[BMWnut]

Just picked up a 2009 Taurus x with AWD. It passed the inspection no problem and the tech noted the front pad thickness is 7mm. Problem is when applying the brakes we'd get pulsing pedal and shaking in the front end.
I take the wheels off and the rotors look perfectly normal.... on the outside. The inside is a different story. Both rotors had heavy corrosion on the pad surface and I would say maybe 25% of the disc is making contact. Surface is uneven.
I took the rotors in to get machined which fixed the shaking problem BTW. I asked the guy at the brake shop what causes the rotors to corrode on the inside only and he told me he didn't know but he's seen this several times.Some cases much worse than mine. He figured maybe moisture is being trapped between the rotor and dust shield. The way the rotor is vented, the air enters the vents from the outside. On the inside, air is blocked from entering the vents. Mainly on the front of newer vehicles the inside rotor surface corrodes.
Anybody have a explanation for this? Causes? preventative measures?
Thanks.

[Graybeard]

Our newish '86 Sable developed pulsating from warped rotors. Dealer had worked on brakes and failed to bleed the rears. They weren't doing any of the stopping, and the front rotors warped from overheating.

GB

[mark v]

I know ford had some issues with the late 80's to early 90's Taurus rotors, if they are the stock ones they were very prone to warpage.

The dust shield has noting to do with rusting, maybe a cheap overseas rotor was used at one time, they are total junk!

[Canuck623]

It's where you live. Most cars will suffer from rotor corrosion issues in the Northern climates. We are free of that down here.

[mark v]

Yes all rotors will rust up in the northern climates if left sitting for a long time since the rotor is made out of unprotected steel however to produce a lot of rust where they are permanently damaged they will have to be sitting out in the open for I would assume for a good year.

Most rotors will get a very thin film of rust after a good driving rain sitting overnight that will disappear at the first stop of the car but never enough to know any difference.

[Poppy]

Originally Posted by BMWnut

<snip> I take the wheels off and the rotors look perfectly normal.... on the outside. The inside is a different story. Both rotors had heavy corrosion on the pad surface and I would say maybe 25% of the disc is making contact. Surface is uneven. <snip> Anybody have a explanation for this? Causes? preventative measures? Thanks.

I'm wondering if you are experiencing wear on one side of the rotor, and not so much on the other becuase the caliper is pushing the pad on one side into the rotor, and the slides are frozen and are not pulling the pad on the other side of the rotor into it.

[Dominick]

It may just be from sitting around for a long period of time.
I've seen new vehicles at the dealership get a surface rust on the rotors front just sitting in the lot.

[BMWnut]

Originally Posted by Poppy

I'm wondering if you are experiencing wear on one side of the rotor, and not so much on the other becuase the caliper is pushing the pad on one side into the rotor, and the slides are frozen and are not pulling the pad on the other side of the rotor into it.

When I dis-assembled the caliper/carrier to remove the rotors I made note of the slides and they are free and working as intended.

I have around 8 vehicles here and I can only drive 1 at a time (well the wife drives too) so I'm well aware of cars that sit and the corrosion that will build up on idle rotors. I am certain this Taurus hasn't had much time standing still....154,000 Km on the clock and barely three years old. This is different from anything I've seen before, inside only.
My best guess is attributed to road salts. Maybe inferior materials too. I will keep an eye on it to see how they hold out over the winter.

[mark v]

I bet you got defective rotors on the car because with that mileage they had to have been replaced by now.