FSL4R/ST calipers provide the pad wear performance advantages of differential bore pistons with the option for ultimate heat protection using Thermlock® pistons in the ST models. Differential piston bores compensate for leading-edge mechanical loading and temperature variances across the pad face to reduce pad taper wear in sustained high temperature applications. Thermlock® pistons in the ST models block heat transfer from the pads and reduce temperatures in the caliper, fluid, and seals by up to 25% over standard stainless steel pistons. Featuring a wear resistant Type III hard anodize finish, these are the go-to calipers for all types sustained hard braking on dirt and asphalt ovals and a wide range of off-road, rally and road course applications.

Grand National GN6R forged aluminum six-piston radial mount calipers bring current state-of-the-art design, materials, and manufacturing technology to this long standing icon in the Wilwood caliper line. With a High-strength forged aluminum body in a Type III hard-anodized finish and compatible with rotors from 1.25” to 1.38” thickness and diameters from 12.19” to 13.06”. Two body widths are available for use with .80” (20,3) or .99” (25,0) thick pads. Stainless steel pistons are included base model GN6R anodized calipers and Thermlock® pistons in the GN6R/ST models. Uses 3.5” or 6.0” center mount bracket kits to replace all previous Grand National caliper models.
Note 1. Caliper uses .80" (20mm) thick pads.