Posted by Keith on Thursday, November 30, 2006 at 0:47AM :
In Reply to: Re: Maybe... posted by MoparNorm on Wednesday, November 29, 2006 at 10:46PM :
The clearest example of shear loads on a bolt on a 4x4 I can think of is on suspension parts. Leaf spring eye bolts have direct shear loads and virtually no tensile load. Ditto for control arms and related bracketry. Yet, I haven't seen any 4x4 or racing aftermarket suspension modification manufacturers sell their lift kits, shackle kits, etc with anything other than Grade 8 or comparable metric bolts. For example: http://www.rubiconexpress.com/Support.aspx?Vid=45C92303
While I've read many internet forum posts from people stating that Grade 8 bolts are "brittle" relative to Grade 5, I've never seen any credible, authoritative source (such as Fastenal) say anything like this. While you are entitled to say whatever you want about the seat of your pants, the mechanical specification charts clearly show that Grade 8 fasteners are substantially stronger than Grade 5. As far as I can tell, the only downside to using Grade 8 is cost, but when it comes to things like brakes, steering etc, I will spend a few extra dollars to ensure safety, and apparently the vast majority of aftermarket automotive manufacturers do too.
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