PCABE5
Platinum Member
I found this: Shear strength is typically 60% of tensile strength, and the minimum tensile strength of a grade 8 bolt is 150,000 psi.
A M14 diameter bolt is near the equivalent to a 9/16" SAE bolt. A grade 8 9/16" bolt has a proof load of 21,850 lbs and a clamp load of 16,388 lbs. Using 60% of clamp load as in this application yields 9,833 lbs per bolt. Eight (8) times 9,833 lbs equals 78,664 lbs before the lug bolts and hubs will move, fatigue and fail. So assuming 3,300 lbs on the front axle, the bolts will provide a safety factor (excess capacity) of nearly 24x before failure. For you engineer types... please validate this assumption.
If I did my math right using a 9/16 or .5625 diameter bolt.
UTS - 150,000 psi
USS - 150,000 x 60% = 91,000 psi
Shear (for specific radius)= 91,000 x (pi x .0791) = 22,600 psi
Now clamp load is entirely different. This deals with you torquing the bolt to spec which should elongate the fastener and create a clamp load or tensile preload.