1-1/4" Grade 2 Bolt Torque: 499.6 ft·lbs / 677.4 N·m

Torque Values by Surface Condition

UNC — Coarse Thread — 7 TPI

Stress area: 0.969 in² · Proof load: 31,977 lbs · Clamp load (75%): 23,983 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	499.6	677.4	5995.7	6907.8
Oiled	0.15	374.7	508.0	4496.8	5180.8
Zinc Plated	0.18	449.7	609.7	5396.1	6217.0
Waxed	0.1	249.8	338.7	2997.8	3453.9
MoS₂	0.12	299.8	406.5	3597.4	4144.7
Galvanized	0.25	624.6	846.8	7494.6	8634.7

UNF — Fine Thread — 12 TPI

Stress area: 1.073 in² · Proof load: 35,409 lbs · Clamp load (75%): 26,557 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	553.3	750.2	6639.2	7649.2
Oiled	0.15	415.0	562.7	4979.4	5736.9
Zinc Plated	0.18	497.9	675.1	5975.3	6884.3
Waxed	0.1	276.6	375.0	3319.6	3824.6
MoS₂	0.12	332.0	450.1	3983.5	4589.5
Galvanized	0.25	691.6	937.7	8299.0	9561.5

Torque by surface condition

UNC thread, ft·lbs. Values from the table above.

Same bolt, same target clamp load: thread friction alone moves the required torque from 249.8 ft·lbs (waxed) to 624.6 ft·lbs (hot-dip galvanized), 2.5× as much. Match the row to the fastener's actual finish and lubrication.

How This Value Is Calculated

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 33,000 psi × 0.969 in² = 23,983 lbs

Step 2 — Torque (dry): T = 0.20 × 1.25 in × 23,983 lbs ÷ 12 = 499.6 ft·lbs

Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. Typical K-factor, consistent with VDI 2230 friction values.

When to Use Grade 2

Large general-purpose bolts, same grade but reduced strength at larger diameters

Important Notes

• 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.

Specifications

Size1-1/4"

Grade2

Diameter1.25" (31.75 mm)

TPI (UNC)7

Tensile60,000 psi

Yield36,000 psi

Proof33,000 psi

1-1/4" Grade 2 Torque Spec