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Discussion Starter · #1 ·
Hey all, i am having to clean up some rust in the bed of my 1994 Bronco (moisture must have gotten trapped under the vinyl floor and in the padding). Anyways, the seat belt bolts were pretty corroded and the Torx part was basically gone. So I cleaned the head up on one of them and welded a nut to it. Went slow and got it to move a hair and rocked the bolt back and forth. Snapped the head off. So i went to the under side, welded a nut to it, same thing. Bolt would snap where the nut was welded on. So I tried an extractor that I have, it bit in, budged a hair, then snapped. So at this point there is about 1/2” of bolt still showing on the bottom side. I’m going to have to drill it. Don’t really see any other option.
My question is, when I drill this bolt out will the seat belt anchor plate come out as well and then I can just replace the anchor plate and bolt? Or will I be able to tap out the existing one to a larger bolt? I don’t see any way of salvaging the original threads in there.
It’s super frustrating because the bronco is in great shape, no body rust or anything, just the bed started to rust from the inside out. I have a small section. That is pretty much through (3”x3”) near the seat belt mount so I’m going to cut the bad spot out and weld in a patch.

any advice is appreciated!
 

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'92 Custom w/ '95 MAF 5.0 M/T, 33's, 4.10 LSD
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I had to do some extraction on one of the center catch bolts, welding a nut onto the bottom (it broke off flush up top) and backing it out that way. I didn't have to do any of the side bolts for the seat's feet, which looks like what you're dealing with, but I would guess they're similar in setup. I would guess the backing plates are spot welded to the bed. That seems to be how everything was assembled, and that would ensure more even pressure distribution of the plates.

I can make out four round-ish marks in your first picture that bear closer inspection. If it doesn't feel like smooth metal there, those are most likely spot welds and you should be safe assuming the backing plates are fastened independent of the part you're drilling out.
 

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Discussion Starter · #5 ·
I had to do some extraction on one of the center catch bolts, welding a nut onto the bottom (it broke off flush up top) and backing it out that way. I didn't have to do any of the side bolts for the seat's feet, which looks like what you're dealing with, but I would guess they're similar in setup. I would guess the backing plates are spot welded to the bed. That seems to be how everything was assembled, and that would ensure more even pressure distribution of the plates.

I can make out four round-ish marks in your first picture that bear closer inspection. If it doesn't feel like smooth metal there, those are most likely spot welds and you should be safe assuming the backing plates are fastened independent of the part you're drilling out.
Yep I think you're right. I'm just going to drill out and retap for this side. The other side I think I will just leave the bolt and seat belt in place and work around it..... Not ideal but better than snapping another bolt and dealing this this all over. I already have two broken seat bolts for the rear sear (one on each side) as well that I'm going to have to extract one way or another.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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I broke off that same rear seat bolt on mine, which i believe is an M8 thread.

I used a reverse drill bit, which if you start with a smaller diameter like an 1/8", then step up to a 3/16, and so on, with each step up in drill bit diameter, the bolts wall thickness gets thinner, hopefully it releases & unthreads.with the reverse drill bit before you hit threads. This usually works pretty good.

If it does not unthread, you can step it up to a pilot hole diameter for a 3/8, which is a 0.358 diameter in inches. An M8 is .314 diamwter in inches, so once you drill it out to a 3/8" pilot hole (.358) the M8 disappears & then you can tap it for a 3/8 thread & buy a new 3/8 bolt.
 

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Had to drill mine out just like Rob did. From the manual, this is what I found...
 

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Discussion Starter · #8 ·
Well, ended up drilling and retapping the hole to a 1/2-13 and all seems good now. When I put the new bolt in, I am going to also put a nut an washer on the bottom side just to make sure that bolt can't work its way free. Since it's a seat belt I don't want to take any chances. If it ever needs to do it's job I don't want to risk that it can't.
 

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I have removed a million rusted bolts and I agree with Rob64's approach on this one
I would go to McMaster Carr and get a CARBIDE drill bit(s). bonus points for reverse thread
The PRIMARY issue is starting the drill so it stays on center and does not walk
Get a dremel tool and cut the remainder off flush with the tiny cut off wheel
Then (important) get the tiny ball-end bit and make a nice nick DEAD CENTER on that bolt
I would CAREFULLY start with a 1/8" CARBIDE bit, dont even need to go all the way through, in fact better if you dont in case
of small bit snapping at break thru
The last dia bit you use should be the TAP DRILL for the M8 thread (look it up)
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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I had a stubborn front seat belt anchor bolt (next to the console) that was stuck. I broke off 3 T-50 sockets and it never budged. I finally got it to come out last night, so I'll be sure to use an overly abundant ammount of anti-sieze on all the seat & seat belt bolts when i reinstall them.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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I also have this self centering drill bit kit that works pretty darn good to center your drill bit in the center of the broken off bolt. It comes in handy for the initial drill hole, cuz its never easy trying to start the first drill hole in a broken off bolt thats sub-flush. Its spring loaded amd when you push, it stays centered in the hole.

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