NEB wet clutch barnyard engineering mods for P11

NEB wet clutch I have does not fit the P11 without barnyard engineering a modification to the design. British Bike Bits sells the clutch I have, and the description of the part on the site says it works in a P11. I'm very skeptical of NEB ever having put one on a P11. The hub is wrong and it is impossible to get the engine and clutch sprockets to align without making changes. It is also possible I was sent a clutch with the wrong hub in it. I've emailed British Bike Bits about the issue, but only received promises of an answer some day.

All my engine and gearbox spacers are in the correct locations. I bought an Andover motor mount kit, changed out all the studs and spacers with new parts. British Bike Bits is saying my mainshaft may be too short. However, it has never been changed and I have a gearbox with a P11 serial number on it, and the AMC clutch fits perfectly. Why not just use the AMC clutch you say? It weighs nearly twice as much as the NEB clutch, and I'm not going to use the AMC clutch on a new engine build in the works, that is why. Plus I am persnickety and persistent. Make a plan stick to the plan.

Here is what I have done to get engine and clutch sprocket alignment. Guys closet engineering degrees that have never owned a P11 should avert their eyes. ha

I made a spacer that is inserted into the hub spline to act as a stop against the mainshaft stop. The spacer off to the side is also used. If the hub was correct all that would be needed is that spacer off to the side. The spacer I made is 9.12mm and is actually hand made with a hacksaw and various files from an electrical service box connector for putting Romax into the service box. It has the right ID and OD. 1/2 copper pipe couplers also work, but tend to compress with the amount of torque required on the clutch nut.

Stop spacer inside the splines. Barnyard engineering.



I also decided to add a 6mm splined addition to the rear of the hub, since the spacer mentioned above eliminated 9.12mm from the overall depth of the hub splines. By the way, the hub is too deep and the clutch sprocket offset incorrect for a P11 or I wouldn't be doing any of this mad science nonsense. I made the splined spacer with files, a hole saw, and some big drill bits. Then drilled and tapped the hub so I could screw the add-on onto the rear of the hub. If I got $1 an hour for my time it would be worth $48. lol

Barnyard engineered hub spline add-on for theoretical added strength.


Scary looking as it is, it will work, but I won't be testing it until the next modification to my motor is done. Also might end up installing a NEB belt clutch instead of the wet clutch if I can get NEB to realize the P11 is not like other Nortons and the clutch hub needs to be changed.

Junglebiker said his NEB clutch sprocket and engine sprocket align when the clutch is installed. I don't know how unless he has a different engine sprocket, a different clutch hub and different mainshaft, or gearbox. The clutch I have can't be installed due to the excessive depth of the hub to the NEB stop spacer. It is deeper than the entire length of the mainshaft splines. The hub hits the sleeve gear and locks up the clutch, and the clutch sprocket offset is nowhere near being aligned with any of the Norton engine sprockets I have. The inner primary cover is in the way as well.

Personally, I’d be inclined to strip the gearbox, remove the mainshaft, measure it, and try and buy one that’s 9.12mm longer.

I have had similar problem with NEB a few years ago now.
The clutch and belt drive was purportedly for an ES2.
The taper on the front pulley was wrong by quite a bit. The rest of the kit was brilliant - to the extent I bought another for my 650SS.
Luckily I had a machinist friend to help correct the problem.
I suspect there may be fitment issues on anything Norton outside Dommies/Commandos.
Cheers

Fast Eddie said:

Personally, I’d be inclined to strip the gearbox, remove the mainshaft, measure it, and try and buy one that’s 9.12mm longer.

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That would be nice and I may look into it to see if such a mainshaft exists. Ideally NEB would have installed one on a stock P11 and designed the hub so the sprocket had the right offset. An amazing amount of people have no clue about the P11. It is not the same as an Atlas, N15 or any of the other Norton models it gets lumped in with.

Edit: The Dominator mainshaft is the one that might work with the NEB clutch I have, and a NEB belt clutch since I think it uses the same hub. Not mentioned on the British Bike Bits website, because well nobody knows much about the 1967 P11. So.. if I want to run a belt clutch and I kind of do because I am tired of cleaning up the dribble out of the primary cases, the gearbox has to come out, and the mainshaft changed. After doing that the AMC clutch sprocket would no longer align, but that is the price I would have to pay to play. The engine has to be removed to get the gearbox out. Fortunately, I planned on doing that anyway.

This is a link to the Dominator mainshaft

The mainshaft in a 1967 P11 gearbox. Lot of threads for the clutch nut and shorter splined section.


