Try switching to a SAE hardended steel flat washer instead of a split lock. They're available in various thicknesses- - - -about .080" should be about right for the main cap bolts. There's lots of them on Ebay. You could also grind one thread off the end of the main cap bolts to keep them from bottoming. I'd do both.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!