The DB9 is notorious for its squealing brakes. I was very fortunate that the first set of brakes didn't squeal at all. When this had to be replaced a couple of years later by Textor pads astonishingly no seueal was there either Wow great!. I thought i had a no squeal car, but boy was i wrong:
For the next Maintenance i replaced not just the main brake pads (Yellow stuff) but also the disks. As for the last replacement i used the pad grease between caliper and pad and was expecting an easy ride. However at the next reafficlights i was greetrd by a terrifying squeals at low speed i.e. the last few meters before a full stop. How annoying!
OK, sometines the brakes nead a little break in, so i started with a high speed brake first to burn in the surface, then drove a couple of hundred kilometers and did several hard and soft brakes, but the squealing persisted. So i again remodved the pads, put on additional pad lubricant and .. it squealed again!
However, when puttin on the lube i realized that there is a major difference between main calipers (cylinders on both sides) and the hand brake calipers (cyclinder just on one side) plus the hand brake pads were sightly used on one half of the pad surface while the other was in not used at all. So very slightly unparallel to the disk.
Might the fact that the hand brake only has a cylinder at one side an the other side is floatingat almost no distance abovethe brake diskbe tha cause for squealing? Especially with this little unparallelity? That might lead to audible (terrible) oscillation at very low speed.