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Car Forum / Mercedes-Benz Cars / October 2005Broken caliper bolt won't extract
It s a 1985 300 SD. The upper/fwd bolt securing the LH front brake caliper to the wheel broke when pads were being replaced. It was frozen and I forced it too much. Big mistake! I think that part that the shank of the bolt is lodged inside (that the caliper bolts to) is part of the strut/hub assembly. Not sure of the exact name of this assembly. My Haynes manual doesn't show a complete breakdown of the front wheel/suspension. This is very bad, as no matter how much I tighten the other remaining bolt, the first time you hit the brakes in reverse, the top of the caliperl moves backward, and then it rubs against the inner surface of the wheel. Anyway, I bought a Sears screw extractor and matching Ti-Ni drill bit. Had a reverse-spiral and square end. Drilled out the center of broken bolt stud, all the way to the tip. Hammered extractor in. Put a lot of rust-dissolving lube on it. Waited for lube to do its thing a long time. With a pipe wrench on it, the broken stud still wouldn't turn out. So I applied blowtorch to the area next to the bolt hole while turning. The extractor broke! It broke flush, so there is nothing to grip on to, in order to back it out. So now I have an even worse problem. Need some advice on what to do next. Have never removed rotor from a car before, can I get access to the broken bolt stud from the outer side by removing the rotor? I could try just drilling it out the full diameter of the bolt and then re-thread both strut/hub for a little bit larger bolt. But trying to drill it out now is going to be next to impossible, as the hardened steel broken extractor is in there. Thanks for the help. > So now I have an even > worse problem. Run incrementally larger drill bits into there, until one of them reaches the very edge of the broken bolt. This will cause the broke stub to collapse and allow you to remove the remains. If you are VERY careful with this process you will not even need to retap anything. Make sure to really clean out the whole your stub comes out of! Running a proper sized tap into is the best way. I can't believe you actually tried to drive the car with this bolt missing? CRAZY! Marty Is not going to work....now that there is a broken (5/16th in. I think it was) extractor in the middle of the stub. Yea, if I could get the broken extractor back out, then it would be easy to do as you suggest. regards, Jim >> So now I have an even >> worse problem. [quoted text clipped - 11 lines] > >Marty This is beyond hope unless you have a home machine shop. Start shopping the salvage yards for another caliper or just buy a rebuilt one. A repair shop would have potential liability if this caliper fails so they'd install a rebuilt caliper; they wouldn't waste their time on this kludge. And the customer would pay for it. End of story. "This is beyond hope unless you have a home machine shop. Start shopping the salvage yards for another caliper or just buy a rebuilt one. " I think the bolt doesn't go into the caliper, it goes into part of the wheel assembly, doesn't it? So it's more involved than simply replacing the caliper, which would be easy. Your point is well taken. I read the post and thought the brake pad pin had broken, not the caliper's mounting bolt. Why was THAT bolt loosened to change the brake pads??? The 126 parts diagram shows the caliper's mounting bolts to the steering knuckle (piece between the ball joints)to be BEHIND the rotor. If that's so then how are you drilling them with the rotor in place? Isn't the broken bolt one of the brake pad pins? It's a 1985 300 SD. The upper/fwd bolt securing the LH front brake caliper to the *(left) STEERING KNUCKLE *broke when pads were being replaced. It was frozen and I forced it too much. Big mistake! I think that part that the shank of the bolt is lodged inside the STEERING KNUCKLE. Anyway, I bought a Sears screw extractor and matching Ti-Ni drill bit. Had a reverse-spiral and square end. Drilled out the center of broken bolt stud, all the way to the tip. Hammered extractor in. Put a lot of rust-dissolving lube on it. Waited for lube to do its thing a long time. (1 or 2 DAYS?) With a pipe wrench on it, the broken stud still wouldn't turn out. So I applied a blowtorch to the area next to the bolt hole while turning. The extractor broke! *DON'T USE a torch on suspension parts - ever.