Cost of brakes, e39

My 2003, 530i (71,000 miles) is about ready for new brakes. The warning sensor light has not come on yet, but the dealer said I'll be needing brakes very soon.
Could some of you experienced folks answer a few questions for me:
Am I likely to need brakes on all four wheels?
Will I need to have the rotors replaced?
Can I trust this work to a local shop versus the dealer? Will a local person replace the sensor or is this the kind of thing that only dealers do?
What am I likely to pay for this work?
Thanks in advance.
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The rear brakes typically last at a ration of 2:1 for the front brakes. For every second brake job on the front brakes, you should expect a brake job on the rear. This is a very loose rule of thumb, but it's a reasonable rule to live by.
Rotors should also last a ratio of about 2 to 1, but they are destroyed if the pads get too thin, and they are generally designed these days for weight savings, and do not generally lend themselves to machining to remove any warpage that comes as a result of hard braking with thin pads -- which causes heat that leads to warpage. So, if your rotors are straight and smooth, it is possible that you can get a second set of pads on them before they must be replaced.
You can get a feel for the cost of the parts by doing an eBay search for E39 BRAKES. (Adjust the search parameters to narrow the hit list.) My limited experience leads to a rule of thumb that says the pads should cost in a range of $50 per axle set, and the rotors should run about $50 each. Given this formula, front pads and rotors should run to about $150 and rears should run another $150. You need a wear sensor, one for each axle, at a cost of about $10.
So, you can buy a 12-pack and the parts for the entire car for roughly $300. At 71k miles, I doubt you need rear brakes at all, so you can do the job on the front only for about $150 in parts.
BEWARE of El Cheapo brake parts. Odds favor being unhappy with the results.
I bought slotted and vented rotors for all four corners of my car ('94 3 Series), and the front rotors were not true (warped) out of the box. I called the seller and they sent another set, and told me to toss the first set. The second set was also not true, and because they were slotted and drilled, they could not be turned on a lathe, and I had to get them ground on a machine that cleans up flywheels. This cost $35. So, I got two sets of front rotors turned for $70, and I now have a set of rotors under my bench for when these wear out.
Your proboem is, you won't be doing the work, so you have to rely on a shop to do it properly and well.
When doing your eBay search, look for BREMBLE (I think that's the brand) Rotors. They are generally accepted as high quality parts with good quality control and long life. They will be a bit pricey, but they are good parts that you will be happy with.
There is no need to go to the dealership for this work, you can have the local Independent BMW garage do this for you. Personally, I'd suggest you develop a relationship with the local independent shop and stop going to the dealership.
You can look at your own brakes by simply removing the tires and looking. The edge of the pads are exposed and you can see for yourself how much material is remaining. If the BRAKE WARNING is lit, you must replace the wear sensor, but if the warning is not lit, you can often transplant the old sensor to the new pads and save the cost of the sensor.

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In article

Depends on what has been replaced before, and when.
I get about 25k front pads and double that back. Discs need changing every second set of pads.

It's a very straightforward job - I do it myself, and using OEM (ATE) parts costs about 1/4 dealer price. For a light day's work. The sensors are also ATE parts and common to other cars.

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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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At 71,000, probably. Won't hurt to do it if the thing is up on the rack anyway.

At 71,000, there's a chance of it. Some mechanics just want to swap the rotors out pre-emptively whether or not they are too thin, just because the rotors are cheap enough that it doesn't add much. I'm too cheap to do that myself, though.

Sure, find a good independent shop. It's easy work to do... you can do it yourself if you can read a micrometer.

I don't know, it depends entirely on how much rust is under there. It takes me about two hours do four wheels, but I don't have a lift and have to get the car up on jackstands which adds a bit of time. A professional mechanic can probably do it in a good bit less. --scott
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