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chrissyb 12-07-2009 11:45 PM

Broken caliper bolt
I Have a 1996 Pontiac Grand AM and the caliper bolt tread has broken off in the base. I have tried an 'easy out' with no luck. It has gotten to the point of ther caliper grinding on my inner rim so bad there is a huge hole resulting in a flat tire. I now have to get a new tire and rim. I have talked to others about it and eveyrone has suggested WD-40 or Liquid Wrench to loosen it up. What would work best for this broken caliper bolt without haveing to replace the entire calpier system???

nap 12-07-2009 11:53 PM

you have succeeded in actually breaking the bolt? so the head is missing from the bolt? or worse, the bolt is broken flush with the surrounding bracket?

If the first, you should be able to remove the other caliper bolt, tip the caliper up and slide the caliper off the broken bolt.

Then copious amounts of heat and a pair of vice drip pliers would be the next step. Heat the caliper bracket right near the bolt. When it is hot, clamp the vice grips onto the bolt and try to work it out.

Sometimes applying wax to the area will allow some of the wax to be wicked into the threads and make it easier to remove. Be cautious though since was is flammable when heated and the last think you want is a fire. Then you would need much more than a caliper.

Now, if you have broken the bolt flush with the bracket, you are in a world of bad. I can't give you an easy way to remove a bolt that is flush with the surrounding metal.

so, is anything sticking out?

47_47 12-08-2009 06:43 AM

Use a left twisted drill bit after applying heat (acetylene), the bolt threads have loctite on the them. As nap said fire is a concern and use caution. If you damage the threads in the knuckle, it will need to be replaced (junk yard) and you will need a front end alignment.

Thurman 12-08-2009 10:30 AM

As "nap" stated" IF you have any of the bolt left to grab onto, heat the area the bolt screws into, grab the remaining bolt with vise-grips locked on really good and apply pressure to remove. "47-47", I'm not sure GM used Locktite at the factory on these bolts, but even if they did-getting the area of the bolt threads to about 300 degrees will help loosen the Locktite. A small propane torch will NOT may be enough to do this job with by the way. IF the bolt is broken off so there is no bolt body to grab onto: you do have a real problem. These can be drilled out by someone who knows how to do this, saving your spindle. I would suggest that IF you can safely, slowly, drive your car--take it to a reputable repair shop to have them remove the broken bolt end. Good Luck, David

chrissyb 12-08-2009 05:52 PM

There is nothing sticking out of the base. its just so old and rusty. I don't have those tools to heat it and whatnot. Do you think if I just douse it in some wd-40 for a few hours so it can get in the treads, it would be easy to remove with a reverse drill?

Thurman 12-08-2009 07:12 PM

One word answer--NO! I actually do not like WD-40 for much of anything. It is not a good penetrant for this type of application. I highly recommend "PB Blaster" for this type of problem. It is in a spray can. PB Blaster will "wick" into rusted threads if you let it set long enough. Spray this area liberally, let it set for 30 minutes or so, and spray again. I don't know you're capabilities, or your access to help, so I'm going to give you my best advice from auto repair experience. You will need to have the correct sized E-Z-Out to remove the damaged thread portion, I'm guessing a #3, and the correct sized drill for that E-Z-Out. The drill size is on the E-Z-Out. Drill the hole through the broken portion of the caliper bolt, take your time, it's not going to be like drilling butter. The PB Blaster will also be a good drilling lubricant. After you have the hole drilled, place the E-Z-Out in the hole, use a good adjustable wrench, and apply steady pressure to the broken bolt while tapping on the area it is screwed into. The broken portion of bolt should come out. If you don't have these tools, find a friend, or friend-of-a-friend who does. The last thing you want to do is mess up the threads of the housing the caliper bolt screws into. Good Luck, David

nap 12-08-2009 08:18 PM

I am pretty sure GM did use a thread locker (Lok tite or something similar) on the bolts and they almost have to have a lot of heat on them to get them out.

I do remember the next size up GM car and many brake jobs where I used a quite powerful 1/2 drive impact gun and still would heat the caliper mount up to get the thread locker loose. I think it is the same with the Grand Am but not positive.

I really to to help folks DIY but I think this is just beyond your capabilites and tool resources.

Bondo 12-09-2009 09:40 AM


Originally Posted by chrissyb (Post 363628)
There is nothing sticking out of the base. its just so old and rusty. I don't have those tools to heat it and whatnot. Do you think if I just douse it in some wd-40 for a few hours so it can get in the treads, it would be easy to remove with a reverse drill?

Nope,... You need to Replace the part it's threaded Into...

brokenknee 12-09-2009 02:26 PM

Can you post a picture for us to look at so we can give you a better idea how to proceed?

pald 12-10-2009 03:52 PM

Have you tried using screw or bolt extractor?

Here is a some information on it and pictures.

I had an similar problem where one of my screw that holds my oem intake box got broken off and was not holding the box tightly... so I purchased a set of screw extractors and I was able to get it out.

Hope this helps and these screw extractors comes in handy! :thumbsup:

NoHax 12-10-2009 05:37 PM


Originally Posted by chrissyb (Post 363628)
There is nothing sticking out of the base.....

