Bill Miller wrote:
>
> I don't believe this is correct. Everything I have ever been told, and from
> what I have read on ARP website and others is that you should:
> first; chase and clean the holes. Second; well lubricate the studs. Third;
> FINGER tighten the stud only.
>
> Not being an ME, I really don't want to start an argument, but from racing
> to street, I've never heard to torque a stud, just the opposite.
I'm not entirely sure about either of these requirements, but I'll offer
some possible reasons for both. In the case of the methodology Randall
cites, torquing the stud may be necessary in any case when the stud is
not further retained by a nut. If the stud acts as a hanger or locator
and there is no nut, the need to torque it would be apparent, and the
only means of doing that would be to bottom it in the thread bore.
However, when the stud is used to retain something in conjunction with a
nut, when the nut is torqued, the stud will engage all threads (both the
body studs and the nut threads) and the loading on all threads will be
according to the torque applied.
Moreover, if a stud, used with a nut, is bottomed in the bore and
torqued, the stud itself at that point is loaded in compression.
Torquing the nut then loads the stud in tension. I have the feeling that
the effect of that would be a reduced total load on the stud, even
though the individual torques of the stud into its bore and the nut on
the stud are to specification.
The other concern about driving the stud into its stud bore to lock it
is the matter of initiating cracks. One of the required specs of a
high-strength fastener is that it have rolled threads, to minimize
failure from cracking. Trying to lock the stud into its bore by running
it out of thread could have the effect of creating microscopic
deformations which could be starting places for cracks.
Cheers, all.
--
Michael D. Porter
Roswell, NM (yes, _that_ Roswell)
[mailto:mporter@zianet.com]
The gulf between content and substance continues to widen....
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