In the aircraft and aerospace industry, the standards required for various components, parts, and specifications are considerably higher. Everything built for the aircraft and aerospace industry is light and strong. It is the “AND” part of that sentence that makes the parts expensive, not the “light” part. Automobile manufacturers today who build high-performance and sophisticated vehicles understand the “light” part, but not necessarily the “strong” part. But what they do understand is how much force can be applied to these parts before they succumb to failure.
Today’s brake rotors (or disk brake system) are built very light with advances in technology such as slotting, cross-drilling, cryo-treating and many other advances to allow the brakes to breathe better and last longer. However despite all this technology that goes into the rotors, they are still not strong enough to withstand a mechanic’s error. How often have you had a car pulsate when applying the brakes? The reason this happens is because the lug nuts on your wheels were not torqued down to specifications set out by the manufacturer. Every mechanic shop you walk into, you can always hear the distinctive sound of the air wrench being used to loosen and tighten parts and lug nuts. These air tools are capable of putting out an immense amount of torque, but that is where the problem starts. The torque setting on these air wrenches are preset to a single setting (usually the strongest), never changed, but used to tighten down everything on your car. BAD!
Today’s modern vehicles are built almost like airplanes and have very acute specifications that must be followed. The most commonly made mistake by mechanics and car owners are to over-tighten the lug nuts on the wheels of their cars. Some even go as far as jumping on the tire wrench to ensure that the lug nuts are “tight” and that the wheels will not “fall off” while driving. However, over tightening your lugs will lead to premature failure of your brake rotors as seen by warping or deformations in the rotor. It may also lead to wheel bolts “snapping” when over-tightening the wheels stretches and weakens the bolt.
It is therefore important to ensure that your lug nuts are tightened to the appropriate specifications and to do that, there are several things you can do. For most vehicles, the lug nuts need to be tightened down to 70-100 ft-lbs using a good quality torque wrench. However, you do not need a torque wrench to tighten your lug nuts correctly.
The approach I have always taken is to tighten the nuts as tightly as can be done with your fingers first. Then taking a tire wrench, tighten the nut without apply much effort until you feel some resistance. Then simply (without jumping on the tire wrench), put your body weight on the wrench until it stops turning. You do not need to jerk your body to ensure that there is more room to tighten. In general, if you follow this practice, you will put about 80-90 ft-lbs of torque onto the lug. Do this consistently for all your wheels to ensure that your brake rotors have maximum life. However, for best results, I still recommend acquiring a quality 1/2″ drive torque wrench, my favorite being the Neiko Pro line that I use religiously for every mechanical work conceivable.
It is a worthwhile investment and they typically range in price from $20-40, which is cheaper than a single brake rotor for your car. The brakes and wheels are the most important components of your car and therefore, requires the most care and attention. Go check your lug nuts today.