Okay, so it's not as "easy" as everyone is portraying here. There is more to it than just "replacing pads". This dangerous work (the car can fall on you if the wheels are off) and not doing the job properly can lead to brake failure.
First off, to get the most effective performance and longevity out of the new pads, the rotors need to either be replaced or resurfaced. If the rotors do not have a flat surface (as new rotors do) then the new pads will not bed properly to the old rotors and will not last as long and not perform as well. It's been my extensive experience with BMW brakes that the original set of rotors, once resurfaced as should be done for a proper brake relining (that's old dude speak for brake job), will not last all the way through the 2nd set of pads and may get too thin and can warp before the pads are used up. IMO it is just better to spend the money on a new set of rotors when relining BMW brakes.
Second, if you’re not well versed in wrenching on cars, and don't have all the proper tools to do the job correctly and safely, have a professional mechanic perform the work. Safely doing a brake job means raising the car on 4 high-quality jack stands (so it won't have the ability to roll off) using a high-quality floor jack that can reach the center lifting points of the chassis, and having a good set of quality tools to do the work with. It is dangerous work as well because as an example, there are anti-rattle springs attached to the calipers, which if improperly removed can fly off and hit you in the face. Also, you should not let the caliper hang on the brake hose as it could compromise the hose and at some point fail under pressure months after you did the brake job
Last edited by Efthreeoh; 01-20-2013 at 08:07 AM.