Engine shock absorber - plunger A10

[Jackson]

I am just putting engine back together on my '53 plunger A10.
There is an oil seal in the drive side crankcase around the crankshaft end. I have replaced it with a modern rubber one. According to the parts list it shouldn't be present. It is there in the '54 parts list though - so I am assuming that I have a later '53 engine to '54 spec.
My problem is that if I reassemble as things stand the end of the splined sleeve that the drive sprocket (duplex) slides on will rub against the oil seal.
Have I used the wrong oil seal or is there a spacer or something missing?
I don't seem to have any sprocket distance pieces or shims.
Any help greatly appreciated.
Adrian

[JulianS]

According to my old Payens catalogue there were 2 different seals

67 1243 listed for 1949-57. Payen part B253

67 674 from 1954. Payen part C738. This is the common one certainly used on swinging arm bikes.

Photos shows dimensions of the 2 seals which may help you figure it out.

[Jackson]

Thanks for the reply.
This is odd, the Payen catalogue has 67-1242 as a crankshaft oil seal but in the parts list it is the "crankcase oil seal" round the gearbox input shaft - held in place by a riveted washer. I've just replaced this.
The other part 67-674 appears to be used on both plunger and swinging arm from '64 onwards as the crankshaft oil seal. It is he correct diameter for the hole I have (o/d) but seems a bit too big on the inside, perhaps I should use a bit more force when I install the engine shock absorber.

[JulianS]

I think payen mis described 67 1242, it should have been described as chaincase/gearshaft seal.

[Jackson]

Yes - I  think you are correct.
Do you know how tight the inside of the standard oil seal is on the shock absorber sleeve?