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M36×4 — 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)
32 mm
Nearest inch drill: 81/64 (1.2656") · Clearance hole (normal fit): 39 mm ·
8.8 torque: 2558 N·m dry
Thread dimensions
Major diameter
36 mm
Pitch
4 mm
TPI (equivalent)
6.35
Pitch diameter
33.402 mm
Minor diameter
31.67 mm
Tensile stress area
816.72 mm²
Tap drill sizes for M36×4
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% | 33.402 mm | 33.5 mm | 1.3125" (21/16 drill) |
| 65% | 32.622 mm | 32.5 mm | 1.2812" (41/32 drill) |
| 75% | 32.103 mm | 32 mm | 1.2656" (81/64 drill) |
| 85% | 31.583 mm | 31.5 mm | 1.2344" (79/64 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 M36×4
| Fit | Hole | Use |
|---|---|---|
| Close | 37 mm | Located joints, dowel-like alignment |
| Normal | 39 mm | General assembly — use this unless you have a reason not to |
| Loose | 42 mm | Weldments, sheet stacks, tolerance build-up |
M36×4 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 | 992 N·m | 744 N·m | 732 lb-ft | 137.8 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 2558 N·m | 1918 N·m | 1887 lb-ft | 355.3 kN |
| 10.9 Alloy steel, Q&T — high strength | 3661 N·m | 2745 N·m | 2700 lb-ft | 508.4 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 4278 N·m | 3208 N·m | 3155 lb-ft | 594.2 kN |
| A2-70 304 stainless, cold worked | 1985 N·m | 1488 N·m | 1464 lb-ft | 275.6 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
55 mm
Hex key (socket head)
27 mm