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E90 M3 (Sedan) | E92 M3 (Coupe) | E93 M3 (Convertible) (2008-2013) {Engine: S65 - Max Hp: 414 hp (420 hp Euro) at 8,300 rpm / 295 lb/ft at 3,900 rpm}

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Old Mon, Jan-02-2017, 08:16:34 PM   #23
2008 M3 - Red
Join Date: May 2008
Posts: 846
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Default Re: New m3 and rod bearings

Originally Posted by Rez View Post
Assuming that majority of cars with original BMW bearing won't fail, almost all the bearings removed looked "bad". The question was asked because the original bearings are largely being judged by their appearance, excessive wear. It is not clear if any of the bearings that were replaced were distant to fail, it is mainly an assumption.
Many bearings that have been replaced have been deemed on the verge of imminent failure. Beatings that are wiped all 180 degrees down to copper are on the verge of imminent failure. There's been plenty of these seen.

It is nice to look at the graphs and analysis that you provided but the ultimate proof is cars with BE bearings showing statistically less failure than original ones. I am also curious to see how they look compared with original ones after similar mileage of driving.
It will take a few years before anything like this will be available.

Originally Posted by Rez View Post
Why would you think BMW did not do what you have done with all their resources and reputation on the line? Why would they spec the bearings so tight for it to fail on their super expensive engines?
I believe BMW bought into a bunch of politically correct engine designing philosophies. Tighter clearances are known to make the engine quieter, and known to get slightly better gas mileage. Given idiotic government meddling and micromanaging in the auto industry, if you were BMW and about to introduce a very low gas mileage, high strung, naturally aspirated V10/V8, you might be willing to do anything you can to mitigate the political backlash from the EU snobs and American EPA. But in the process of going this direction, BMW chose a clearance that is far under industry recommendations and best practices. Long established engine designs, and those recommended by Clevite themselves, are to use 0.001 inch clearance per rod-journal inch diameter. BMW chose roughtly 70% that value (0.00071). Some engines have been disassembled and measured at less than 60% that value. Most engine builders consider that dangerously too little clearance.

To your second question: why didn't BMW do what we did? I personally believe they would be slapped with a class action lawsuit the moment they changed the design to "fix" it. If they quietly changed the clearance to industry accepted best practices, everybody that doesn't have those bearings will now demand them. A class action lawsuit would be launched almost immediately IMO. It's probably cheaper for BMW to wait out the warranty claims, replace engines under good will, than to go through a class action lawsuit, lose, and issue a recall for 65000 engines. So it's pure business economics why BMW wouldn't do it IMO.
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Discussing New m3 and rod bearings in the E90 M3 (Sedan) | E92 M3 (Coupe) | E93 M3 (Convertible) (2008-2013) Forum - {Engine: S65 - Max Hp: 414 hp (420 hp Euro) at 8,300 rpm / 295 lb/ft at 3,900 rpm} at BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)