Clutch rubbing on inner chain case.

Two areas needed attention in that case: There is an "eyebrow" above the gearbox main shaft sliding plate, presumably to deflect drips from the top run of the chain. At least one of the spot welds had failed, allowing the "eyebrow" to move out towards the clutch. I was able to pop-rivet that back into place. The bracket that secures the inner case to the lower gearbox bolt should also be checked. It may be deformed, or someone may have fitted a washer between the bracket and the gearbox bolt head. It takes very little to push the case outwards enough to contact the back of the clutch basket. A third possibilty to consider - could all that welding have distorted the inner case?

Ian McD

The chain runs on these bikes are very close, barely enough room to slip a fag paper in, yet Norton expected front chaincases and rear chainguards to fit into the equation !

Is this a new problem or has it just occurred ? If clutches have been run loose then wear on the shoulder of the internal splines can allow misalignment. Is it an original type clutch and not a later AMC type with bonded back plate as they're thicker ?

I've seen a number of variations in chaincase inners, sometimes a simple pressing on the crankshaft boss and others with a spot-welded lip. If it's sitting too deep at the front, perhaps due to lack of a sealing ring, this will push the back of the case outwards.

The biggest problem is usually the rear chainguard, squeezed as it is between saddle stay and mudguards, tweaking the inner primary outwards as the whole assembly is bolted together.

If you've checked primary chain alignment with a straight edge,then I'd say that the problem lies with the chaincase and no block of wood is too large and no hammer too heavy to bash the blasted thing back into line :-)

I have the opposite issue with my 16H. The footpeg tube is too short it seems, so the outer cover has to be jammed on and the nut turned down thinner just to get the footpeg on. Is there any way the inner can be too far out?

David, I have that problem too. My excuse is that I built it from autojumble parts but I have a couple of primary side footrest tubes in WD paint and they're identical...I had to turn the nut down in order to leave the footrest serrations clear....and I can't work out why, unless it's rubber thickness ?

My clutch rubbed until I replaced the clutch spider,  the stop had worn over the years until the clutch was rubbing on chaincase. If you do alter the clutch position remember check alignment with the engine sprocket - 3 different offsets are available to ensure that all is in line.

dan 

Richard.. it's very odd. Mine is civilian so I think the peg is a bit different but the problem is the same. I keep trying to design some kind of sleeve nut arrangement but I don't want to damage the chain case by making a bigger hole. The issue is that the outer is jammed on to the rubber far too hard. When I got the bike it was stuck so hard I had to saw the rubber out with a hooked steak knife! A couple of hour of very hard work. I hope it's not like that again now! I think the tube is welded to the engine plate. I'm not taking it all apart to weld another one on.

Don't despair, Richard! You know it's worth it in the end!

I wonder if the problem is a build up of tolerances, including washers and spacers present or absent or in the wrong place. All the books assume you are reassembling a machine that was put together correctly in the first place. So they never say how to put it together from scratch. Washers, seals etc. no information usually given.