Kind of hard to tell, but I think the splined section of the Dominator mainshaft is longer and it has fewer threads for the clutch nut. That would help with engine and clutch sprocket alignment.

Bear in mind that my P11 has a gearbox made from parts I pulled out of a box of assorted Norton gearbox parts, my gearbox case is not P11 stamped, and, perhaps most importantly of all, mine hasn't even been started yet. I may yet find that things don't line up as well as I thought they did, though I don't think so.

Junglebiker said:

Bear in mind that my P11 has a gearbox made from parts I pulled out of a box of assorted Norton gearbox parts, my gearbox case is not P11 stamped, and, perhaps most importantly of all, mine hasn't even been started yet. I may yet find that things don't line up as well as I thought they did, though I don't think so.

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You won't have any problems. I think you would have noticed and fought the chain a lot. 9mm out of alignment with the engine sprocket is a bunch, and it would grind away the inner primary since it is 9mm offset toward the gearbox. The Dominator mainshaft, which is probably what you have will work. For some uneducated reason NEB just lumped the P11 in with the wideline and slimeline framed Nortons which use the Dominator mainshaft in the gearbox. Then again I may have the only P11 on earth with the mainshaft I have in the gearbox and an AMC clutch that works with it. A real prototype number 11. lol

After doing all the redneck barnyard dirt floor shade tree garage engineering I can use a carpenter's square or any long straight edge across the face of the engine sprocket and it lines up perfectly with the face of the NEB clutch sprocket.

I also plan to take 1mm off the big spacer around the crank behind the inner primary. It will make R&R of the engine sprocket and chain easier.

Even though the Featherbed/Hybrid gearbox shells are listed as different in the 'Master Parts List', it shows mainshafts as common to all...
FWIW

EstuaryBoy said:

Even though the Featherbed/Hybrid gearbox shells are listed as different in the 'Master Parts List', it shows mainshafts as common to all...
FWIW

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Well, that clears that up. All there in black and white on page 12. Guess I'm just out of luck on getting the shaft. Oh wait, maybe I did get the shaft from NEB.

Schwany said:

Well, that clears that up. All there in black and white on page 12. Guess I'm just out of luck on getting the shaft. Oh wait, maybe I did get the shaft from NEB.

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When was the master parts list printed. And what came after that? What about Commando shafts ?

And as you pointed out in those pics earlier, yours does look different to the Dominator one you linked…

My thinking is… what else can it be? There are only so many variables at play here, a different / incorrect mainshaft really comes high on my potential culprits list…

The P11 gearbox that I have has not had the mainshaft changed in it.

Edit: Since I acquired it in 74, so it could be a shorter version. Although I'm not sure why, since it works with the AMC clutch. EstuaryBoy sent me a helpful link with a variety of available mainshafts for pre-Commando AMC boxes.

DeJa'Vu section: My logic says if the AMC clutch sprocket aligns with the engine sprocket when the AMC clutch is installed on a correctly assembled 1967 P11, the mainshaft in my gearbox is the correct one for the 1967 P11 I have, and NEB never installed the NEB clutch I have on a 1967 P11.

Still waiting on an answer from NEB via British Bike Bits. I asked if the hub depth was the same on the belt drive clutch for 500-750 Nortons. The NEB engineer that supposedly has the answer is out sick.

EstuaryBoy said:

Even though the Featherbed/Hybrid gearbox shells are listed as different in the 'Master Parts List', it shows mainshafts as common to all...
FWIW

Click to expand...

Thanks for the link to RGM. That pic with the various mainshafts for AMC boxes makes more sense to me than the Master Parts List

Schwany said:

NEB wet clutch I have does not fit the P11 without barnyard engineering a modification to the design. British Bike Bits sells the clutch I have, and the description of the part on the site says it works in a P11. I'm very skeptical of NEB ever having put one on a P11. The hub is wrong and it is impossible to get the engine and clutch sprockets to align without making changes. It is also possible I was sent a clutch with the wrong hub in it. I've emailed British Bike Bits about the issue, but only received promises of an answer some day.

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I suggest you write to the maker (Maxwell Engineering) rather than BBB. Do enclose some pics to highlight the problem. Maxwell Engineering should deliver an answer to the fitting problem. Maybe they have a different chain hub for Matchless and Norton bikes? I wouldn't trust BBB if I were you/ They are general aftermarket part resellers, and their sole interest is pushing parts.

- Knut

Schwany said:

That would be nice and I may look into it to see if such a mainshaft exists.

Edit: The Dominator mainshaft is the one that might work with the NEB clutch I have .... the gearbox has to come out, and the mainshaft changed.

