Removing Sheared Lug Bolts
The W126 is a technological masterpiece, but like most, has its occasional Achilles' heel. The biggest one, in my opinion, is the long-head lug bolts, prone to shear if over-torqued and also well-shrouded by the deep recesses in the wheels designed to house them. Many cars feature lug nuts rather than bolts - this is to ease repair if a lug stud shears. The stud can simply be tapped out from behind. Not so with lug BOLTS. Typically, they have the seat, or contact surface for the wheel, just below the head. The W126 lug bolt, however, has a considerable distance between the head and the seat - the result is often a sheared bolt.
Just imagine - your tire/wheel/brake/suspension/whatever job is going along swimmingly, when all of a sudden - SNAP! The doomsday scenario. This happened to me courtesy of a previous owners lack of care and proper technique - REMEMBER, ALWAYS TIGHTEN W126 LUG BOLTS TO 80LBS WITH A TORQUE WRENCH, AND USE THREAD ANTI-SEIZE COMPOUND. It took me over ten hours of trial and error to come up with a solution, but it works fantastically well, so I thought I'd share it here, having read other members sob stories of sheared bolts.
First, this method assumes you have some bolt body left to work with. If your bolt sheared at the seat, you will need to use some type of extractor and drill out a hole - which, from my experience, may not work at all. Assuming you have some bolt body, first forget everything you know about extracting bolts or screws. First, the metal of the bolt is so hard, it is barely possible to drill into. I used 11 cobalt drill bits, as shown in the photographs. This got me a hole about half an inch deep, and took six hours. To put it bluntly, don't bother. Also note the number of extractors I demolished: five, at roughly $9 per unit. I especially like the one in the second-to-last photo. The drill bits averaged seven dollars per. Then, add one dead drill to the tally, at $65. The third photo below shows the full trail of carnage this little project left. My total in destroyed parts, prior to discovering a solution: $187.00 The total cost of the tools you actually need, besides standard ones you likely already have: about $10, and you need to consider these tools DISPOSABLE.
Here's the list of what you will need:
1) Floor jack, either scissors or hydraulic, but NOT the factory type supplied with the car.
2) Very long, very strong tube or hollow bar. Shower curtain rods aren't going to cut it. I used a support beam from a home gym, as shown. You will be applying a TON of torque to it, so make sure it is basically strong enough for you to do a pull-up on without bending it.
3) Breaker bar, the longer the better. This will probably limit you to 1/2" drive; mine was such, at 18" long. If you have a 12" or longer breaker bar with 3/8" drive, skip the next item.
4) 1/2" to 3/8" adapter
5) 3/8" driver extension, at least 6" long. Consider it disposable - these are usually only $5 or so.
6) 12-point, 11MM socket, as deep as possible. You will need to use a very hard steel socket, and it will need to be at least 1" deep - the available point surface, that is, NOT the total length of the socket. Deduct slightly more than the length of the drive bar end from the overall length to get your point surface. The longer the better. I went to Sears and got a Craftsman brand hardened steel socket of the same type for $5. Again, this will need to be considered disposable. Think a 10MM or 3/8' socket will be close enough? YOU ARE WRONG! See the last picture for graphic evidence.
7) Hammer, as wide a head as possible. I suggest a sledgehammer, or a large framing hammer (which is what I used.)
8) Patience.
9) Luck.
Procedure:
Park your car, preferably NOT on grass (as shown. Doh.) Leave your parking brake on, your transmission in Park, and blocks on both sides of as many wheels as you can block.
Line up your deep, 12-point 11MM socket on the exposed broken bolt body. Tap it gently while holding it in place with your GLOVED hand. The gloves will protect your hands from accidental blows, and will also protect your wheel from the same, most likely. Once you have tapped it in enough to hold on its' own, stand up and begin striking the socket progressively harder until it is driven at least 3/4" onto the bolt body. Make sure you guide the socket on slowly and in a straight line - you don't want an off-angled socket flying out like a bullet and hurting you, killing you, or breaking your car.
The reason this works, if you care to know, is that the lug bolt shaft is very nearly as wide as the median point of the socket points or teeth. As the socket is driven on, the bolt body is cut and compressed, and it expands to fill the gaps between the teeth. The socket will do the same, and the result is 24 interlocking teeth, fused together as solidly as if they were welded on. Mathematically, this only will work with an 11MM socket; unless you have a bolt shaft wider than the longest distance between point peaks in the socket by 50% of the length from the innermost of the point to the outermost of the point OR LESS, but not less than 1%, the materials won't split the space filled evenly, and the socket will split. The socket in the last photo was more like 75% of the differential I just described, and it split pretty damn fast. Trust me, use an 11MM.
Enough science. Next, once the socket is on, attach your driver extension. You will need your hammer here too, as the end of the socket you were just pounding will have been deformed, and the driver extension will need to be forced in - this also puts more force to work on securing the socket on the bolt head. Once the extension is in, it is not likely to come out, ever. Next, slide your jack under the extension driver and raise the jack until it is just barely holding the extension higher than level. This will prevent the socket from being torqued off the bolt. Attach your breaker bar such that it faces away from you at as close to a 45 degree angle as you can get. You can ensure this by lining up your socket properly before pounding it on, such that the bar can be attached at this angle. See the first photo. Next, place your bar or pole (the black bar shown) over the breaker bar handle. Place your foot on the extension - you are going to keep it from doing anything other than rotate. See photo #2. Pull the bar toward you rapidly - turning too slow can shear a bolt. Hopefully, if you have done this right, you will have freed the bolt. Go have a beer!