42521-04 Rear Brake Master Cylinders with Remote Reservoir for Sportster

This rear brake master cylinder is a complete assembly that includes the remote reservoir, making it a perfect replacement for 2004–2006 and 2007–2013 XL Sportster models. While it was originally stock equipment on these rubber-mount Sportsters, its compact design and integrated reservoir also make it a popular choice for custom builds where space is at a premium. It replaces OEM 42521-04 and provides the reliable hydraulic pressure needed for consistent stopping power. Whether you are performing a standard repair or fabricating a one-off frame, this genuine Zodiac part offers the quality and fitment you expect for your Sportster’s braking system.