Dimensional data for M27 Hex Nuts, Grade C to ISO 4034, with the drive and the installation notes for this type.
Values are taken from the governing standard rather than from a general machine-thread table, because this type is not selected on one.
M27 Dimensional Row (ISO 4034)
| Size | Pitch (mm) | Width across flats s (mm) | Width across corners e min (mm) | Nut height m (mm) | Product grade | Reference standard |
|---|---|---|---|---|---|---|
| M27 | 3.0 | 41.0 | 45.2 | 23.8 | Grade C | ISO 4034 / DIN 555 |
Spanner & Drive for M27 Hex Nuts, Grade C
M27 Hex Nuts, Grade C have a width across flats of 41.0 mm — fit a 41.0 mm open-ended spanner or socket. A 6-point socket grips all six flats of the 41.0 mm hex and is what to reach for once a fastener has been on and off a few times; a 12-point ring spanner starts rounding a worn head. For repeatable preload, torque rather than feel.
Tightening Torque for M27
| Class 8.8 (dry, ~µ 0.125) | ≈ 1064 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 1516 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 1774 Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M27
Nuts are graded to ISO 898-2 by the proof load the nut itself will hold (classes 04, 05, 5, 6, 8, 10 and 12), not by the 8.8 / 10.9 / 12.9 scale used for bolts. A class-8 nut is the correct mate for a class-8.8 bolt, and the joint is designed on the bolt, so no bolt-tension figure is quoted here.
Installation Tips for M27 Hex Nuts, Grade C
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
- At M27 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
Mating Parts for M27
Pair M27 with the matching M27 bolt or screw, plus a M27 flat washer where required to distribute load on softer materials.
Custom manufacturing · Made to drawing
Need hex nuts, grade c in a size this table does not list?
This page covers M27 hex nuts, grade c. Thread, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. Made by cold heading or tapping.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
