WHAT ARE WHEEL TORQUE STICKS?
I never grew up in a tire shop so when I first came across a torque stick I was pretty curious how it worked and how accurate it would be. I could immediately see the benefits of the tool, especially at track days when you are removing and installing wheels multiple times a day. I also like the simplicity of it, as its one less tool you need to have out. You can have a dedicated impact gun with a torque stick attached and that's all you need for tire changes.
Before I get into the science behind them, let's just have a quick refresher of what torque is and why it's important.
Torque is the measure of a force that can cause an object to rotate about an axis. In layman's terms, its the clamping force created by fasteners and is what allows wheels to function properly. All fasteners are intended to stretch slightly when tightened. This stretch is measured indirectly by the torque (measured in foot-pounds in the USA) required to turn the fastener. If a wheel is not fastened properly, it can cause damage to the wheel, or worse yet, come off while in motion. Because of this scare, some technicians will over tighten the wheel lug nuts or bolts which is just as bad. As stated above, all fasteners are intended to stretch slightly. By over tightening a fastener you will in turn over stretch the bolt or stud and it will never go back to its original dimensions. This will permanently damage the fastener and could possibly break under stress.
Now lets get to these little colored sticks. Torque sticks come in all different flavors (please do not lick them). Each color represents a torque value. Unfortunately, there is no standard for color to corresponding torque value, so each manufacturer is different. For the sake of this article, I will use the colors that we offer on the website which is gray, and blue. The gray torque stick represents 100 ft lbs, and the blue torque stick represents 80 ft lbs. These will be the closest torque value for most BMW wheels.
If you want to look up the torque value of your wheels, please see our BMW Wheel Spec blog here:
Torque sticks are used to prevent the over tightening of fasteners. They work by flexing like a torsion bar. Once the proper torque is applied, the steel bar twists preventing anymore torque from being applied. The higher the torque value on the stick, the thicker the bar. The lower the torque value on the stick, the thinner the bar, as it takes less effort to flex it. Torque sticks have to be used with impact guns around 350-400 ft lbs. Under valued impact guns will not have the strength to twist the bar giving you an inaccurate torque value. All of the torque sticks we offer have a 1/2" drive with a 1/2" socket end.
Some people say there is no substitute for a traditional torque wrenches, and it most cases I agree. I would not rebuild an engine, or install head bolts with a torque stick, but for wheel lug nuts I have found them to be quite accurate. If you want to verify the torque value, I recommend using a deflection type torque wrench (click wrench will not be accurate for this test) to see how much torque the sticks actually put on your wheels. In my testing I have found them to be as accurate as +/-3 %.
I am always looking for cool tools, and ways to save time on track. Along with the simplicity of just having a dedicated battery powered impact gun with a torque stick installed, these simple tools have really changed my life.