Diameter Thread Threads Length Grade Finish Weight
0.2500 (1/4) N/A 28 GR C Zinc Clear Trivalent & Wax 0.0067
Diameter 0.2500 (1/4)
Thread 28
Grade GR C
Finish Zinc Clear Trivalent & Wax
Weight 0.0067

  • GR C

Crowned Top Lock Nut, Stover Lock Nut, Prevailing Torque Lock Nut, Top Lock Locking Nut, and Auto Style Lock Nut all describe the Top Lock Nut. This common metal lock nut is crimped or slightly indented at the top to increase its grip strength. The crimping creates metal-to-metal contact that prevents the nut from loosening in high-vibration applications. Earnest offers the Top Lock Nut in Grade C (equal to Grade 8) to ensure its strength in durability.

Top Lock – Grade C

  • Top crimp creates its grip strength from metal-to-metal contact with male thread
  • Used in high-vibration applications
  • Must be wrenched into place
  • Sizes over than 1 are Collar Style Nuts
  • Rockwell Hardness:
  • 1/4to 5/8: Rc 24/32
  • 3/4to 1”: Rc 26/34
  • over 1”: Rc 26/36
  • Proof strength of 150,000 psi
  • Sizes range from 1/4 to 1 1/2
  • Meets IFI 100/107 standards

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