The brief
The X3's front brakes had run their course, picked up on inspection with the pads worn low and the discs scored, the pedal not feeling as confident as it should. He had both done together, which is the sensible call, and on a BMW it's worth fitting genuine parts so the braking feel and the wear behave as designed. The front brakes do most of the work on any car, and on a heavier vehicle like the X3 they work harder still. The pads are the wear item, designed to be used up and replaced, and the discs they clamp wear too, thinning and scoring over their life. When the pads go right down, the wear runs into the disc surface, scoring it. By that point you're not just changing pads, the discs are scored past serviceable, so the front needs pads and discs together.
The diagnosis
On the lift the front brakes told the story: the pads worn near the end, and the discs scored and below minimum thickness. The calipers and slides were freed off and checked, they were fine, just the pads and discs gone. The rears still had life. So it was a front axle set: new genuine BMW-spec pads and discs on both sides together, because you don't fit fresh pads to a scored, undersized disc, and you do the pair so both sides bite the same.
The work
Both front discs and the worn pads were removed, the hubs cleaned up, and a new genuine BMW-spec set of discs and pads fitted, the calipers and slide pins cleaned and greased so they move freely, every fastener torqued to spec. The pads were bedded in properly so they'd grip evenly from the start. A road test confirmed quiet, even, progressive braking with a firm pedal and no pulling.
The outcome
Quiet brakes, a firm pedal, even bite, sharp progressive stopping, and the confidence back. The X3 went home stopping properly again. Worn pads turn into scored discs the longer they're left, so doing the front pads and discs as an axle set with genuine parts put the braking back where it should be, the safety job you don't put off.
