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      09-23-2014, 09:45 PM   #101
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Drives: '16 F87 M2
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Quote:
Originally Posted by Freon View Post
Where are you seeing it is a "stretch" bolt? I would not think aluminum has the right properties for that. I'm betting you'll rip the threads right off an aluminum bolt before you actually get a real "stretch" tension. I cannot find any information on such a thing as an aluminum "stretch" bolt in any application.

Not saying "don't bother replacing" just challenging the "stretch" part.
I doubt the bolts are aluminum. I believe they are some type of low-grade steel. Bolted joints rely on the bolt being stressed to a high percentage of its capability... to some point of permanent deformation... in order to provide the necessary clamping force. Once you start stretching a bolt (original installation to the proper torque), re-stretching it by repeated applications of torque is simply working the bolt to eventual failure. I may have already overtorqued my bolts... I've got new ones on order. I'll get under my car in the next day or two with a torque wrench... if I set the wrench to 74 lb ft and any of the bolts move at all, I know I've found my problem.
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