Rusted cut bolt through nut help needed

Hi guys. This isn't my first rodeo with this, but its my first one where I am running out of patience/hope. I'm installing some adjustable rear toe arms on my Accord, and long story short, I have to cut them out because they are basically rust welded to the bolt. Now on one side, the bolt head fell out no problem, however the other side has a nut seemingly welded to the chassis that the bolt goes through. Of course, I cut it but now have to deal with this little bit of bolt left in there.

I've been trying heat/rust penetrant very carefully as the gas tank is nearby. Vice grips aren't cutting it unfortunately to twist it out. I have been thinking of possibly welding a nut to it and trying that, but before I do, I wanted to get some other opinions.

So before I get the welder out, anyone have any other ideas on what I can try here?

I'd weld a nut to the remaining stub and use a box end wrench on it after it cooled down. 

I don't object to the welder, but you might want to put a piece of ni-cop brake line in there first and weld down the middle to keep from welding to the sides of the hole. The heat from the welder seems to do the bulk of the work in convincing the stuck bits to let go.   If the other side is flush to the surface I would consider welding the nut to that surface. I have pretty good luck welding nuts to bolts that are broken at or even a bit below the surface.

I would also consider drilling down the middle using a transfer punch to locate the middle of the bolt and then try an easy-out to drive the bit of threaded bolt out. Disclaimer: I am not a big fan of easy-out tools.

Thanks guys, I'll give the welder a go and see how we make out!

I'd heat it with this and then use vice grips.

AAZCD-Jon (Forum Supporter) said:

I'd heat it with this and then use vice grips.

Do these work pretty well? I've thought about investing in one but was hesitant to pull the trigger.

In reply to Japanspec :

I was removing the exhaust system from a Fiero parts car and the bolts would not budge even after soaking for two days. Less than a minute with this, they were glowing orange and came out with the threads still intact.

In reply to Japanspec :

They're also great for situations where you have rubber or plastic near the bolt you want to unstick and open flame would likely damage the melty bits.

In reply to AAZCD-Jon (Forum Supporter) :

Awesome thanks! I'll have to give that a thought. The welder is likely a no go because I just started a small fire due to oils that got spread around. I thought I cleaned it well enough but guess not! Live and learn, this ones on me lol. I panicked and used my fire extinguisher for the tiniest of flame so now I gotta get a new one. Well, worst case I can try to cut the welded on nut from the other end somehow and just nut n bolt the arm on, we'll see.