subject: Auto Repair Torque Frenches Guide [print this page] Auto Repair Torque Frenches Guide Auto Repair Torque Frenches Guide
A torque wrench is designed to tighten a nut, bolt, or screw to an exact degree. A torque wrench is extremely handy because, until you become familiar with a job, you always run the risk of undertightening or overtightening things.
If you're replacing a spark plug and you don't tighten it enough, it will work itself loose and fail to deliver a spark. If you overtighten a spark plug, you can strip the threads or crack the plug. Similarly, parts that have gaskets can leak if the bolts that hold them aren't tightened enough. But if you overtighten the same bolts, the gaskets will be crushed, causing the fluid to leak anyway.
Most really good torque wrenches are expensive, but a cheaper one is good enough to serve your purposes. If you'd rather not spend the money until you're sure that you're really going to like working on your car, borrow a torque wrench just to get the feel of how tight a nut, bolt, or other part should be. Or you can just forget the whole thing. I've never used a torque wrench; my set of socket wrenches accomplished everything quite well for the work in this book. If you are planning to buy a torque wrench, get one with a slim profile, because torque wrenches are bulky anyway and often don't fit into tight places.
If you use a torque wrench, keep the following in mind:
Grip a torque wrench well down the shaft (not up close to the dial) and operate it smoothly.
Tighten a series of nuts or bolts in a sequence that distributes the pressure evenly, instead of in strict clockwise or counterclockwise order.
When tightening a series of bolts, tighten them all just until they're snug. Then go back and tighten them all a bit more. Then go back and tighten them all the way to the torque specifications. Doing so ensures that the entire part you're tightening is under even pressure, prevents leaky gaskets, and increases the life of the bolt and the part. This and the preceding tips are good to follow when you're using any kind of wrench to tighten anything.
Before using a torque wrench, make sure that the nut or bolt turns freely so that the torque wrench gets a true reading of the proper nut tightness. You can use a lubricant such as WD-40 on the threads and run the nut up and down a few times to free it before using the torque wrench on it.
