I just noticed this a few days ago. Initially, it was only happening everyonce and a while in reverse, but just today, my dad and I noticed it happening when slowing down in D4 (I have an Auto). It sounds like a really harsh grinding noise from below the driver/passenger seat, so originally we thought it might be the transmission (afterall, it was only happening in reverse originally) but the transmission isn't located in that area so, now we don't know what it might be. It sounds as if something is dragging below the car, but we jacked it up and there aren't any loose parts or anything. Any ideas? It's a really loud grinding noise, as if you were driving along at 40mph and slammed it in to reverse. Could it be the transmission?

Worn brakes
Bad wheel bearing

I agree withjackasssi sounds like bad bearings

How urgent is it that the bearings get replaced (are you talking about the front wheel bearings?)

is it gear grinding noises or a grinding noise like if u were dragging ur fingure nail across ur desk kinda noise. if its gear grinding try check trany fluid levels with the dip stick to see if it is low. if its dragging fingure across desk kinda noise then check brake rotors for any carvings. if none of those then my help is no use.

It sounds more like gear grinding (really loud and deep) except it's coming from the middle of the car, not the front (where the transmission is actually located). We checked the fluid levels, they're all fine. It also seems to only do it when the car has been driven (mildly) hard, i.e. after hauling ass uphill, etc.

Maybe your exhaust is touching the the floorboard. That could cause grinding/rumbling types of noises, especially if you have a bad motor mount. The exhaust routes near the area you describe.

Maybe your exhaust is touching the the floorboard. That could cause grinding/rumbling types of noises, especially if you have a bad motor mount. The exhaust routes near the area you describe.

uh... he said it sounds like a gear grinding noise. But yea the gear grinding noise could be from something vibrating that makes it sound like gears grinding.

uh... he said it sounds like a gear grinding noise. But yea the gear grinding noise could be from something vibrating that makes it sound like gears grinding.

Here's a question then - Does the sound change with vehicle speed or engine speed?

Here's a question then - Does the sound change with vehicle speed or engine speed?

It didn't seem to, it sounded like a more constant grinding noise. But then again, when your car makes that kind of a sound, you tend to stop as soon as possible.

It hasn't happened since I posted this, but I haven't driven it a whole lot either. It seems to do it only after the car has been under hard driving conditions (heavy accelerating, uphill climbing, etc.) and I'm still curious why it was only doing it in Reverse initially.

I'm 95% sure that its your brakes. I had the same problem and I was like wtf? Thought it was my rear wheels...it was so hard to tell...almost like it was comming from right underneath me. Took my front right tire off and my rotor was pretty ripped up. new rotor and pads, and now she runs fine.