* It broke flush,*(WITH the caliper?? or with the steering knuckle?) *If even with the steering knuckle remove the caliper's other mounting bolt and remove the caliper. If even with the caliper remove the caliper's other mounting bolt and try, between the caliper and steering knuckle, to cut off the stud so you can remove the caliper for a full frontal attack on the stub in the steering knuckle. There's going to be a lot of bruised knuckles and colorful words before this is done. He needs another spindle. No problem here in Fresno, Calif. I can get you a good used one tomorrow morning. Pmail me with the side you need. > This is beyond hope unless you have a home machine shop. Start shopping > the salvage yards for another caliper or just buy a rebuilt one. > > A repair shop would have potential liability if this caliper fails so > they'd install a rebuilt caliper; they wouldn't waste their time on this > kludge. And the customer would pay for it. End of story. I see in your 1st post you need the left spindle. And you need to know that the caliper bolts come from the factory with blue locktight on them. Sounds like someone over torqued them..... > He needs another spindle. > No problem here in Fresno, Calif. I can get you a good used one tomorrow morning. Pmail me with the [quoted text clipped - 6 lines] > > they'd install a rebuilt caliper; they wouldn't waste their time on this > > kludge. And the customer would pay for it. End of story. > Is not going to work....now that there is a broken (5/16th in. I > think it was) extractor in the middle of the stub. Yea, if I could > get the broken extractor back out, then it would be easy to do as you > suggest. Sorry I misread that bit... I think Karl can get you a replacement spindle... Dumb question: WHY did you want to remove the caliper bolts to replace the pads?!?!? You drive out the 2 pins, remove the spacer, open the bleeder, take a screwdriver and pry the pads back so the piston goes into the caliper. [connect a hose to a jar and have it at the bottom, this way you won't suck air back in.] Some people don't open the bleeder to dump the old fluid, but this just pushes the old fluid back into the master cylinder. > It s a 1985 300 SD. The upper/fwd bolt securing the LH front brake > caliper to the wheel broke when pads were being replaced. It was [quoted text clipped - 23 lines] > impossible, as the hardened steel broken extractor is in there. > Thanks for the help. Yea....the bolt (and later the extractor) broke off flush with the SPINDLE. Actually slightly below...thus nothing at all to keep top end of caliper from rotating. Sorry for the confusion from not knowing the proper terminology for that part. By turning the steering wheel all the way to the right, I could work on the broken stub from the INSIDE of the left spindle. Yea, I'd have to take off the rotor to attack it from the outside. Okay, how much would a new LH front spindle and a couple of caliper bolts cost me, Karl? Its a 1985 300SD, W126. Do you have an internet store? If it is something real expensive, then I would have no choice but to remove the spindle and have a machine shop fix it....that is if they have any way to deal with drilling out a hole with a hardened steel extractor in it! Thanks all. >Dumb question: WHY did you want to remove the caliper bolts to replace the pads?!?!? > [quoted text clipped - 32 lines] >> impossible, as the hardened steel broken extractor is in there. >> Thanks for the help. New is big $$$. I am talking good used. Nothing wrong with good used as long as it has a good lower ball joint. Not sure on price until I go get it. But you are probably in the $40 range + postage. Pmail at my email address in my post. ASAP > Yea....the bolt (and later the extractor) broke off flush with the > SPINDLE. Actually slightly below...thus nothing at all to keep top end [quoted text clipped - 47 lines] > >> impossible, as the hardened steel broken extractor is in there. > >> Thanks for the help. If in the $40 price range, you got a deal...but charges need to be on mastercard if at all possible. Really need to get this fixed soon. Thanks! Jim >New is big $$$. I am talking good used. Nothing wrong with good used as long as it has a good lower >ball joint. [quoted text clipped - 55 lines] >> >> impossible, as the hardened steel broken extractor is in there. >> >> Thanks for the help. "By turning the steering wheel all the way to the right, I could work on the broken stub from the INSIDE of the left spindle. Yea, I'd have to take off the rotor to attack it from the outside. " Uh, oh! I think I might know a big part of what went wrong here. Geronimo said he broke the screw extractor off. Well, a screw extractor is made to wind a bolt out to the left, ie it has a curved face pattern to grab into the drilled hole when turned to the left, counterclockwise. BUT, since he was attacking the broken bolt from behind, he was working on the tail end of the bolt, not the head end. That means you would need to turn the bolt to the RIGHT, clockwise to remove it. But a regular