#8" Grade 8 Torque Specification

Torque Values by Surface Condition

Stress area: 0.014 in² · Proof load: 1,680 lbs · Clamp load (75%): 1,260 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	3.4	4.6	40.8	46.9
Oiled	0.15	2.6	3.5	31.2	35.7
Zinc Plated	0.18	3.1	4.2	37.2	42.8
Waxed	0.1	1.7	2.3	20.4	23.5
MoS₂	0.12	2.1	2.8	25.2	28.6
Galvanized	0.25	4.3	5.8	51.6	59.1

Stress area: 0.01474 in² · Proof load: 1,769 lbs · Clamp load (75%): 1,327 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	3.6	4.9	43.2	50.0
Oiled	0.15	2.7	3.7	32.4	37.7
Zinc Plated	0.18	3.3	4.5	39.6	45.9
Waxed	0.1	1.8	2.4	21.6	24.5
MoS₂	0.12	2.2	3.0	26.4	30.6
Galvanized	0.25	4.5	6.1	54.0	62.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.014 in² = 1,260 lbs

Step 2 — Torque (dry): T = 0.20 × 0.164 in × 1,260 lbs ÷ 12 = 3.4 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. K-factor per VDI 2230.

High-strength applications, heavy equipment, critical joints, suspension components, trailer hitches. Equivalent to ISO 10.9.

• Torque values are for standard hex bolts with unified threads per ASME B1.1. 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.
• Re-used bolts may have altered friction characteristics. Inspect threads before reuse.

Size#8"

Grade8

Diameter0.164" (4.17 mm)

TPI (UNC)32

Tensile150,000 psi

Yield130,000 psi

Proof120,000 psi