[ATOMANT]

I have had to file paint off pads where they engage the bracket. Sometimes the coating is very thick. Of course you need to clean all the rust from the bracket as there is often a thick layer that will chip off under the stainless steel slide caps.
Pads that cannot slide easily will burn out in no time.

 

[ATOMANT]

The rust on the brackets is not really noticeable untill you start chipping away at it. It's called rust jacking and it's a real problem. The salter the roads the worse the problem. You see it on brakes and abs sensors or anywhere a sensor is mounted to cast iron and exposed to salt or salty air.
On brakes it's a perfect environment for rust to form as the moisture gets under the stainless clips and stays wet.

 

[ATOMANT]

Well, you don't want to remove too much, otherwise you'll have the pads rattling around side-to-side. Since he mentions rust, I'd go with a wire wheel on the brackets first.

Ya a file is the only real safe tool to not remove too much. As soon as the metal starts getting a bit silvery color I stop. It hard work and lots of angles to work at. That why I use the chipping method followed by a light file. You don't want to use a sharp object to chip away either because the cast iron is soft and you don't want to make dents which will make raised areas defeating your purpose.

 

[ATOMANT]

What's rust jacking? That's where they steal your rust?

When you see bubbled paint with rust poking through is a form of rust jacking. The rust pentrates the metal and forms it into layers like scales on top of each other.