How do I use a socket set and torque wrench?

A socket set is straightforward until something is tight, at which point the difference between the right socket and a nearly-right one becomes a rounded fastener and a much longer afternoon.

Safety

Step by step

1. Understand the drive sizes.1/4 inch for small fasteners and tight spaces, 3/8 inch as the general-purpose size, 1/2 inch for anything needing real force such as wheel nuts. Adaptors exist but each one adds flex and a failure point.
2. Match metric and imperial properly.They are close but not the same. A 13mm socket on a 1/2 inch nut is slightly loose and will round it. Almost everything modern in the UK is metric; older machinery and some imports are not.
3. Use six-point sockets on tight fasteners.Six-point grips the flats of the nut; twelve-point grips the corners and is far more likely to round a tight or corroded one. Twelve-point is for access in awkward positions, not for force.
4. Push the socket fully on.A socket sitting partly on the fastener concentrates the load on the top edge and rounds it. Seat it fully every time, especially on something recessed.
5. Set the ratchet direction before applying force.The small lever sets tighten or loosen. Pushing hard against a ratchet set the wrong way is how knuckles get hurt and fasteners get overtightened.
6. Pull rather than push.So that if it releases suddenly you do not fall into whatever is in front of you. Where you must push, use an open palm rather than gripping.
7. Use a breaker bar for anything seized.A long solid bar, not a ratchet. Ratchet mechanisms are the weak point and applying maximum force to one is how they break, usually suddenly.
8. Do not extend a ratchet with a pipe.It multiplies the force well beyond what the mechanism is rated for. Use a breaker bar designed for it.
9. Understand what torque is for.A specified clamping force. Too loose and it works free; too tight and the fastener stretches or the thread strips. Wheel nuts, cylinder heads, brake components and anything with a published figure need it.
10. Set the torque wrench correctly.Unlock the handle, wind to the figure reading both the main scale and the vernier, then relock. Pull smoothly until it clicks and then stop — a second pull after the click adds more torque.
11. Never loosen with a torque wrench.It damages the calibration mechanism. Use a normal ratchet or breaker bar to undo, and the torque wrench only for final tightening.
12. Wind it back before storing.To its lowest setting, not zero unless the manufacturer says so. Storing a torque wrench under spring tension puts it out of calibration over time.
13. Tighten in the right sequence.Wheel nuts and anything with several fasteners go in a star or crossing pattern, in stages, so the component is pulled down evenly. Going round in order distorts it.
14. Recheck wheel nuts after driving.Standard practice after any wheel change — usually after 25 to 50 miles. They can settle and lose torque.

Tips

• Six-point sockets for anything tight. The single change that prevents most rounded fasteners.
• Stop at the click. A torque wrench clicks once at the setting, and continuing to pull applies more than you asked for.
• Breaker bar to undo, torque wrench to tighten. Using either for the other job breaks something.

Common mistakes

• Using a torque wrench to loosen fasteners — It damages the internal mechanism and puts the calibration out, so it no longer reads correctly on the jobs that matter.
• Using a nearly-right socket size — A 13mm on a 1/2 inch fastener is slightly loose and rounds the corners under load. Once rounded it needs an extractor.

If it doesn't work

Questions people ask