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Hexagonal steel nut with zinc finish and nylon insert visible inside threads

MIDWEST FASTENER CORP

MIDWEST FASTENER CORP Nylon Insert Lock Nut 5/16"-18 Steel Grade 2 Zinc 03650

SKU CH-8CPD-T8GPT

Nylon insert lock nut with 5/16"-18 thread resists loosening under vibration and torque

  • Product typeNuts
  • Nylon insert resists loosening under vibration and torque
  • Steel Grade 2 construction provides reliable strength for fastening
  • Zinc coating protects against corrosion in harsh conditions
  • 5/16"-18 thread fits standard coarse-thread bolts
  • Manufacturer part 03650 ensures correct identification and ordering

5/16"-18 Nylon Insert Lock Nut

This zinc-plated steel Grade 2 nut features a nylon insert that resists loosening caused by vibration and torque. It is suited for automotive, machinery and general fastening tasks where a secure threaded joint is required. The 5/16"-18 thread pitch matches standard coarse-thread bolts and studs.

Check thread size and grade before ordering

Verify that the mating bolt or stud uses a 5/16"-18 thread to ensure proper engagement. Confirm that a Grade 2 fastener meets the strength requirements of the application. Ensure the nylon insert is compatible with the operating temperature range of the assembly.

Fits standard coarse-thread hardware

The nut installs with a standard wrench or socket and requires no special tools. Its nylon insert eliminates the need for separate lock washers or thread-locking compounds in many vibration-prone joints. The zinc finish provides corrosion resistance for indoor and protected outdoor use.

How it compares

Measured against everything we stock in General Hardware & Accessories, at today’s prices. Recalculated every night.

Price $9.99
Cheaper than about 80% of the 2,607 comparable items (median $18.99).

Specifications

Product
Brand nameMIDWEST FASTENER
Product typeNuts

Questions about this item

Does the 5/16"-18 lock nut come in a pack or must I buy each piece separately?

The listing shows a single MIDWEST FASTENER 03650 nylon-insert lock nut; order the quantity you need for the job.

Should I choose the Grade 2 zinc version or a different grade for this thread size?

Grade 2 steel with zinc plating suits general-purpose fastening; select a higher grade only if the application demands greater tensile strength.

How does the nylon insert keep the 5/16"-18 nut from backing off under vibration?

The nylon collar grips the bolt threads when tightened, creating prevailing torque that resists loosening from shock or cyclic loading.

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