> That all depends on so many things. Torquing a bolt is not very precise no
> matter what.
No argument there.
> If you have a hard washer, good lube, and clean bits the
> stretch you get from a given torque can be much greater than dirty bolt,
> soft washer, no lube.
Quite true, which is why good torque specs also specify the condition. Most
(not all) OEMs specify clean, dry, original quality hardware ... somewhere, if
not where the torque specs are given. Again, I was taught to assume clean & dry
unless otherwise specified.
> That's both good and bad--stretch is what breaks the
> bolt (close enough anyway). If you really want answers about this kind of
> stuff you need Carroll Smith's book on fasteners.
Got my copy of "Screw to Win" right here. But he's really addressing a
different area, that of engineering fasteners, not of following the OEM's
specification. I was talking about how to follow the OEM's specification.
Try it the next time you torque a head nut down dry. Stop 5 ftlb short of the
goal, and then try to turn it again. Many times it won't turn at all. But if
you back it off and turn all the way to the goal, it will turn farther.
Randall
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