Stress area: 0.606 in² · Proof load: 51,510 lbs · Clamp load (75%): 38,632 lbs
| Surface Condition | K Factor | ft·lbs | N·m | in·lbs | kgf·cm |
|---|---|---|---|---|---|
| Plain/Dry | 0.2 | 643.9 | 873.0 | 7726.5 | 8901.9 |
| Oiled | 0.15 | 482.9 | 654.7 | 5794.9 | 6676.4 |
| Zinc Plated | 0.18 | 579.5 | 785.7 | 6953.8 | 8011.7 |
| Waxed | 0.1 | 321.9 | 436.4 | 3863.2 | 4450.9 |
| MoS₂ | 0.12 | 386.3 | 523.8 | 4635.9 | 5341.1 |
| Galvanized | 0.25 | 804.8 | 1091.2 | 9658.1 | 11127.4 |
Stress area: 0.663 in² · Proof load: 56,355 lbs · Clamp load (75%): 42,266 lbs
| Surface Condition | K Factor | ft·lbs | N·m | in·lbs | kgf·cm |
|---|---|---|---|---|---|
| Plain/Dry | 0.2 | 704.4 | 955.0 | 8453.2 | 9739.2 |
| Oiled | 0.15 | 528.3 | 716.3 | 6339.9 | 7304.4 |
| Zinc Plated | 0.18 | 634.0 | 859.6 | 7607.9 | 8765.3 |
| Waxed | 0.1 | 352.2 | 477.5 | 4226.6 | 4869.6 |
| MoS₂ | 0.12 | 422.7 | 573.1 | 5071.9 | 5843.5 |
| Galvanized | 0.25 | 880.5 | 1193.8 | 10566.6 | 12174.0 |
UNC thread, ft·lbs. Values from the table above.
Same bolt, same target clamp load: thread friction alone moves the required torque from 321.9 ft·lbs (waxed) to 804.8 ft·lbs (hot-dip galvanized), 2.5× as much. Match the row to the fastener's actual finish and lubrication.
Formula: T = K × D × F
Step 1 — Clamp load: F = 0.75 × 85,000 psi × 0.606 in² = 38,632 lbs
Step 2 — Torque (dry): T = 0.20 × 1.0 in × 38,632 lbs ÷ 12 = 643.9 ft·lbs
Proof stress per SAE J429 Table 3. Stress area per ASME B1.1. Typical K-factor, consistent with VDI 2230 friction values.
Automotive, agricultural equipment, general machinery — the most common high-strength SAE grade. Equivalent to ISO 8.8.