>>Ed Devinney writes,"
>>The question is what bolt strength to use: Grade 8 may be strongest
>>overall, but in this use do I actually want Grade 5, to allow some
>>stretch rather than having them shear? My mechanical-enginerd friends
>>and I went round on this, but we figured the race-volk would know
>>best. Any takers?
>Ray W. James replies
>Ed..it is a technical question, not a race question; listen to your
>mechanical e-nerd friends.
**SNIP a good explanation of Gr 5 and 8 bolts**
>the deformations in the other components. Note that whether a bolt
>"shears" or "stretches" (fails in tension?) depends on how it is
>loaded, not on what grade of steel is used.
If his system is designed properly the bolt will only see a small
portion of the applied load as long as the bolted joint remains
preloaded (read Shigley or your favorite ME design text). Since a Gr 8
bolt can be preloaded to a higher torque, it makes sense to use a Gr 8
bolt to ensure preload is not exceeded.
>Finally, the question is probably moot, unless the bolts represent the
>weak link in the system (ie., something else may fail first.) If bolts
>are the weak link, then it sure makes sense to use the higher strength
>bolts!
As a mechanical_enginerd who makes his living analyzing structures and
bolted joints, I agree with Ray here. The question is moot. I believe
you will die before you fail the bolts if a well designed harness is
used with appropriate anchor points and the bolts are torqued to
correct values.
Also
Mike Burdick writes
>engine at 1296cc. The Mk4 Spitfire got a new (heavier) body while
>retaining a 1296cc engine. This car was only available 1 year in the
>US (1971). For '72, the Spitfire got a 1496cc engine and was called
>the Spitfire 1500. If you are interested in a more detailed history,
>the book by Lindsay Porter on the Spitfire and GT6 is worth reading.
Check your Porter. I believe the '72 is a Mk IV and had a 1296 engine
as that is what I own. Spit 1500s were '73s.
Regards,
* Pat Willems * "When I started programming we didn't have *
* pbw@chong.dseg.ti.com* any of these sissy `icons' and `windows'. *
* Applied Mechanics * All we had were zeros and ones--and sometimes *
* Texas Instruments * we didn't even have ones." Dilbert *
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