your stack...

Should be 5 frictions and 5 steels, with a one-sided friction under the pressure plate, and they should all fit.

No plates should be spinning outside the clutch basket or the hub. I bought a brand new set for the AMC clutch last year or the year before and it came with an extra friction, which I thought was odd. It fit like the originals without the extra friction. I never reinstalled the clutch with the new plates. Lost my mind and installed a belt clutch.

For more bite at the adjuster nut, you could get a Commando length clutch push rod. They are 1/4" or so longer. You could also cut one to length out of 6mm drill rod and harden the ends with a propane torch. Get the end red hot from tip in about 1.5" and quench it in oil.

Engine oil in the primary: Replace the crank main seal and remove and thoroughly clean the 3 inner case screws and threads in the crank case. You might have to remove the little bolt in the big sump plug and let it drain while doing the work. Use a high temp silicon sealer just under the screw heads and on a couple of threads under the screw head. Don't put any sealer out toward the end of the screw. Excess sealer may end up in the crankcase. It does get trapped in the sump screen, but still it's not what ya want. Ask me how I know. I use a Permatex sealer product called Optimum Max Torque. It's good to 700F degrees. Permatex Optimum Max Grey is a little cheaper. Both need 24 hours cure time. You could also use Right Stuff if in a hurry on the cure time.

Gear oil can migrate out of the sleeve bush, but it is very slow unless the sleeve bush is shot. Also get a clutch rod seal and try just a little less gear oil in the gearbox.

Get a bike stand if you want to keep the bike parked level. It won't prevent wet sumping, but it might help a little with the drainage into the primary. A block of wood to set the side stand on is less expensive, but not as stable.
Thanks, well I have the pushrod seal and it seems to be working fine. I will check more carefully on the stack, it has the same exact number and type as before, but perhaps some warpage in the steel discs. My puller, which worked on the sprocket when I originally tore the engine down, won't hack it and is bending. So yet another obstacle. I think the case screws are leaking.
 
Yeah getting that engine sprocket off is a chore. I destroyed a couple of cheap pullers on that sprocket. I ended up ordering the Norton tool for pulling the single row sprocket. It still works but is wearing more than I thought it would.

What would have been helpful is if Norton had drilled and threaded two holes in the sprocket one can use a two bolt puller on. On a clean motor and crankshaft sprockets or pulleys pop right off that taper with a two bolt flat plate style puller. They do for me anyway. I'm sure there are horror stories though.
 
Yes. Then legendary Norton tool. I have researched and heard tell such a beast. Yet I have found no picture or part number. Oh, but I found one listed on eBay with a part number (but no picture) 06-7500 Engine Sprocket Puller Norton Atlas W17083. That lines up with exactly nothing I can find anywhere so far in my several regular search areas. Do you have a picture of either method you used that worked? It's getting tiring. I will continue with the method of heat/cool cycle with pressure on the puller I have - till the junky puller breaks, probably.

I'm a bit grumpy because I also ordered parts on Sept 6 for my other bike and 2x been lost in the mail. At least that's a Suzuki where I don't encounter bizarre engineering choices like putting a dry clutch in with a chain that needs lube, a sprocket that isn't just bolted on, and a dry sump that, well, isn't. And so it goes.
 
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This is what the tool looks like. I got it from Baxter Cycle maybe. Might have been the last one they had. If the one on ebay looks the same, it is the one. I paid $45 plus shipping for it new old stock pre-Covid times.

Clutch work on my N15CS, some interesting challenges
 
This is what the tool looks like. I got it from Baxter Cycle maybe. Might have been the last one they had. If the one on ebay looks the same, it is the one. I paid $45 plus shipping for it new old stock pre-Covid times.

Clutch work on my N15CS, some interesting challenges
Thanks that is a lot more robust than what I just broke LOL. Have asked seller if he has a picture. It's only 17 plus 15 shipping. But seems every other USPS package goes missing these days. All the way across the USA then in southern CA goes AWOL. I checked Baxter and that looks like what he's selling, cool.
 
