5/16" Grade 5 Torque Specification

Torque Values by Surface Condition

Stress area: 0.0524 in² · Proof load: 4,454 lbs · Clamp load (75%): 3,340 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	17.4	23.6	208.8	240.7
Oiled	0.15	13.0	17.6	156.0	179.5
Zinc Plated	0.18	15.7	21.3	188.4	217.2
Waxed	0.1	8.7	11.8	104.4	120.3
MoS₂	0.12	10.4	14.1	124.8	143.8
Galvanized	0.25	21.7	29.4	260.4	299.8

Stress area: 0.058 in² · Proof load: 4,930 lbs · Clamp load (75%): 3,698 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	19.3	26.2	231.6	267.2
Oiled	0.15	14.4	19.5	172.8	198.8
Zinc Plated	0.18	17.3	23.5	207.6	239.6
Waxed	0.1	9.6	13.0	115.2	132.6
MoS₂	0.12	11.6	15.7	139.2	160.1
Galvanized	0.25	24.1	32.7	289.2	333.4

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 85,000 psi × 0.0524 in² = 3,340 lbs

Step 2 — Torque (dry): T = 0.20 × 0.3125 in × 3,340 lbs ÷ 12 = 17.4 ft·lbs

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

Automotive, agricultural equipment, general machinery — the most common high-strength SAE grade. Equivalent to ISO 8.8.

• 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.

Size5/16"

Grade5

Diameter0.3125" (7.94 mm)

TPI (UNC)18

Tensile120,000 psi

Yield92,000 psi

Proof85,000 psi