1938 inner chaincase cover gearbox shaft hole

Glenn, they have a sort of gutter to drain the oil either side of the hole{sometimes], i think its spotwelded to the case or sometimes a turned up edge over the shaft hole. It seems to work ok. Regards John.

GLEN, YOU WILL GET THE PART YOU NEED FROM FRED WILLIAMS ITS 2 PIECES OF TIN OF THE CORRECT SIZE THAT YOU RIVET TOGETHER 1 EACH SIDE AND IT AS THE HOLE IN FOR THE SHAFT TO GO THROUGH YOU CAN GET IS NO FROM ANY NOC MEMBER HE IS VERY WELL KNOWN I DONT WANT TO ADVERTISE IT ON THE FORUM IN CASE HE GIVES ME SOME B----K LOOKS NEXT TIME I SEE HIM ,

Glen, if you have the postwar inner chaincase, with a larger hole, the dished pieces are required. The prewar and wd case had a smaller elongated slot that just fitted the shaft. The whole idea is more of a dirt guard than an oil seal, in fact Norton seem to have had some reluctance to fitting oil seals anywhere. John.

This is the view inside a diamond-frame mounting inner primary case. There is an identical dished washer riveted on each side of the slot (which from memory follows an arc to reflect gearbox movement).

[IMG]http://i248.photobucket.com/albums/gg164/commando16h/NOC/P8211454.jpg[/IMG]

Unlike later (Dominator) discs, there is no facility to include a felt sealing ring.

There is not actually a lot of oil in the chaincase, just enough to dip the chain in, not enough to swamp the clutch.

Running without oil won't cause immediate mechanical disaster but will reduce chain life (including increasing the risk of shedding rollers) and it will reduce sprocket life. The small engine sprocket in particular has quite a hard time.

Run dry, there is also no run-off lubrication for the clutch rollers. They are only rotating when the clutch is disengaged but they do benefit from a bit of lube.

I haven't yet dared to try posting two images at once. This is the view from the rear of the case.

[IMG]http://i248.photobucket.com/albums/gg164/commando16h/NOC/P8211455.jpg[/IMG]

Here's a view of the rear of a chaincase with the rear disc removed (the inner disc is held in place by the half-moon pressing above the disc.

You should be able to see the slotted opening which is normally covered from both sides.

[IMG]http://i248.photobucket.com/albums/gg164/commando16h/NOC/16h005.jpg[/IMG]

The discs are indeed rivetted to each other and free to move through a slight arc as gearbox position alters. They can't revolve as the rivet position radius is greater than the height of the slot.

The only sealing is the tight(ish) clearance between the centre hole and the mainshaft.

If you can't find discs and decide to make your own, I'll happily measure them up for you.

Previously wrote:

I'm in the process of trying to get my 38 ES2 going and the gearbox is my main concern at the moment. However a fellow enthusiast came by and commented on the hole in my inner chaincase cover where the shaft comes through to the clutch. Mine is just that; a hole with a reasonable gap around the shaft. I have no idea if this is correct or not. I can see nothing else in the parts manual that should fit there. My friend has a 54 ES2 and his has a sliding plate on the inside which has the hole in it very close to shaft size and can adjust depending on gearbox position. He is adamant that mine will throw all the oil out the hole and therefore onto my rear tyre. In any case it's obviously not good to be loosing oil at any substantial rate from anywhere. As I have not run mine yet I have no idea whether it will or it won't. What do your inner chaincases look like in this area ? Thanks, Glenn

Hello Glenn, I have attached a link to my photobucket album showing a pair of loose discs, as you can see thy are slightly dished in the centre and as already mentioned they are simply riveted together and are a floating fit in the inner case.

