1-1/8" Grade 8 Torque Specification

Torque Values by Surface Condition

Stress area: 0.763 in² · Proof load: 91,560 lbs · Clamp load (75%): 68,670 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1287.6	1745.8	15451.2	17802.3
Oiled	0.15	965.7	1309.3	11588.4	13351.2
Zinc Plated	0.18	1158.8	1571.1	13905.6	16020.8
Waxed	0.1	643.8	872.9	7725.6	8901.1
MoS₂	0.12	772.5	1047.4	9270.0	10680.5
Galvanized	0.25	1609.5	2182.2	19314.0	22252.3

Stress area: 0.856 in² · Proof load: 102,720 lbs · Clamp load (75%): 77,040 lbs

Surface Condition	K Factor	ft·lbs	N·m	in·lbs	kgf·cm
Plain/Dry	0.2	1444.5	1958.5	17334.0	19971.2
Oiled	0.15	1083.4	1468.9	13000.8	14978.7
Zinc Plated	0.18	1300.0	1762.6	15600.0	17973.6
Waxed	0.1	722.2	979.2	8666.4	9985.1
MoS₂	0.12	866.7	1175.1	10400.4	11982.7
Galvanized	0.25	1805.6	2448.1	21667.2	24963.8

Formula: T = K × D × F

Step 1 — Clamp load: F = 0.75 × 120,000 psi × 0.763 in² = 68,670 lbs

Step 2 — Torque (dry): T = 0.20 × 1.125 in × 68,670 lbs ÷ 12 = 1287.6 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.

Size1-1/8"

Grade8

Diameter1.125" (28.57 mm)

TPI (UNC)7

Tensile150,000 psi

Yield130,000 psi

Proof120,000 psi