Grade of Nuts?

[Afazz]

I'm in the process of ordering nuts and bolts for the suspension system on our car, and someone brought up the fact that when using grade 8 bolts with grade 5 nuts, the entire setup will only be as strong as grade 5 bolts/grade 5 nuts. I can see how this would apply in high-torqued nut applications where parts rely entirely on friction to keep them together, but is this still true in a-arm mountings (i.e. rod ends in double-shear between two tabs)?

Would I find an answer to this in a machinery handbook or something?

[Afazz]

I'm in the process of ordering nuts and bolts for the suspension system on our car, and someone brought up the fact that when using grade 8 bolts with grade 5 nuts, the entire setup will only be as strong as grade 5 bolts/grade 5 nuts. I can see how this would apply in high-torqued nut applications where parts rely entirely on friction to keep them together, but is this still true in a-arm mountings (i.e. rod ends in double-shear between two tabs)?

Would I find an answer to this in a machinery handbook or something?

[Rob Davies]

I would say in that load case the overall strength is much more dependent on shank strength rather than bolt strength.