At Home Mechanic

Finding a level piece of ground, securely setting the brakes, and properly jacking the car up is all covered in your car's owner's manual. The manual will also suggest that you apply the tightening wrench in a criss-cross pattern and in a progressive manner to prevent over tightening any one lug nut.

While you are looking through your owner's manual for the jacking and other instructions, check to see if they also give you a torque wrench setting for replacing the lug nuts. A torque wrench you say? Yes, a precise device for setting just the right amount of twist on a secured nut or bolt. Every manufacture has a precise amount of torque for their lug nuts; not enough torque and your wheels could fall off (a very bad thing). And too much torque will cause... what?

Is it even possible to torque a lug nut too much? The more the torque on those lug nuts, the merrier, right? WRONG. Strange as it may seem, putting all of your might into that lug nut wrench is damaging your brake rotors. In some cases you can actually bend the brake rotors out of shape by over tightening your lug nuts. "Warped rotors" is often blamed on poor materials or brake over-heating, but the over whelming majority of all warped rotors is caused by over-tightened lug nuts.

Most car manufacturers specify between 80-110 pounds of torque on the lug nuts. If that sounds like a lot of twist on the lug nuts, you will not think so when you actually apply it. In fact you will double check your torque wrench setting and be afraid that the lug nut are not on nearly tight enough. It just does not "feel" tight enough. But you will have to trust in your torque wrench and the manufacturer's recommendation, because if you decide that standing on the wrench to get those lug nuts really tight you could be bending your brake rotor.

But as bad as it is when the At Home Mechanic uses his hand tools to over tighten a set of lug nuts, imagine how much damage could be done by a guy with an air wrench at the local repair shop. Nine times out of ten, the slack jawed yokel with the air wrench is only looking for the fastest and easiest way to get your wheels on. Using a torque wrench takes extra time and effort to dig the torque wrench out of the toolbox, set it to the proper setting and then applied accurately.

The next time you have any kind of work done on your car that involves removing and replacing the wheels, be sure to ask the service writer just exactly how that shop tightens lug nuts. If he gives you a blank stare, ask specifically if his shop uses torque wrenches to replace lug nuts. Unless he tells you that his shop uses exact torque specifications, take your car somewhere else.