Brake Pad Warning Light

[Richmond325CI]

A week ago, the "brake pad warning light" came on. I didn't know what the heck the light meant until I looked it up in the manual. Never heard of such a thing. Usually in all of my past cars, all you heard was the horrible screeching of the metal inserts scraping against the rotors to let you know your pads were low. I have 23k miles on my '04 325CI, drive to work and back and to the gym every day. All city driving...

So I took it in to the dealership to have it checked out. I had visually inspected the pads and didn't see anything unusual. Two hours later, I was told they replaced the brake pads and rotors for the front. Of course it was covered under warranty. But to replace the rotors at 23K? The service guy told me BMW engineers the two components to wear at the same rate. If you "turned" your rotors and just replaced the pads, the brakes would warp under the demands of the car. I agree in theory since these cars can stop on a freakin' dime. But should these be worn out at 23K miles?

On one hand this shows how good BMW is in their engineering. The other hand is that upkeep on this can be very expensive if we have to change rotors and pads (front and back) every 25k miles!!! (assuming past warranty period)

 

[olcrazy1]

there is a sensor built into the pad, when the pad wears to a certain point the sensor makes contact with the rotor and grounds itself to turn the light on. This is very handy in knowing when to change the pads before damage to the rotor occurs.

Dealers like to change pads and rotors becaue it gives them more work to do and more funds to claim back from BMW for service on the car. If your rotors are not warped or pitted there is no reason to change them. If your brake pettal does not pulsate during hard breaking then they are fine, you can get away with just changing pads.

Rotors can be cut and they will be fine depending on how much metal must be taken off to straighten them out. Their is a min-spec the rotors must conform to. No one likes cutting them any more because it is easier and faster to just change the rotors. Once they are cut they will be easier to warp, this mostly depends on driving habits and conditions.

The dealer would liek to train you into thinkin gthat you need rotors everytime you change the pads beacsue it is easy money and makes for a cleaner break job.

I'm certified in brakes and would never change rotors unless they are warped (pulsating) or pitted, rusted, damaged, etc..... The average car can use Chineese rotors which can be bought for like $15 each, but I would never use them on a BMW, better off cutting the ones you have if they are within spec thickness.
Hope this helps.

 

[Abdoman]

I drive a 528 which is a heavier car, but I always replace the front rotors (never had to less than 40k) but the back rotors can run through two pad sets.