It is the Hyundai disc brake pads that, when worn out, make a metal to metal sound when the brake pedal is depressed. The timeframe for this brake part to wear out is dependent on the aggressiveness of the driver of the vehicle and how frequently the brakes are applied over time. The disc brake pads can be replaced by the Hyundai owner if they have access to basic tools. With the car lifted up the wheel has to be removed. This will expose the disc and the caliper. The disc brake pads are located in the caliper. Care must be taken when removing the caliper because the brake hose can be damaged. The hose does not need to be removed; the caliper can be hung so the hose does not hold all of its weight during this repair. Once the old Hyundai disc brake pads are removed, the piston in the caliper has to be manually pushed back into the cylinder. This should be done with a large C clamp and the lid on the brake master cylinder off. Make sure to clean up any brake fluid that spills over from the master cylinder during this process. Then anti squeak is applied to the new disc brake pads, they can then be inserted into the brake caliper and it remounted over the disc on your Hyundai. Since the brake hose was not taken off of the caliper, the brake lines do not have to be bled since this closed hydraulic system was not opened. If you notice the disc brake pads were so worn that the metal backing place was exposed and came in contact with the rotor, grooves might be present on the rotor. This should be smoothed with the help of a machine shop. If not the new pads will wear prematurely on your Hyundai.