I have a 99 F-150 "Off Road" 4X4 Super Cab. I bought it with 33k on it 5 years ago and last year, at appx 120K, I noticed the brakes were getting softer. Inspection revealed the pads were well worn as could be expected, but not gone. Also, the inside of the drivers side rotor had a half inch wide glaze stripe right about in the middle of the contact area. So, given it's age, I decided on new pads and rotors. I bought a set of Autozone PFC Carbon/Metallic Pads and a set of their rotors. I forget which model, but they were around $50 each. The rotors were soaked with oil, I assume to keep them from rusting in shipment/storage. I thoroughly degreased them before installing them. Removal of the old ones went mercifully easy. Light tap with a brass hammer and they fell off. I cleaned and tested the calipers. They worked fine. The brakes have worked fine ever since then. The truck rarely sets for more than a day without being driven until last week when we went onvacation for a week. Upon returning, my neighbors told me it rained cat-and-dogs for several days straight, over 4 inches total.
The first day I drove the truck to work I noticed a barely perceivable pulsing when breaking both in the morning and on the way home. The pulsing has gotten worse the past several days and I decided to have a look at them. The outside of both front rotors look shiny and show wear you'd expect on them. To my horror, the inside of both rotors are deteriorated in a fashion I've never seen in 27 years of doing my brakes. Both have what looks like severe galvanic corrosion on the surfaces. Not shined rust pitting. I know what that looks like. I mean dark gray corrosion with clearly defined high and low spots. The calipers are not seized and the wheels rotate freely up on jacks. I can't comprehend how the inside surfaces could be so deteriorated with the outside surfaces looking normal given the pistons are on the inside pads. It was late in the day when I looked at them and I will dismount them tomorrow. Has anyone seen such a phenomenon before? Could I have gotten some wierd, bad manufactured rotors or is this a sign of some other problem with my brake system? If it had been only one rotor, I would not have been so surprised, but for both to have deteriorated in the same fasion seems really odd. Right now, I'm figuring new pads and rotors again. I will certainly not get the "Chinese Charlie" rotors like the last time.

Thanks,

John

 

Well, despite looking like galvanic corrosion in the failing light of yesterday evening, what I found after removing the rotors was that both inside surfaces were delaminating. There was clearly a blackened substrate with gray steel on the surface. Where it had peeled away, there appeared to be somewhere around .005 of the surface steel left. No sign of delaminating on the outer sides though. The inside pads were gouged and striped, not to mention more worn away, from rubbing against the rough surface. The good (I think) news is that Auto Zone replaced both the rotors and pads free of charge since they were still under warranty, though barely. Their records were more accurate than my recollection, showing I had bought them in October of 2004, not last year. Still, they were just under the 2 year warranty. The manager was mortified when he saw the rotors. He said he had never seen such a strange manifestation. I'm a regular customer there and despite the poor performance of that particular produce, their lack of haggling over the problem and instant replacement will keep me coming back there.

Unfortunately, I wound up with more Chinese rotors, but at least they are no longer rebuilding them like they used to (according to the manager) and delaminating should not be a problem with them. You wouldn't think it would be cost effective to ship the duds all the way to China, acid etching the rust off, plating them back up, milling them to spec, shipping them back to the US and selling them for $39.95 but that's what they used to do. I got the same PFC Carbon/Metallic pads. I was surprised at how little they had worn down in two years, at least on the good sides, so they seem to be a good value. All told, I am out the gas to drive there and back, along with two hours labor for a new set of rotors and pads. I've had worse Sundays....

John