Justin W. writes:
>The inserts that we are talking about are threaded...not press-fit. So
>they're much like the helicoil... but it's a more solid piece that is
>screwed into place.
>I would think these would be better than helicoils
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Yes, thanks for clearing that up. It helps when one knows what the actual
item someone is referring to -
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>If failure of one or two is an indication that they've all been
>over-stressed... then I guess it makes sense to replace them all. But
>would you install new threads (heli-coils or inserts) in a head, just
>because the threads of one stud stripped?
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Good question, but they have stripped for different reasons. The head
bolt/stud probably stripped because of corrosion and/or over tightening or
repeated use, not because the head pulled apart from too much pressure.
The trailing arm on the other hand pulled the threads out because of
dynamic loading exceeding the design limits of the parts involved. It
therefore stands to reason if the loading for original studs are at their
limit or beyond, then a larger area or 'bigger' stud (or less loading) is
in order. The heli-coil or threaded insert will in effect provide in the
softer aluminum, a larger area for loading, increasing the pull-out force.
The key here is that the stud pulled out, shearing the softer threads in
the aluminum. The larger the surface area (larger stud) the more force it
takes to pull it out. It would be the much the same as if you installed a
special stud, one with a larger dia corse thread into the aluminum, and a
smaller dia extended portion used for the mating part. To the aluminum it
looks like a bigger stud, so to speak.
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Steve L. adds:
>I'm very sorry, I don't buy that.
>
> I feel that these inserts are the best idea. They perform to our
>Military Standards for everything from rockets to jet airplanes to
>helicopters. I'm sure that they will more than be sufficient for my TR250.
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I'm not sure what you don't buy, the fact that the heli-coil provides an
increased pull-out force or that the insert described above isn't as good
or better as a heli-coil? As mentioned before, I wasn't aware of which
insert we were talking about. and in this case, the insert mentioned would
be superior. By the way, why didn't you supercharge the mower? I tried
that when I was 14 :-)
Barry Schwartz in San Diego, CA
Bschwartz@encad.com
72-V6/5sp Spitfire ( daily driver )
70 GT6+ ( when I don't drive the Spitfire )
70 (sorta) Spitfire ( project )
73 Ford Courier ( parts hauler )
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