M52 Bolt Torque
An M52 8.8 bolt with a coarse M52×5 thread needs about 7832.1 N·m (5776.6 ft·lb) when dry and 5786.0 N·m (4267.6 ft·lb) when oiled, tightened to 70% of yield (clamp force 787.5 kN).
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 295.3 kN66390 lbf | 2937.0 N·m2166.2 ft·lb | 2169.8 N·m1600.3 ft·lb | 1402.5 N·m1034.4 ft·lb |
| 4.8 | 393.8 kN88520 lbf | 3916.0 N·m2888.3 ft·lb | 2893.0 N·m2133.8 ft·lb | 1870.0 N·m1379.2 ft·lb |
| 5.6 | 369.1 kN82987 lbf | 3671.3 N·m2707.8 ft·lb | 2712.2 N·m2000.4 ft·lb | 1753.1 N·m1293.0 ft·lb |
| 5.8 | 492.2 kN110649 lbf | 4895.0 N·m3610.4 ft·lb | 3616.3 N·m2667.2 ft·lb | 2337.5 N·m1724.0 ft·lb |
| 6.8 | 590.6 kN132779 lbf | 5874.0 N·m4332.5 ft·lb | 4339.5 N·m3200.7 ft·lb | 2805.0 N·m2068.9 ft·lb |
| 8.8 | 787.5 kN177039 lbf | 7832.1 N·m5776.6 ft·lb | 5786.0 N·m4267.6 ft·lb | 3740.0 N·m2758.5 ft·lb |
| 10.9 | 1107.4 kN248961 lbf | 11013.8 N·m8123.4 ft·lb | 8136.6 N·m6001.2 ft·lb | 5259.4 N·m3879.1 ft·lb |
| 12.9 | 1328.9 kN298753 lbf | 13216.6 N·m9748.1 ft·lb | 9763.9 N·m7201.5 ft·lb | 6311.2 N·m4654.9 ft·lb |
| Grade | Clamp forcepreload | Dryμ 0.15 | Oiledμ 0.11 | PTFE / moly pasteμ 0.06 |
|---|---|---|---|---|
| 4.6 | 307.1 kN69049 lbf | 3022.5 N·m2229.3 ft·lb | 2219.7 N·m1637.2 ft·lb | 1416.9 N·m1045.0 ft·lb |
| 4.8 | 409.5 kN92065 lbf | 4030.0 N·m2972.4 ft·lb | 2959.6 N·m2182.9 ft·lb | 1889.2 N·m1393.4 ft·lb |
| 5.6 | 383.9 kN86311 lbf | 3778.1 N·m2786.6 ft·lb | 2774.6 N·m2046.4 ft·lb | 1771.1 N·m1306.3 ft·lb |
| 5.8 | 511.9 kN115082 lbf | 5037.5 N·m3715.5 ft·lb | 3699.5 N·m2728.6 ft·lb | 2361.4 N·m1741.7 ft·lb |
| 6.8 | 614.3 kN138098 lbf | 6045.0 N·m4458.6 ft·lb | 4439.4 N·m3274.3 ft·lb | 2833.7 N·m2090.1 ft·lb |
| 8.8 | 819.1 kN184130 lbf | 8060.0 N·m5944.8 ft·lb | 5919.2 N·m4365.8 ft·lb | 3778.3 N·m2786.7 ft·lb |
| 10.9 | 1151.8 kN258934 lbf | 11334.4 N·m8359.8 ft·lb | 8323.8 N·m6139.3 ft·lb | 5313.2 N·m3918.9 ft·lb |
| 12.9 | 1382.2 kN310720 lbf | 13601.3 N·m10031.8 ft·lb | 9988.6 N·m7367.2 ft·lb | 6375.9 N·m4702.6 ft·lb |
Torque for M52 hex head bolts and nuts, standard ISO/ASME heads on steel with a 56.0 mm clearance hole. Friction μ applies to both the threads and the bearing face. Always follow the manufacturer's value where one exists.
M52 thread and dimensions
- Coarse thread
- M52×5 — pitch 5 mm
- Fine thread
- M52×4 — pitch 4 mm
- Tensile stress area Aₛ
- 1757.8 mm² (coarse), 1828.2 mm² (fine)
- Pitch diameter d₂
- 48.752 mm
- Tap drill
- 47 mm (coarse), 48 mm (fine)
- Wrench size (hex head)
- 80 mm
- Clearance hole
- 56.0 mm
How the M52 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% × 640 MPa × 1757.8 mm² = 787.5 kN
T = F × (0.16·P + 0.58·μ·d₂ + μ·Dₖₘ/2)
T = 787.5 kN × (0.16·5 + 0.58·0.15·48.75 + 0.15·68.00/2) mm = 7832.1 N·m
Here d₂ is the pitch diameter and Dₖₘ the effective bearing diameter of the head (68.00 mm). Change the grade, lubrication or preload in the calculator below.
Frequently asked questions
What is the torque for an M52 8.8 bolt?
About 7832.1 N·m (5776.6 ft·lb) with dry threads, 5786.0 N·m (4267.6 ft·lb) with oiled threads and 3740.0 N·m (2758.5 ft·lb) with PTFE or moly paste, for a coarse M52×5 thread tightened to 70% of yield. The resulting clamp force is 787.5 kN.
What is the torque for an M52 10.9 bolt?
About 11013.8 N·m (8123.4 ft·lb) with dry threads, 8136.6 N·m (6001.2 ft·lb) with oiled threads and 5259.4 N·m (3879.1 ft·lb) with PTFE or moly paste, for a coarse M52×5 thread tightened to 70% of yield. The resulting clamp force is 1107.4 kN.
What size wrench fits an M52 bolt?
A standard M52 hex head bolt or nut takes a 80 mm wrench or socket.
What drill size do I need to tap M52?
Use a 47 mm drill for M52×5 and 48 mm for M52×4.