screw extractor wouldn't work that way, it would just slip. Did you use a special left handed screw extractor (assuming there is such a thing), or were you turning it in the wrong direction? If so, that would explain why it wouldn't come out! > "By turning the steering wheel all > the way to the right, I could work on the broken stub from the INSIDE [quoted text clipped - 12 lines] > (assuming there is such a thing), or were you turning it in the wrong > direction? If so, that would explain why it wouldn't come out! No, that is a nice theory, but I believe the inside of the spindle is the head of the bolt. Marty Jim, I have emailed you this morning. Waiting for a reply. > If in the $40 price range, you got a deal...but charges need to > be on mastercard if at all possible. Really need to get this fixed [quoted text clipped - 59 lines] > >> >> impossible, as the hardened steel broken extractor is in there. > >> >> Thanks for the help. >[connect a hose to a jar and have it at the bottom, this way you won't >suck air back in.] > >Some people don't open the bleeder to dump the old fluid, but this just >pushes the old fluid back >into the master cylinder. Karl. thanks for the tip!! I was always one of the latter people, but getting rid of that bit of fluid makes a lot of sense and, in addition, no more spilling in the engine bay :-) cheers, guenter You can pulverize the extractor by repeatedly hitting it with a hardened center punch and a heavy hammer. Even though the extractor material is somewhat brittle it might take a while so be patient. . The last time I had to do this on my boat engine it took about half an hour. I had to deal with a stainless bolt and the extractor. Peter > It s a 1985 300 SD. The upper/fwd bolt securing the LH front brake > caliper to the wheel broke when pads were being replaced. It was [quoted text clipped - 23 lines] > impossible, as the hardened steel broken extractor is in there. > Thanks for the help. > You can pulverize the extractor by repeatedly hitting it with a hardened > center punch and a heavy hammer. > Even though the extractor material is somewhat brittle it might take a while > so be patient. . The last time I had to do this on my boat engine it took > about half an hour. > I had to deal with a stainless bolt and the extractor. Good idea! WEAR EYE PROTECTION!!!! Marty Hopefully, he won't need to do this. He has a spindle with all the bolts on the way. > > You can pulverize the extractor by repeatedly hitting it with a hardened > > center punch and a heavy hammer. [quoted text clipped - 7 lines] > > Marty Believe it or not you can buy drill bits that will go right through that broken extractor. I bought a set of them at the San Diego Fairgrounds about a year ago. I watched the guy repeatedly drill through a file, all without any cooling fluid. Anyway, he also drilled right through taps, stainless steel, etc. Here's part of the secret of using these drill bits. You need to turn them at the highest possible speed. I have a drill press that can be belted up to 3,000 rpm. It goes right through the hardest material you can imagine. As I recall I paid about $90 for a set from 1/8 inch to 1/2 inch in 1/8-inch increments. Was well worth the price since I recently had to drill three alignment holes in a 16-inch diamond saw blade for my son's granite cutting saw. If you'd like more information I can get it for you. Problem in your case is that you'd have to get a really high speed drill motor in order to get proper speed on the bit. Also, the bit really smokes and screeches when you begin drilling but it soon starts cutting right through the material. One other thing, I did have to drill out a broken 1/4-20 tap I'd broken off in a piece of steel and the drill went through it almost like butter! Hard to believe but true. > Hopefully, he won't need to do this. He has a spindle with all the bolts > on the way. [quoted text clipped - 13 lines] >> >> Marty "Believe it or not you can buy drill bits that will go right through that broken extractor. I bought a set of them at the San Diego Fairgrounds about a year ago. I watched the guy repeatedly drill through a file, all without any cooling fluid. " While these sound like a wonder tool, do you think they will really work to actually drill out a relatively small broken screw extractor lodged in a bolt in the backside of a wheel spindle? That's a lot different than drilling through a flat file on a bench. In addition to being able to hold the drill securely, the other problem is that what you're trying to now drill out is pretty damn small and irregular. The drill will typical wind up in the area betweent the broken off extractor and the bolt, then jamb and break. |
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