1-1/4 inch bolt torque
A 1-1/4-7 bolt takes 500 ft-lb in Grade 2, 1120 in Grade 5 and 1817 in Grade 8, dry, at 75% of proof load; the 1-1/4-12 fine thread takes 553, 1241 and 2012. Oiled threads take a quarter less.
Sources checked
| Thread | Grade | DryK 0.20 | Zinc platedK 0.20 | OiledK 0.15 | WaxedK 0.10 | Clamp load |
|---|---|---|---|---|---|---|
| 1-1/4-7UNC (coarse) | Grade 2 | 500677 | 500677 | 375508 | 250339 | 23,983 lbf106.7 kN |
| Grade 5 | 1,1201,519 | 1,1201,519 | 8401,139 | 560760 | 53,780 lbf239.2 kN | |
| Grade 8 | 1,8172,463 | 1,8172,463 | 1,3631,848 | 9081,232 | 87,210 lbf387.9 kN | |
| 1-1/4-12UNF (fine) | Grade 2 | 553750 | 553750 | 415563 | 277375 | 26,557 lbf118.1 kN |
| Grade 5 | 1,2411,682 | 1,2411,682 | 9301,262 | 620841 | 59,552 lbf264.9 kN | |
| Grade 8 | 2,0122,728 | 2,0122,728 | 1,5092,046 | 1,0061,364 | 96,570 lbf429.6 kN |
Work out 1-1/4 inch torque
Change grade, threads or preload
1-1/4-7 Grade 5, dry, plain steel
1,120ft-lb1,519N·m
- Clamp load
- 53,780 lbf (239.2 kN)
- Proof load
- 71,706 lbf
The working
- Tensile stress area. A = 0.7854 × (D − 0.9743 ÷ n)² = 0.7854 × (1.25 − 0.9743 ÷ 7)² = 0.969 in²
- Proof load. Grade 5 proof stress is 74,000 psi, so A × stress = 71,706 lbf.
- Clamp load. 75% of proof load = 53,780 lbf.
- Torque. T = K × D × F = 0.2 × 1.25 in × 53,780 lbf = 13,445 in-lb ÷ 12 = 1,120 ft-lb (1,519 N·m).
Where the 1-1/4-7 numbers come from
The 1-1/4-7 UNC (coarse) thread has a tensile stress area of 0.969 in². A Grade 8 bolt’s proof stress is 120,000 psi, so its proof load is 116,280 lbf, and 75% of that is a clamp load of 87,210 lbf.
Torque = K × D × F = 0.20 × 1.25 in × 87,210 lbf = 21,803 in-lb, or 1,817 ft-lb (2,463 N·m) dry. With oil (K 0.15) it’s 1,363 ft-lb (1,848 N·m).
Other sizes
All sizes on one page: the SAE bolt torque chart.
Questions
What torque for a 1-1/4-7 Grade 8 bolt?
1,817 ft-lb (2,463 N·m) dry and 1,363 ft-lb (1,848 N·m) oiled, at 75% of proof load. That clamps the joint with 87,210 lbf (387.9 kN).
What torque for a 1-1/4-7 Grade 5 bolt?
1,120 ft-lb (1,519 N·m) dry, at 75% of proof load; a quarter less with oiled threads.
Coarse or fine thread?
Use whichever the bolt has. The fine 1-1/4-12 thread has a bigger stress area than the coarse one, so it takes slightly more torque for the same clamp. A thread gauge settles it.
Does this apply to wheel nuts or engine bolts?
No. Use the vehicle maker’s value for those: see lug nut torque by vehicle. These numbers are for general-purpose steel bolts where no spec exists.
Sources
- Portland Bolt: SAE J429: proof load, yield and tensile strength for Grades 2, 5 and 8 (checked October 14, 2026)
- Portland Bolt: Thread pitch chart: UNC and UNF threads per inch and tensile stress areas (checked October 14, 2026)
- Fastenal: Mechanical properties of inch fasteners, with UNC and UNF tensile stress areas (checked October 14, 2026)
- Engineering Toolbox: Threaded bolts: tensile stress area formulas for unified and ISO metric threads (checked October 14, 2026)
- Fastenal: Torque–tension relationship for A307 A, Grade 5, 8 and 9 coarse thread bolts (75% of proof load; K 0.15 and 0.20) (checked October 14, 2026)
- Portland Bolt: Bolt torque chart: T = KDP at 75% of proof load, with K for plain, waxed and galvanized bolts (checked October 14, 2026)
Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.