Yes. Then legendary Norton tool. I have researched and heard tell such a beast. Yet I have found no picture or part number. Oh, but I found one listed on eBay with a part number (but no picture) 06-7500 Engine Sprocket Puller Norton Atlas W17083. That lines up with exactly nothing I can find anywhere so far in my several regular search areas. Do you have a picture of either method you used that worked? It's getting tiring. I will continue with the method of heat/cool cycle with pressure on the puller I have - till the junky puller breaks, probably.

I'm a bit grumpy because I also ordered parts on Sept 6 for my other bike and 2x been lost in the mail. At least that's a Suzuki where I don't encounter bizarre engineering choices like putting a dry clutch in with a chain that needs lube, a sprocket that isn't just bolted on, and a dry sump that, well, isn't. And so it goes.
The second third sentences in the last paragraph made me laugh. So true.

Sucks about the lost package.

That Norton puller works well. You do have to hold it in place while starting or it gets wonky like the cheap pullers. However, it is a lot stronger and easier to hold. I stopped using heat after I got that puller.
 
Maybe try a couple of the old plates so it will engage, just clean them real good. Then once the plates have a little time on them (wear) you could put the new ones back in??
I may have to do that. Each old, probably original one is .14" thick and the new double sided (qty 5) are .17" Those originals had sat for 30 years and were quite oily, but I cleaned them up and they worked just fine until more oil entered the primary, dang it. I probably could just clean them all again and they'll be fine.

Anyone want a set of new fiber discs? They fit perfect! :p
 
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I may have to do that. Each old, probably original one is .14" thick and the new double sided (qty 5) are .17" Those originals had sat for 30 years and were quite oily, but I cleaned them up and they worked just fine until more oil entered the primary, dang it. I probably could just clean them all again and they'll be fine.

Anyone want a set of new fiber discs? They fit perfect! :p
I would hang onto them and look for a couple thinner plates, I would think they make them?
 
I would hang onto them and look for a couple thinner plates, I would think they make them?
Just being silly. I gotta take a look closer at things, The metal plates seem fine, no warpage. It's just a tiny bit too much thickness all stacked together so one older plate cleaned up may do it. I have some time to think about it while I wait for my puller and main seal (which was new and shouldn't have leaked, hmmm).
 
Thats the only puller worth having. Go back to your old plates (well cleaned) Give them a final wash in hot sugar soap water solution. Fit some sort of anti wet sump solution. Use ATF type F . Life will be good again !. You could get your new plates sanded down to match thickness to the old. If your clutch pressure plate adjuster is in its normal (for your bike) position then you do have more issues than you know. Check the lever position in the box, should be as close to the outer cover as possible. If necessary modify pushrod and cables to suit. I have a one finger Atlas clutch ,all std parts.
 
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You might be able to determine exactly where the oil is weeping from once you get that sprocket off. The screws are common leakers if not sealed. If you are going to replace the crank seal run enough electrical tape around the taper to cover the keyway so you don't cut the new seal while installing it. The tape pulls off easily once the seal is in place. You probably know all that, and all this unsolicited advice is just noise.

The old frictions might hold if you can get all the oil out of them. There are water soluble degreasers that will do it with a lot of soaking and scrubbing. Oil Eater if you can find it works. Wear gloves though. It is nasty stuff. I would mix old and new frictions to get a good stack height inside the basket. Better chance of no slip success with the new plates.

Old Nortons are for closet masochists. :)
 
Thats the only puller worth having. Go back to your old plates (well cleaned) Give them a final wash in hot sugar soap water solution. Fit some sort of anti wet sump solution. Use ATF type F . Life will be good again !. You could get your new plates sanded down to match thickness to the old.

You might be able to determine exactly where the oil is weeping from once you get that sprocket off. The screws are common leakers if not sealed. If you are going to replace the crank seal run enough electrical tape around the taper to cover the keyway so you don't cut the new seal while installing it. The tape pulls off easily once the seal is in place. You probably know all that, and all this unsolicited advice is just noise.

The old frictions might hold if you can get all the oil out of them. There are water soluble degreasers that will do it with a lot of soaking and scrubbing. Oil Eater if you can find it works. Wear gloves though. It is nasty stuff. I would mix old and new frictions to get a good stack height inside the basket. Better chance of no slip success with the new plates.

