Re: [alfa] head nut torque

[hagen_jason@xxxxxxxxxxx]

As a ex-mechanical engineer, it basically comes down to the difference between kinetic friction and static friction.  The idea is to be torqueing a bolt while it is still experiencing kinetic friction, which has a lower coefficient/magnitude relative to static friction.  Kinetic friction levels are also more reliable and repeatatble.  So, yes, you want to loosen the nuts a couple of turns (ideally take off the nut and lube it to ensure that it stays in the kinetic friction "zone" and retorque in a continuous motion without stopping along the way.

By the way, static friction is higher, right!  This is why you want ABS because the minute you start skidding, you are in the kinetic friction zone and are not going to stop as quickly!


--
Jason Hagen
Chicago, IL
'73 Spider
'95 164Q
> >>I seem to recall this procedure was discussed recently, and certain
> Alfisti
> expressed strong feelings about whether or not the nuts should be
> loosened.<<
> 
> My understanding is that a torque wrench only gives an accurate measure of
> of torque when moving smoothly. The idea of cracking the nuts off first is
> to ensure that the torque wrench is moving to give an accurate reading.
> 
> Personally yes I would crack them off, but only by a tiny amount, and not
> enough to allow oil to easily get between the nut and the washer.
> 
> All the best
> 
> Keith
> --
> to be removed from alfa, see /bin/digest-subs.cgi
> or email "unsubscribe alfa" to majordomo@domain.elided
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided