Brake pad change problem

I tried to change my front brake pads today and I ran into a problem. I've only changed the rears on this car and other than some hard to turn bolts it went fine. I got the wheel off, took the caliper bolts off and the caliper wouldn't budge. I had to knock it off with a rubber mallet. I thought maybe it was just really on there tight. I took off the old brake pads which looked like shit and put on some new Hawk HPS pads. I compressed the pistons back into the caliper as far as they would go, greased everything and tried to put the caliper back onto the rotor - only it wouldn't go back on . It was like the pads were too big for the caliper because the old pads went back on there fine.

 

Against my better judgment I forced it back into place with the new pads and bolted everything up. I could turn the wheel by hand so it wasn't binding or anything. I took off the other side wheel to replace those pads hoping everything would work out normally but I ran into the same problem. Wtf?? I thought about forcing it into place but I decided to just throw the old pads back on and try to figure out what the problem is.

 

I've attached a picture with the new pads fitted and no caliper on. Again the pistons ARE compressed back down to the rubber so I don't think that's the issue. Can the bolt I circled be adjusted? One of them seemed to be able to move and the other was stuck. That seems to be the thing making the caliper not fit over the pads. Any help would be appreciated, I haven't done this on the front of this car yet.

The more I look at it the more I'm thinking those bolts should be able to just come right off and the whole caliper assembly should just come right off with it. I guess they were just stuck? Hoping that's the case.

the two bolts you circled are sliding/guide pins that go into the the metal brake bracket. the pins are normally lubricated (hence the boot) and have rubber bushings at the other end, presumably to act as sort of a piston to help keep the front of the caliper snug against the pad.

 

I'm guessing that the lubricant has dried up and/or the rubber pieces have swollen, sealing themselves to the inside of the metal tube (not surprised considering Canada winters and your description of the existing brake pads). if significant corrosion has occurred, the metal pins may have rusted to the inside of the bracket.

 

Are you able to turn them by hand? it would probably be best for you to remove them to re-lube and inspect the sliding pins. Just turn and pull them out, if they turn and don't pull out, you can try tapping them back in to loosen things first. Otherwise, pull the boot back a bit to get a better grip on the bolts. If you're absolutely hosed, pull the boots off and use a crowbar or vice grip; those pins need to slide.

 

Regardless, it would probably be best to pick up new rubber hardware for the brakes and replace everything while you're at it - they're pretty cheap at ~$5. eg: http://www.rockauto.com/en/moreinfo.php?pk=541623&cc=1432596&jsn=346

 

Good luck!

Yeah, those things need to slide freely, but you don't want them to have extra play. See if you can get em out, sand or file away the rust, then reassemble with some grease, that should help.

Don't worry if the caliper and new pads barely fit over the rotor, as long as it goes together you're good. Once they're bedded in it's not an issue. Just make sure the caliper can slide back and forth, and the piston can slide inside the caliper, which it obviously can since you said you compressed them. The other thing is, make sure the slots where the pads sit in the caliper aren't all rusted up. The pads need to be able to move easily back and forth inside the frame.

And why is the inside pad sticking above the rotor? That shouldn't happen.

Thanks guys so on the passenger side, the top slider pin I was able to move in and out without too much effort. The bottom one was completely stuck. On the driver's side, neither slider pin was moving for me. So I notice they have a hex head bolt on the ends of them. Can I break them loose by putting a wrench on that head and turning or is there a risk of breaking them if I do that? I don't have heat available so I'm wondering whether I should try and loosen these myself with PB blaster and a breaker bar or take it to a shop so they can heat everything and loosen as necessary. My biggest concern is forcing it too much and snapping a bolt. Fotofan - I think I just pulled it out of place when I was removing the caliper to take the picture.

Yeah that head should take a fair bit of force without problem, I'd try to just break it loose that way. PB wouldn't hurt but I'd be surprised if it doesn't cover loose ok. If it breaks it should drill out fairly easy so I wouldn't stress it too much. And of course you could always pick up another caliper bracket from a junkyard or something.

like fotofan said, you should be able to break them loose with torque, but that still might not be it if the rubber is still stuck inside the tube. Make sure you pull out the rubber piece at the end too!

 

this guy has a good video on it: