Rebuild Testing
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I don't see how increasing the side clearance is going to help prevent the rod from twisting. I would expect the opposite. The tighter the side clearance, the less room there is for the rod to twist. The twist would be restrained by the washers, right? Which would, of course, start wearing the washers.
Unfortunately, I don't have much to offer on what the problem really is. I'd have to be looking at #4, but it seems unlikely it was a BAD bearing. Especially considering this is apparently a recurring problem. My first thought is that it flat out isn't a strong enough bearing, not capable of carrying the load it's seeing. This is reinforced by the fact that many of the 450's are what are dying. The 440's are lasting a lot longer.
I like your observations that it may not be an oiling problem, too. You can only tell that be looking at the parts, which I can't.
Unfortunately, I don't have much to offer on what the problem really is. I'd have to be looking at #4, but it seems unlikely it was a BAD bearing. Especially considering this is apparently a recurring problem. My first thought is that it flat out isn't a strong enough bearing, not capable of carrying the load it's seeing. This is reinforced by the fact that many of the 450's are what are dying. The 440's are lasting a lot longer.
I like your observations that it may not be an oiling problem, too. You can only tell that be looking at the parts, which I can't.
does it say the bearing manufacturer on the race?
i think i remember winky saying something like they regrind the crank pin when they balance them to within .0004". that is a HUGE tolenance for a needle bearing. if you could mic the crank pin and get the bearing # maybe a bearing store could give you the bearing ID.
i think Nrath is right about the side clearance. more would make it worse. and lack of oil would create heat, and from the pics it doesn't look like it got hot.
could it maybe be a piston/wristpin issue? something could be slightly out of line thus putting undo stress and binding on the big end bearing? i don't know how far back these failurers date to but it seems like just recently(last few months) all the 450's are dropping dead. is everyone using the same pistons? bad production run? is anyone running a 450 without a winky crank?
i think i remember winky saying something like they regrind the crank pin when they balance them to within .0004". that is a HUGE tolenance for a needle bearing. if you could mic the crank pin and get the bearing # maybe a bearing store could give you the bearing ID.
i think Nrath is right about the side clearance. more would make it worse. and lack of oil would create heat, and from the pics it doesn't look like it got hot.
could it maybe be a piston/wristpin issue? something could be slightly out of line thus putting undo stress and binding on the big end bearing? i don't know how far back these failurers date to but it seems like just recently(last few months) all the 450's are dropping dead. is everyone using the same pistons? bad production run? is anyone running a 450 without a winky crank?
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Okay there was no wear at all on wristpin.I think the tighter sideclearance could be a issue since with a tighter clearance if the piston is slightly cocked in bore AND the crank walks back and forth which we know it does this would either **** the rod or put alot of pressure onto thrust washers which arent designed for that much.With a bigger clearance the rod could just slide over.All really just theories but very possible.Combine that with the fact Cannondale made ALL the cranks with big clearance and the fact that my clearance grew to almost same as stock crank and it isnt so easy to dissmiss.
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