Bolt heads breaking off...
 

Shit.... What do I do now?

Where is that bolt located?

But it looks like you have the right idea, you're going to have to drill out the center a little and use a bolt extractor. These bolts tend to get rusted in really well, hell even just the paint is sometimes enough to seal them in nice and tight.

I agree, soak it in penetrating oil, drill out the center, (carefully) and use an bolt extractor. The on in the pic looks like it may be just a little too big, but it may work.

Another thing to try for those still intact but hard to remove bolts...
http://www.loctitefreezeandrelease.com/

I haven't used it yet myself, but a lot of people I work with and know swear by it.

I used penetrating oil, I torched it, I used the bolt extractor. The picture you see is the bolt extractor after it snapped off from me turning it too tight.

Also it's located on the right side fender.

Ooo... those fender bolts are a bitch...

And if you snapped the extractor off inside of the bolt you're pretty much SoL unless you can find a carbide drill to drill it out, but at that point you might as well just cut it out and weld a new nut...

If you can get a drill bit started into the extractor it may turn the extractor clockwise and remove it and allow another attempt with a new extractor. You may have better luck using the extractor with a drill rather than the tap handle. Sometimes turning the tap handle introduces the kind of sideways torque that breaks the extractor. They can be very brittle.

It will be very difficult to get the drill started, maybe if you have a dremel with a small diameter diamond tip grinding bit you could grind a recess into the top of the extractor to help center the drill bit. IDK just trying to be creative, difficult problems!!!!!!!

Just another thought -- what about drilling a new hole and using a tap to create a new thread? Is there any reason why this won't work?

you can drill the hole thing out and weld a nut with same thread in its place flush so it will still take the same bolt. i personally would try welding a bead in top of the bolt without hitting the frame work, then weld a scrap piece like a "wrench" and turn it it out.

u can use a drill bit that's the same size as the bolt and drill thru. then go back with a metric tap to clean the threads up.

Yeah I've done this plenty of times and unless the thing is completely frozen in there is usually works... Otherwise just drill the whole thing out, blind nut and all and just weld a new nut in there.

Soak it in Kroil:

http://www.kanolabs.com/

Then weld a nut to it and back it out. I don't do any work on rusted bolts with Kroil. It's the best penetrating oil out there.

Story: I was working on my 7 at my grandpa's house, and I couldn't get a bolt out. I soaked it with PB Blaster and left it for an hour while I worked on other things. Came back to it and put a little force into it, and the head started to shear off. I stopped and my grandpa came over, shot it with AeroKroil (aerosol version), let it set for ~30 seconds and it came right out. It's amazing stuff.

Those screw extractors are hard. A carbide drill bit is about the best bet for drilling out the extractor. But, they are expensive, very brittle and break easily. You might be able to loosen it up with a sharp punch then squirt it with an air nozzel. The air gets underneath and lifts it up. Once out, I'd drill through the entire broken bolt with a drill slightly smaller than the minor thread diameter of the bolt and re tap the hole. Just be careful and don't break the tap. You'll be learning about tap extractors then.......

FYI, they also make a square type extractor which are a little more robust and don't snap as easily as the LH sprial type.

frozen, rusty fixings are a right pain...

I had to drill quite a few out on my project car. Mazda used a 6mm hexhead taptite that cut it's own thread as it went into pre welded captives... it saved Mazda having to pre tap all the captives first.

I bought a box of these ( about 500) for £10 and I put them in with a touch of copper grease so they should come out a bit easier next time.

You don't need to tap the thread yourself or mess about with stud extractors.
If the head breaks off a bolt, drill it out with a drill bit just under the size of the threads and then drive in a new taptite.
The shank of the taptite is slightly triangular and will cut a new thread as it goes in giving you a stock looking secure fixing. Easy!!

I don't have a welder... and as long as I'm in University I won't be able to buy one. What I have right now is an SAE tap & die set and other misc hand tools.
Also what are these taptite bolts I've heard about?

self tapping screws might work next to the broken one

Use a punch to make a small dimple in the center of that extractor bit that broke off in there. Use a drill bit one or two sizes smaller than the bolt and drill right into it. Buy good quality bits as those extractors are hard metal.

Some times you'll get lucky and the clockwise rotation of the drill bit will cause the bolt to loosen and spin. Switch drill to reverse direction and it comes out. If you're lucky. Otherwise just keep going up in drill bit sizes until just the outer shell of the bolt is in there which will flex / collapse and come out eventually.

Soaking it in a rust neutralizer before drilling is a good idea. Like that pink navel jelly from the auto parts store.