Torque Wrenches

Torque Wrenches  Socket turning handles designed to apply a known force to the fastener are called Torque wrenches. A clicker-type torque wrench is set to the specified torque and “clicks” when the value has been reached.

Using a torque wench to tighten connecting rod nuts on an engine.

When force is removed from the handle, another click is heard. The wrench should be set back to zero after use and check for calibration regularly.

A beam-type torque wrench is used to measure torque. Instead of presetting the value, the actual torque is displayed on the dial as the fastener is tightened. Beam-type wrenches are available in 1/4, 3/8, and 1/2 inch drives, in English and metric units.

Check Torque Wrench Calibration Regularly

Torque wrenches should be checked regularly. For example, Honda has

a torque wrench calibration setup at each of their training centers. It is expected that a torque wrench be checked for accuracy before every use. Most experts recommend that torque wrenches be checked and adjusted as needed at least every year and more often if possible.

Double-Check the Specifications

Misreading torque specs is easy to do but can have serious damaging results. Specs for fasteners are commonly expressed lb-ft. Many smaller fasteners are tightened to specifications expressed in lb-in.               

                                              1 lb-ft = 12 lb-in.

If a fastener were accidentally tightened to 24 lb-ft instead of 24 lb-in., the actual torque applied will be 288 lb-in. instead of the specified 24 lb-in. The extra torque will likely break the fastener, but it could also warp or distort the part being tightened. Always double-check the torque specs.

Is it Lb-Ft or Ft-Lb or Torque?

The unit for torque is expressed as a force times the distance (leverage) from the object. Therefore, the official unit for torque is lb-ft (pound-feet)

or Newton-meters (a force times a distance). It is commonly expressed in ft-lbs and even some torque wrenches are labeled with this unit.

Safe Use of Sockets and Ratchets  Always use the proper size socket that correctly fits the bolt or nut. All sockets and ratchets should be cleaned after use before being placed back into the toolbox. Sockets are available in short and deep well designs.

Select the appropriate drive size.

For small work, such as on the dash, select a 1/4-inch drive. For most general work, use a 3/8.

For suspension, steering and other large fasteners, use a 1/2-inch drive.

When loosening, pull toward yourself.

Use Socket Adapters with Caution

Socket adapters are available and can be used for different drive size sockets on a ratchet. Combinations include:

Using a larger drive ratchet or breaker bar on a smaller size socket can cause the application of too much force to the socket, which could crack

or shatter. Using a smaller size drive tool on a larger socket will usually

not cause any harm, but would greatly reduce the amount of torque that can be applied to the bolt or nut.

Avoid Using “Cheater Bars”

Whenever a fastener is difficult to remove, some technicians will insert the handle of a ratchet or a breaker bar into a length of steel pipe. The extra length of the pipe allows the technician to exert more torque than can be applied using the drive handle alone. However, the extra torque can easily overload the socket and ratchet, causing them to break or shatter, which could cause personal injury.