Brake pads appeared much earlier than the car and will probably survive more than one generation of “hybrid”, “hydrogen” and its other offspring. A more irrational, yet effective and, note, safe way to reduce the kinetic energy of a moving crew has not yet been invented. It translates into heat - not only useless, but also harmful, because it boils and boils the fluid, leading to brake failure, and the failure of the rubber cuffs of the pistons, and warpage of the discs.
These problems are common to all cars, from Ferrari to Zaporozhets. Their designers decide in different ways. The third force also intervenes - the owner himself, who selects consumables to his taste and wallet. Only clairvoyant can determine the frictional properties (if we are not talking about an open fake) by clairvoyance, and even if they make out, the pads will work together with which disks. But we will try to figure out the purpose of the cuts, protrusions, springs and pads in order to choose and install the pads correctly.
On many modern cars, special stainless steel plates protect the pistons from overheating. Sometimes they are riveted to the base of the block (photo 1), sometimes they are put on it, and can be fixed in the piston with spring protrusions. In many non-original sets of pads these plates do not have, so we will take care not to accidentally throw them away when replacing - the stainless steel has been working for years.
There are also similar-looking anti-creak plates. (Recently, instead of them, a layer of special mastic has been used on the base of the block.) Some blocks even stick to the pistons (photo 2). Designed to reduce noise and cut on the block, "part-time" wear indicator: missing a dash in the middle - it's time to change the pads.
However, there are real indicators. Here, the design idea went in two ways. One school (these are mainly Europeans) uses electrical sensors. The block worn out, the contact closed, the light on the panel lit up - we went to the service. But in practice, instead of a polite light warning, the brakes often reminded themselves of themselves with a rude rattle, announcing the upcoming replacement of not only pads worn to metal, but also disks. The "decimal" details sinned with the same refusals. Their wires often bent off, broke off. The same problems were on foreign cars, but today they are in the past: a double-insulated flexible wire and a sealed connector defeated the salt.