I have a 03 Impreza and I wanted to do a rear break job and I noticed that there was a 32mm nut in there with a dent in it (assuming it keeps it from coming loose) and I have never worked with this kind of break system before. Any help would be great.
hmm....I don't recall finding a 32mm nut on my rear brakes when I replaced the pads and rotors. remove the two (I believe they are 17 mm) bolts holding the caliper onto the rotor, slip the caliper off (have something nearby to rest the caliper on so lines aren't damaged), take your e-brake off so you don't fail like I did and wonder why the hell the rotor won't come off, pull the rotor off. If it gets stuck, whack it with a deadblow or something. Although, they do also have threaded holes in the rear rotors for a tool that screws in and pushes the rotor off the hub assembly. You can also use properly sized bolts/screws. But, with the e-brake off it shouldn't be a problem.
Edit: Come to think of it, 32 mm is a pretty big nut. Good chance that's the nut on the hub assembly, which you shouldn't have to mess with for brakes. If you were replacing the rear axle shaft maybe, but not for this.
You most certainly don't need to loosen that nut. Just get the wheel off, and that's it. If the rotor is stuck, use a bolt in one of the holes toward the center of the disk to push the disk from the hub (if I remember correctly, it's an m12 bolt hole if you have the factory disks). This will loosen the disk, and it will pull right off. Also make sure the parking brake is off, as it's a drum brake contained within the center of the disk.
Thank you all for the information. I have the caliper off and the bracket that holds it but I cant get the rotor off! and yes the e-brake is off. I tried to hit it with a hammer and it sound solid and I don't want to break the rotor (they are thin)
Hit it harder. Not really though. Go to your local hardware store and try to find the proper bolts. It works best with both holes filled and the bolts being tightened down fairly evenly. There's a chance your local autozone, advance auto, AA auto, pepboys, or what have you, will have the actual tool designed for this job for rent for a very cheap price. My rotors were a pain to get off, but I spent literally two and a half hours trying to get them off before I realized the e brake was a drum brake in the center of the rotor, so the twenty minutes it took to get it off after i realized that really wasn't that bad. I think rambo's right about it being an m12 bolt; I do not, unfortunately, know the specific pitch.
And wait..are you replacing the rotors? If you're replacing the rotors, who cares about breaking them. If you aren't, then they don't need to come off anyway.