General Tech Question. Need ideas.
 

I recently purchased a 1991 Supra Turbo. I already combed all the Supra forums and really found little to nothing. So I thought I would try my luck here. There seems to be a plethora of good quality info and knowledgable folks.

Straight to the point, this is where I need some direction:
The Supra diff was leaking, so I decided to pull the diff and change the seals/gaskets. One each on the axle side and the carrier gasket.

There are 6 bolts holding each axle, no problem here, very easy. There are 4 bolts connecting the driveshaft, no problem here either. Finally, there are 4 bolts holding the diff to the rear cross member. 2 are 17mm bolts while the 2 big ones towards the front of the car ar 19 mm. The 17s came out no problem. The 19mms were pretty rusty and I could not get them by hand, so I used a breaker bar. I got them lose, so then I started to take them out, come to find that they just spin and spin.

I did find on the Supra forums that there are nuts welded to the inside of the subframe that the bolts go into. It seems these nuts can come lose causing these to spin and not come out.

I cannot access the inside of the crossmember. I was planning on cutting the head of the bolts off and drilling out the remainder. However, that leaves me with a pretty big issue. What and how do re-install new bolts? I found some info were folks have tried liquid epoxy steel and tapped the liquid steel, BUT these 2 bolts have to be torqued to 122 lbs.

I am at a loss honestly, please help.

If you cut of the heads and safely drill out the remainder you should still be able to re-thread the hole and use it for a new bolt, may not be the same pitch but you can certainly find bolts of that size and strength

I'm thinking a cutoff wheel or sawsall?

absolutely no way to reach the nuts huh?

Ran into a similar problem when putting new leafsprings on a 90s XJ.. bolt with a welded-on nut held the leaf pack, but the unibody covered any access to it in the unfortunate event as similar here- snapped the weld. Barbarically fixed it by cutting a slot into the unibody from above just wide enough to fit a box-end in. Sigh.. young and dumb ha

This is one of the suggest ways to remove a bolt from a GM Colbalt. front control arm has a bolt that has a welded in nut that may break lose. causing the bolt to just spin and not come out.. you pull back the carpet on the passenger foot well and cut a hole to punch it out. That sucked...

Some VWs had a similar issue and the answer was to break the nut off, cut an access hole into the subframe, weld a new nut in then weld your access hole shut.

Really a pain in the ass to do correctly.

exactly what we did hahahah. Ugh... to be 16 and dumb. We put that rubi express kit on in the snow using jackstands and a tarp for cover, during the only week that it snowed in Washington 2006. What a learning experience..

I was hoping to avoid any type of "surgical" measures. LOL. I reckon I will cut the bolt heads off first and drill out the remainder and then attempt to re-thread the hole. If that doesn't work, then suppose I will have to do some cutting and welding. I am at work right now, and cannot check, but I thought too about drilling a hole all the way through the crossmember and then take a long ass bolt all the way through with a nut on the top if possible. There is a used crossmember on eBay for $350 shipped. I guess worst case would be to buy this and just replace the entire crossmember. But God, that will be a metric-shit ton of work too.

After you cut the head off how are you going to get the rest of it out? Since the weld is broken won't it just be loose inside, aka impossible to drill because it's moving? Then won't it just rattle around in there for the rest of your life?

I feel like you're going to have to cut into it.

just cut a slot big enough to fit a wrench into and call it a day

maybe I'm missing something but there is no hole to rethread. if this is a welded-on nut, whatever the hole is in is probably not substantial enough to thread. You would have to replace the nut, or as others suggest, get to it with a wrench.