Quote:
Originally Posted by Green-Eggs
There's a new and "shocking" development for the people following this thread and the BMW S65 rod bearing issue. After 10+ years, BMW has finally published their rod bearing clearance specifications. To put it mildly, the specs are shocking and are worse than we had imagined.
Every time a new TIS is published, Bert checks to see if BMW has finally published the rod bearing clearance specs. Such was the case last week when Bert was researching the rod bearing specs for S63 motor. That's when Bert pulled up the S65 engine specs, and noticed that they finally contain rod bearing clearance. [ LINK]
The specs aren't good and confirm a worse-than worst case scenario. When Van Dyne measured the original bearings @ 0.0013 inch, they didn't imagine that was at the top end of the clearance specs. Stewart Van Dyne gave the following comment over the phone: "Well, BMW just confirmed that they're doing what we all know doesn't work."
Minimum clearance: 0.0004 inch
Nominal clearance: 0.0009 inch
Maximum clearance: 0.0013 inch
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Thanks Green-Eggs, how interesting! Yeah certainly seems to be on the (extremely) tight side and assumingly a good reason to the wear issues we see. BMW engineering certainly been around so bit of a mystery.
These numbers also make me curious about your own measurement of BMWs shell which comes out with quite a bit more clearance?
Nominal Rod Bearing Clearance 0.0381mm
Bearing Clearance Variance 0.0292 - 0.0508mm
Just trying to understand what we're comparing here.
Thanks