S-90409A210 3/4"-16 x 2 1/4" IFI 111, SAE J429 High-Strength Grade 8 Steel Flanged Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional Load-Bearing Capacity: Grade 8 classification and 150,000 psi tensile strength ensure reliable performance in the most demanding, high-stress applications.
• Superior Wear and Deformation Resistance: Rockwell C32 hardness provides excellent durability and long-term fastener integrity, reducing replacement frequency.
• Optimized for Secure Fastening: The UNF fine thread and Class 2A fit offer a tighter, more vibration-resistant connection compared to coarse threads.
• Enhanced Stability and Simplified Assembly: The integrated flange distributes clamping force over a wider area (1 19/32" diameter), eliminating the need for a separate washer.
• Rugged and Efficient Installation: The external hex head drive (1 1/8" width) allows for high-torque application with standard tools, speeding up assembly.
• Proven Industry Compliance: Manufactured to meet IFI 111 / SAE J429 specifications, guaranteeing material quality, dimensional accuracy, and performance consistency.
• Versatile Thread Engagement: The partially threaded design provides a strong, unthreaded shank for shear strength while allowing for precise clamping on the threaded section.

Professional Applications & Engineering Value

This Grade 8 steel hex head screw is engineered to solve critical challenges in heavy machinery, construction, and automotive assembly. Its high tensile strength and Rockwell C32 hardness directly address the need for fasteners that can withstand extreme dynamic loads and shock without failing. The UNF fine threading and Class 2A thread fit create a precise, leak-resistant seal in pressurized systems and offer superior resistance to loosening under vibration, a common industrial pain point. The integrated flange streamlines assembly by combining the bolt and washer function, providing a larger bearing surface that helps prevent material damage and maintains joint integrity. This makes it an ideal, high-reliability choice for engine mounts, structural frames, and heavy-duty equipment where failure is not an option.

Specification Summary & Compliance

This fastener adheres to strict dimensional and performance standards. The thread fit is Class 2A, ensuring consistent interchangeability and assembly. It is manufactured in accordance with the IFI 111 specification SAE J429, confirming its compliance with established standards for material, mechanical properties, and dimensions. The specified UNF (Unified National Fine) thread form and partial threading are produced to precise industrial tolerances for reliable performance.