When the rear brakes on my '90 740 GL started squealing a few weeks ago, I pulled the wheels and found nearly new looking pads (I have only had the car for 9 months). One rotor was grooved pretty badly, so I ordered Brembo rotors for both sides and PBR Deluxe pads. I installed them and followed the break-in directions. Result: no squealing. . .for about two days. Now the noise is back with a vengeance, even louder than before. What gives?? Additional info: there were no shims with the old pads, so I installed the new ones without shims, too. My thinking was that I drove for six months without the shims with no squealing. A mistake? Also, I did coat the backs of the new pads with NAPA anti-squealing compound. Braking is smooth and responsive, but the godawful noise! Anyone have suggestions on how to make it go away? Many thanks.