Quote:
Originally Posted by oldskewel
Put aside common practice, standard practice or whatever and focus only on the bolts. The bolts are torque to yield bolts. Torque to yield bolts are designed to be used only once, never reused. It doesn't matter where they they are installed.
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on the attempt to clarify terminology. That usually helps. But while we're trying to keep the discussion precise and positive, I'll point out an error in your second sentence here.
"The bolts are torque to yield bolts."
That's not true. They are regular M10 - 1.5 x 55mm, class 10.9, hex head with captive flat washer, and a 10.9 hex nut with flange ... nuts and bolts. Some bolts are specially designed to be used in a torque to yield application, for example with a long unthreaded reduced diameter neck, so all the yield happens there rather than in the threaded section. These are not. They are regular bolts.
Never heard they are standard bolts before. Where did you find documentation? Great! Anybody have a link to the exact bolt?
BMW specifies that they be torqued using an initial torque plus an angle. TTA. They also specify that they be replaced when removed, which suggests that they are TTY, or torque-to-yield (that following the TTA spec will cause plastic deformation). But it is not 100% certain that they yield when following the TTA specs. To be careful, I assume they do.
Didn't you just write that you assume there is plastic deformation (stretched to point they won't return to original specs)? That means they are not reusable. Standard or otherwise. If there is plastic deformation they should not be used again as the clamping power will be less than spec. We can't be 100% sure but oh well?
So in short, there are regular bolts that may be used in a TTY application.
So BMW states the torquing process of a TTY bolt just for grins, so forums can debate this forever?
Carry on.
EDIT - and a similar situation I thought of just now is the breakaway bolts on the auger shafts of my Honda snowblower. They're sold by your Honda snowblower dealer as special bolts, and when I bought the blower I bought a 10-pack for convenience. But as my supply dwindled and I looked into it, they are just M6 hex head, Class 8.8 bolts. Not even annealed or anything. Regular bolts, used in a breakaway application. Which makes sense, of course. Why make something special (like an annealed M10 when you can just use a standard version of a regular bolt). Same idea.[/QUOTE]