Clicking noise from rear wheel
 

2004 mercury mountaineer makes clicking noise when you slow down or make a turn at a slow speed. I have heard it on the explorer also. Read that it could be the parking brake shoes inside the rotor. I have disc brakes all the way around. Could it be possible to have brake shoes too. If anyone had this problem please let me know what this could be. Thanks in advance.

Did you tried to find out exactly from where the sound was coming? It can come from engine bay or from near the wheels also?

remember even tho you see thru the wheels a rotor on all four corners that dont mean you dont have brake shoes, they use shoes for the emergency brakes and the wheels stop under pad and rotors.

Rear Brake Shoes
 

Your car has brake shoes that are used as parking brakes inside the rear rotors. They are bonded to metal with a glue type material. In northern areas of the country where salt is used on the highways in winter these brake assemblies get very rusty and the rust will cause the shoe lining to come off of the metal backing. It is possible for the lining to become lodged between the brake adjuster parts and the internal drum so tightly that it can lock the rear wheel causing a skid. Ask me how I know.