On Mon, 14 Jan 2008 14:54:01 -0800, Jon Danniken wrote:

Howdy,

I recently purchased some (metric) bolts to attach a receiver hitch to
my Jeep. While the factory doesn't specify the grade, the nuts they go
into have a six (or possibly a 60) on them.

I didn't purchase the bolts from the stealership, because they want
$11.00 (eleven dollars) *per* bolt, so I bought them from Fastenal
instead.

When I bought the bolts, I got them in a grade 10.9 (metric).

Earlier today, I came across a discussion on a Jeep forum where someone
alluded to their belief that higher grade bolts would be too "brittle"
for this application.

Personally, I think I'm going to be just fine, but I know someone here
will have something more substantial than my gut feeling.

So, do you think I should order some different bolts, or will I likely
be just fine with the ones I already have?.

Thanks,

Jon

Higher carbon steels that are hardened as much as they'll take are much
more likely to break, rather than bend.

El cheapo "high strength" bolts that are _improperly_ hardened are much
more likely to break than good ones that are tempered properly.

If a bend is a bad thing and a break is a disaster, a lower grade bolt
may be indicated, or just sucking it up and buying from the dealership.

I'd try to find out the grade of bolt called out by Jeep, and buy that,
from a reputable source.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html