M14 Grade 9.8 Torque Specification

Torque Values by Surface Condition

Stress area: 115.44 mm² · Proof load: 75,036 N · Clamp load (75%): 56,277 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	157.6	116.2	1394.9	1607.1
Oiled	0.15	118.2	87.2	1046.2	1205.3
Zinc Plated	0.18	141.8	104.6	1255.0	1446.0
Waxed	0.1	78.8	58.1	697.4	803.5
MoS₂	0.12	94.5	69.7	836.4	963.6
Galvanized	0.25	197.0	145.3	1743.6	2008.8

Stress area: 124.55 mm² · Proof load: 80,958 N · Clamp load (75%): 60,718 N

Surface Condition	K Factor	N·m	ft·lbs	in·lbs	kgf·cm
Plain/Dry	0.2	170.0	125.4	1504.6	1733.5
Oiled	0.15	127.5	94.0	1128.5	1300.1
Zinc Plated	0.18	153.0	112.8	1354.2	1560.2
Waxed	0.1	85.0	62.7	752.3	866.8
MoS₂	0.12	102.0	75.2	902.8	1040.1
Galvanized	0.25	212.5	156.7	1880.8	2166.9

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 650 MPa × 115.44 mm² = 56,277 N

Step 2 — Torque (dry): T = 0.20 × 0.0140 m × 56,277 N = 157.6 N·m

Proof stress per ISO 898-1:2013 Table 4. Stress area per ISO 898-1 Annex A. K-factor per VDI 2230.

Heavy-duty automotive, high-performance machinery (limited availability, mostly M16 and smaller)

• Torque values are for standard hex bolts with ISO metric threads. Socket head cap screws may have different requirements.
• Lubrication reduces required torque significantly — using dry torque values on lubricated bolts risks exceeding yield strength.
• For critical or safety-related applications, always consult the manufacturer's specifications or applicable design standard (e.g., VDI 2230).
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

SizeM14

Class9.8

Diameter14 mm

Pitch (coarse)2.0 mm

Tensile900 MPa

Yield720 MPa

Proof650 MPa