How To Remove a Broken Bolt

Broken bolts just suck to deal with. You, however, don't have to suck at removing them. With the right tools and a little bit of know-how, you can master this otherwise day-ruining obstacle. There is a bit of an art to removing broken bolts and the right technique is heavily reliant on the exact situation you find yourself in. That said, I have three basic techniques you can use to remove broken bolts that’ll cover most situations. 

To be perfectly clear, we're talking about bolts that are broken flush with the surface or below—not the kind that can be handled with a set of vise grips or stud extractors. Those situations are pretty straightforward, while the ones I’m focused on here are a little more specialized. 

Before we get going, you should know that you have the option to take bolt removal jobs to a professional if you aren't comfortable doing it yourself. It's also important to note that you may be in for more than simply removing a broken bolt. We're dealing with cars here, and that means you don’t always have the space you need to get the job done. You may have to remove the part in question to access the bolt you need to extract. You will need to do your homework to determine what that all means for your specific situation. 

As for removing a broken bolt itself, you will need a few special tools to get the job done. We're covering three different methods, each of which relies on different tools, and the route you take is largely determined by what you have on hand. 

All right. Let's face your nightmares. Removing a broken bolt isn't all that bad. Again, the right approach depends on the exact situation you're in, but the three basic techniques below should cover instances. 

By far the most popular and most effective method is to use a screw extractor. A lot of people will tell you it’s a waste, but they do work as long as you take your time and do the prep work the right way. 

If there’s a little bit of the bolt protruding from the surface, carefully grind it flat. This creates an even surface that’s easier to work with. 

If the bolt is broken below the surface of the workpiece and has a jagged edge, a drill bit can be used to clean it up. Using a drill bit that runs opposite of the thread may help loosen it up, and can even save you from having to follow the next steps. 

Carefully mark the center of the bolt with a punch. This prevents the bit from walking as you run the drill. Take your time with this, as the key to success here is making sure the hole is perfectly centered and deep enough for the tool to work.

Drill into the center of the divot left by the punch with a small drill bit. Don’t drill all the way through the bolt, just deep enough for the screw extractor to grab onto it. 

Determine what size drill bit is needed for the screw extractor the job calls for. Continue to drill out the hole until you reach the necessary drill bit size. 

Use a hammer to tap the screw extractor into place. There’s no need to fully insert it as you’re only trying to get it started.

Place the adjustable wrench on the end of the screw extractor and twist it into place while pressing the extractor into the bolt. These use a reverse thread pattern. Tightening the extractor forces the bolt in the opposite direction of the threads, eventually breaking it free. You can use a torch and to heat up the internal threads around the bolt to help ease extraction. 

An alternative solution is to weld a nut to the broken bolt. This essentially recreates the bolt so you can remove it with a wrench, just like you would normally.  

We need to make a good, strong weld and you need good, clean metal to make that happen. Start by cleaning up the bolt with a wire brush or wire wheel. 

Take a washer with an opening to match the broken bolt diameter and center it perfectly. Tack it in place with the welder. 

Take a nut with a thread size to match the bolt and center it over the bolt and washer. Carefully fill the center with weld. 

Once the weld has had a minute to cool, simply put a wrench on the nut and break it free as though everything is normal. 

This last method recently got me out of a bad spot when I broke a bolt off in the new flywheel for my 440 V8. In the case that you're dealing with a blind hole, a rotary tool with some cheap carbide bits and a flat-head screwdriver can be used to run the bolt through to the other side. This can also be used to back the bolt out of a blind hole. 

This one is very risky as you can easily damage the threads if the bolt breaks below the surface. Using a drill bit to clean up the top of the bolt is essential to minimizing that risk.

Take a small carbide bit and create a slot in the center of the broken bolt. Again, be very careful not to touch the internal threads of the bolt hole. The hole needs to be deep enough for the screwdriver to really grab on and not cam out. Take your time. 

Insert the screwdriver and turn the screw in or out of the hole. It's best to use a screwdriver with a square shank or some kind of hex built into it that allows you to use extra torque to break it free. 

There are a lot of variables to consider when removing broken bolts. Enough to make your head spin, really. Not only that, but you can only learn so much just by reading about it. That's why I've attached this video. It covers a variety of techniques in easily digestible bites to help you get a better grasp on how to deal with broken bolts in many different situations.

A: You can opt to drill out a broken bolt. If you're careful, you may be able to drill it just large enough to easily break out the fragments of the bolt before you run into thread. However, this almost always leads to thread repair or enlarging the hole to accept a larger bolt.

A: It can be virtually free if you have everything to do the job on hand and perform the work yourself. Otherwise, you can pay a professional to do it. Professional bolt removal can cost anywhere from $50 to several hundred dollars. 

A: Cobalt or HSS bits are your best bet. They can be costly, but trust me, they'll pay for themselves in this situation.