S-94239A103 1/4"-20 x 1 1/4" SAE J429 High-Strength Grade 8 Steel Serrated-Flange Hex Head Screws

Key Features & Benefits at a Glance

• Maximum Load-Bearing Capability – With 150,000 psi tensile strength and Grade 8 classification, these screws withstand extreme mechanical stress and vibration in heavy machinery and structural assemblies.
• Superior Corrosion Resistance – Zinc-plated steel construction provides reliable protection against rust and environmental degradation, extending service life in outdoor or humid conditions.
• Effortless Installation & Non-Slip Grip – External hex drive and coarse UNC threads enable quick fastening with standard tools, while serrated locking flange prevents loosening under dynamic loads.
• Precision Thread Fit – Class 2A thread tolerance ensures consistent engagement and reduces cross-threading risks, maintaining joint integrity in repetitive assembly operations.
• Enhanced Durability – Rockwell C33 hardness offers excellent wear resistance, making these screws suitable for high-abrasion applications and frequent disassembly/reassembly cycles.
• Versatile Flange Design – Integrated flange distributes clamping force evenly, eliminating the need for separate washers and simplifying inventory management.
• Full Thread Engagement – Fully threaded shank maximizes grip length across the entire 1 1/4" span, providing uniform stress distribution in thick materials.

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these Grade 8 hex head screws combine high-strength zinc-plated steel with coarse UNC threading to deliver reliable performance where vibration resistance and fatigue life are critical. The serrated locking flange creates permanent friction against mating surfaces, effectively solving loosening issues in automotive chassis, construction equipment, and machinery frames. Unlike standard fasteners, the 150,000 psi tensile rating and Rockwell C33 hardness ensure consistent performance under cyclical loading, while the external hex drive accommodates high-torque installation without stripping. Ideal for heavy-duty assembly where Class 2A thread fit guarantees precise alignment in steel-to-steel connections.

Specification Summary & Compliance

Manufactured to IFI 111 and SAE J429 Grade 8 specifications with Class 2A thread tolerance for consistent dimensional accuracy. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental standards. Thread configuration follows UNC coarse pattern (1/4"-20) with right-hand direction and fully threaded design.