Pillow block bracket studs

[AVMECH]

81 Spider 2000, installing driveshaft pillow block bracket and broke a stud trying to reach the 18 ft. lbs. Want to replace them both, difficult to get the good one out. Put a little heat on it, did not work. Want to weld a nut on the broken end and get it out, but just want to make sure that this is just a stud in a threaded hole, and that there is no nut or anything holding it in under the carpet. Anyone replaced these?

[18Fiatsandcounting]

....but just want to make sure that this is just a stud in a threaded hole, and that there is no nut or anything holding it in under the carpet. Anyone replaced these?

It's a stud, but it's welded to the body and not threaded in. So, I'd leave the good one alone and repair the broken stud.

Probably the best solution is to drill out the bad stud and weld in a new one, making sure that you don't set your carpet on fire. Another option is to drill out the bad stud and just use a bolt with the head on the carpet side of the floorpan, but you'd have to secure it somehow so it doesn't spin as you tighten the nut that holds the bracket. Tack weld or the like.

Curious as to how 18 ft/lbs broke the stud? Was it rusted? These usually don't give much problem.

-Bryan

[AVMECH]

It was rusted, snapped as it was getting tight. I was surprised as well, not much torque. Too late for the good one, I used two nuts jammed together to try and remove it so I could match it up at the store. Now it is bent, didn't realize they were welded to the body. Thank's for the reply, I assumed they were threaded into something and lock tighted, would have gotten nowhere trying to weld nuts on it to twist it out. I see no weld from the bottom so I am assuming it is welded form the floor side? Curious way to attach the studs. If I remove the carpet, can I grind it off and reweld it from there? Figure a few good tacks would do the job. Thinking that would be better than welding from the bottom, I want the bracket rubbers to sit flush on the body.

[AVMECH]

Drilled through the stud, it's under the folded metal piece that the seat mounts to. That part seems to be welded to the floor, and there is no way to get a bolt in there without taking that off. Don't want to so that. I can see the round flat head where the floor side part of the stud is coming out from under the folded piece. Figure I have two options. 1: Drill out the shank of the stud from the bottom, tap the head of the stud up through the floor from the bottom, and put in a new bolt up from the bottom into the threaded head of the old stud with blue locktite and hope it holds the 18 ft. of tourque (I logically think it will.) The head of the old stud would act like a nut welded to the floor, but be thinner that a nut. 2: Put in a stud and weld it to the body from the bottom and grind/file around it back flush with the body and the radius of the shank. Probably the stronger of the 2 options but the most work. Thinking of going with option 1. If it dosn't work, move to option 2. Any thoughts or other ideas?

[AVMECH]

Opened up seat rail, drilled out old stud, tack welded in a m8x1.25x30 bolt, cut out enough of rail flap to allow it to go over new bolt, welded the flap back in place and primed. Seems like the best fix for this problem. Torqued nuts to 18 ft. lbs. and everything held.