Black spots on Brake Rotors

[thrasher]

I just changed to my summer tires and noticed that my brake rotors have black spots all over them. I know rotors rust, but this is definitely not rust. It also does not come off after driving it like rust normally does. Anyone have this problem? The car is less than a year old, surely I don't need the clean the rotors already...

[Cardinal Fang]

Do you have any pictures you can post?

[x_o_k_x]

grease, paint or maybe even defect rotor...?? but yeah pictures please, im curious now

[thrasher]

Here are some photos, hope you can see them

http://www.facebook.com/photo.php?pid=41026337&l=a7fdb&id=58010863

http://www.facebook.com/photo.php?pid=41026338&l=727d8&id=58010863

[thrasher]

Hmm looks liek that didn't work.. How can I post pictures? I don't have anywhere to host them.

[cwp_sedan]

Looks like hot spots, or maybe some kind of grease/oil has got on them when they were hot.

[thrasher]

There we go, please let me know what you guys think... Maybe my brakes are just dirty? I've never seen a rotor like this tho.

[thrasher]

Odd enough the front are the only ones with the spots. The back are perfectly fine. I don't brake hard either.

[theurgy]

Check the pads and make sure they are OK.

[Flagrum_3]

Looks like hard spots or corrosion!, most likely due to a bad casting as opposed to heat since you say you don't brake hard...New rotors and pads are in your future!...What's the mileage on your car? If you're not over 20k or a year the dealer might replace them under warranty!


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[thrasher]

Under 10000 km, I suppose at this point I can take it in for a service adjustment and it will be free to check it out. :)

[thrasher]

http://img208.imageshack.us/img208/7036/img1680xu7.th.jpg (http://img208.imageshack.us/my.php?image=img1680xu7.jpg)

http://img208.imageshack.us/img208/7914/img1677so8.th.jpg (http://img208.imageshack.us/my.php?image=img1677so8.jpg)


http://img208.imageshack.us/img208/4588/bimg1679wk0.th.jpg (http://img208.imageshack.us/my.php?image=bimg1679wk0.jpg)

http://img208.imageshack.us/img208/493/img1692cb2.th.jpg (http://img208.imageshack.us/my.php?image=img1692cb2.jpg)

[Ex-Rolla]

It should be cleaned... a little bit of 200 grit sand paper and some elbow grease, then wipe with rubbing alcohol should do the trick...

OR

Take it to the dealer because it's still a new car. :)

[thrasher]

I think a dealer would charge me to clean this considering if it is greased it's not a defect of any kind????

I think i can attribute this greased to Sam's club, who greased my hubs because they had such a hard time getting the winters off to balance them. I guess they went a little crazy and greased the flat part around the hub too.

[thrasher]

Can the brake cleaners used by people on this forum get this stuff off if it is grease?

[Mike]

I have the same thing on my brakes too. I never looked at it carefully, but it did catch my eye. Car has 12,000 km on it. But actually I am going to get an oil change at the dealership in 40 minutes, so I'll ask them what is up with that. I'll post back if I get a good answer.

[Mike]

well to follow up on the story, I ask my dealer about the black spot and he said it was rust and it should go away with time.

The car brakes fine and there's no issues so far except cosmetics, so I'll give him the benefit of the doubt. But I don't remember seeing black rust before, and it's been like that for a while now, so I have a hard time believing what he says.
Anyway, we'll see. If someone has a good explanation or solution, let me know.

[thrasher]

I'm 100% sure it is not rust because if you let yoru car sit for days the rust would disappear as soon as you hit the brakes. Where as, I've been driving the car to and from work and the spots are still there. It probably is grease

[mazda lover]

Just curious but do you get the early morning brake squeal

[Flagrum_3]

well to follow up on the story, I ask my dealer about the black spot and he said it was rust and it should go away with time.

The car brakes fine and there's no issues so far except cosmetics, so I'll give him the benefit of the doubt. But I don't remember seeing black rust before, and it's been like that for a while now, so I have a hard time believing what he says.
Anyway, we'll see. If someone has a good explanation or solution, let me know.

That is definitely not 'just rust', it looks, as I mentioned earlier like metal corrosion from a bad casting!!-(not uncommon with Japanese quality forgings).Sanding will not take it out and it will not disappear on its own!!.Try it for awhile but don't let yourself go over the 20k/1yr limit or they can then refuse to replace the parts...I would definitely take it back to the dealer asap and complain, also demand replacement under warranty of both rotors and pads because the pads have undoubtably been contaminated already-(telling from the scratches).


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[Mike]

No early morning brake squeal.
And I agree, it doesn't look like rust at all. I can't even wipe it off like if it was grease. So bad casting sound like a possible solution. I'll do a it of research on that and see what I come up with. Then I'll go back to Mazda and get them to do something about it. It's easier to complain and get things accomplished if you understand the problem as opposed to just guessing.

[Flagrum_3]

Well don't take my word for it then, but research will do you no good.Test it!!; by sanding down the rotors with some fine sandpaper or emery cloth.If its oil (which would seep into pours), and which is why you can't wipe it off, it'll never come back but if its corrosion it will within a short period.Or better yet, take it to a trusted quality mechanic or another dealer and ask them what they think....but like I said do it asap...so you don;t go over the numbers and loose out on some new rotors and pads!


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[thrasher]

Interesting, well if you go to a dealer let me know how it works out!

I will probably book a service appointment soon anyhow.

And no I do not really get morning squeal.