Steering Coupler Steel 5/8-36 X 3/4 Smooth Bore

The Steering Coupler Steel 5/8-36 X 3/4 Smooth Bore (BORGESON 311800) is a precision universal joint adapter designed to bridge mismatched steering shaft splines in custom vehicle builds and restoration projects. Whether you're fabricating a hot rod chassis, installing an aftermarket steering column, or adapting a donor steering box to non-OEM geometry, this coupler eliminates the need for expensive custom shafts or compromised steering feel. Built by BORGESON, a trusted name in high-performance steering solutions, it handles the mechanical reality that modern performance builds rarely follow factory spline patterns.

Machined from solid steel and finished in natural (uncoated) material, this coupler features a weld-on design that allows permanent installation into your steering column or shaft assembly for maximum rigidity and zero play under load. The 5/8-inch 36-spline input accepts industry-standard steering box output shafts, while the 3/4-inch smooth bore output accommodates universal steering shafts without requiring press-fit installation. The smooth bore design eliminates the need for keyed shafts, simplifying fabrication and allowing direct slip-fit assembly with set screws or pinning for final securement. Its compact footprint—3.75 inches long with a 1.6-inch diameter body—fits tight engine compartments and minimizes driveline angles without sacrificing strength or reliability.

Street rodders, vintage truck restorers, and custom chassis fabricators rely on this coupler when original spline patterns don't match available modern components. Its universal design works across domestic and import platforms, making it ideal for engine swaps, independent front suspension upgrades, and full-frame restorations where steering geometry deviates from stock. The weld-on construction demands proper TIG or MIG welding technique and heat treatment consideration, making it best suited for shops with fabrication experience or professional installation. At 0.28 pounds, it adds negligible weight while delivering the precision needed to maintain responsive steering feedback and eliminate troublesome vibration at highway speeds.