Primary chain alignment

Previously wrote:

I have a 1946, Model 18, 500 Single and am putting it back together. I find that the clutch does not align with the engine sprocket and rubs on the inner chain case. Is there a sleeve or some thing to stop the clutch from going on the shaft too far? I find that the inner clutch body centre has splines with no shoulder to stop it from sliding around when the nut is tightened except that it would be too far in to align with the front sprocket and would be tight against the inner chain case. I am at a loss as to what keeps things in alignment. Am I missing a sleeve behind the clutch??? I do not see a part in any of the manuals but do see a drawing of the clutch but it has a shoulder on the inner clutch body centre.

Darwin

I too have a 1946 Model 18 which I have restored. In regards to your challenge, the clutch body center which has the splines has a step or stop that should locate it by abutting to the end of the gear box main shaft. There are not any sleeves or distance pieces involved.

So when you look into the clutch center from the outboard or attaching fastener side, you should see that the clutch center splines do not continue the full depth of the clutch center and the ID is slightly smaller on the outboard compared to the inboard. If this is present and the depth of the clutch center bore is approximately 3/4" when measured from the inboard side to the step or stop. The clutch center should be ok.

The gear box main shaft splines should be set back from the outboard end of the shaft by approximately 1.050".

When the clutch is offered to the main shaft and you look into the clutch center, the threads on the main shaft that the clutch retaining nut threads on to, should show that the locking washer and nut would nip up tight against the clutch center holding it in place. If the clutch center can slide on to the main shaft and you can see the splines of the main shaft then the clutch center is damaged.

I have photos of these assemblies if you care to provide an email address I would be happy to send them to you.

The only other thing I can think of would be that the gear box main shaft is incorrect and perhaps a main shaft from a lay down box is installed. This would move the clutch inboard by about .160"

Make sure there is not much end play in the gear box main shaft while you are here. a large amount of end float would indicate a badly worn thrust washer.

Mark Zenor

Darwin

The part is called a clutch spider and readily available.

Peter's classic bike in the Netherlands has them

http://www.petersclassicbikeparts.nl/contents/en-us/d94_01.html

Norvil has them part #043443

Our own NOC spares for singles has one listed and is the best price. It is AMC but I think they are interchangeable. Not sure though.

http://www.cornucopia-enterprises.de/spares.html

also shows them available. Peter has most stuff and these are for the older Norton clutch.

George Cohen says this

The AMC clutch was a re-design of the oldNorton clutch. Dimensionally, it is the direct replacement and the two areinterchangeable. But the internals are quite different. Whereas, the Norton hasinserts in the chain-wheel and externally driven friction plates, the AMC isexactly opposite. The chain-wheel is solid and the friction plates driveninternally. This was an improvement over its predecessor, especially in racing,where the old Norton clutch had some shortcomings. So although the two clutchesare identical externally, and completely interchangeable, the components arenot, with the exception of the pressure plate, which is pressed steel on theNorton, and alloy on the AMC. You can use the AMC pressure plate on a Nortonclutch, the only advantage is that it won't rust when you run with open primarydrive. The AMC was fitted to all the big AJS, Matchless and Nortonswhich used the AMC box from 1957 right up to the Commando. Either clutch willfit any Norton or AMC box from 1934 to 1978 including Commandos.

You could get and install a AMC clutch, pre-commando, (ebay or NOC spares). You most likely would have to use your pressure plate or modify the AMC alloy one as it has the adjustment screw and your 46 won't need that as it adjusts on the other side. This would also make clutch plates way more available. I have one but was able to get the original Norton clutch to work and got some clone metal plates from DomiRacer for the narrow tang center. Had to hand file the tangs a bit to fit properly.

Hope this helps or at least generates some ideas.

Mark

Hi all,

log into the wdnorton.nl/ website, go to the opening page and click on 'download' page; them open 'The Norton Clutch.pdf.'

This opens a document from 1953 which obviously was aimed at those people who vandalised Manx Nortonsfor use in Formula 3 car racing.

The article talks about using the WD gearbox and advocates fitting a sleeve behind the clutch, though no dimensions are quoted.

Another point is that it advocates fitting a thrust race to the clutch cover, all very interesting!

Derek

I'm having a similar problem with my 1955 ES2. I replaced the old worn spider with a new one to try and stop the clutch assembly fouling on the swingarm mounting area. I'm doing a dry assembly without the chaincase at this stage.The chainwheel now onlyjust clears the swingarm mounting when bolted to the shaft, but when the primary chain is fitted it fouls the swingarm mount area.

I can't help thinking that the mainshaft is too short. If I can get and fit a longer one where does the extra length appear, i.e. will it move the clutch further outboard and solve my problem?

Duncan Smith.

Today I stripped the mainshaft out of my gearbox and measured it at 8in+9/16th". Then I stripped the mainshaft out of the spare gearbox.....8in+13/16th"

Put the longer one back in the gearbox in the bike, andthe clutch/primary chain is now well clear off fouling anything.

One problem solved I think....Unless the brake pedal hits the chaincase....

Duncan.

Having just fitted a new spider supplied by RGM, I can say that no machining was required, just the "special tool" as illustrated in the manual. So that is probably the best route for you, buy a new spider.

Alternatively if you have got machining facilities and you want to spend ages making a stepped bush to bolt to the front of the spider to act as a stop for the shaft......

Duncan.