Here's how I changed the front brake discs and pads on my 2001 S80 T6. It has 76,000 miles. The pics reference the right front wheel, but the procedure is the same for the left front wheel.
(Looking for S80 rear brake pad and rotor tutorial?)
Pic of my right front wheel that I'll be working on. This one is 17":

Here's one of the new discs:

And the new pad set:

I put the car in park, set the parking brake, and put chocks under the left side wheels. I loosened the lug bolts with a 3/4" socket and a breaker bar. Then I used a floor jack under the front jack point to pick the car up just enough so the tire cleared the driveway. I then removed the lug bolts and the wheel.
Here's the old, worn out disc:

A top view showing how worn the disc is. I'm assuming it's original. The service limit is 25mm in thickness, according to Brembo. I'm sure this disc is at or below that:

I used the "poor man's piston compressor" (two screwdrivers) to push the piston back into the caliper all the way. This clearance is needed for the new pads to fit over the new disc. I applied constant, firm, outward pressure on both screwdriver handles until the piston was forced all the way back into the caliper.

Closeup of screwdriver between pad and disc. Some people might say I shouldn't do this because of possible damage to the disc and/or pads, but I'm replacing them both anyway, so it doesn't matter. Also, you can see the huge groove that's been cut into the disc by the pad. The disk was originally the thickness of the lip at the outer edge.

Notice the gap between the disc and pad after piston compression:

This pic shows the top mounting bolt that needs to be removed. It's in the center of the pic and is a 15mm bolt.

Removing the top bolt:

Removing the bottom bolt:

I set the caliper on a paint can to prevent strain on the brake hose:

Removing the disc retention bolt. It's 10mm and also the stud for wheel alignment on the hub. I liberally applied WD40 to the lug bolt holes and disc retention bolt. I had to be very careful not to strip this bolt. There's only one hole in the hub for it to fit into; if that's stripped, I'd have to drill and tap a new hole or install a new hub.

Here's the retention bolt 1/2 way out:

Hammer time! After the retention bolt is removed, a few taps with a hammer are needed to break the disc loose:

And the old disc is off. The metal bar with the bolt through it laying next to the disc is the steering stop - both caliper bolts go through this stop before screwing into the caliper:

Frontside view of the new disc (left) next to the old disc:

Backside view of the new disc (left) next to the old disc:

Edge view of new disc (left) next to old disc:

I wire brushed the hub to remove the rust and insure the surface was clean for the new disc:

Then I cleaned the new disc with brake parts cleaner, placed it on the hub and fastened it with the retention bolt. I put a dab of Loctite on the bolt to keep it from working loose.

I pried the inside pad out of the piston with a screwdriver:

I removed the spring from the outside of the caliper with a screwdriver:

I slid the pads to the center of the caliper and removed them. Here is the old inside pad next to a new one (bottom). You can see how much thicker the new pad is. The old pads are probably still serviceable, but new ones will bed into the new disc better and I only wanted to do the work once, so I changed them now:

I slid the new pads into the caliper. It took quite a bit of force to get the springs to snap into the piston on the inside pad, but the outside pad slid into place easily:

Then I placed the caliper over the new disc:

I inserted first the top bolt, remembering to put the steering stop on:

Then the bottom bolt. These had to be really TIGHT. After all, they hold the brakes to the car. I put Loctite on both bolts. The steering stop is the metal bar to the left of the ratchet handle.

I stepped on the brake pedal a few times to push the pads into contact with the disc, then reinstalled the spring:

The finished product:

I then reinstalled the wheel, lowered the car to the ground, and torqued the lug bolts down (Volvo recommends 103 ft-lbs). I repeated the process for the left side wheel.
The parts cost about $165. I have no idea how much a Volvo dealer would charge for this service, but I assume it's a lot. Remember, don't try this at home!
To see how the rear brake pads are done, go here: S60 and S80 Rear Brake Pad Sevice. The rear disc procedure is basically the same as the front.






