Tech Tips
Nuts
- Well boys and girls, this month’s topic is the world of lug nut torque and the correct way to arrive at same. Every mechanic knows that incorrectly tightened lug nuts will lead to broken or bent wheels, warped brake rotors or uneven wheel to hub contact. However, there are still many of my colleagues that ignore the rules of the road when it comes to tightening lug nuts. Well mister wise guy, what are the rules?
Initial tightening must be done one lug nut at a time by hand. This means installing each nut onto the stud one at a time using your fingers. We have all seen the uneducated install a lug nut and then crank it down with an air wrench before moving on to the next one, WRONG!! With the wheel hanging freely on the studs, it is not squarely against the hub. While hanging in this position, tightening one nut jams the wheel against the hub and pins it there unevenly. Tightening the next nut pulls the wheel more-or-less even. But, because part of the wheel is already pinned against the hub, that section cannot move. In other words, the center web of the wheel is being twisted with a lot of force. The stresses caused in tightening the remaining nuts in sequence work to distort both the wheel web and the hub of the brake rotor. - The next stop is to SNUG the nuts using a breaker bar and a 6 point socket. This is the time to employ the criss-cross pattern shown in our factory service manual. Don’t have a factory service manual? DO NOT WORK ON ANY AUTOMOBILE WITHOUT ONE!!
- The final step is to tighten the nuts, using the same pattern in step 2, to the torque indicated in the manual. The only way to know if the required torque has been achieved is by using a torque wrench.
- It is wise to recheck the wheel nut torque after driving 50-100 miles.
So, the next time you or anyone else has occasion to remove and reinstall the wheels on your Z car, be sure that the steps I have outlined are followed.
Mike McGinnis
Banzai Motorworks