Regards, Karl.

http://s1101.photobucket.com/albums/g428/fsx3/

Glen, as has been mentioned earlier, the chaincase oil is only deep enough to wet the plates of the primary chain.Theoretically any oil that drains down the case onto the clutch will be thrown off by centrifugal force,away from the back of the clutch and shaft area.The two dished pieces of tin do not seal this hole effectively,one edge fits against the sprocket,the other up against the back of the clutch.The wd models were notorious for getting sand into the primary case through the slot, so in the 48 redesign,the dished tin bits were added.Not much improvement,but cheap.All the horror stories you hear about primary chain failure are B/S.Harley big twins never had an oilbath chaincase until the electric start era ,just a drip oiler and total loss,no chain problems with a duplex chain.I have piped both the magneto case drain,and the engine breather into the primary case onto the bottom run of the chain,and run the case dry otherwise.Any oil that builds up runs out through the rubber seal ring while youre riding.Saves the floor from being flooded every time someone moves the drip tray aside. If I wanted a more effective seal on the mainshaft I would fit something like the BSA sliding plate,possibly made from hard plastic .One common cause of chain problems is 19t engine and 76 pitch primary ,two badly worn spots which write off the chain at low mileage.Regards John.

Glen, as has been mentioned earlier, the chaincase oil is only deep enough to wet the plates of the primary chain.Theoretically any oil that drains down the case onto the clutch will be thrown off by centrifugal force,away from the back of the clutch and shaft area.The two dished pieces of tin do not seal this hole effectively,one edge fits against the sprocket,the other up against the back of the clutch.The wd models were notorious for getting sand into the primary case through the slot, so in the 48 redesign,the dished tin bits were added.Not much improvement,but cheap.All the horror stories you hear about primary chain failure are B/S.Harley big twins never had an oilbath chaincase until the electric start era ,just a drip oiler and total loss,no chain problems with a duplex chain.I have piped both the magneto case drain,and the engine breather into the primary case onto the bottom run of the chain,and run the case dry otherwise.Any oil that builds up runs out through the rubber seal ring while youre riding.Saves the floor from being flooded every time someone moves the drip tray aside. If I wanted a more effective seal on the mainshaft I would fit something like the BSA sliding plate,possibly made from hard plastic .One common cause of chain problems is 19t engine and 76 pitch primary ,two badly worn spots which write off the chain at low mileage.Regards John.

Glen, as has been mentioned earlier, the chaincase oil is only deep enough to wet the plates of the primary chain.Theoretically any oil that drains down the case onto the clutch will be thrown off by centrifugal force,away from the back of the clutch and shaft area.The two dished pieces of tin do not seal this hole effectively,one edge fits against the sprocket,the other up against the back of the clutch.The wd models were notorious for getting sand into the primary case through the slot, so in the 48 redesign,the dished tin bits were added.Not much improvement,but cheap.All the horror stories you hear about primary chain failure are B/S.Harley big twins never had an oilbath chaincase until the electric start era ,just a drip oiler and total loss,no chain problems with a duplex chain.I have piped both the magneto case drain,and the engine breather into the primary case onto the bottom run of the chain,and run the case dry otherwise.Any oil that builds up runs out through the rubber seal ring while youre riding.Saves the floor from being flooded every time someone moves the drip tray aside. If I wanted a more effective seal on the mainshaft I would fit something like the BSA sliding plate,possibly made from hard plastic .One common cause of chain problems is 19t engine and 76 pitch primary ,two badly worn spots which write off the chain at low mileage.Regards John.

I'm sure that the sealing discs were fitted pre-war and in fact they appear in the 1933 - 35 parts book, as well as subsequent editions, including the WD16H. There is however no facility for a felt seal within the assembly, simply a large felt washer placed behind the case so perhaps this was the aspect improved for 1948 ?

I can well imagine that desert sand would find its way in anywhere that wasn't 100% sealed, such as between the two plates, especially as they wore a little.

1933 - 35 Parts Book extract :-

[IMG]http://i248.photobucket.com/albums/gg164/commando16h/Commando%20info/18.jpg[/IMG]