My son has an F150 that has a history of breaking wheel studs. First, some background. It is a 2000 4WD we bought when it had 187000 miles in July of 2016. He is running 20" slightly aggressive mud tires with 1 1/2" spacers and a 6" rough country lift. When we got it the front end was about wore out so we replaced all front end components, ball joints, tie rod ends, pitman arm, idler arm and wound up replacing both wheel hubs. This is one from 2000 that has 12mm studs, that year could be 12 or 14. We also rebuilt the 5.4 Triton which is irrelevent. During that time he had several studs to break. We didn't to begin with but we have since torqued all lug nuts to 100 ft/lb every time. The spacer nuts are at 150 ft/lb as determined by the machine shop that made the spacers. We've never had a spacer stud to break, it's always the truck studs and it's usually been the front end moreso than the rear. We thought we had it resolved by torqueing them til yesterday when he felt the front end begin to bounce. We wound up replacing 3 on one side then. We checked the other side tonight and one of them was broken. Tonight we took everything back off and applied some blue loctite to the truck studs and retorqued everything. We've tried 2 different torque wrenches and both seem to be the same. What else could be causing this? Everytime it happens the studs break right at the bottom of the wheel even with the inside end of the nut and the nuts screw right off by hand with no damage to the threads.
Thanks in advance for any suggestions.

 

I would guess it's the wheel spacers. They put a tremendous amount of lateral tension on the wheel studs.

 

spacers.

upgrade truck wheel studs to a better quality . try "ARP".

you are running lots of NON stock parts.. why run "Stock" wheel studs.?

my opinion.

 

Your 1-1/2 inch spacers are changing the dynamic load on the stock studs, not to mention screwing up your front end alignment geometry, At the very least you need to up grade the studs to a larger size and ARP replacements would be a good Idea, best idea is to get rid of the spacers!