How come my rear calipers keep sticking?

[Velo Dog]

I used to be a decent mechanic in my Fiat 124 days, but our 2003 Protege5 has been so trouble-free I've barely touched a wrench in 10 years/180,000 miles....
But now I have problems with both rear calipers sticking. Initially I just replaced the pads, but they wore out in a few thousand miles, and it's obvious that the pistons aren't moving freely. The car doesn't get much use anymore, just back and forth to work, and I'm reluctant to replace the calipers if I don't have to. If the pistons can be removed, I'd try smoothing them out and lubing them, but I can't figure it out. Anybody know?
Also, do the rotors just knock off once the wheels are removed, or is there some secret brake-disc securing device I don't know about? They're a little worn and as long as I'm in there, I figured I'd replace them.
Thanks...

 

[dieselmiata]

There is a small hole in the rotor designed for inserting a bolt that will pry the rotor from the hub.

As far as sticking calipers, they're really no different from any other ones. Over time, moisture will find it's way into the cylinders and corrode the bore. You can buy a rebuild kit and use a small cylinder hone to smooth the bore out again, but with the cost of a new caliper at Napa being $80.00, it's more cost effective to replace them.

If you choose to rebuild, you need to remove the pad adjustment screw from the caliper and (what I usually do) is apply compressed air to the bleed screw port. This will cause the cylinder to pop out allowing you access to the bore.

Rebuilding a rear caliper is about a 2-3 hour job. Replacing one can be done in 30 minutes.

YMMV.

 

[Velo Dog]

Perfect, thanks. I got an estimate of $600+ to replace the calipers, $400 for parts alone. Since then I've found them cheaper online, so it looks like that's the way to go. I'm looking at a Mazda 6, but I want to keep the P5 as a daily driver.

 

[kms1990]

82.99 each at autozone, or 75.99 unloaded rockauto.com or 95 for one with pads in it

 

[dieselmiata]

It really is a simple job. Even with little experience, replacing the old caliper shouldn't take more than an hour from start to finish. All you need are 8,10,12, and 14mm wrenches. I replaced both of my rear calipers last weekend in about an hour, and that included getting the car in the air and bleeding the brakes.