What is the material build up on my rotor?

[Joker5354]

First post, so i hope this is the right form.

Ok, so a brief history. My car is a 2007 Ford Fusion SEL AWD. Probably less than eight months ago i installed a new set of rotors and break pads on my car after finding my old pads and rotors were worn down. I bedded them in as per the manufacturers instructions and didn't seems to have any issues with them.

I should mention that I bought the complete set through a company on ebay. The reviews seemed good and the price for the complete set was less than what the local shops wanted to change me just for the front rotors alone.

Anyway, I recently had left my car undriven for a few weeks and those rotors rusted right over, my bad, but I do live in eastern Canada so everything rusts! Now, here I am a couple weeks later and I'm finding my car vibrates/pulses pretty bad when breaking (frequency of pulses slow as car slows). There is also a very slight vibration when driving as well. After some research, I've concluded that the issue is variation in rotor thickness due to material build up.

So, my question is what is this material build up on my rotor. As you can see in the pic there is a ring of rough material,which is on all four rotors, but i'm not sure if this baked on rust, material from the break pads or cementite due to overheating. I'm starting realize that I'm probably going to need new rotors "again", but maybe someone here has another idea.

Thanks for your help!

[vgames33]

It looks like pitting from the rust. Turning is an option since they're fairly new.

[curtis73]

It looks to me like cheap pads + foreign material = baked-on mess. Is it possible you got something on the rotors? A glob of grease from a ball joint? A squirt of tire dressing?

At any rate, turn them. You shouldn't have to remove much at all which will maintain the integrity of the rotor.

[shorod]

What about the anti-corrosion film that rotors typically ship with, might that be the baked on substance? At any rate, I'd agree that it's worth a shot at machining the rotors to see if you can true them up and reuse them.

-Rod

[Joker5354]

Thanks everyone for the help. It's certainly possible that something else got on them, but since I'm having similar problems with all four rotors I'm leaning towards the surface rust that built up after not driving it for a bit. I'm going to try and get them turned to see if that works. Should hopefully save me some money!

[shadows]

you can wash your car- spray water on the wheels and rotors- you can leave it sit- the rotors will rust

you can sand rotors to remove rust- you can drive it to remove rust- you can pay good money to have the rotors turned- they will still rust

in short- have a professional mechanic at a respected place check your brake system