1-1/8 inch bolt torque
A 1-1/8-7 bolt takes 354 ft-lb in Grade 2, 794 in Grade 5 and 1288 in Grade 8, dry, at 75% of proof load; the 1-1/8-12 fine thread takes 397, 891 and 1445. 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 |
|---|---|---|---|---|---|---|
| 1-1/8-7UNC (coarse) | Grade 2 | 354480 | 354480 | 266360 | 177240 | 18,884 lbf84.0 kN |
| Grade 5 | 7941,077 | 7941,077 | 595807 | 397538 | 42,347 lbf188.4 kN | |
| Grade 8 | 1,2881,746 | 1,2881,746 | 9661,309 | 644873 | 68,670 lbf305.5 kN | |
| 1-1/8-12UNF (fine) | Grade 2 | 397539 | 397539 | 298404 | 199269 | 21,186 lbf94.2 kN |
| Grade 5 | 8911,208 | 8911,208 | 668906 | 445604 | 47,508 lbf211.3 kN | |
| Grade 8 | 1,4451,958 | 1,4451,958 | 1,0831,469 | 722979 | 77,040 lbf342.7 kN |
Work out 1-1/8 inch torque
Change grade, threads or preload
1-1/8-7 Grade 5, dry, plain steel
794ft-lb1,077N·m
- Clamp load
- 42,347 lbf (188.4 kN)
- Proof load
- 56,462 lbf
The working
- Tensile stress area. A = 0.7854 × (D − 0.9743 ÷ n)² = 0.7854 × (1.125 − 0.9743 ÷ 7)² = 0.763 in²
- Proof load. Grade 5 proof stress is 74,000 psi, so A × stress = 56,462 lbf.
- Clamp load. 75% of proof load = 42,347 lbf.
- Torque. T = K × D × F = 0.2 × 1.125 in × 42,347 lbf = 9,528 in-lb ÷ 12 = 794 ft-lb (1,077 N·m).
Where the 1-1/8-7 numbers come from
The 1-1/8-7 UNC (coarse) thread has a tensile stress area of 0.763 in². A Grade 8 bolt’s proof stress is 120,000 psi, so its proof load is 91,560 lbf, and 75% of that is a clamp load of 68,670 lbf.
Torque = K × D × F = 0.20 × 1.125 in × 68,670 lbf = 15,451 in-lb, or 1,288 ft-lb (1,746 N·m) dry. With oil (K 0.15) it’s 966 ft-lb (1,309 N·m).
Other sizes
All sizes on one page: the SAE bolt torque chart.
Questions
What torque for a 1-1/8-7 Grade 8 bolt?
1,288 ft-lb (1,746 N·m) dry and 966 ft-lb (1,309 N·m) oiled, at 75% of proof load. That clamps the joint with 68,670 lbf (305.5 kN).
What torque for a 1-1/8-7 Grade 5 bolt?
794 ft-lb (1,077 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 1-1/8-12 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.