I just bought a 2007 Mazda RX-8 as a trade in from a dealership (not a Mazda dealership). The day after I brought it home I noticed the brakes were squealing. Not all the time, but more often than not (it seems to happen when I press on them lightly or slowly, like stopping at a stop sign, as opposed to slamming on them at a yellow light or something). I thought that they had told me that all brakes were checked, and replaced if necessary. So I called the guy who sold me the car (they’re also waiting to get my keyless ignition piece in) and he tells me a charming story about how all brake pads are replaced if there is less than 50% of the pad remaining. And that the brake pad is made up of a fiber composite with a metal coating. And that the squealing I’m hearing is simply the metal coating wearing off and once it is gone, the squealing will stop. I am highly suspicious of this story.
I’ve not taken it to a shop yet, I don’t know of any decent Mazda places in town (I know they’re just brakes but I’d rather start with a good mechanic). If I take it in to the dealership I have a feeling they will pull the pad off, show me the measurements and send me on my way. I’m wondering if maybe they didn’t lubricate it properly and the caliper is rubbing on the pad?
I am definitely not overly knowledgeable about cars and I do rather look like the kind of girl you can just pat on the head and send on her way so I’d rather get some external opinions before I start a) taking their word for it or b) getting angry and asking them to fix the problem.
What you may be hearing is “wear indicators”, metal tabs that rub on the disc when the pads get low to warn the driver that it’s time for a checkup. It’s also possible that there’s some glaze on the pads, or the pads need a dab of “antisqueal grease” behind them (some brakes do have a tendency to squeal…but that’s what the grease is for). Getting them checked is the only way to find the source and correct it.
Is the dealer lying? Did his lips move? Mountainbike is right though. The dealer may have put on new pads, and if they did, they were probably the cheapest he could find. If they are coated with either molycoat 77 grease or some other anti squeal compound, they will squeal.
Some brake pad compounds are notoriously noisy… Usually the cheaper pads do this… I coat every set of brake pads I ever install with “High Temp Permatex Ultra Black” It is thicker than the orange anti squeal compound that is made specifically for this purpose… I find the thickness of the Permatex keeps it where I intended it to be…and stay there… NONE of my brakes done on any vehicle squeal.
If your pads are down to the wear indicators…well thats what they are supposed to do…but most guys just slap them on the car…and dont look to see if the are adjusted properly…sometimes they are so maladjusted that they squeal at half pad life…which is WAY too early. they should hit the rotor at say a 1/4 inch of pad material remaining…no amount of anti squeal compound will help you if its the brake pad warning squealers…making the noise…because that is what they are for…to warn you.
The compound on the back of the pads is supposed to stop the pads from squealing during normal use…the compound quiets the noise created from normal brake pad oscillation. This occurs when the pads move microscopically within the calipers…they oscillate at a high rate of speed and frequency…and whistle sort of…the compound stops this rather nicely.
You need to check that the brake pad warning tabs arent contacting too early…or at all from worn pads. Then if the warning tabs are NOT the culprit… I would deglaze the rotors with emery cloth…and then apply THICK Ultra Black to the back of the pads…this will STOP your noise…works EVERYTIME.
Unclear? DID owner replace pads prior to trading in car? Don’t really care about his theories on changing pads at 50% thickness. It sounds like he did change pads at least once? You do not say miles on car. Maybe he did pads 40k miles ago and car has 133k miles now?