I want to start by saying I f%&king hate Allen heads and think they belong nowhere in a car. IKEA furniture, sure, but not on a car with bolts requiring higher torque specs. They strip their heads so easily, it amazes me Allen heads are in use commonly instead of the much better Torx heads.
Removing a rounded Allen head is a major pain, but having done it a few times before in different cars for different things (again, why they are on cars is beyond me) I've tried different methods and only one works reliably every time. It's the method below:
Tools Needed:
- Drill. Cordless is ideal.
- Left-Hand Drill Bit Set.
- Screw/Bolt Extractor set.
- Pliers.
- Compressed air or portable vacuum.
- Eye protection.
A few words on the special tools:
A Left-Hand Drill Bit Set is very useful in drilling out broken bolts. What makes them special is that they cut going the opposite direction from other bits; counterclockwise. This allows them to drill into something while actually rotating to make them come out. These are hard to find in my experience (Home Depot, Lowes, and most hardware stores don't have them readily available) but are found easily at Harbor Freight Tools. This is the very set I used: http://www.harborfreight.com/left-hand- ... 61686.html
The other special tool is the extractor set. Again, they work by cutting and extracting counterclockwise, much like the LH Drill bits. While you can get them at places like Home Depot with fancy names and higher prices, I found mine for very cheap online and they worked great. I got them here: http://www.gearbest.com/other-tools/pp_ ... tml?wid=21
Together, the special tools cost me about $10 from two of my favorite low-cost stores for my hobbies.
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Get direct access to the stripped bolt. In the case of the OE accessory roof racks, remove the racks so the mounting hardware is accessible. Set your drill to Reverse so it rotates Counterclockwise. This is crucial and the drill should remain in this reverse rotation the entire process. For using the drill bit, also set the drill to the highest torque setting for drilling and higher speed setting. Insert the drill bit size that is suitable. In my case, I used a 9/64 drill bit. Make sure to always wear eye protection when using a power tool like a drill.
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Center on the rounded Allen head and drill in high speed. Use light to moderate pressure and make sure that the drill bit is biting into the bolt and cutting into it. You'd see metal swarf (the shavings from the drilling) if it's cutting properly. Make sure to drill it straight and deep enough for your extractor bit to get into. In my case, I drilled about 4mm into the bolt.
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Using a vacuum or compressed air, clean out the metal swarf. Be careful in removing them as they can scratch the car's finish. Make sure the drilled hole is clear.
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Remove the drill bit from the drill and insert an extractor of the appropriate size into the drill. Use the extractor head (swirled cone side) if it's double-sided. In my case I used a #3. Set the drill to the low speed setting.
Step 5:
Insert the extractor head into the hole you drilled. Make sure it fits snug. Slowly start rotating counterclockwise. It's important to keep the drill speed slow. The extractor should bite into the bolt and start turning it loose, extracting it out.
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Remove the bolt from the extractor bit. Sometimes it will require pliers to be removed.
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Keep in mind that this process permanently damages the bolts but they were already rounded so it's not really a concern. I'll be seeking bolts with with Torx heads as replacements. When I find the appropriate ones, I'll link them as an update here.
Lastly, be careful when using a drill around a car. Drill bits are extremely hard and sharp and will easily scratch things by accident. I was a bit careless and accidentally scratched my previously-flawless leather steering wheel a bit with the drill bit. It's a minor scratch, but I definitely want to warn you all about drill bits around cars, inside and out.
