<JNiolon@uss.com> wrote:
>
> I have a Ford 9 rear end connected to the frame of my truck with ladder
> bars (3 points of mounting) Considering the type load the suspension will
> put on these bolts (shear, I would assume ?) what is the best type bolt to
>use. I currently have grade 8 3/4 bolts and lock nuts in place <...>
What was there originally? Do the bolts pass thru a "U" shaped channel
with the bar located in the middle of the "U"? If so, the bolts are in "double
shear" and not subject to bending loads. If not, then they are in single
shear,
and take a lot of bending... You really shouldn't use Grade 8 in single shear
and probably not in double shear either. The suspension mounts tend to see
a lot of cyclic/dynamic loads which from my knowledge is not where you want
Grade 8 bolts. But on the other hand, Grade 8s are stronger. If they are
passing
thru the "U" then they are acting as clamps on the bushings, and not pivots.
3/4" bolts are pretty hefty no matter what grade. Many people are driving
around with aftermarket Grade 8 bolts in their suspensions without any
problems.
Many more suspensions (most OEM) are using Grade 5 without problems...
I'd use what the factory used (probably, but not necessarily Grade 5), or go
for the proper AN series bolts. I just tend to buy replacement suspension
bolts at the appropriate dealer - yea, I pay more that way, but at least I
know that I have the right bolt...
<standard disclaimer>
But then again, that's just me, and it's you truck and your life. And although
my degree is in Aerospace engineering, I'm not a certified engineer...
Heck, I do computers now instead of engineering - and that was nuclear
reactors, space shuttles, and ICBMs... 8-)
</standard disclaimer>
Tim Mullen
Chantilly, VA
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