I have 3 transmission crossmember nuts installed because 1 transmission crossmember is stripped and I want to remove it, weld a new nut in its place. Has anyone done this before? What's the easiest way to remove it from inside the car. Access has been made to start.

 

Hole saw in the floor above it. Push-in plug to fill the hole afterwards.

 

I have done that task, I'm asking if anybody has removed the nut things to replace them

 

A lot of people have, drill the 3 little spot welds. Some have even used solid thread repair kits to fix it.

 

oh ok. I read an older thread regarding this topic, and it was discussed that thread repair/heli coil was not safe but I read it has worked for some.

They said just drill it out but wasn't clear where, and just was seeing what's the easiest way. Thanks

 

those fasteners are in tension, and could be under a lot of stress at times like when the car bottoms out or bounces across bad road surfaces.
can you weld or know someone that can?
the most sure fire way would be to remove both of the factory 'nuts'. cut a plate, 1/8" thickwould be fine. drill matching holes and then tack weld new nuts to the plate. then you can drop the plate & nuts in through your cut hole and tack it in place.

I'd use same-sized metric 10.8 (parts car, junk yard, spares etc) to keep original bolts & thread specs.

 

Curious if you could drill the threads out of the existing plate and weld a nut on top of the plate. use a longer bolt. I’m asking as much as suggesting. Thanks.

 

Not really. There's no "plate" there.

The factory nut is some kind of chinesium, captivated in a thin weenie sheet-metal cage, and not very thick. Which is why drilling & tapping larger (a stupid idea no matter what) or Heli-Coil, is not a good choice. There'd be nothing left of the nut to hold the larger threaded thing. Oftentimes the failure mode is, the nut splits in half; even with just the factory size hardware. (10mm). Almost guaranteed that if tried to do that to all 4, at least 1, and maybe more, would split.

The nut thing is kind of under the seat. If you take the seat out and pull the carpet back, then center punch through the nut, you can see exactly where it comes up underneath the floor pan. Then hole saw that to about 1½" or so to expose the original crap, get rid of it entirely, drill the "frame" out a little bit larger from underneath to expose more space (so as to reduce risk of the new nut being off-center to the hole in the "frame"), tack-weld in a new nut which would be easiest if it has a flange, and put a plastic hole plug in the floor pan over it.

Reinforcing the "frame" with a plate isn't a bad idea at all. I've seen it crack around the nuts, especially with something like a T-56 crossmember, that adds extra leverage to the usual force on the holes.

 

I can agree with that without contest.

 

Those nuts in the picture are solid steel weld nuts. Like a 3/16" thick washer with threads in the hole. Easy fix would be to drill and tap to the next larger size. Assuming the spot welds don't break, it'll be as strong as the original nut.

The three divots in the nut are where the nut is spot welded to the frame. If you drill through them with that size drill bit, they'll pop right off. Weld nuts are pretty common, getting new ones isn't really a problem. Getting them welded back in place with a MIG is a bit of a pain. Originally they used a tool that clamped and spot welded them in place, if there's a home-gamer version of the tool, I've never seen one.