Shipskym

so i tore down my dana 60 front on my dually and was curious how we can get away with, a one ton that has 8 5/8 lugs and the spindle that holds that hub on only having 6 1/2 studs?

mknittle

Several factors come into play here, fastener grade and what and how it is mounted and what material it is threaded into. Also forces are big factor.

The two things that come to mind for me is the spindle sets into a counter bore that takes the vertical forces so all the bolts have to do is to is keep the spindle from coming out of the counter bore. with little to no shear the bolts can be harder with less chance of breaking. The wheel studs are subjected to forces in many directions and fully support the load. They must have some elasticity which makes them softer (less tensile strength) which needs more and thicker bolts. Then add the safety factor.

I have actually had a situation where I was breaking grade 8 1/2" bolts. The heads were popping off. I tried not tightening them so tight with lock nuts but it still broke.
Going to a grade 5 stopped the breakage. The extra give in the grade 5 allowed enough flex to not break.