This message was posted to the DiRT list. It has some info on different bolt
grades. It could be more informative, but it is something to whet the
appetite and start some discussion on bolts and their proper uses.
Also, the skid plates bolt on. Mine were installed at the factory.
Look at http://www.hobson.com.au/class_8.htm that gives you grade 8 specs,
grade 5 should be about 1/3 less than an 8.
I've heard that a grade 5 has a higher "shear" strength than a grade 8.
Meaning a 5 is better when there is a lateral load and an 8 is better when
there is only tension on it. I couldn't find any grade 5 charts that list
shear strength like your chart does, but I did find this Q&A on a fastener
site.
Q) What's the difference between a tension and a shear load on a bolt, and
why aren't SAE "graded" fasteners good for shear loads?
A) A bolt stressed in tension is loaded along its central axis: a tension
load can best be visualized as grabbing the respective ends of the bolt and
trying to pull it apart lengthwise (like extending a telescope). A bolt
stressed in shear is loaded perpendicular to its central axis: this can be
visualized as trying to snap the bolt in half (like a twig or stick). The
reason SAE graded (i.e., Grade 5, Grade 8, etc.) bolts should not be used
for shear loads is because the bolts are typically made from high carbon
content alloys. These alloys are very strong when loaded in the "stretch" or
tension mode, but tend to be brittle and snap when loaded in shear. Aircraft
bolts are typically made from "tougher" alloys which deliver both excellent
tensile performance and are also very strong when loaded in shear; they are
designed with both types of loading in mind. SAE graded bolts are designed
and rated for tension loads only.
John
98 Dak 4X4 CC Sport, 5.2L, Auto, Mopar Headers
<snip>
This way too I made sure I put on good quality Grade8 bolts/nuts rather than
the Grade5 most hitch places use; Just as a peace of mind(additional cost is
about $8). I not bitching; just curious why you decided to order the hitch
through the dealer. As far as the skid plates go, do they get bolted on or
welded on?
<unsnip>
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