crankshaft pin question

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funmachines · #1 Post by **funmachines** » Tue Jun 05, 2007 8:33 pm

I'm new to these motors, but I understand the problems that the rod bearing can cause (my X440 has bits of metal in the oil - bad stuff). Anyway, my question: is there any influence of the hardness and/or heat treat of the crank pin? Is it the bearing elements that are failing or is it the crank pin from excessive loading? It would seem if it was the crank pin a harder/better yield strength pin wouldn't get chewed up even if it has higher pressure loading from fewer bearing elements. I'm sure this has been looked at before but I never found anything in my searches.

If the bearing elements themselves are failing it of course wouldn't make any difference.

Just curious...

Happyboy · #2 Post by **Happyboy** » Tue Jun 05, 2007 8:47 pm

Neither of what you said is the problem. The cage of the bearing is actually rubbing on the pin and rod. The z400 bearing actually has 2-3 more rollers than the stock bearing adding more bearing surface contact and keeping the pin further away.

funmachines · #3 Post by **funmachines** » Tue Jun 05, 2007 9:33 pm

Thanks - now I understand. That's worse than I thought.

Happyboy · #4 Post by **Happyboy** » Wed Jun 06, 2007 12:26 am

Yeah, its a nasty little bug.

wistech · #5 Post by **wistech** » Wed Jun 06, 2007 3:43 am

Yep but nothing a $40 bearing could fix permanently if you were smart enough to do before failure.