You are torquing a nut to 100 in-lbs. Using a 2-inch dog bone to extend the lever length on an 8-inch torque wrench, what should the wrench indicate to achieve proper torque?

You are torquing a nut to 100 in-lbs. Using a 2-inch dog bone to extend the lever length on an 8-inch torque wrench, what should the wrench indicate to achieve proper torque?

• A. 60 in-lbs
• B. 80 in-lbs
• C. 100 in-lbs
• D. 125 in-lbs

Answer: (B)

Torque is the product of force and the lever arm. Adding a 2-inch extension to an 8-inch torque wrench makes the effective lever arm 10 inches, so for the same tightening force the bolt sees more torque: actual bolt torque = indicated torque × (10/8) = indicated × 1.25. To reach 100 in-lbs at the bolt with the longer lever, you set the wrench to 100 ÷ 1.25 = 80 in-lbs. So, the wrench should indicate 80 in-lbs to achieve the proper 100 in-lbs at the fastener when using that extension.

Torque is the product of force and the lever arm. Adding a 2-inch extension to an 8-inch torque wrench makes the effective lever arm 10 inches, so for the same tightening force the bolt sees more torque: actual bolt torque = indicated torque × (10/8) = indicated × 1.25. To reach 100 in-lbs at the bolt with the longer lever, you set the wrench to 100 ÷ 1.25 = 80 in-lbs. So, the wrench should indicate 80 in-lbs to achieve the proper 100 in-lbs at the fastener when using that extension.