Wilwood FSL4R/ST calipers use a differential bore piston arrangement to compensate for leading‑edge loading and temperature variance, reducing pad taper. ST models add Thermlock pistons to block heat transfer and cut caliper and fluid temperatures by as much as 25% over standard stainless pistons. With a Type III hard anodize wear‑resistant finish, these calipers are a strong choice for sustained hard braking in dirt, asphalt oval, rally, and road‑course environments.
Wilwood ST FSL4R Caliper 1.88/1.75 1.25 Rotor