M10×1.5 Torque Spec
Calculated preload torque by grade, plus what actually changes the number.
M10×1.5 · 8.8 · dry threads
50.5 N·m
37.2 lb-ft · targets 25.2
kN clamp load (75% of proof)
By grade
| Grade | Dry (N·m) | Lubed (N·m) | Dry (lb-ft) | Clamp load | Ultimate tensile |
|---|---|---|---|---|---|
| 4.6 Low-carbon steel, general purpose | 19.6 | 14.7 | 14.4 | 9.8 kN | 23.2 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 50.5 | 37.8 | 37.2 | 25.2 kN | 46.4 kN |
| 10.9 Alloy steel, Q&T — high strength | 72.2 | 54.1 | 53.2 | 36.1 kN | 60.3 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 84.4 | 63.3 | 62.2 | 42.2 kN | 70.7 kN |
| A2-70 304 stainless, cold worked | 39.1 | 29.4 | 28.9 | 19.6 kN | 40.6 kN |
Why lubrication changes everything
Roughly 90% of the torque you apply is consumed by friction — under the head and in the threads. Only about 10% becomes useful bolt stretch. That means the friction coefficient, not the bolt, sets the relationship between torque and clamp load. Here is the same M10×1.5 8.8 fastener under different conditions:
| Thread condition | Nut factor K | Torque for same preload |
|---|---|---|
| Plain / as-received, dry | 0.20 | 50.5 N·m |
| Zinc plated, dry | 0.22 | 55.5 N·m |
| Black oxide, lightly oiled | 0.18 | 45.4 N·m |
| Machine oil on threads | 0.15 | 37.8 N·m |
| Molybdenum disulfide / anti-seize | 0.12 | 30.3 N·m |
| Waxed or PTFE coated | 0.10 | 25.2 N·m |
Torquing a lubricated bolt to the dry spec overloads it — the
25.2
N·m row and the
50.5
N·m row produce the same clamp load. Apply the dry
number to a waxed fastener and you are at roughly twice the intended preload, which
for a 8.8 is past yield.
Assumptions behind these numbers
T = K × D × F with K = 0.20, F = 0.75 × proof load, and proof load = tensile stress area (57.99 mm²) × the grade's proof strength. This is a general-engineering starting point for a reusable steel-on-steel joint. It is not a substitute for a manufacturer's torque sequence on an engine, a suspension component, a pressure vessel or any structural connection.