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If your gearbox is a genuine one, you already have a Dominator type mainshaft, p/n 040001. Please peruse the enclosed picture (clutch end is to the right).


On my work bench I have a couple of complete G15 gearboxes, and also a complete and genuine P11 gearbox. If you want to verify length of the protruding part of the splined section, I will be happy to take a reading.

- Knut

mdt-son said:

On my work bench I have a couple of complete G15 gearboxes, and also a complete and genuine P11 gearbox. If you want to verify length of the protruding part of the splined section, I will be happy to take a reading.

- Knut

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Thanks for the offer Knut, but I'm in no hurry on this and may or may not swap mainshafts for a few weeks.

Using my Captain Negativity hat I think the incorrect or a different mainshaft was put in there at the factory because that mainshaft or complete gearbox is what they had close at hand that day for a P11 build, and it is close enough with an AMC clutch. The one RGM sells as a 040001 is the correct length eyeballing it.

What is actually in the P11 stamped AMC gearbox I have is a 040001M if the image on RGM is accurate (see below). It's a Manx mainshaft. I did not put it in there.

Sorry about all the BS guys. I did the work on the NEB clutch hub because I had a bee in my bonnet to do it. Kind of nuts all things considered. Although what I did would work and it is done.

Take look at the link below to see the early AMC mainshaft selections.

Inset image of early mainshafts on RGM site

Schwany said:

<snip>
What is actually in the P11 stamped AMC gearbox I have is a 040001M if the image on RGM is accurate (see below). It's a Manx mainshaft. I did not put it in there.
<snip>

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So the photo in post # 5 is not your box? Unfortunate that RGM didn't include the length in their compairson photo; but the 040001M shaft has noticeably fewer threads on the clutch end than the 040001. The one shown in post # 5, and the one for my P11, appear to be the 040001.

Longtimegone said:

So the photo in post # 5 is not your box? Unfortunate that RGM didn't include the length in their compairson photo; but the 040001M shaft has noticeably fewer threads on the clutch end than the 040001. The one shown in post # 5, and the one for my P11, appear to be the 040001.

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Good catch on the fewer threads. I was only looking at overall length figuring mine had to be the incorrect mainshaft given the advice.

The photo in post #5 is my P11 gearbox. As is this one. P11 18057. Unless that 1 is a slash making it P11/8057



To tell you the truth one of the pre-AMC shafts looks closer to the same if mine is incorrect and shorter than it should be. A2/324, but I have no clue if that would go in the AMC box. If mine is the correct length and the correct mainshaft, NEB is blowing smoke up people's butts, or I was sent the wrong clutch. However, I usually get that smoke award.

After some discussion with Andy Molnar about NEB clutches, and getting a Commando mainshaft measurement from him it appears to me that the NEB clutch sprocket may align with my engine sprocket if I put a Commando mainshaft in the gearbox. The stop spacer that comes in the NEB clutch might need to be removed. In that case the heavy washer held on the hub with 3 long counter sunk screws would act as the stop. A Commando mainshaft is .75" longer than the P11 mainshaft.

Would have been nice to know the NEB clutches require a Commando mainshaft from the start. My P11 gearbox has the correct mainshaft in it for a P11. And the NEB clutch does not work with a P11 gearbox as they came from the factory.

So a Commando mainshaft is probably the answer for a P11 anyway. I'm not sure if the other model pre-Commando Nortons have the same issue with NEB clutches. Andy sells NEB clutches. If I get a belt clutch, he is the one I'll get it from. Might cost another $100US, but his support is worth the extra cost.

The NEB wet clutch and belt clutch use the same hub.

Which do you think is lighter: your stock clutch, the RGM clutch or the NEB clutch?

I'm comparing all the belt drives right now for my 650 domi, including the Bob Newby (BNR) which I think is my favorite but its quality comes at a price.

elefantrider said:

Which do you think is lighter: your stock clutch, the RGM clutch or the NEB clutch?

I'm comparing all the belt drives right now for my 650 domi, including the Bob Newby (BNR) which I think is my favorite but its quality comes at a price.

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The NEB wet clutch for single row chain is the lightest. The stock clutch is the heaviest.

I'll weigh the clutches "without" belt chain or front sprocket/pulley when I get started on a TTi 5 speed install and update this thread.

The NEB belt clutch is similar to but not the same as the Bob Newby clutch. If I could turn back the clock knowing what I know today, I'd cough up a little more money and get the NEB belt clutch from Andy Molnar.

The pull at the lever is heavier with the NEB 6 spring clutch than it is with a RGM diaphragm spring clutch. No experience with the BNR 6 spring clutch.