Trying to get the piston on a 2013 C70 rear brake caliper to retract so I can replace the rotor and pads, but no matter how much I turn the piston, and how hard I push, it won't go in. The cap for the brake fluid res is cracked open, and even removed once. Yet, still nothing.

What do I do, open the bleeder and use a hose to let the pressure out that way? Why is the piston turning, but not grabbing any threads (it does look like it is extended way out.).

Please, I need some help on this one, after I just put it all back together, the rear brakes were dragging so badly that I am afraid the car is not roadworthy now.
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1955 Human, Scott; 1991 745 Turbo, Thunderbolt; 1994 940, Straxx; 2008 C70, Draco

Are you using one of those clamps that push on the piston and turn it at the same time?

Or does the 2013 have an electric parking brake? If so you may need to apply an electrical current to pull the piston back in.

Am using a disc with two pins that fit the holes in the piston. I turn the disc with a socket wrench, while pressing quite hard. Yet nothing happens. Don't have the fancy Volvo tool that provides push too. Have to do that by hand, but have been pushing with all my might, and FCPEuro videos say that it will work (ha ha ha).

Parking brake is good old manual, but I may need to find the adjuster for it by the base of the lever and loosen it up some.

What is kind of amazing is the condition of the whole wheel/brake assembly aside from pad wear: it is nearly immaculate, like a car with 10,000 miles on it. It actually has about 86,000. Thus it is especially vexing that the damn piston is fighting so hard. Don't want to add $206 per caliper to have to put new calipers on too, if they are shot somehow.

Thanks Chris, long time since seeing your kind advice, and since I have been here on the forum too. Am losing my confidence in ability to work on cars, and mostly anything else.

PS, thanks for the tip about the electric parking brake. Just bought a Mazda CX-30 that has one, and it figures that they would make it more complicated these days.
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1955 Human, Scott; 1991 745 Turbo, Thunderbolt; 1994 940, Straxx; 2008 C70, Draco

I recall buying a cheapo caliper piston turning block from NAPA and filing/grinding it to fit our '04 V70. Then I think I used a C-clamp to provide the pressure and turned the block with an open end wrench. There was no way I could push it back by hand.
Greg

Parking brake is off. Got the left caliper retracted easier than I thought with t tool set from Advanced Auto. BUT (There is always a "but", the left caliper wouldn't budge, to the point that I almost ruined the tool. Note that the left side inner pad was metal to metal and the heat must have been horrible.

Gonna order a genuine Volvo caliper from whomever can get one to me the fastest. Probably the local Volvo dealer, but $$$$$$.

Thanks guys.
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1955 Human, Scott; 1991 745 Turbo, Thunderbolt; 1994 940, Straxx; 2008 C70, Draco

“…. Parking brake is good old manual, but I may need to find the adjuster for it by the base of the lever and loosen it up some….”

Not to be a wise guy or anything, but you did release the parking brake before you started all this, right? I ask because that’s the type of boo-boo I’m capable of making. Or could the cable be rusted/stuck to the point that even if you release the parking brake lever the caliper end of the cable isn’t moving? That could be your obstacle along with rapid brake wear.