Stock Rotors?

[Spedracer81]

I'm hearing a grinding noise when I apply the brakes, I believe its coming from the rear drive side, I'm not sure if its the rotor, the pads look like they have some life left in them. I doubt they've been changed..when should I change them? I got 49,xxx on the clock.
Are rotors covered under my extended warranty?
Should I replace both rear rotors if thats the case?

thanks guys

[dubsesd]

brakes are typically wear and tear items and are not covered. i doubt it but it doesnt hurt to ask

[Pheonix]

The inside pad might have worn down to the metal wear indicator. The should be a miminum thickness require for rotors (should be stamped on the rotor hub). You only need to replace it if below specs.
Pads and Rotors are not covered under warranty. They are however covered under Free Maintenance and the dealers will only replaced the rotors if the pads are also worn out. It is very strange policy.

[The HACK]

There are no "metal wear indicators" on BMW pads. There are plastic sensors with wires embedded to tell the system when two of the inside pads are running low (front driver's side, rear passenger side).

How long have you had the car, did you recently wash the car, is this a recent occurrence, and what have you changed recently in the brake system? When you mentioned the pads have some life left in them, how much pad material can you actually see?

I've often said it's impossible to diagnose a car problem sight unseen, and it's doubly impossible without the proper input. It could be as simple as a small rock stuck between the pad and the rotor, or a bigger problem with a caliper piston requiring a rebuild.

If you're mechanically inclined, take the wheels off, take the calipers off and inspect each pad individually, and take a micrometer to the caliper to see how thick it is. If you're not mechanically inclined, take it to an independent mechanic.

On a slight tangent, grinding noises are not uncommon with slotted and drilled rotors.

[Pheonix]

I stand corrected that OEM pads do not have "metal wear indicator". However, the OP might have aftermarket pads and this is very standard practice for brake pads.
Anyhow, try to do what the Hack recommended and you should good.

[Spedracer81]

thanks for all the input...I did just go to bmw, and its covered under free maintenance package, but my car is not covered anymore, figures but worth a shot.

I did take the calipers off to paint them and I noticed the slight grinding after I put them back on..I did a visual check, but have not taken them off and re-mounted..thats going to be my next step..

Its an 08', just about to hit 49k..never tracked, driven aggressive but not for long periods of time..theres no wearing on the rotors..

Didn't know if theres a mileage at which they should get replaced eventually..

it also seems to make that noise when the car is cold..when the car is first driven..or under light braking..I do a lot of downshifting, and barely use the brakes unless I have too..not sure if this is something to be concerned about...

[Spedracer81]

I took off the wheel, then the caliper, inspected the pads...seemed like plenty of pad left..

Its hard to see but it seems like its grinding around the perimeter of the rotor, its about 1/4" wide... but I can't see anything getting caught on it..

Attachment 1023538

Attachment 1023539


Kinda at a loss...I don't even know what part to replace..

any ideas?

[fullerra]

can't view the attachment

[Spedracer81]

[fullerra]

It does look like there is something grinding on the periphery of your rotor.

This may work:

Use a bit of colored side-walk chalk, and rub it on the periphery of your rotor, just where it is ground down. With the car on 4 jack stands, put the car in neutral and turn the back wheel (E-brake is of course off)

After a couple revolutions, take off the rear brake pads, caliper and carrier and see where the chalk has accumulated.

[Spedracer81]

fullerra - Good idea, I'll try that over the weekend...thanks

[PLCZ4MC]

My makes noises too ones while not all the time. I know all 4 break pads have been change last year there is still a good amount. Sometimes i wonder too why makes such noise.

[The HACK]

When you took the calipers off to paint it, did you torque the guide pins and the caliper carrier brackets to spec?