2000 Pontiac Bonneville 6 cyl Front Wheel Drive Manual 46000 miles
I had new brake pads put on all around. A moaning sound started. Not a squeel; not a grinding. A moan. The sound reminds me of when you fill a glass with water half full, wet your finger, and slowly move your finger around the brim of the glass - that makes a ghostly moan. The sound on my car happens only at the end of a slow stop. I took it back and the guy put on another set of pads - he said it was a different brand but i'm not so sure, now. The sound went away for a while but it's back. My research suggests such a sound may be caused by vibration given the materials in the make up of the pad - ceramics are supposedly the worst for sound, metals second worst, and organic the best at avoiding sound. Is this true? If not the pad material, then what else could be the culprit?
I had the same problem with my 2001 Bonni. The problem is that there needs to be a small cut or groove in the middle of the rear pads. I think there is a service bulletin out on this too. I replaced mine and still had the same problem so I took them back to the store. They did not know that they needed to have the cuts in the middle of the pads. When you buy new pads make sure they have this cut in the middle. It stops some kind of harmonics from happening when you make a gradual stop. I re-replaced mine and have not had any trouble since then. I bought them at Auto Zone.