How to Remove Stubborn Caliper Bolts

by Jody L. Campbell
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It's inevitable; work on enough cars, and sooner or later you're going to run into a bolt that's just determined to make a very simple job much harder than it needs to be. Brake caliper bolts are particularly susceptible to getting stuck, particularly on Rust Belt cars that regularly run on wet or salted roads. The bad news is that there's no guarantee you'll be able to remove the bolt without breaking something. The good news is that your odds of doing so are much lower than your odds of getting it out after a bit of torch time.

Step 1

Spray the caliper bolts with penetrating spray and allow the lubricant 10 to 15 minutes to soak in. If applicable, remove the rubber boots covering the bolts by gently prying them off.

Step 2

Choose the suitable sized socket, hex-head bit or Torx-head bit to remove the caliper bolts. Attach the tool to a breaker bar and try to remove the bolt. Do not use excessive force if the bolt does not break free.

Step 3

Light up the torch and apply heat around the bracket the bolt threats into on the back of the brake assembly. Do not apply heat to the sliding caliper itself. Be sure all the rubber boots have been extracted or you will damage them with the torch. Keep the torch away from the bleeder screw and the caliper piston. You can also heat the head of the bolt, very slowly; a hot bolt can be easier to extract, just make sure you don't torch the caliper or its rubber components.

Step 4

Apply the breaker bar and suitable tool to the caliper bolt and try to break it free again. In the event the caliper bolt head strips, pound a bolt extractor onto the head of the bolt and use a suitable sized socket to mate to the end of the extractor.

Step 5

Repeat Step 3 as often as necessary in order to break the internal corroded seal of the bolt. The hotter the bracket gets, the more it will expand away from the bolts, and better chance of success. Once the caliper housing is very dull red, apply Step 4 again in order to break the caliper bolt free. Once the bolt is ready to come out, you will hear it squeaking as you turn it counterclockwise. Reheat as necessary until the bolt is freed.

Step 6

Drill or hone the caliper bolt hole in order to clean the internal corrosion that caused the bolt to seize. Use a suitable sized drill bit to match the diameter of the bolt. Some floating calipers may need to have the internal slides removed in order to properly re-lubricate.

Step 7

Bring the old caliper bolt to the bench grinder and clean the surface and threads off using the wire brush wheel. In the event the caliper bolt was compromised in the extraction process, replace it with a new one.

Step 8

Apply a coat of anti-seize compound to the threads of the caliper bolt, and a fresh coat of grease to that flat bolt shanks. The grease will prevent sticking the next time, and allow the caliper to slide more freely on the bolts, making for better breaking and more even pad wear. Reinstall the bolts, and torque them to the appropriate setting for you vehicle.

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