MIDWEST FASTENER CORP 8211 Nylon Insert Lock Nut 5/8"-11 Steel Grade 8 Yellow

Grade 8 Lock Nut

The Midwest Fastener Corp 8211 is a nylon-insert lock nut built from Grade 8 steel with a yellow finish. It provides a 5/8"-11 thread for securing bolts in automotive, industrial and general hardware assemblies. The nylon insert creates prevailing torque that resists loosening when the joint is subjected to vibration or cyclic loading. This fastener suits mechanics and fabricators who need a reusable, high-strength locking nut for critical connections.

Sustained Vibration Resistance

Under continuous vibration the nylon insert maintains a constant frictional grip on the bolt threads, preventing the nut from backing off over time. Unlike free-spinning nuts that rely on a single tightening event, this design absorbs shock loads and thermal cycling without losing clamp force. The Grade 8 steel core withstands high tensile stress so the locking action remains effective throughout the service life of the joint. Installers can remove and reinstall the nut several times before the insert loses its prevailing torque.

5/8"-11 Thread Specification

The single specification that determines fit is the 5/8"-11 unified coarse thread pitch. Only bolts or studs cut to this exact diameter and pitch will engage correctly; any mismatch in diameter or thread count will prevent assembly or compromise the locking function. Verify the mating hardware before purchase, as this nut does not adapt to metric, fine-thread or other inch-series sizes.