I'll post the same here as on M3cutters
Quote:
Originally Posted by Redd
My key takeaways from the article were:
1. Wear showing copper is normal. The copper is an lubricating layer to protect the components. Mahle does say it is ok to replace the shells at that point.
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No, that's not correct. The bronze (copper) can show if the overlay is damaged for any number of reasons. Bronze showing does not mean imminent failure if the bronze is undamaged.
Quote:
Originally Posted by Redd
2. Due to normal workshops not having the equipment and tolerances of a raceshop, it is ok to have more clearance for the bearings.
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Wrong again. When MAHLE Motorsport state "In motorsport, the engine assembly is very tightly controlled" they mean engines designed solely for racing i.e. F1, Moto GP, WRC etc. In this environment all relevant parts are controlled to within a very small range, and in some cases to the exact micron. Anything that replaces and OEM bearing they class as "performance aftermarket". It is nothing to do with the capability of the "shop" doing the work. The extra clearance Is effectively due to having a single grade part (as all other manufacturers) to ensure the part stays in tolerance. We could ask MAHLE to produce graded bearings as per OE, but this would mean each engine would need crank and housing measured to select the correct parts. This wouldn't work. But if any distributor WANTS to do this then for sure the parts can be made. If it was wanted the parts could be manufactured to exact size with no deviation (tolerance) with individual serial numbers.
Quote:
Originally Posted by Redd
I'm not an engine expert but I am an engineer by education and interest. Corrosion wear does not bear friction marks at one specific area in one specific direction like we see on worn bearings. Only one thing does that - bearing to metal contact.
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Many innovations in engineering have been by people without a formal engineering degree :-) MAHLE has not stated that this is the ONLY failure made. I'm sure there are bearings out there where metal to metal contact has occurred. The fact remains, all parts examined showed overlay loss due to corrosion. The isn't anything unknown, feel free to research this subject, as well as the benefits of lead indium as an overlay vs lead tin copper. This subject has been discussed many times in peer reviewed papers and engineering journals.
I'm happy to put your theories to MAHLE for discussion, just drop them here or in a private message.
Quote:
Originally Posted by Redd
I think it's important to note that Mahle as the manufacturer of said bearings will of course present the information in a way that makes them look good. I work in Product Management and know when I'm reading a product brochure. So pardon me if I don't read the article the same way that some of you do.
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An interesting point. Glacier Vandervell (Now MAHLE) was the manufacturer of the bearings. However, until I released that information it was generally incorrectly assumed it was Clevite. Why would MAHLE correct this misunderstanding and then release information explaining the data? Surely it would be easier to leave everyone assuming MAHLE was nothing to do with the original parts? Given this part represents around 0.0001% of global turnover and the OE part has been out of production for around 14 years I really don't see what they stand to gain?
The document is written by one of the Race Unit engineers. He is not a marketing person and the document has not even been viewed by anyone in MAHLE marketing. The document is written as he talk. An earlier draft had additional information, including a section on the BMW grading system. Ultimately he thought it was starting to get a little too in depth as the goal was to try and present the information that would be easily understandable even to those without engineering knowledge. Maybe judge the document on its data rather than tone, of course after independently researching and validating it.