Grinding brakes Options

[Mattattack]

So I've been hearing some metal on metal grinding while braking AND while in motion, I figured it was brake pads grinding into the rotors so I put some new rotors and pads on. While the old rotors were warped, even after i put the new ones on the sound is still there if not worse after spinning the wheel while the car was on jacks. could a wheel bearing or caliper be the culprit? Any knowledge would be greatly appreciated.

[Langing]

I assume you are hearing the scraping sound at the front wheel, since you replaced pads (disc brakes), and likeky have either drum brakes or comb. drum/disc on rear, and since you could hear the sound when spinning the tire by hand (on jack stands).

I've just gone through something similar, and it took a while to figure it out. Let me tell you what my problem was so you can check and eliminate first.

A few years ago, my wife had driven the car into a curb; not such a hard swipe but bad enough to cause the only bolt left holding the passenger side motor mount to break, letting the motor fall an inch or so. I fixed that problem, but what I didn't realize was that the hit had bent the 'ears' on the steering knuckle which the caliper mounting bracket mate with. Recently, I decided to replace or rebuild all brake parts, and so put on new everything. When I tried to put the car back in service there was a very loud 'metal on metal' scraping sound that I hadn't heard before.

The additional thickness of the new rotor and pads combination (on rt front wheel) showed up the problem. The lower edge of the mounting bracket was rubbing against the rotor, eating into the rotor surface. You have to remove the tire and just the caliper to be able to see if this is happening. The rotor ought to be perfectly centered in the space inside the caliper mounting bracket, but my rotor was actually rubbing against the inside metal front edge of the bracket. It was doing that because the mounting ears on the steering knuckle were bent.

People here pretty much ALL told me that the knuckle is made of cast iron, and cast iron does't bend. Don't believe them. Whatever steel the knuckle is made from can, and does bend. I located six other examples of bent ears on various car forum websites. If you have kinda-sorta brushed up against a curb at some point in the car's lifetime, yours might be bent, and it is extremely hard to prove to yourself that those ears are actually bent. The best way is to examine the relationship between the rotating rotor and the caliper mtg bracket. When the rotor is scraping, it makes a mark around one surface of the rotor, which provides a second way to know if this is the problem.

If your problem is a bad wheel bearing, put you car on jack stand and spin the tire while holding your hand on the coil spring of the strut. If it is bad, you will feel the vabration in your hand. You might have to be under the car to do that, but it works.

Another possibility is that your wheel's major dust cover (which is attached to the knuckle by four torx bolts) could be bent and is rubbing against the rotor. The clearance with the back of the rotor is small, and since it is at the back, it is a little hard to see, but not hard to check.

Try those suggestions and if none of them are your problem, let me know and I will do some more thinking. Good luck!