Spacer disc between primary cover and crankcase

[route 66]

So guys,is it only bikes with the enclosed chainguard that have the spacer? I'm building an engine from bits and I've spent ages lapping in the joint between the primary case and the crankcase.Was that work all in vain? There are 2 gaskets listed,does one go either side of the spacer?

[muskrat]

G'day Route66.
My 56-57 s/a has one without the chain guard. Yes there's a gasket either side of the disc.
On mine I use a 1mm washer between the inner case and frame mounting lug.
Cheers

[route 66]

Thanks Musky,I suppose I could have gone to the garage and looked at my flash

[bikerbob]

I have a 1956 A7 S/A model with the fully enclosed chaincase. I had to remove the spacer because it was putting to much stress on the rear chaincase with the spacer fitted, the rear of the chaincase was pressing against the rear frame mounting and when tightening the crankcase bolts you were in effect trying to bend the casing. Removing the spacer I then had a slight gap between the casing and the rear frame mount which I filled with a suitable washer. It would have made no difference if a chaincase was fitted or not, I know the front section of the enclosed chaincase bolts to the rear of the rear chaincase using the sliding plate bolts and that is the only difference in fitting a fully enclosed chaincase you have longer bolts for the sliding plate.

[Colsbeeza]

That seems odd Bob, My 61 Flash has the 2.3mm engine spacer with a gasket either side. I have to use about 1-1.5mm washers for the gap between chaincase and rear mount.
Col

[bikerbob]

This was about 7 years ago and I only discoverd it when I had to take the engine out to renew the timing side bush, I noticed that with rear mounting bolt in place the rear chaincase was not parallel with the crankcase only a small amount but if I removed the spacer everything lined up perfect, so I left it out as I did not want to put undue strain on the rear casing. I did think maybe the rear mounting was distorted but could not see anything wrong and it has run OK for the past 7 years. I di d have a 1957 Gold Flash some 25 years ago and it had the spacer in.

[muskrat]

G'day Bob.
Sounds strange, mine is the same as Col's. Every one I've seen has the plate.
Three possible causes. Motor not square in the frame, bent engine plates or bent frame.
I know my frame is straight (Laurie Alderton) and made my own plates out of durallium plate.
Cheers

[bikerbob]

I take your points Musky but I have had both engine and gearbox out and when I refitted them everything lined up Ok if either the frame or plates were bent then surely I would have had a problem getting the mounting bolts to line up, I had no such problem.  When I say the rear casing was not in alingment with the crankshaft I stress this is only a very tiny amount and I could fit the spacer only I felt that it was putting stress on the casing so I decided to leave it out and fit a washer between casing and  the rear mount this washer is only slightly less in thickness than the spacer. It also solved another slight problem the rear of the 6 spring clutch had been rubbing slightly against the rivets on the sliding plate now this no longer happens.

[morris]

If it’s of any comfort to you, I had the same thing happening on the SA after a gearbox/engine out job.

[orabanda]

Musky makes a good point re alignment of engine to gearbox.
It should be checked; can be out for any or all the reasons he listed.
I am currently re-aligning this bike; the engine sprocket - clutch alignment is significantly out; indicated by the wear marks on the clutch sprocket.

Alignment of rear wheel sprocket with gearbox sprocket should be checked first.
Rickity Dick

[sean]

Without the spacer, you need to make sure the 3x 5/16" screws holding the front section of the outer cover do not protrude through
the crankcase too far & foul the crankshaft.

someone in my motors previous life used a longer 5/16 screw which lucky for them bent over when the flywheel came round but they must of had a hard time starting it as the bolt was rubbing on the flywheel apart from a groove on the flywheel no other damage when I stripped the motor and rebuilt it .