8K Hydraulic Trailer Brake Assembly – Right Hand

Description The 8K hydraulic trailer brake assembly, part #31-5121-HF, delivers smooth and reliable braking. It is built for 8,000 lb trailer axles. The right-hand design fits the passenger side. It uses a 12.25″ x 3.375″ drum and shoe setup, so you get strong stopping power for equipment, dump, agricultural, and utility trailers. This brake bolts directly to a 4-bolt flange. Therefore, installation is fast and simple. It replaces many Dexter 8K hydraulic brakes and other major axle brands with the same 12-1/4″ x 3-3/8″ configuration. In addition, the free-backing design lets the trailer reverse smoothly without drag. As a result, shoe wear drops and maneuvering improves in tight yards and job sites. Part #31-5121-HF comes fully assembled. It includes a hydraulic wheel cylinder, bonded shoes, return springs, and free-backing hardware. Because everything is pre-installed, technicians save time. Downtime drops for fleets and repair shops. Plus, it pairs easily with a matching left-hand unit for full axle service. After installation, burnish the brakes for best results. Tow the trailer in a safe area. Then apply moderate braking cycles at a steady speed. Avoid hard stops at first. Over time, the linings seat evenly and deliver consistent hydraulic performance under load. If you need an 8K hydraulic brake with Dexter compatibility and free-backing performance, part #31-5121-HF is a dependable choice. It is durable, easy to install, and built for confident stopping power. Additional part #: K23-403-00, BK-8KH-02, 23-403, 77-1208H-2