I just realized due to that your OP isn't very clear that it may be the caliper bracket you are having trouble with. I believe the bolts for the bracket require a 17mm socket size to remove. And yes these also typically have Locktight on them. If that is the case they are usually very tight and the pipe in the breaker bar trick usually works if your without air tools. Once again good luck and careful not to bust your knuckles.
God bless, Jaredjosh
God bless, Jaredjosh