CC005 POST-WAR OIL LEAKS/CHAINCASE

In my opinion for the neoprene chaincase seal to function, it must touch the clutch outer plate very lightly. Otherwise it will shear of in a couple miles after leaving home. Which of course did happen in my case.
Now the problem is the gap between clutch and chaincase isnt wide enough. Especially when your clutch is new. Needless to say my clutch is new.
I made a new distance piece between the chaincase halves. Its 2 mm longer and gives a little more room, but not enough. (By the way you dont notice by looking at the chaincase that the distance piece is not orginal!)
Do you think it is feasible to make a groove (or channel) in the outer clutch plate on a metal lathe, just deep enough for the neoprene seal to just touch the clutchplate. A few mil deep and something like 10 mm wide? - Hein Rollmann, Amsterdam 3/4/2003

I think you may have been trying one of the newer 'silicone' seals rather than the older, firmer, 'neoprene' seals?
The silicone seals are very delicate. Although they are designed to seal just at their edge in the standard chaincase, I do not think it matters if they are just a little compressed. However, I do think that it is vital that they are well lubricated from the start.
They need a good film of grease on assembly, and oil in the chaincase from then on.
I do not like the idea of a longer distance piece because it would distort the chaincase if it made enough difference. Turning a deeper channel for the seal would work OK, but I would call it a 'last resort'. It is hard work to make, and damages a good chaincase outer.
Instead I would first try again with good lubrication - but I would also try to use a 'thicker' cork gasket. You do not say if you have a screw fixing chaincase, but if you do I would be careful to use only a light tightening of the screws, since this can make a 1mm or 2mm difference in the compression of the cork gasket - and it also distorts the cases. Instead I would use a silicone sealant to seal the cork gasket to each side of the chaincase and to hold the screws in position even though they are only just tight. This holds the chaincase outer a little further from the clutch - but, of course, not so far that the rear chain rubs on the outside..........!
If you have the earlier 'band-fixing' chaincase then perhaps try better lubrication first, but then either turn a deeper groove or try the soft felt seals from VSL - they are what Velocette used, and I think they are very good! - TW 3/4/2003