The *proper* method to re-use if you can't TTY would be to use a torque wrench and use lubricated torque values for M10; you'll have a decent clamp force and won't damage the bolt, it will be on the order of 7000 vs 9000# clamping force, which clearly has been working 'ok' for 'most everybody'.

(the reason for using lubricated torque, other than the bolt will likely be auto-lubricated on a 17 yr old car, is that without lubrication the torque to clamp force changes each re-use, so you either have to add torque or you'll lose clamp force).

My personal estimation is that the 9000# spec is more than needed and that if everybody just torqued the re-used bolts to normal spec or close, maybe a little higher, but not close to yield.

In my testing, I didn't get to yield until about 105 N·m so it would probably be pretty safe to use a dry torque of 80 N·m or such (again, i plan to experimentally derive some useful numbers).

Here's the idea: until you get to yield there will be a little bit of internal deformation but not much; if you pull to say half the way to yield strength, (10% over normal torque), especially if you start with a new bolt, coincidentally the math just worked out to 54 N·m to achieve that level of tension. (almost identical to the 56 N·m from design spec).

I'm very curious about the 56+45° solution it's a great hypotheses and definitely deserves testing. I'm sold on the just use bigger bolts properly torqued though it's too nice of a coincidence to get the same clamping force as design with normal torque, i call it kismet.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)