IT depends, if you are changing pads too, i would remove the caliper, unload the pads remove bracket, clean everything from rust, install new rotor, grease slider pins and glide paths on the brackets, install new pads and then the caliper. If you are not bothering with pads I would remove as assembly and install after you swap the rotor itsef.
Be sure to spread the pads before you remove it.
I take the caliper off the bracket first. It's only 2 bolts. You don't have to but I find it easier. The way I do it is I take the caliper off, then the bracket, swap the disc, put the bracket back on and then the caliper, only one bolt. Then I swing the caliper up and compress the piston, change the pads, and then do the other caliper bolt.
Thanks for the responses. I initially tried to remove the entire assembly together, but I was unable to remove it from the rotor. The assembly was loose and could rotate about an inch on the rotor, but wouldn't budge otherwise. Could rust have been taking hold? Do I need to give it a nudge with a hammer to coax it loose?
Thanks for the replies. I removed the two caliper bracket bolts, but I was unable to remove the entire assembly. I could rotate it about an inch back and forth over the rotor, but it wouldn't easily come off of the rotor. Could there be some rust that's causing it to catch? Will I need to use a hammer to break it free?
I don't off the top of my head. I recommend removing the caliper bolts because you can use the caliper bracket for leverage with a screw driver to pull the caliper off...
You should definitely get a set with all the sizes if you're going to work on a Volvo. I got one at home depot for like 15 bucks that had all the major sizes. And a set of torx keys too because some spots are very tight and you can't fit a long socket into it