on my mothers sable the passeger rear tire has had a rub/howl sound like when you just start to press the pedal and get some squeak. Apparently my father had it to a mechanic who said the piston I believe is keyed and was put in incorrectly (wrong position). The problem went away for a bit but soon came back. I finally got tired of it and took the tire and pads off myself to check the rotor to see if it was warped. As thats the way it sounded to me as if it were doing it everytime the warp rubbed the pads. I noticed there were no I believe they are called caliper sliders. Thin metal that clips on the frame of the caliper/mount that the ends of the pads slide on. I had them on the original and my new pads came with them as well for front and back on my 98 towncar. I greased where the end of the pads slide and it seems quiet now. Should there be clips on here which are missing, or are they not always on disc brakes?