I bought these off of fcpeuro.com for my 2008 xc90 3.2, made sure the size of the rotor was right which was the biggest. Soon as I got the car back with the new rotors, brakes pads all around and new tires.When I press on the brake on the brakes hard enough i would hear a few low sounding knocks coming from the wheel. I then took the car back and he said he would take a second look at it. I took it back and he told me he took both wheel off in the front and brakes and rotors and re-installed them and didn't find anything. He mentioned something about my differential fluid. Could it be the brakes need to settle in? Can someone suggest anything or what could be going on?

https://www.fcpeuro.com/products/vol...t-vbbrakekit14