How to remove broken bolt stubs from brake caliper bracket?

Question

Here's the bracket from the passenger (right) side front brakes on my Subaru Impreza. Both (17mm) bolt heads snapped off when I tried to remove them using a socket using manual pressure only, no impact wrench, though I couldn't budge them with just the ratchet and had to use a breaker bar (which deserves its name...)

Fortunately although the heads came off, I was replacing the rotor anyway and so could get the bracket out with the rotor. So the bolt stubs are available to hopefully grip & get them out.
Looking for advice on how to proceed with this from here. I've already started to soak these using PB blaster - should I try to spin these out using eg a vice-grip and the bracket in a bench vice? Use heat? Some other method?
I would ideally like to preserve the bracket. But if the advice is just to replace it that is by no means unacceptable.
Also when I eventually go to reassemble this, should I use something like Permatex anti-seize to prevent future problems?

Martin · Accepted Answer

Those are some badly rusted brackets...
I would not use heat to loose the bolts, as that will seriously weaken the bracket. Those means are for parts that will be discarded anyway.
To remodel them you need to

drill out the stubs, as I see no chance to remove them by other means. The "blockade" is strong enough to shear off a 10mm shaft, so vice grips or other means will be futile.
re-tap the holes, most likely some Heli-coils will be needed
get new, matching bolts
remove the rust from the guide slots

It depends on the value of your time and your skill on drilling and re-tapping. I personally would get two new brackets.
I do not know if the use of anti seize is acceptable here. While it will prevent future rust-blocking of the bolts, it lowers the friction of them, raising the possibility of loose bolts, especially if one drops the anti-seize on the flanges of the bracket. And the front brakes are not really places where one should perform experiments.

How to remove broken bolt stubs from brake caliper bracket?

One Answer

Add your own answers!

Ask a Question