At 01:39 PM 4/13/2011, neil n wrote:
>Does the nut grade matter much in this application?  I suspect not,
>but double checking.

Any time you've got an assigned torque, it was assigned with a
specific grade of fastener in mind.  So yes, it does matter.*  But
knowing the size and thread you can use a bolt torque calculator on
the web to figure out the grade that is high-likelihood what they had
in mind.  And I would guess it's probably 8.8.

http://www.google.com/search?q=bolt+torque+calculator

*Prime example is the axle nut - if you still have the old axle nuts
with six slots you're supposed to toss them next time they come off
and replace with the ten-slot ones; because if you tighten the old
ones to the new spec you'll probably wipe the threads.  Similar issue
with alternator pivot bolt on diesels.  And conversely if you don't
tighten the nut sufficiently for the grade of bolt, the bolt can
break, so you can't be *too* far off in either direction.

Yrs,
d