--- In
DSN_KLR650@yahoogroups.com, "Mike Peplinski"
wrote:
>
> Hey guys, just so you understand, harder, higher "grade" bolts are
not
> necessarily better. My limitted metallurgical knowledge tells me
that the
> standare bolt, a grade 2 (I think) is plenty hard. Just get hit in
the head
> by one. It has a certain amount of carbon in it. This bolt is fine
for many
> applications where a low cost, positive attachment is required. It
is pretty
> vibration and fatigue resistant as well. Understand that carbon is
what
> gives steel its "hardness". Lets leave it at that without going too
deeply
> into it. The grade 5 bolt is heat treated to give it additional
hardness on
> the surface. The bolt is "harder" and has a somewhat higher tensile
> (stretch) and yield (bending) strength. If the application calls
for a
> harder surface, more resistant to scuffing or nicking, grade 5 may
be OK.
> The grade 8 is actually called an alloy, higher in carbon and is
definitely
> harder, on a Brinell or Rockwell scale (higher tension and yield
strengths)
> but the brittleness is also higher so if the application calls for
some
> bending, because some attachments are meant to give a little, the
grade 8
> bolt will fail sooner than a 2. Grade 8 bolts are also typically
not used
> in a high vibration application because they stress crack.
Obviously the
> frame attachment is not meant to flex. The higher tensile strength
of a
> grade 8, or its metric equivelant, 12.5, can be tightened more and
is less
> likely to stretch and come loose.
>
>
> >From: "Robert Melvin"
> >To:
DSN_KLR650@yahoogroups.com
> >Subject: Re: [DSN_KLR650] Sub Frame Upgrade
> >Date: Fri, 17 Mar 2006 10:31:22 -0800
> >
> >Hi,
> >
> >(sorry for the confusion with my emails - Gmail has some features
that
> >have caused me some difficulty / confusion - I think I have it
taken
> >care of now. This is what I meant to send.)
> >
> >Yes, $35 is a lot of difference - but not if you have to drill a
> >hardened bolt out - especially if you are not doing so at a time /
> >place of your choosing with all the correct tools and the ability /
> >time to go back to the store for more bits, etc... Such an
experience
> >will easily cost $35 even without taking into account time, missed
> >plans, and aggravation.
> >
> >I used to have a '72 Volvo with a modified Delco alternator and it
> >would break grade 8 bolts - I finally found a Caterpillar track
bolt
> >that was supposed to be something like a grade 11 equivalent - it
> >never broke.
> >
> >However, what I would do though is put a nut on the bolt, slot the
> >thread end of the bolt with a hacksaw or grinder, unscrew the nut
> >(repairs threads a bit) and then use the bolt. On the Volvo, I had
> >access to the slotted end of the bolt after it had broken and I
would
> >unscrew it with a straight bladed screwdriver (easy), replace the
bolt