S-90211A432 3/4"-10 x 4" SAE J429 Left-Hand Threaded High-Strength Steel Hex Head Screws

Key Features & Benefits at a Glance

• Exceptional strength with Grade 8 classification and 150,000 psi tensile strength for reliable performance in high-stress applications
• Superior corrosion resistance from zinc yellow-chromate plating, extending service life in harsh industrial environments
• Precise thread engagement with Class 3A thread fit ensuring secure fastening and vibration resistance
• Left-hand threading provides specialized functionality for applications requiring reverse-threading safety
• Heavy-duty construction with Rockwell C33 hardness offering excellent durability and wear resistance
• Easy installation with external hex drive and standard 1 1/8" head width for straightforward tool compatibility
• Full threading along the 4" length enables maximum grip and load distribution across the entire fastener

Professional Applications & Engineering Value

This Grade 8 hex head screw delivers critical engineering solutions where reverse-threading requirements meet extreme mechanical demands. The left-hand UNC coarse thread design is specifically engineered for applications where standard right-hand rotation would cause loosening, such as rotating machinery components, counter-rotating assemblies, and safety-critical equipment. Manufactured from high-strength steel with zinc yellow-chromate plating, this fastener combats corrosion in industrial environments while maintaining structural integrity under loads up to 150,000 psi. The Class 3A thread fit ensures precise engagement with mating components, reducing the risk of cross-threading and providing reliable performance in vibration-prone applications. These industrial screws are particularly valuable in heavy machinery, automotive, and construction sectors where failure prevention is paramount.

Specification Summary & Compliance

This fastener features 3/4"-10 UNC coarse threads with Class 3A thread fit precision and complies with SAE J429 specifications for Grade 8 mechanical properties. The left-hand thread direction and fully threaded 4" length provide consistent performance across the entire fastener. Manufacturing adheres to industry standards for dimensional accuracy, including the specified 1 1/8" head width and 1/2" head height for proper tool engagement. The zinc yellow-chromate plating meets corrosion protection requirements while the material composition and hardening process achieve the specified Rockwell C33 hardness and mechanical properties.