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      12-28-2016, 09:23 AM   #14
deansbimmer
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Quote:
Originally Posted by JoeM3SSII View Post
replacing main bearings is not a DIY it's more involved. Besides all what he did is to make himself feel better. There is no evidence that this type of bearing wear correlates with engine failure at all, the link only exist in people's mind not in reality. Each engine crank will leave its own footprint on the bearings. This is why the wear is not homogeneous from one bearing to the next. In other words he paid $$$ for a big placebo. The reason for this abnormal bearing wear is BMW design removed too much mass from the crankshaft and it vibrates and distorts too much.
So let me understand... Your opinion is that these bearings didn't need to be replaced and the owner wasted his money on a "placebo" service?

Also, it's an almost universally held understanding that the S65's bearing wear is due to low and inconsistent bearing clearances, but you believe it's actually due to a lower mass crankshaft design and resulting distortion? Where is the evidence and documentation for that school of thought?

I have observed first hand bearing wear similar to that of the first post in dozens of S65's that I've serviced, upgraded, or dismantled. The bearings worn that far into the copper were either next to other bearings that seized, or were present in engines with main bearing seizure. So to call the service an unnecessary placebo cure or to dismiss the mains based on an unfounded belief seems quite foolish when so much documented evidence suggests otherwise.
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