You need new brakes. IF its really bad you're going to need new rodars.
Check the front brakes. the most common problem for grinding is worn brake pads allowing the metal backer to rub the rotor.
When the "Brakes" light on your dash comes on, or if you hear "metal to metal" scraping from them.
axle bearing or brakes or pinion bearing
Diod you check front brake pads
Replace rotor / cut rotor & replace brakes.
A wheel bearing could be going bad in a 2002 Ford Focus if a grinding or rubbing sound is heard. A trip to a mechanic is advised as a bad wheel bearing that's not fixed can lead to damaged brakes.
Brake pads are probably worn out. Have a trusted mechanic inspect the brakes soon!
The Grinding noise in the passenger rear of a 2002 Explorer is most likely either a bad wheel bearing, or a brake problem. Check the brakes then the bearing to find the cause.
brakes?
A grinding sound / feel is most typically due to something related to the brakes. In my 2001's case, it was the rotor - even after changing the pads, it was still grinding. 2 new rotors and it was *smooth* sailing, and braking. Sidebar: bad wheel bearings usually create a very noticeable humming - like someone who doesn't know the words to the song... See "Related Questions" below for more about wheel bearings and front brakes
DID YOU CHECK YOUR CALIPERS?
On a Ford Explorer : There are disc brakes on the front and ( starting with the 1995 model year ) there are disc brakes on the rear also ( instead of drum brakes on the rear )