Hex Head Bolt 5/8-18 x 4 Grade 5

The Hex Head Bolt 5/8-18 x 4 Grade 5 from ALLSTAR PERFORMANCE is a heavy-duty fastening component engineered for high-vibration automotive applications where reliability under load is non-negotiable. Whether you're assembling an engine block, securing suspension components, or fastening critical drivetrain assemblies, this fastener delivers the tensile strength and corrosion resistance required in demanding mechanical environments. Mechanics and fabricators rely on Grade 5 bolts for applications where standard hardware would fail prematurely under stress.

Grade 5 classification provides minimum tensile strength of 120,000 PSI, making this fastener suitable for structural loads and high-stress connections that experience constant vibration and thermal cycling. The 5/8-inch diameter with 18 threads per inch (TPI) thread pitch offers precise engagement and optimal clamping force distribution across wider bearing surfaces—critical when securing components to aluminum or composite materials prone to galling. At 4 inches in length, this bolt accommodates moderate-depth counterbores or stacked washers while maintaining sufficient thread engagement for secure locknut application.

This fastener excels in engine bay assembly, frame-to-component attachment, and any restoration or custom build where OEM-grade hardware is essential. The hex head design provides excellent wrench access and torque application without cam-out, while the coarse 18 TPI thread pitch resists vibration loosening better than fine-thread alternatives in high-movement scenarios. Pair with hardened washers and appropriate locking mechanisms for maximum security in performance or heavy-duty applications.