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M60×5.5 — Full Fastener Spec
ISO 68-1 / ISO 261 · Coarse series · Tap drill, clearance hole, torque, strength and tool sizes — every number on one page.
Tap drill (75% thread)
54.5 mm
No standard inch drill this large · Clearance hole (normal fit): 66 mm ·
8.8 torque: 12330 N·m dry
Thread dimensions
Major diameter
60 mm
Pitch
5.5 mm
TPI (equivalent)
4.62
Pitch diameter
56.428 mm
Minor diameter
54.046 mm
Tensile stress area
2362.02 mm²
Tap drill sizes for M60×5.5
Percent of thread is a trade-off: 75% is the shop default because the last 25% of engagement adds only a few percent of strength while roughly doubling tapping torque. Drop to 50–65% in tough or gummy material, or for blind holes where a snapped tap means scrapping the part.
| Thread engagement | Exact | Metric drill | Nearest inch drill |
|---|---|---|---|
| 50% | 56.428 mm | 56.5 mm | no standard inch drill |
| 65% | 55.356 mm | 55.5 mm | no standard inch drill |
| 75% | 54.641 mm | 54.5 mm | no standard inch drill |
| 85% | 53.927 mm | 54 mm | no standard inch drill |
Roll (form) taps need a larger hole than cut taps — add roughly
0.4× the pitch to the 75% cut-tap drill and confirm against your tap maker's chart.
Clearance hole for M60×5.5
| Fit | Hole | Use |
|---|---|---|
| Close | 62 mm | Located joints, dowel-like alignment |
| Normal | 66 mm | General assembly — use this unless you have a reason not to |
| Loose | 70 mm | Weldments, sheet stacks, tolerance build-up |
M60×5.5 torque specs
Calculated with the short-form equation T = K · D · F, using K = 0.2 (plain, dry, as-received steel) and a target clamp load of 75% of proof load — the standard preload target for a reusable joint.
| Grade | Dry | Lubricated | Dry (lb-ft) | Clamp load |
|---|---|---|---|---|
| 4.6 Low-carbon steel, general purpose | 4783 N·m | 3587 N·m | 3528 lb-ft | 398.6 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 12330 N·m | 9247 N·m | 9094 lb-ft | 1027.5 kN |
| 10.9 Alloy steel, Q&T — high strength | 17644 N·m | 13233 N·m | 13014 lb-ft | 1470.4 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 20620 N·m | 15465 N·m | 15209 lb-ft | 1718.4 kN |
| A2-70 304 stainless, cold worked | 9566 N·m | 7175 N·m | 7056 lb-ft | 797.2 kN |
The nut factor K dominates this result. Zinc-plated, waxed, anti-seize
and lubricated threads all shift K between roughly 0.10 and 0.25, which is a 2.5×
spread in torque for identical preload. If preload actually matters, torque-to-yield,
angle control or a load-indicating washer beats a torque wrench every time.
Tool sizes
Hex head wrench
90 mm
Hex key (socket head)
41 mm