Brakes rumbling in reverse?

[Rickmaan1]

My car is an '09, base V6 with just 13k on the clock. About a month ago I noticed a rumbling noise when I hit the brakes while backing out of my driveway. This has only happened when the car has sat overnight, and only after being washed or when it was raining pretty hard. It has never happened going forward, and never after driving the car for any distance. It happened again today, only today there was no water present. No rain, and I didn't wash the car yesterday or today either, so I'm afraid what ever is causing the noise is getting worse. Has anyone else experienced anything like this, or have a clue what it might be? At 1st, I thought it was just water on the rotors causing a little chatter between the pads and rotor surface, but as I said, today the rotors were dry and I got the rumbling backing out of my driveway anyway.

I do intend to take it to the dealer for a warranty check, but I really hate going there with a "special circumstance" issue, one that only occurs under certain conditions. I waste my day off waiting around the service dept and end up going home having nothing done because we couldn't duplicate the problem at the dealership. That's exactly what happened when I took it in for an engine idle vibration that goes away when the A/C is turned off. This only happens when the car is fully warmed up and driven for at least a few minutes, then at a stop and in gear I can feel a subtle vibration, turn the A/C off and the idle is so smooth you can't even tell the engine is running. As sublte as the vibration is, it is very noticable compared to how smooth it is with the A/C off. Of course I could not duplicate that in the service dept and ended up leaving with the tech telling me "some harmonics are to be expected". Harmonics my ass, I know a vibration when I feel it.

But I digress , this post is about the brake noise. Hopefully someone can give me a clue of what to look for so maybe I can see something wrong myself that I can point out to the tech at the dealership instead of just wondering if they'll bother doing anything and send me home with out making any repairs or adjustments (again).

 

[67&05STANGS]

What you are experiencing is moisture and rust on the rotors. This can occur overnight even if it hasn't rained or you didn't wash the vehicle. Humidity or dew overnight will cause rust on the bare metal of the rotor. The problem will go away after using the brakes a few times. This is completely normal and happens on my F150 because it sits out overnight. By the time I get to the main highway the problem is gone.

 

[Rickmaan1]

OK, I'll take your word for it that it's normal, it does sound logical. It's odd that I never had an issue like this on any cars I've had before (and I've had alot of different cars over the years), makes me wonder if Ford is using a cheaper grade of iron in the rotors these days. Now that I think about it, my ex complained about a similar brake noise from her Jag that started when the car was around a year old, same as my 'stang. I hadn't remembered that 'til now cuz I really try not to think about my ex .
Since Jag was owned by Ford when her car was built, this might be a trend with late model Ford brake rotors.

 

[67&05STANGS]

Ford as well as the other Automakers forced their suppliers to cut costs a few years ago. This was accomplished by the suppliers cheapening the products they supply to just meet the minimum standards. Rotors and drums for instance are so thin now that you can consider them thow-aways when you go to do a brake job. They are so close to minimum tolerance when produced that you won't be able to get them resurfaced. This also makes them more prone to warpage from heating up.