1-1/8" Bolt Torque
A 1-1/8" Grade 5 bolt with a coarse 1-1/8"-7 UNC thread needs about 779.5 ft·lb (1056.9 N·m) when dry and 581.4 ft·lb (788.3 N·m) when oiled, tightened to 70% of yield (clamp force 192.3 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| Grade 2 | 85.5 kN19218 lbf | 346.4 ft·lb469.7 N·m | 258.4 ft·lb350.4 N·m | 170.4 ft·lb231.0 N·m |
| Grade 5 | 192.3 kN43241 lbf | 779.5 ft·lb1056.9 N·m | 581.4 ft·lb788.3 N·m | 383.4 ft·lb519.8 N·m |
| Grade 8 | 308.9 kN69433 lbf | 1251.7 ft·lb1697.0 N·m | 933.7 ft·lb1265.9 N·m | 615.6 ft·lb834.7 N·m |
| A307 | 86.2 kN19373 lbf | 349.2 ft·lb473.5 N·m | 260.5 ft·lb353.2 N·m | 171.8 ft·lb232.9 N·m |
| A325 | 192.3 kN43241 lbf | 779.5 ft·lb1056.9 N·m | 581.4 ft·lb788.3 N·m | 383.4 ft·lb519.8 N·m |
| A490 | 308.9 kN69433 lbf | 1251.7 ft·lb1697.0 N·m | 933.7 ft·lb1265.9 N·m | 615.6 ft·lb834.7 N·m |
| A574 | 356.4 kN80127 lbf | 1444.5 ft·lb1958.4 N·m | 1077.5 ft·lb1460.8 N·m | 710.5 ft·lb963.3 N·m |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| Grade 2 | 95.8 kN21546 lbf | 377.2 ft·lb511.4 N·m | 276.9 ft·lb375.4 N·m | 176.5 ft·lb239.3 N·m |
| Grade 5 | 215.6 kN48478 lbf | 848.7 ft·lb1150.7 N·m | 622.9 ft·lb844.6 N·m | 397.1 ft·lb538.4 N·m |
| Grade 8 | 346.3 kN77843 lbf | 1362.9 ft·lb1847.8 N·m | 1000.2 ft·lb1356.2 N·m | 637.6 ft·lb864.5 N·m |
| A307 | 96.6 kN21720 lbf | 380.3 ft·lb515.6 N·m | 279.1 ft·lb378.4 N·m | 177.9 ft·lb241.2 N·m |
| A325 | 215.6 kN48478 lbf | 848.7 ft·lb1150.7 N·m | 622.9 ft·lb844.6 N·m | 397.1 ft·lb538.4 N·m |
| A490 | 346.3 kN77843 lbf | 1362.9 ft·lb1847.8 N·m | 1000.2 ft·lb1356.2 N·m | 637.6 ft·lb864.5 N·m |
| A574 | 399.6 kN89832 lbf | 1572.8 ft·lb2132.4 N·m | 1154.3 ft·lb1565.0 N·m | 735.9 ft·lb997.7 N·m |
Torque for 1-1/8" hex head bolts and nuts, standard ISO/ASME heads on steel with a 30.2 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
1-1/8" thread and dimensions
- Coarse thread
- 1-1/8"-7 UNC — pitch 7 TPI
- Fine thread
- 1-1/8"-12 UNF — pitch 12 TPI
- Tensile stress area Aₛ
- 492.4 mm² (coarse), 552.1 mm² (fine)
- Pitch diameter d₂
- 26.218 mm
- Tap drill
- 63/64 (coarse), 1-3/64 (fine)
- Wrench size (hex head)
- 1-11/16"
- Clearance hole
- 30.2 mm
How the 1-1/8" torque is calculated
Preload is 70% of the bolt's yield strength times its tensile stress area. Torque then follows the ISO 16047 / VDI 2230 formula, which splits it into thread pitch, thread friction and friction under the head:
F = 70% × 558 MPa × 492.4 mm² = 192.3 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 192.3 kN × (0.16·3.63 + 0.58·0.15·26.22 + 0.15·36.51/2) mm = 1056.9 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (36.51 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for a 1-1/8" Grade 5 bolt?
About 779.5 ft·lb (1056.9 N·m) with dry threads, 581.4 ft·lb (788.3 N·m) with oiled threads and 383.4 ft·lb (519.8 N·m) with PTFE or moly paste, for a coarse 1-1/8"-7 UNC thread tightened to 70% of yield. The resulting clamp force is 192.3 kN.
What is the torque for a 1-1/8" Grade 8 bolt?
About 1251.7 ft·lb (1697.0 N·m) with dry threads, 933.7 ft·lb (1265.9 N·m) with oiled threads and 615.6 ft·lb (834.7 N·m) with PTFE or moly paste, for a coarse 1-1/8"-7 UNC thread tightened to 70% of yield. The resulting clamp force is 308.9 kN.
What size wrench fits a 1-1/8" bolt?
A standard 1-1/8" hex head bolt or nut takes a 1-11/16" wrench or socket.
What drill size do I need to tap 1-1/8"?
Use a 63/64 drill for 1-1/8"-7 UNC and 1-3/64 for 1-1/8"-12 UNF.