Your mechanic knows a whole bunch of tricks to prevent causing noises and vibrations, and he knows a lot of things do-it-yourselfers accidentally do to cause problems. There's a lot more to a quality brake job than just hanging on new parts. I can run through them if you still want to pursue the job yourself. As for cost, what you were quoted is about three times the normal cost, which is about right for a BMW. Parts for all four wheels for any of my Chrysler products comes to between $100.00 and $150.00. If I had to pay $380.00 for two rotors and pads, I'd get a different car.
Your mechanic might have been including the calipers in his estimate. Unless they're causing a problem they do not need to be replaced. The old rotors can be machined if they will end up still above the published legal minimum thickness. We used to always machine rotors but that was when there was a lot of metal that could be removed. Today they are made so thin to save weight that often they can't legally be machined. The other factor is new rotors have come down so much in cost that it is cheaper to replace them than to spend the money on labor time and lathe cutting buts. If your rotors are uncommonly expensive, machining them might be a less expensive option.
As for instructions, nothing is better than the manufacturers service manual, and BMW, as I have been told numerous times, is the only manufacturer in the world that will not release theirs to anyone. All you can do is disassemble one side at a time and put the new parts on the same way. You'll have the other side to look at for reference if needed.
Tuesday, November 13th, 2012 AT 11:16 PM