# M36 bolt torque

Tighten an M36 × 4 class 8.8 bolt to 2,646 N·m (1,952 ft-lb) with dry threads, or 1,985 N·m when lubricated. Class 10.9 takes 3,661 N·m and class 12.9 takes 4,278 N·m.

## M36 × 4 torque by property class

| Property class | Dry torque (K 0.20) | Lubricated (K 0.15) | Clamp load | Proof load |
|---|---|---|---|---|
| Class 8.8 | 2,646 N·m (1,952 ft-lb) | 1,985 N·m (1,464 ft-lb) | 367.5 kN | 490.0 kN |
| Class 10.9 | 3,661 N·m (2,700 ft-lb) | 2,745 N·m (2,025 ft-lb) | 508.4 kN | 677.9 kN |
| Class 12.9 | 4,278 N·m (3,155 ft-lb) | 3,208 N·m (2,366 ft-lb) | 594.2 kN | 792.2 kN |

Clamp load = 75 % of proof load. Method: T = K × F × d.

## M36 bolt data

- Thread: M36 × 4 coarse
- Tensile stress area: 816.7 mm²
- Wrench: 55 mm (ISO 4014/4017)
- Socket head cap screw hex key: 27 mm
- Tap drill: 32 mm
- Clearance hole (ISO 273): 37 close, 39 normal, 42 loose (mm)

## Method

Proof stress from ISO 898-1 (600 MPa for 8.8 at this size, 830 MPa for 10.9, 970 MPa for 12.9) × tensile stress area As = π/4 × (d − 0.9382 p)². Target clamp load F = 75 % of proof load. T = K × F × d with K = 0.20 dry, 0.15 lubricated.

## FAQ

**What is the torque for an M36 8.8 bolt?**
About 2,646 N·m (1,952 ft-lb) with dry threads and about 1,985 N·m lubricated, based on 75 % of proof load.

**What is the torque for an M36 10.9 bolt?**
About 3,661 N·m (2,700 ft-lb) dry and 2,745 N·m lubricated.

**What is the torque for an M36 12.9 bolt?**
About 4,278 N·m (3,155 ft-lb) dry and 3,208 N·m lubricated.

**What size wrench fits an M36 bolt?**
55 mm for ISO hex bolts. An M36 socket head cap screw takes a 27 mm hex key.

**What drill size do I need to tap M36?**
Use a 32 mm drill for M36 × 4 coarse thread.

Source page: https://machinistcharts.com/bolt-torque/m36/
Updated: 2026-10-05
Publisher: MachinistCharts (https://machinistcharts.com)