it's been a long time since, but we converted the front brakes to disc from an 80's era buick. A year or two ago, we snapped 2 studs just taking it for a spin. We just put on Weld Prostars, and now one more stud has snapped off! what the hell!

The car has seen close to 0 street use. It's been at the house under the carport being restored, or down the street at the bodyshop, but on occasion, rarely, i'll take it for a spin JUST around the body shop complex to keep everything moving.

WTH IS GOIN ON!

How about you just replace all of the wheel studs. Do you know the history of this donor '80 buick? I'd check the runout of the hub, condition of the other studs that have not broken, and lastly the runout of the wheel itself to make sure everything is true.

Nothing to do with your studs but if you got those brakes off an 80s era G body. They are quite inadequate for stopping an A body. They werent even adequate enough to stop the G body in the first place. Much to small for older cars.

what are you torquing the nuts to? if you use an air impact and rattle till they stop they will be way overtightened. Or, somebody could have done that to them long before you ever saw them. I'd replace them if more than one broke. Buy them at a NAPA store, you don't want cheap china junk from some chain store.

do the wheels have lug nuts with a long shank?
if so, make sure that the shank doesn't stick out past the mounting flange of the wheel- if they do, then the wheel never actually gets tight and has a little bit of a wobble to it.

Got new studs, and lugs, but when when you tighten everything down, and drive the car for a short distance and recheck the lugs, some of the washers on the right front tire spin freely, and lugs won't tighten any further. the other 3 wheels are 100% fine. what the hell is goin on. lol

edit: also, the brakes could be from an 80's A body or G body, FWD or RWD. I don't know which though.

pull the offending wheel off and stick a lug nut in the mounting hole in the wheel- with the washer in place, of course- and see if the shank of the lug nut sticks out past the hole. it should be a little bit below the surface- if it is flush or sticks out at all, the wheel isn't getting properly clamped to the hub and it moves a little when you drive, which loads the studs, which causes them to break.
while you've got the wheels off, screw the nuts onto the studs and see if they go all the way on. if they don't, then you either need to shorten the studs or get open ended lug nuts.