Brake hardware - the small clips, shims, springs, and slide pins around the pads and caliper - is cheap and easy to overlook, but it does more for quiet, even braking than most people realize. Here is when to replace it and why skipping it causes trouble.
What brake hardware does
The hardware kit holds the pads in the correct position, lets them slide freely as they apply and release, and damps vibration to prevent noise. Abutment clips give the pads a clean, rust-free surface to move on; shims cut squeal; slide pins let the caliper float evenly. When these work, braking is quiet and wear is even.
Replace it with every pad job
The simple rule: replace the clips and shims every time you replace the pads. Most quality pad sets include new hardware for exactly this reason. Old clips lose their tension and trap rust behind them, which makes new pads stick, wear unevenly, and squeal - see brake hardware corrosion. Reusing tired hardware is the most common reason a fresh brake job is noisy.
Signs hardware is worn
Look for rusted or distorted clips, pads that do not slide freely in the bracket, missing or cracked shims, and dry or sticking slide pins. Uneven or tapered pad wear is a classic symptom of bad hardware or seized pins - see reading pad wear patterns. Any of these means the hardware is due.
Slide pins and grease
Slide pins should be cleaned and re-greased with the correct high-temp brake grease at every service - see where to apply brake grease - and replaced if pitted or seized. Fresh hardware installed with quality pads is the cheapest insurance for a quiet, long-lasting brake job.