Crankshaft seals

[saluki42]

Hi can anybody tell me if a lip type seal was fitted to any of the  600cc crankshafts at the flywheel end. I know that my Model Z has some differences from both earlier and later models but the flywheel side crankcase definitely has a recess accessed internally but behind the self aligning bearing which is where I would expect to see this type of seal.

I'd be grateful for any advice with this.
Chris

[eddie]

Chris,
           I think you will find that the 'oil seal' is in fact a steel sleeve with a large flange. This sleeve is a sliding fit on the crankshaft and a loose fit in the crankcase. It has a light wavy washer between it and the bearing, pushing the flange up against the end of the bearing housing. When fitted, there should be about 2mm clearance between the outer edge and the boss of the flywheel.
     You refer to the main bearing as being self aligning - I think that is wrong - it should be a double row rigid bearing (30 x 62 x 20), otherwise all the transmission loads will be transfered to the drive side crankpin.

   Regards,
                  Eddie.

[saluki42]

Thanks for that Eddie I know I hadn't seen a seal in any of the myriad boxes this jigsaw puzzle came in. Regarding the bearing I was going by the description of an engine strip down featured in an old Classic Bike magazine, though I have just re read this to find it is the multi piece crank from a 300 they are talking about, and using the part number on the bearing I removed from the crankcase. If the engine is set up to run properly the only thrust loading through the crank should be from the clutch operating I would have thought.

Chris

[eddie]

But you have to take into account the pull on the primary chain - with a self aligning bearing, the bearing flexes and transfers the load to the drive side crankpin (and eventual crank failure). My advice would be, don't treat advice in Classic Bike comics as gospel - it's probably that advice that persuaded the previous owner to make do with an inferior bearing.

  Regards,
                 Eddie.