3/4" Grade 8 Torque Specification

Torque Values by Surface Condition

Stress area: 0.334 in² · Proof load: 40,080 lbs · Clamp load (75%): 30,060 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	375.8	509.5	4509.6	5195.5
Oiled	0.15	281.8	382.1	3381.6	3896.4
Zinc Plated	0.18	338.2	458.5	4058.4	4675.4
Waxed	0.1	187.9	254.8	2254.8	2598.2
MoS₂	0.12	225.5	305.7	2706.0	3117.3
Galvanized	0.25	469.7	636.8	5636.4	6493.6

Stress area: 0.373 in² · Proof load: 44,760 lbs · Clamp load (75%): 33,570 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	419.6	568.9	5035.2	5801.2
Oiled	0.15	314.7	426.7	3776.4	4351.1
Zinc Plated	0.18	377.7	512.1	4532.4	5222.0
Waxed	0.1	209.8	284.5	2517.6	2901.1
MoS₂	0.12	251.8	341.4	3021.6	3481.3
Galvanized	0.25	524.5	711.1	6294.0	7251.2

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.334 in² = 30,060 lbs

Step 2 — Torque (dry): T = 0.20 × 0.75 in × 30,060 lbs ÷ 12 = 375.8 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.

Size3/4"

Grade8

Diameter0.75" (19.05 mm)

TPI (UNC)10

Tensile150,000 psi

Yield130,000 psi

Proof120,000 psi