Floating caliper pistons are compressed using ______.

Floating caliper pistons are designed to move within the caliper housing as the brake pedal is pressed, which applies hydraulic pressure to the brake fluid. This pressure forces the piston to engage the brake pads against the rotor, facilitating the braking action. The operation of floating calipers relies on this hydraulic principle, where the force applied by the brake fluid translates into the movement of the piston.

Using brake pressure is a fundamental part of how hydraulic braking systems function. When the brake pedal is pressed, hydraulic fluid is sent from the master cylinder through the brake lines to the caliper, increasing pressure within the caliper and causing the pistons to compress and activate the brake pads against the rotor.

Other tools or devices like a caliper adjusting tool, a hydraulic press, or a pad spreader have specific uses in brake maintenance or installation, but they do not play a direct role in the normal operation of compressing the floating caliper pistons during braking. Therefore, brake pressure is the correct mechanism for this process.