DIN 985Nylon insert lock nutExternal hexagon

DIN 985 M8 Nylon insert lock nut

DIN 985 M8 is a nylon insert lock nut, on a M8 × 1 mm metric thread. A full hex nut with a nylon collar that grips the thread and resists vibration loosening. Note that the nylon insert has a temperature limit — above roughly 120 °C it loses its locking effect.

Dimensioned drawing — DIN 985 M8s 13m 9.5
DIN 985 M8 — Nylon insert lock nutNominal dimensions in mm · Not to scale
Diameter8 mm
Pitch1 mm
Socket size s13 mm
Thickness h9.9 mm
Height m9.5 mm
DriveExternal hexagon

Dimensions

Standard
DIN 985
Type
Nylon insert lock nut
Size
M8
Thread
M8 × 1
Socket size s
13 mm
Height m
9.5 mm
Total height h
9.9 mm
Drive
External hexagon

Nominal values in millimetres as published in DIN 985. Estimated weight 4.437 g per piece in steel (4.465 g in stainless), calculated from the nominal geometry — real parts vary with tolerance and head chamfers.

Thread data

Full M8 thread page
DesignationM8 × 1 fine
Pitch1 mm
Nominal Ø8 mm
Pitch Ø7.35 mm
Minor Ø ext6.77 mm
Tap drillØ 7 mm

Other lengthsDIN 985 M8

All M8 specifications
M8

Interchangeability

DIN 985 is catalogued with ISO 10511 as its equivalent designation. Dimensions are compared field by field rather than assumed identical.

Equivalent standardISO 10511Prevailing Torque Hexagon Nut with Non-Metallic InsertComparisonDIN 985 vs ISO 10511Field-by-field differences and a substitution verdict

Choosing and fitting this size

DIN 985 M8 is a M8 nut, on a 1 mm coarse pitch. Mating threads should be a matching class nut in the same property class.

Common stock grades are 8.8, 10.9 and 12.9 in steel, plus A2-70 and A4-80 in stainless. Class 10.9 and 12.9 carry roughly 1.25 and 1.5 times the proof load of 8.8, but they also need a properly rated mating nut — a class 8 nut under a 12.9 bolt simply moves the failure into the thread. Zinc-plated 10.9 and above should be baked to avoid hydrogen embrittlement.

For a tapped hole, M8 × 1 mm takes a 7 mm tap drill, and the external thread's minor diameter is 6.77 mm — that is the section carrying the load, not the nominal M8 figure. Thread engagement of at least one times the nominal diameter is what lets the bolt fail before the thread strips.