My son drives a 2005 Mazda3. It has disc brakes on all four wheels. All four rotors appear to have a pretty healthy amount of red rust on the flat surfaces. I have never observed this on any other car I have owned, including Mazdas. My son says that the car stops with a normal amount of effort. He has had no problems with the brakes, nor do they make any noise.
Is this rust something I should be worried about? Being a Mazda, I shudder to think what new rotors will cost. However, I do not want my son to crash into something because his brakes are faulty.
Thats a new one on me? I would ask him if I could drive it to test it for myself. Is it possible they have grooves worn into them from previously worn out pads? They would rust in the grooves but still stop normaly.
Almost all rotors pick up surface rust when the car isn’t driven for a bit, especially in humid or rainy conditions. Some rotors will retain a reddish hue. Others will polish to the more usual gray. As long as the rotor surfaces are almost glassy smooth after driving - and after they cool down, but before they sit overnight - they are probably fine.
Any roughness, grooves or visible rust after driving is a possible problem.
I should have said that the car has more than 70K miles on it. It has never had a lengthy period of not being driven. It has spent most of its non-driving time in a garage. The car used to belong to my mother,who kept it in a garage. When it was handed down to my son a year ago, it started living more of its life outside when he parked it at his college. Neither our home nor his college are in unusually humid or caustic environments. I will check for grooves. I had that happen on a Toyota I had many years ago. The rotor looked like a phonograph record. These don’t look like that all.
Rotors rust, especially in humid surroundings. They have a lot of flat surface, not all of which is in contact with the brake pads. Normally the swept area (in contact with pads) is somewhat shiny, but it’s not unusual for any other part of the rotor to show rust, as in thesetwo photos.
I would find it odd if the swept area were rusty, but if the car stops normally I wouldn’t lose any sleep over it.
I’ve never found the price of Mazda rotors to be shudder-inducing. Mercedes or BMW, however, can generate apoplexy.
Chiming in on this. Yes, brake rotors rust. Even the swept areas. They are made of cast iron, after all.
I have seen rotors rust over in varying amounts of time, from a standard work day to sitting multiple days in a row. I’ve never owned a car whose rotors didn’t rust.
It’s normal, and the thin layer of oxide goes away as soon as you tap the brakes while moving.
Not only do rotors rust, but in some cases the pads can rust onto the rotors, especially if the car is not driven for a while and left in wet conditions.
My wife’s old Renault was terrible for this. If you hadn’t driven it for a few days then you could feel the resistance when moving off and then there was a noticeable “clunk” as the pad came free.
I have had to rock the cars back and forth to break the pads loose. All rotors will get some rust after sitting but I have never seen them rusty right after having been driven.
Depends on the rotor. You have cheap ones that rust fairly quickly, as in after it rains you’ll see beads of rust on it from humidity. To ones that take a long while to rust. At 70k he probably had them changed already from a local garage or the like and they used something cheap.
Since the DC area is rather humid and rainy in the summers I switched to Raybestos rotors and pads and they, so far, have been the best for this environment.
This has indeed happened to me, on an older car that had been driven in months (and already had crappy, grooved brake pads and rotors). I’ve never had issues with a vehicle I drive fairly regularly.
My current daily driver, a 2004 Dodge SRT-4, gets parked at 7PM and has rust-covored rotors by 9AM. I am in Houston and it is pretty humid.
If OP is still looking for something definitive, then yes, brake rotors CAN accumulate rust overnight, with the right combination of rain/moisture/humidity.
Yep. I have to slowly brake coming out of my garage because of a hill. I routinely hear the pads sanding off rust after sitting overnight on humid days.
I will say that after 190K miles my rotors were complete trash. chunks of metal came off like flaking mica. Never seen anything like it. Had to limp home on the rear drum brakes by downshifting and using the parking brake.
I had forgotten that it was a puzzler but I do remember that episode. I think they were rear drum brakes on a car that had been dormant a long time. The owner tried to bang them loose.
Rotors are turned if there will be enough left after turning. This is measured with calipers against recommended thicknesses. I just got two different opinions on mine about whether or not they could be turned. But I just replaced them b/c I think it was only about $60/ rotor or something.
I think the puzzler was one where there was a high speed chase and the cops later find an identical car owned by someone who claims they haven’t driven the thing for a week, with the question being how did he prove it.
