Your caliper bolts are designed to keep your caliper bracket in place and the caliper bracket holds the caliper itself together. If you snap the head off of your caper bolt, you’re definitely in a pickle because that’s not something that you want to mess around with and fix another day.
If you break the head off your caliper bolt, you have a few options, depending on how much of the remaining bolt is sticking out. You can drill a new hole, use an extractor, or grab a pair of pliers with teeth and use some old-fashioned elbow grease.
If you can’t grab ahold of the remaining portion of the bolt and you don’t have any leverage, your options may be a little more limited. Any way it goes, it’s going to be a pain in the neck unless you’re really lucky and the remaining bolt is nice and loose.
Drilling the Bolt Out
One of the simplest methods that you can use is to drill it out. You want to use a much smaller drill bit—in terms of diameter—than the bolt. What you are doing is turning the bolt into a hollow bolt and it may start to work the bolt out if you run the drill bit in reverse.
If it doesn’t budge the bolt at all, you can drill all the way through and then switch over to the next size-up drill bit. As your drill bit bites deeper and deeper into the bolt, reverse it occasionally to see if it will draw the bolt out.
Once you get close to the diameter of the bolt, you may be able to gently tap the metal out of the hole and it will simply break apart. You can use a tap tool if you are reaching the point where the drill bit is close to the same diameter.
Retap the Threads
If you end up drilling it out to the point where you may have smoothed out the threads, you will have to retap them. Since caliper bolts are generally so long and only have threads on the very tip, it makes for a labor-intensive process and not one that you want to do.
This should be an absolute last resort method, when all else on this list has failed, as well as any tricks of the trade you try on your own. To rethread the female portion, inside of the caliper, that the male bolt secures, you will need a tap.
The tap and die come from the fact that the “die” portion rethreads the male end. However, you are only looking to rethread the female portion, inside the caliper and will probably purchase a new caliper bolt from the auto store.
This is also dangerous because you will have to drill a slightly larger hole through the caliper, which means that you will have to do two of them—one through the bracket and one through the caliper itself. You may not be able to do that, depending on the caliper and how your brake pads are assembled.
Weld a Bolt Onto Your Bolt
Of course, if you don’t know how to weld or simply lack the rig, you won’t be able to use this method. But if you do, this is likely to be the simplest way to get the caliper bolt out of the entire list.
All you have to do is tack weld another bolt onto the broken bolt. It may be extremely difficult to do if there is no bolt sticking out of the caliper to weld it to, however. The heat from the welding process will cause the bolt to expand and contract as well, helping it to break free of any corrosion that’s holding the threads tight.
Try to weld the new bolt on as straight as you can because you are going to need to be able to grasp the head on the new bolt with a socket or wrench and you want it to spin the old bolt out without being ridiculously off-center.
A MIG welder is the best option to go with because you lack the necessary control with a stick welder. Some of you may view that statement as a challenge and that’s fine as well.
Use an Extractor
To properly use an extractor, you will need to drill a pilot hole first. An extractor bit has left-hand threads so when you drill your pilot hole, you can use these reverse threaded bits to spin the caliper bolt out as it spins counterclockwise.
The only thing that you have to worry about with an extractor bit is the potential it has for breaking off inside of the caliper bolt, which will just double your problems. When you are finished drilling your pilot hole, use a hammer to knock the extractor into the hole you made.
Once the extractor is seated well enough, place your drill on it and tighten it down. Now flip the drill into reverse and ease it on. Don’t just hammer the trigger on the drill as this will risk snapping the extractor, leaving embedded in the caliper bolt.
You just want to ease into it, very slowly applying more and more pressure on the trigger. Let the motor in your drill do the work incrementally. Don’t get impatient with it and it should start to withdraw the remaining caliper bolt.
Use WD-40 and Heat
It goes without saying that the reason a caliper bolt is stuck so hard that you end up popping the head off is because of corrosion, which is almost inevitable where your calipers are concerned, at least on some level.
WD-40 and heat will help to break through the corrosion. When you install a new caliper bolt, be sure to use some caliper grease, as it will defend the new bolt from corrosion over time and create the same problem yet again.
All Things Considered
There you have it, just a few tips and tricks if you’re facing a broken caliper bolt. It can be a pain in the neck, sure, but if you are armed with the right tools and don’t mind a little intensive labor, you should be able to get it out at the end of the day.