Crankcase assembly - 1953 G80 engine

TommoT · Post by **TommoT** » Wed May 13, 2009 10:23 am

When assembling the crankcases with the crankshaft fitted, I have too much endplay. I believe it should be 0.020-0.025"? One method to reduce the endplay would be to move the timing side bush inwards. In my case this will move the whole crankshaft towards the driveside, which in turn will move the conrod away from the centre line by the same distance. Is this acceptable or should I look for a way to reduce the endplay from the other side, i.e. the driveside and what would be the correct method here?

TommoT · Post by **TommoT** » Wed May 13, 2009 4:49 pm

Disregard above, once I got my math right, I have exactly 0.020" endplay, so no worries here! But anyone has an answer to my now hypothetical question? I wouldn't mind being in the know. It will be a strange world if I don't stumble over this problem again, after all a few projects are waiting on the shelves!

itma · Post by **itma** » Wed May 13, 2009 4:58 pm

I have in the past used a bronze crankpin washer faced down and loctited to the TS flywheel cheek.

It would be the new bush at fault, as the later ones should not be moved in or out like the early ones, but faced off on the inside.

TommoT · Post by **TommoT** » Wed May 13, 2009 5:06 pm

quote:
I have in the past used a bronze crankpin washer faced down and loctited to the TS flywheel cheek.

It would be the new bush at fault, as the later ones should not be moved in or out like the early ones, but faced off on the inside.

got it, but my question was if I have to worry about centering the conrod in the crankcase mouth. If I move the crankshaft over to the drive side the conrod will move with it. Is this something to worry about or is it of no significance?

itma · Post by **itma** » Wed May 13, 2009 8:38 pm

well, I have never worried overmuch, the rod gets pulled over anyway when the nut onthe drive shaft is done up... its free to move along the gudgeon pin; as long as the whole lot revolves freely and smoothly when its all bolted up[oil pump in] I can't see a problem.
20 thou is only half a millimetre.
IKBA as some folk say.

TommoT · Post by **TommoT** » Wed May 13, 2009 10:17 pm

Thanks Ken, I guess you're right, over analyzing and thinking up problems is easier than to solve them! If it ain't broke...

Peter Lecompte · Post by **Peter Lecompte** » Tue Sep 25, 2012 2:16 am

Hi Thommo, I am just putting together my 1950 Matcless G80 engine. When assembled I get 0.045" crankshaft end float. I have the washers between the drive side bearings, new big end bearing and newly fitted timing bush. I have read that 0.020" end float is correct for this engine? So I need to move the timing bush inward? I haven't pinned it yet so it is possible. But how do I do this... Do I need to heat case and drift the bush inwards by about 0.025"? Or can I do this at room temperature? Will this affect my oil pump allignment with timing axle? Cheers, Peter

Marty · Post by **Marty** » Tue Sep 25, 2012 6:09 am

I can not see a problem with 45 thou. When the shock absorber is fitted the crank assy is pulled to the drive side and locked in. If the rod is central in the cases when tightened, I would leave it. I consider the 20 thou endfloat to be a minimum, not maximum. Within reason of course.
Marty

Peter Lecompte · Post by **Peter Lecompte** » Tue Sep 25, 2012 11:46 pm

Hi, i was able to drift the bush inwards by 0.025". I did this by using an old bush as the drift and placing the assembly driving axle downwards. The old bush is the perfect size and a reasonable hit was able to move the newly fitted bush. Constant measuring of the end float made sure that I did not go to far. I am happy with the result and the oil pump still fits nicely in the timing bush cut-out. Learning everyday. Cheers Peter