[MN-Subaru] How to do the single piston caliper rear disc brakes on a Subaru
First, my apologies to those who were expecting the factory manual pages to be scanned - I left them at my buddy Norm's house with the old pads. (d'oh!) Anyway, reports that my right rear caliper was hung were greatly exaggerated. True, the pads on that side were worn down to a millimeter or so of material, but the caliper was fine.
A couple of references:
http://www.autotruck.net/ms/archives/1997/0197/197brake.html
http://www.autoweb.lycos.com/garage/encyclop/ency14d.htm
I'm just writing this in the hope that those people who might need the info would get it - I'm not a mechanic, and hopefully I'll have the right view of it for neophytes to understand.
Loosen the lug nuts on the wheels you need to work on so that you can remove them easily when the car is in the air. Jack up the car and place appropriate jackstands under appropriate places. You shouldn't work with the car on the jack. Jackstands are much more stable. I did it with jackstands under the rear of the car (I don't remember where) but, the weight was really on the jack. My bad.
With the rear end safely supported, take the rear wheels off. The caliper is held on by 1 bolt. A big pin helps to position the caliper. The pin is in the top/front of the caliper, on the inside (towards the wheelwell). The bolt is in the bottom/rear of the caliper, on the inside (toward the wheelwell).
Undo the single bolt. Pull it out and set it aside. Pull up on the bottom/rear of the caliper so that it swings up and clear of the pads and rotor. It should pivot on the pin at the front. You may need a pry tool to move the caliper.
With the caliper clear of the pads and rotor, you should be able to slide it off of the big pin and rest it on top of the rotor to one side of the pads. Some people recommend using a piece of wire to hang the caliper from the suspension. Your mileage may vary.
The pads will now be visible. They are held in by clips on either end of the pad. The clips are clipped onto the saddle-like piece that sits over the rotor. I had to pry my pads off of these clips. They had pretty much welded themselves into place. Be careful not to gouge your rotor when you are prying.
Since I had purchased the Subaru pad kit, I had new clips. I took off the old clips and put the new ones on where the old ones came from. Easy enough. There were also plates on the backs of the pads. I put dollops of thick, smelly anti-seize onto the back of the pads, and put the little plates on the new pads where the old ones had been. I put the pads onto the clips.
Next, I used a pad spreader (from NAPA) to force the caliper back into its little home. I made sure to center the spreader plunger on the caliper piston. I used moderate pressure and looked for any sign of binding or seizing. It went back in just fine. Some people say that you should clamp the brake line and open the bleed screw before you do this, so that you don't force back any crap that may have collected in the brake line. There is some danger of forcing crap back to the ABS pump - remember that the lowest point in the brake system is probably your caliper. Your mileage may (again) vary.
Next, I checked the pin and the bolt to see if there was any dirt, damage, or other evidence of binding. There wasn't any, so I put a dollop of antiseize onto the end of the pin and the end of the bolt. I filled the holes on the caliper that the pin and the bolt go into with synthetic grease and slid the caliper onto the pin. I then rotated the caliper back into place and slid the bolt through. I torqued the bolt down to a firm setting. You can always look up the torque specs if you are concerned.
At that point, I was done, and moved on to the next corner. The first one took about 30 minutes, the second took about 15 minutes. I worked slowly and carefully, and had a buddy who had done brakes on many other cars help. Overall, it was really a simple process.
What to do if your caliper really is binding in some way:
Most likely, it's binding on the float pin (or maybe the bolt). When you pull it off, you should see various bits of dirt or other gunk on the pin and maybe in the hole where the pin was. This is what you would clean out. I had one friend who used a bench grinder (I didn't see what he did). I didn't have to deal with it, so I'd just be guessing, but I'm sure you can figure out a way…
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