SFC Replica racing - Mallory Park

I am reasonably sure that real SFC's have a bigger diameter swing arm pin, if correct, it does have to be said that they probably knew more than we do, my memory is too vague here, but when I built my Clegbiverdason, I made a 20mm swing arm pin, I seem to remember that it was because the SFC used that size?
CLEM
 
I agree that there must have been damage to the spindle to cause it to shear off. It is not a known problem, but the factory did go to a slightly larger spindle for those SFC. SFC also have the whole area of the frame strengthened around that area, but my take is that it was to stop the rear engine mounts from breaking. The needle roller vs bush choice has been discussed before, for me it is six or the half dozen, both are fine if correctly assembled and serviced. When my road SF bushes wear out I will fit the needle rollers that have been waiting patiently in the box for 25 years. It has been said that needle rollers won't last as long as bushes, but mine have been there for ages and are still fine. Bushes are easy to forget to grease.
 
I've not taken the swing arm out yet but there is (what I think is) too much side-to-side movement. Could be because the top hats have worn away or that the spindle spacer is worn too, or perhaps the frame is bent.

That's my Bank holiday work set out for me !
 
I also don't think the factory went for a 20mm swingarm spindle on the SFC because it was stronger. The pivot assembly relies on the clamping forces holding the centre spindle firmly against the frame plates.

I looked at this area on the SFQ and decided that the area bound by the four M12 lower engine bolts and engine plates, the frame tube sections between them, plus the rigidity of the swingarm mounting plates and properly tightened swingarm axle is more than adequate. My only mod was to use thicker engine mounting plates.
 
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