Brett said:
Still have a hard time believing that the nut failed in some way. I think that either it wasn't tightened properly at the factory or the sprocket material was soft and couldn't hold up to the stresses generated on it.
Mine failed at 13k (01 RC). I was the last one to torque it down (by the book I might add) 3000 miles before the failure. When I pulled it tight according to the manual it didn't "feel" as tight as I would expect, but then, I've had that happen before on other stuff with no ill effect. Apparently my experience was right and the book was wrong that time
My best guess based on the torque-to-yield spec on a new retaining nut versus a simple torque on a re-used one, is that you really shouldn't re-use that nut in the first place. Torque-to-yield assumes some "stretch" in the fastener when making final adjustments. I figure the nut is weakened after being used once and you're rolling the dice on re-using it. If the threads give out, that locking bracket doesn't do you any good. Sooner or later, regular engine vibration will pound on those threads and the assembly will start wobbling, first wiping out the oil seal, then breaking hard parts the longer it stays that way.
I was fortunate not to have damaged the output shaft or bearings. New sprocket, seal, and retaining nut and everything's good. The symptoms were the trans oil leak followed soon with a mild vibration as speed increased.