Can somebody torque sense to me?
QI’ve just inherited a torque wrench in a shed clearance. At the risk of asking a silly question, how do I use it – and what for? Kelly Smith, Manchester
Matt says:
AIt’s not silly at all people often assume a torque wrench is to ‘get things tight enough’. But mostly it prevents overtightening and consequent damage. To use the wrench, find the correct torque for the nuts or bolts you want to fit. The workshop manual will tell you this. If it doesn’t name the component specifically, look for a list of general tightening torques for the various thread sizes on the car. Set the dial on the wrench and lock it if a screw is provided. If there’s more than one nut or bolt, go round them in stages, a bit at a time, working up to full tightness. If fastening, say, a cover plate, start at the centre nuts and work outwards in a crosswise fashion. Never make long, sweeping motions with the wrench – a nut requires much less force once it’s moving and this can lead to studs and bolts snapping. Instead, make short, smooth strokes, about 45º at a time. When the nut is tight enough, you’ll hear the wrench click loudly and will feel this through the handle too. Stop at this point. Torque settings usually assume the threads are lightly-oiled. Grease allows the same torque to wind the nut down much further, so it’s not really to be recommended. A wrench is usually marked in ft.lbs or Nm. Be aware that manuals sometimes give slightly different units, which can make a big difference. Be sure to check this carefully. Look up the conversion factor and convert where necessary.