All OEM rear disc brakes are 280mm from D2 to more powerfull D4/T5.
The images for the 320mm calliper and brake disc are not loading on my end . I am assuming I must have the 320mm brakes as my front callipers look like this, and not like the 280 & 300 mm callipers show.Is it a 1.6 or 2.0 D2? The 1.6 usually has the 278mm discs.
You can tell the difference between the 320mm and 300/278mm brakes just by looking though the wheels.
The 320mm calipers look like this:
They are usually only fitted to the higher-powered variants.
The 278mm and 300mm brakes are slightly more difficult to tell apart as they use the same caliper but with different caliper carrier brackets. The 278mm caliper and carrier looks like this:
The caliper carrier has the size cast into it along with the Volvo part number.. If the wheel spokes are in the right position then if you stand in front of the driver's side front wheel and look at the front of the top part of the caliper carrier you will see the part number and '278' cast into it, like this:
The 300mm caliper carrier has more prominent 'horns' at the top and bottom:
Again, they also have the size cast into the front o the top, along with the part number:
As far as replacement goes, the brake systems are made for Volvo by ATE. You can get OEM ATE parts that will be a bit cheaper than Volvo's It's mostly direct from the Mk2.5 Ford Focus parts bin (the 320mm brakes are the same as the ones fitted to the Focus ST).
The 278mm/300mm versions at least are really easy to change yourself. You need a jack, a wire brush (to clean off any brake dust and rust), a pair of pliers (to remove and reinstall the retaining spring) 7mm hex/allen key or socket (to undo the slider bolts the caliper rides on), a 13mm spanner or socket (to remove the caliper cariier from the hub), a crosshead screwdriver (to remove the disc retaining screw), some copper grease (to lubricate the slider bolts, back of the pads and wheel mating usrface on reassembly) and some blue Loctite (to secure the caliper carrier bolts on reassembly, though this is optional).
Well, mine look nothing like yours, and they're 278. I do remember reading the auto's often have larger brakes...The images for the 320mm calliper and brake disc are not loading on my end . I am assuming I must have the 320mm brakes as my front callipers look like this, and not like the 280 & 300 mm callipers show.
Interestingly this is on a 2016 T2 auto 1.6 R-design, so the lowest power variant with the largest brakes.
If I am wrong please correct me before I purchase the wrong brake discs for a second time facepalm