Brake problem
 

So I got off my ass and changed the pads finaly. And to my horror the passenger side was completly gone while the driverside pads were still some 50% left.

Hmm thats no good, while compressing the caliper I found that the passenger side had the O ring around the pistion ripped and I could see rust behind the rip. It was also really hard to compress compared to the drivers side.

This is the cause, right? If I replace the O ring and possibly the piston it should be fine. Where can I get this stuff, dealership?

I would say that yes, your passenger side caliper needs repair. You can get the parts from the dealer, or try your local auto parts store (Auto Zone etc). You might also ask there what they charge for a rebuilt caliper, it would probably be cheaper than buying parts from the dealer. Items like that usually have a core charge that you get back when you bring in your old part.

Were your brakes squealing? The right front should have been. As far as I know, all brake pads have wear indicators which is basically a piece of soft metal that drags on the rotor and makes a horrendous noise. This lets you know your pads need to be replaced (unless you are old and/or oblivious). Make sure you check your rotors over really well for any damage, might be a good idea to have them turned while you are into this job. Or you can replace them with some nice Brembos, Sportbrakes.com has a set on eBay for $98.00 shipped. I got a set for my gf's car from them, they are good to deal with.

www.mazmart.com
www.auto-parts.com

don't go to the dealer. If you HAVE to have new OEM pieces call Ken from protegegarage.com and tell him I sent you. He'll take care of you.

The brakes werent even squelling it was right up to the wear indicators, though didn't start yet. The rotors seem fine, its ok that the one side used up the pad quicker right. It wont be slightly thinner causing problems right?

Autozone has some frapson product for pretty cheap $42 after core refund. These are rebuilt oem pecies right, just as good as OEM. I asked the guy and he was like um there new. Does this sound fine?

Under normal conditions when the car is moving the piston on a disc brake will retract slightly which prevents the pad from continuously dragging on the rotor. Sounds like your right caliper piston wasn't, which caused the extra wear on the pads on that side. It's good you caught it before it hit the wear indicators, I have seen people who ran them right down to the metal backing plate.

Any of the big auto parts stores carry reputable parts. You may occasionally get something you have a problem with (like anything else) but they will usually make good on it. I would recommend cleaning the inside of the new caliper the best you can with some brake cleaner to make sure there isn't anything inside. If you hold it with the hole the hose attaches to upside down and spray up into it, the cleaner will run back out and carry along anything that might be in there.