I have a 92 Ford Temp, 4 door. When I break hard I have a noise very similar to pad warn out. I have inspected not only the front pads but the rear shoes and I have plenty of material left. I am not afraid of the breaks failing but am very anoid and stumped by this sound. On inspection I do not see any groves on the front discs.
Ramron

 

Check the front end for any loose or failing parts.

Also have you checked the brakes all the way around? You might have something wrong in the rear.

Also, poor quality pads, shoes, hardware or rotors/drums will grind as well. Only use quality US or Canadian made replacements.