Paint and Repaint
On steel wheels, paint is important to keep wheels firmly attached to trucks. But too much paint around the area where the lug nut contacts the wheel or on the back side of the wheel where it is in contact with the spindle can create a problem. This typically happens when wheels are repainted. If the thickness of the paint exceeds 3.5 mils, about the thickness of a sheet of paper, it can wear away and a lug nut that was once properly tightened can become loose.
On the other end of the scale is no paint at all. No paint on a steel wheel eventually leads to rust. Rust not only looks bad, but rust under a lug nut can also cause looseness and loss of clamping power.
Tools to make the job easier
There are now pneumatic torque wrenches on the market, and while more expensive than the old mechanical torque wrenches, they certainly are simple and easy to use. Simply set the torque value at the desired number and tighten the lug nuts.
If you’re still old school, there are several other types of torque wrenches:
* Beam Torque Wrench: TMC says this is the most accurate wrench (+-2%) and it needs little calibration. The wrench measures the deflection of the beam of a known length to determine the amount of torque.
* Dial Torque Wrench: About a +-3% accuracy range, these wrenches are easy to use. The torque value is set on the wrench, and the technician tightens the lug nut until the indicator light illuminates to set the desired torque.
* Ratcheting (Clicker) Torque Wrench: When the target torque level is hit, an audible clicking is heard, which means you’re at your mark. But, if the actual torque of the nut is higher than what the wrench is set for, you must increase the setting of the wrench until movement is noticed.
* Break Handle or “Breakaway” Wrench: A very simple wrench with a degree of accuracy (+-5%), this wrench is pre-set for a certain torque level. Once it’s met, the handle “breaks,” indicating you’re at your torque level.
Once finished with your torquing wrench, return the torque level to its lowest setting and be sure to calibrate periodically (how often depends on the type of wrench, so check your manual).
Another source of potential wheel end issues are the wheel bearings. You should check bearing looseness to help prevent premature tire wear and lubricate your bearings per the manufacturer’s recommendations to ensure long bearing life and cool running.
Special thanks to Dave Walters from ALCOA for providing much of the information found in this article.