In my 20+ years of racing, building and servicing Legends cars, I have heard all kinds of theories.
Theory #1: has always been "oil starvation" for the #2 rod. I have a hard time believing that theory...
If there was an oil starvation issue for #2, then there should also be the same problem for #1 since they both oil from the same oil galley. But #1 always looks fine.
Theory #2: The engine gets so hot, the case is flexing. This somehow puts undo pressure on the #2 rod and it spins the bearing.
How does the engine only flex in one specific area and cause that single rod to spin the bearing and the others are unaffected?
If there was that much "flex" why don't we break more crankshafts?
Theory #3: #2 is the "hottest" cylinder due to the way the engine is put sideways into the car. That additional heat causes excessive expansion of the rotating assembly, including the big end of the rod. This expansion allows the rod bearing to spin.
I guess that one just seems unreasonable, especially if the oil temps are controlled in the low to mid 200* range.
As far as I can tell, it is just one of those things. I have seen each and all rods hanging out of the engine. From #1 sawing the alternator off the engine to #4 blasting the clutch basket into pieces.
Randy -
RPM