What are these, 1/4"? Grade 8 are 91,000 lb/inē so the loss in surface area at the threads is ... about 40%?
nominal cross section ~ ? * (.125 in)ē = .0491 inē
thread cross ~ ? * (.098 in)ē = .0301 inē
Which is the difference between 4,419 and 2,709 lbs shear.
It gets better as american standard bolts get larger:
5/8" is .625 in to .598 in is 27600 lb to 25300 lb
Well, better as a percentage anyway... being on the threads is probably more prone to fatigue and then it's whether these are under load when driving...
Guess who worked on winch mounting vs Aluminess fasteners today?
I do think the failure in the track put more shear on the pivot bolts, and threads or no, better to have those shear then the tubes fail. Have no clue what the numbers for THOSE are.