Semperspeed

So I replaced my back rotors and pads about a week ago. Well there is a grinding sound coming from them when I use them. The car is a 05 mazda3 with no mods. Can someone help me please. Thanks

djs2571

new rotors are rough, so they may make a bit of noise, but it shouldn't be noticable. Have a look to see if the rotors are being marked, like by something stuck in the pad grinding. You may need to take them apart to see where there are marks, could be a crooked caliper bracket or other part reinstalled incorrectly - or forgotten.

Semperspeed

It's not a loud noise. You can only hear it below 5 mph. I didn't see any marks indicating that something is rubbing. Could it be that it's just cheap rotors and pads by any chance?

djs2571

It sounds like it's the finish they put on the rotors, sounding like when it's first in the morning and there's a layer of rust on them. It should go away when the brakes get used a bit and the finish goes from a ground finish to a mirror finish.

Semperspeed

Thanks so much. I have just never heard it from new brakes before. This car has given me so many problems that I hear every little noise that something else is breaking on it

djs2571

As long as you're sure the brakes are installed properly, which is why my first response was to check for evidence of something grinding on the rotor. If it doesn't go away in a few hundred miles (though you said it has been a few weeks) - or a few hard stops, you may want to look at it again.

If the car is giving you so many issues (sorry to hear), you may have a lemon - or need to pay more attention to maintenance. I know i've been unhappy with the brakes just because the calipers tend to drag very shortly after they have been re-lubed. Other than that i've seen no big mechanical issues with the 3 design.

Semperspeed

I would have to say that it's only been like maybe 100. I think the car is a lemon because it always happened right after a oil change.

djs2571

So, to drift away from the brake topic, what other sort of "so many problems" have you run into that needed repair?

Semperspeed

I have been through 3 engines. All 3 the lifters weren't getting oil. 1 transmission. It just went out right after the 2nd engine. A engine mount which caused the cv shaft to break

djs2571

I haven't heard of so many issues from a person, much less a single vehicle over 5 years. I'm more suprised you kept the car / model.
Hopefully the drivetrain won't cause you any more issues, though i'm sure it's now time for suspension replacement parts
I wish you luck.

jhon martan

The mechanic should put a dial indicator on the rotor and measure the run out. That's how many thousandths of a inch the rotor is out of true. Next he use a micrometer to measure the thickness of the rotor. This will determine if they can turn or resurface the rotor and still have at least minimum thickness.

Semperspeed

The only reason I have kept it is because I am upside down on it