If this is the case, you're mostly backed into a corner where you will probably have to drill an appropriate-sized hole in the broken bolt and use a broken bolt extractor to remove the offending piece. You can try using conventional twist drills made of HSS (high speed steel), titanium, or cobalt, and with a variety of drill tip geometries, too. A left hand drill is also an option.

First, are you or anybody else able (or capable) to easily access the broken bolt with a drill and drill motor? How deep is the bolt sheared off in the threaded hole?

A photo of what you are facing would be worth a thousands words of explanation!

If the broken bolt is sheared off with an irregular (slanted) face that is visible in the bolt hole, don't let the drill skate to one side when you are first starting to cut into the bolt with the drill. If you are not paying attention when attempting to get the drill to start cutting, the drill can take a bite out the inside of the bolt hole. This is probably not a danger in your case, but if any female threads are in the bolt hole exactly where you are drilling, the threads can (and will) get dinged by the drill if you are not very careful.

Unless the broken bolt has a high Rockwell Hardness (HRc scale), the normal array of right or left hand drills can be used along with the correct-sized extractor to screw into the freshly bored hole. If you use the wrong type of drill, or use an improper drilling technique and inadvertently harden the face of the broken bolt, or the drill will not “bite” into the slanted face of a broken bolt, I have a solution for you.

Purchase a square shank carbide die drill. These short drills are on the pricey side. Depending where you purchase one, a ¼” drill is in the $18-$40 or more range. With its exotic tip geometry and carbide hardness, the drill will penetrate slanted, jagged and hardened faces with ease. These carbide die drills will cut through hardened surfaces created by using improper drilling techniques or a dull drill bit, or both.

Use a moderate drilling speed (not pedal-to-the-metal fast) and feed the drill slowly into the surface to be bored. Let the drill do the work. A carbide die drill actually melts the surface of the metal under the tip of the drill and strips away the metal in the form of chips. You will know that you are drilling with the proper feed pressure and correct drilling speed when the drill starts sounding like the ripping of cloth. Imagine the sound of your shirt ripping and tearing. When you hear that sound, you are boring properly with this type of drill. I admit, this explanation does sound weird, but it is true.

Quickly rip a piece of rag cloth. Try an old shirt or the like. The tearing sound you hear is very much like the sound of a carbide die drill being properly utilized. Don’t use a typical red-cloth shop towel. These towels are much too soft and loosely woven to properly simulate the “cloth ripping” sound effect.

When boring the broken bolt, the waste chips spilling from the bored hole should be shiny curly shavings that look like small christmas trees. Withdraw the drill if the chips begin to cluster at the bore hole and fail to drop away. Clean away the chips out of the bore hole and start boring again.

A major drawback is that carbide die drills are extremely fragile. You must bore straight and easy. Did not move the drill laterally (sideways) inside the bore hole. There can be NO “hogging out” the bore hole, either. The cutting tip of a carbide die drill will fracture very easily and quickly under such rough treatment -- guaranteed! Bring the drill up to speed then feed it into the bore hole. Don’t cram the drill into the surface to be bored. Be slow and deliberate in your use.

You can bore a hole quickly and easily in the hardest of steel with one these drills. Just use the smallest square-shank carbide die drill matched with the appropriate bolt extractor to get the job done. There is no need to hammer away and remove more broken bolt material than is necessary.

Most caliper bolts are torqued in tightly (or at least should be). You will need the proper bolt extractor tool to break loose the broken bolt once a hole has been bored into it. The proper extraction tool to use will of course be dictated by the available access to actually get to the broken bolt to drill and remove it. High torque could (and most probably will) be needed to break loose and remove the bolt. Use this type of left-hand twisted-flute extractor called a 'Wedge-Pruf' extractor. This tool will allow you to use a proper hand wrench to generate the needed torque to back out the broken bolt.

See a 'Wedge-Pruf' extractor here:

[I have no affiliation with the tool company web site. I am just listing a tool that will work under your circumstances if proper access, tools, and know-how are available.]

Other people have mentioned that if a thread locker has been previously used, some heat could be required to remove the broken bolt. If hi-strength “RED” Loctite 271 Threadlocker (or the like) has been slathered on the threads, a torch capable of heating the threads to around 500℉ will be needed to soften and break the thread locker bond. Then, a lot of muscle power could be needed to torque the heated bolt loose in the threaded hole.

Good luck.

n0c7 12-11-2009 09:33 AM

I would just quit wasting time trying to save damaged stuff. It's a mid ninety's American car. There has to be a handful of them in the local scrap yards, and brand new parts can't be very much.

Get the angle grinder and sledge out.

zackinma 12-28-2009 03:18 PM

I concur with N0c7. That make/model is a dime a dozen in junk yards and you will spend more on the tools necessary to do this job then you would on a new spindle and brake caliper from a bone yard and an alignment. Plus you will save yourself a few busted knuckles.

to do this "right" i would

1 clean the work surface
2 mig-weld a nut onto the snapped off bolt. this is tricky as you have to run a bead inside the nut that welds to the bolt but not the spindle. careful nut size selection is important here.
3. soak the hell out of it with PB blaster and let sit for 30 minutes.
4. put a wranch on the nut and back out your snapped bolt.

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