Car is E46 BMW.
One of my front brakes were squealing on light brake pressure, so I got the rotors machined. As the pads had a lot of material left (9mm), I thought I'd reuse them. However, after fitting everything together and going for a test drive, the car shudders from the front right brake on hard braking.
After examining the used pads, the outer brake pad was uneven along the long edge. I will be replacing the brake pads to match the newly machined rotors.
What should I be doing / checking to ensure that these pads don't become unevenly worn? I have checked the caliper guide pins and they're moving freely, but not much else. Does the caliper piston seal need to be uniform around the piston?