1-1/8" Grade 2 Bolt Torque: 354.1 ft·lbs / 480.1 N·m

Torque Values by Surface Condition

UNC — Coarse Thread — 7 TPI

Stress area: 0.763 in² · Proof load: 25,179 lbs · Clamp load (75%): 18,884 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	354.1	480.1	4249.0	4895.3
Oiled	0.15	265.6	360.1	3186.7	3671.5
Zinc Plated	0.18	318.7	432.1	3824.1	4405.8
Waxed	0.1	177.0	240.0	2124.5	2447.7
MoS₂	0.12	212.4	288.0	2549.4	2937.2
Galvanized	0.25	442.6	600.1	5311.2	6119.2

UNF — Fine Thread — 12 TPI

Stress area: 0.856 in² · Proof load: 28,248 lbs · Clamp load (75%): 21,186 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	397.2	538.5	4766.9	5492.0
Oiled	0.15	297.9	403.9	3575.1	4119.0
Zinc Plated	0.18	357.5	484.7	4290.2	4942.8
Waxed	0.1	198.6	269.3	2383.4	2746.0
MoS₂	0.12	238.3	323.1	2860.1	3295.2
Galvanized	0.25	496.5	673.2	5958.6	6865.0

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 177.0 ft·lbs (waxed) to 442.6 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 × 0.763 in² = 18,884 lbs

Step 2 — Torque (dry): T = 0.20 × 1.125 in × 18,884 lbs ÷ 12 = 354.1 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

Size1-1/8"

Grade2

Diameter1.125" (28.57 mm)

TPI (UNC)7

Tensile60,000 psi

Yield36,000 psi

Proof33,000 psi

1-1/8" Grade 2 Torque Spec