Old Nortons are for closet masochists. :)
That's right, once the sprocket's off I can see why there's a mist of oil behind the front of the inner primary case. I thought the breather threads might be doing it but don't think so upon closer inspection. I got the plates degreased and working fine the first time with dollar store degreaser - LA's Awesome, the yellow stuff. It's as good as any surfactant I have ever used and is dirt cheap. I expect I will probably only need to reuse one old plate, will see.

Regarding sealing the 3 screws, I was faced with having to stop a fuel leak on a Suzuki petcock that had worn out dowty washers. It was coming out pretty fast. I didn't have time to order the washers so I read up on methods to stop gasoline getting past threads. Several people said blue thread lock would do, and yep, it has been working for several years now on those two screws. I can't recall if I used any thread lock on those 3 will find out soon. If I did I'll be surprised if oil leaked past.
 
Thats the only puller worth having. Go back to your old plates (well cleaned) Give them a final wash in hot sugar soap water solution. Fit some sort of anti wet sump solution. Use ATF type F . Life will be good again !. You could get your new plates sanded down to match thickness to the old. If your clutch pressure plate adjuster is in its normal (for your bike) position then you do have more issues than you know. Check the lever position in the box, should be as close to the outer cover as possible. If necessary modify pushrod and cables to suit. I have a one finger Atlas clutch ,all std parts.
Fekid's oil supply line cutoff switch is only available in 3/8" ID size, whereas my hoses are 1/2" ID. Dang. Even standard ball type levers don't come in 1/2" without fiddling together the right barb fittings and making it into a huge monstrosity. The ones that are compact enough are all 'PEX' ends and too big for my hose size. I could grind it down but jeez this is just getting so annoying. Not a lot of choices that I can figure out on that end yet. Probably enough said about that whole wobegone subject, it's just round and round endlessly.

I will check all the positioning. With the original plates it just popped on, the adjuster fit in snug, the pushrod seal worked, and the adjustment range was fine. Clutch pull definitely tough though. I really just expected to swap the new ones in, clean it up and be done with it. Ha!

One finger clutch would be nice. I have never encountered such a thing on the dozen or so British bikes I've ridden - that would be nice. Right now I have an NOS replacement cable but the lever I'm using is a different, more standard large barrel type fitting. My bike's a hodge podge. I was bummed when I bought the NOS cable from Baxters and my lever is wrong. If I can find a stock lever I'll put the NOS cable on, maybe a bit of improvement from that too. That is yet another research project - what is going on with the cable I got not having what seems to me the standard type of large barrel on the end? It's much smaller.

Edit: maybe I'm confused and it's a Barnett, not NOS. Been a while. It looks like the one on Baxter's site 25036 but is missing that barrel part (shown in 2nd pic off their site). Mabye will ask them what's going on.

Clutch work on my N15CS, some interesting challenges


Clutch work on my N15CS, some interesting challenges
 
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....bizarre engineering choices like putting a dry clutch in with a chain that needs lube, a sprocket that isn't just bolted on, and a dry sump that, well, isn't.
Tom, why don't you fix the root cause? Your oil pump appears to be worn out. Get a new one! Or send the one you have to AMR for an upgrade.

As for your new clutch plates, they can probably be milled down slightly with the correct cutter. Oily clutch plates should be cleaned using a TCE substitution + Fuller's Earth, as described in the Workshop Manual. Oil level in the primary needs to be kept at the bare minimum; lower run of the chain should barely touch the oil surface.

- Knut
 
The clutch lever i was referring to is inside the box . The Bar lever is important too. 7/8 " pivot to nipple centers needed. 1" is no good, 11/8" even worse .
 
After suffering with major clutch slip on my BSA B44 and replacing the friction plates and then replacing the plain plates
Trying an extra plate
Heavy duty clutch springs etc
I hand decked every plate friction and plain both sides until everything was absolutely flat
Plus I tack welded an extra plain plate to the pressure plate and decked that too the clutch was transformed
No more slipping so I could back the tension off the springs which made it lighter to operate
No dragging no slipping and apart from the Norton aluminium pressure plate it's very similar clutch
 
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