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      12-07-2012, 03:12 PM   #69
Private First Class

Drives: 2011 E92 M3
Join Date: Dec 2012
Location: Baltimore, MD

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Originally Posted by m3an View Post
saying it doesn't stand up to basic physics is a stretch as there is def noticeable damage (albeit hard to see) to the finned/heat sink on the diff...Solution= move on...
I respect your viewpoint but I honestly can't fathom how you think this way. The only damage to the differential is in the photograph. So we are talking about a 1/4" area of abrasion.

We know the material (aluminum), a professional engineer would know the exact type, it is then simple to calculate impact velocity to cause that kind of deformation. Because the deformation is so minimal that value is low, associated with a rock or pebble. So that's X.

We know the material of the bolt (high tensile steel), an engineer can calculate exactly the force required to shear that bolt at that thickness (in non-technical terms, A LOT). That's Y.

So we know X < Y. Dealer claim is invalid. For some of you that's not good enough or for some reason you want to speak in relative terms that are not objectively true, which really confuses me, e.g. "there is some damage." Well yes, there are rock chips on the bumper too.

We can then calculate the deformation of the aluminum differential cover when impacted with Y amount of force. As lay people we speculate with some confidence that it would destroy the entire cover. An engineer would be able to tell you exactly how much, that's Z.

So we know that X < Y, this is objective. And we know that to get Y we would have needed to observe Z, but we don't observe Z, we only observe a 1/4" abrasion.

When it is so objectively cut and dry that you're in the right, why would you "move on"?