The Toyota 4Runner uses a fixed, quad-piston caliper design rather than sliding calipers. While this improves clamping force, a common "flaw" is that these calipers (especially on 4th/5th gens) are prone to seizing due to dirt/rust, preventing the piston from sliding back, leading to uneven pad wear and stuck brakes.
- No "Slide": The front calipers are bolted directly to the steering knuckle. Unlike sliding (floating) calipers that move on pins, these use pistons on both sides to apply force evenly.
- The Seizing Problem: Because the pistons must retract slightly for the brake to release, corrosion or debris often causes them to stick (seize) inside the housing, holding the pad against the rotor.
