>I second the notion of using inserts instead of helicoils... but what
>I'd like to know... from someone who's really in-the-know... would it
>be wise to just go ahead and install inserts on the whole arm? Or
>should it be only done on those that are obviously damaged or suspect?
>I guess, in other words, is an insert better than no insert, in this
>application?
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I'm not sure which inserts are being discussed (so I may be off base here)
, but I can say (I've been a mechanical designer for over twenty years now)
that unless this type of insert is installed from the backside of the hole,
and the insert has a flange more or less clamping the parts together much
like a bolt and nut, then it won't be as strong (pull-out force) than a
properly threaded or heli-coil inserted hole in this application. Most
press in inserts I've seen are for sheet metal or for plastic molding where
it is ultra-sonically 'welded' into the material. I've yet to see one
strip the threads when it fails. Typically the insert pulls out. A
pressed in, blind hole application (installed into the same side as the
fastener is installed) depends solely on the material being displaced and
cold forming around the insert to secure it in place. The heli-coil offers
more resistance to pull-out, as long as there is enough material around the
repair, by providing a larger surface area (bigger threaded hole, in effect
a larger stud) than the original one. Also, if you are having studs pull
out then yes, fix them all by repairing them all because if you already
lost a few, then, 1. the remaining studs have been stressed more than they
have been designed for and 2. the design is too highly stressed to begin
with.
Just my two cents worth -
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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