Marble/grinding sound coming to a stop
 

Hi everyone,

I have a 2017 brz and when i come to a stop, at the very end of the stop, i hear what sounds like a grinding sound from my front end (subaru has told me my brakes are fine) as well as almost a marble like sound at extremely low speeds coming to a stop. Does anyone know whats going on here from similar experience?

Thanks!

Does the sound disappear if you release the brakes?

If so, your brakes may not be "fine".

I was working on an F150 last week which had just been inspected by a dealer the day before, the brakes hadn't been flagged despite being worn down to the metal with a seized caliper in the back and nothing but rust for the front pads to grind on.

Have you had the car since new? How long since it's last brake service? I've got a 2017 too and I'm on my 3rd brake service with a .5mm cut on all rotors the last time I did it to keep everything wearing nicely and I'll be up for another round of cleaning/lubing them up before winter. Canada is a bitch on disc brakes, and if you haven't had regular brake services done, you might be looking at completely jammed pads.

Manual? Sounds like chatter

The marble sound is only while braking at extremely low speeds, funny enough, my brakes also screech as soon as i put my winter tires on (with steelies). I also seem to get rust buildup very frequently (seems to be my front brakes) and it goes away after braking a few times. Could that possibly mean anything?

I think I know what you're talking about.
Every now and then when I come to a stop (usually at a stop light) I can feel this vibrating of the brakes. It happens when braking very lightly when you are just about stopped. I think it's the ABS pulsing.

Usually when I've road tested for "brake noise" and the pads were just getting to the metal on the very edge, they've mostly exhibited the grinding noise in the last few feet of a stop.

Or you could have a really low pitch brake squeek. Are the pads original? I've seen some really crappy pads do nothing but make dust and growl. Like NAPA QE brake pads, or that fiat two weeks ago with really aggressive ebay-looking "ceramic" pads with way too much bite. You know the type of pad that has more effort put into a fancy coloured pad shim with text and graphics than good friction material... feathering the brake at sub-1kph speeds or coming to a stop would make the whole car vibrate like a subwoofer.

I wouldn't worry about the alloy-steel noise difference: You're both changing how the rotor is clamped to the hub and the overall weight of the wheel end assembly, so a difference in resonant frequency should be expected. My rears would be quiet on the stock wheels, squeek on steelies, be quiet again on the stock wheels, and now that I've got STi goldies, they briefly squeek all the time at very light brake pressures. It's not even an issue worth investigating.

They are OEM brakes. This is exactly what happens - grinding in the last few feet, I don't hear anything while going normal speeds or even until coming to a complete stop. so no concern?

It doesnt quite vibrate, its just a grinding sound and a marble sound - both at different times

Without actually hearing your sound I still would not take a random dealer tech's word that they're fine. The thing with brake noises is that it can range from not-an-issue to super-danger and it's really hard to tell through text.