GM Metric Race Caliper 2.50 / 1.040

The Wilwood GM Metric Race Caliper 2.50 / 1.040 (Part Number 120-13900) is a single-piston aluminum brake caliper engineered for high-performance racing and motorsport applications. This caliper accommodates 12.190-inch OD rotors with 1.040-inch thickness and features a 5.460-inch floating mount design, delivering the precise hydraulic actuation and thermal stability required for sustained track duty and competitive driving environments.

The single-piston design provides balanced braking force distribution across the rotor face while minimizing unsprung weight—a critical advantage in racing where reducing rotating mass improves handling response and tire grip. The gray anodized aluminum construction offers corrosion resistance and durability across multiple heat cycles, essential for drivers subjecting the brake system to repeated high-temperature transients at the track. The floating mount allows thermal expansion and contraction without introducing binding or alignment stress, translating to consistent pedal feel throughout extended sessions. Compatibility with GM metric rotor standards ensures straightforward fitment into existing brake packages common to modern performance vehicles.

This caliper suits road racers, amateur autocross competitors, and track enthusiasts upgrading from OEM brake systems. Racing drivers value Wilwood calipers for their consistent modulation, minimal fade, and proven durability across club-level and higher motorsport categories. The metric rotor interface makes this caliper particularly relevant for drivers with vehicles using GM-platform brakes or builders upgrading to larger-diameter rotor packages within the metric standard. Weighing 3.58 pounds per unit, the caliper balances structural rigidity with the weight consciousness demanded by performance-oriented builds.