If you’re in the automotive aftermarket as a shop owner, master mechanic, or equipment specialist, you’ve undoubtedly heard of torque—it’s how much rotating force an engine throws out, the engine’s ability to make the crankshaft spin. Diesel and electric motors produce more of it than gasoline motors, and you need it when you’re carrying a heavy load up a big hill. It’s simple, really. Until you remember that other kind of torque the automotive industry needs to know about: static torque. Isn’t this kind of torque also extremely important?
Yes, static torque is critical in the automotive aftermarket. Static torque is the amount of force exerted on a fastener, such as a bolt, screw or stud, to hold it in place. Actually, every fastener in a vehicle—or any other assembly really—needs to have the correct amount of torque placed on it in order to hold properly. If there is not enough torque, the bolt can wiggle loose. If there is too much torque, the bolt can strip, shear or deform, then come loose. If your overtorqued bolts are lug nuts, when they shear, a tire could fall off on the road. If bolts are undertorqued in the engine compartment, they could loosen and damage moving parts, such as belts or fans. In addition, the component they’re intended to fasten will likely vibrate more violently, increasing the stress on other bolts and potentially ripping free as it causes further bolt failures. Torque has only become more important since the growth in aluminum parts and composite gaskets which began in the 1990’s, as these parts have more specific tolerances than older materials. So, yes, static torque is important to keep in mind when repairing vehicles. As a result, choosing a quality way to limit the amount of torque you apply is an essential aspect of managing an automotive repair service.
Determining Static Torque Values in Automotive Repair
In order to properly repair any part of a car or truck that requires a bolt, screw, or stud, you need to:
- Know the proper torque value to achieve, and;
- Apply it using a tool which will allow you to deliver correct, precise amounts of torque.
Finding the correct torque is relatively simple for members of the automotive aftermarket industry. Manufacturers publish repair manuals for each vehicle they produce, and these manuals include the proper torque values for each relevant fastener. To find the proper torque for the vehicle you’re working on, simply locate the correct manual. Odds are, as you’re relying on these manuals for other repair information as well, you’ll have them on hand already. If not, they can be purchased from the manufacturer or from third party parts suppliers such as Autozone or Napa.
Things get a little more complicated when you’re working on a vehicle that has already undergone repairs, either by a different mechanic or by the vehicle’s owner. While you can reasonably expect a factory-produced vehicle to have the right fasteners torqued to the correct specifications, it’s a different story when you’re relying on the work of an unknown shop or DIY mechanic. The biggest aspect to check when you’re going over the work of an earlier mechanic is whether or not they used the correct bolts. Because bolts range in size, hardness, and ductility, using the wrong bolt with the right torque spec is no better than tightening a bolt without paying any attention to torque at all. As with torque specifications, the correct bolts to use will be included in the vehicle’s repair manual.
Tools for Applying Proper Torque in Automotive Repair
Once you’ve figured out the correct torque values, the question becomes how best to apply them. If you don’t already have a set of torque tools, you’ll need to acquire some to properly execute vehicle repairs. A torque tool may be a screwdriver, wrench, or power tool which limits the amount of torque it can apply to a fastener. To gain the ability to apply limited amounts of torque, you have two options. You can:
- Purchase a new set of hand and power torque tools, or;
- Purchase torque limiters to retrofit your existing hand and power tools.
The first option, purchasing a set of hand and power torque tools, will give you torque control for any fastening application on a vehicle. Having a range of tools is necessary because no one tool can provide a small enough amount of torque for the tiniest fasteners and large enough amounts of torque for the heaviest fasteners. That said, each tool does cover a range of torque values. Some can be adjusted to different torque values, while some adjustments must be made internally. Purchasing a complete set will give you the utmost control over your torque applications.
When choosing your torque limiting method, keep in mind that different limiting mechanisms offer different levels of control. The simplest hand wrenches, known as click wrenches, will audibly click when the operator reaches the right torque value but will not mechanically limit the amount of torque applied. These wrenches are available at a lower sticker price but allow for the potential of operator error. Other types of torque control products—like cam-over wrenches, break-over wrenches, and pneumatic, electric, or pulse tools—physically prevent an operator from over-torquing a fastener. These tools cost more, but they drastically reduce the potential for error.
If your operation isn’t ready to invest in an entire line of torque control products, other options are available. First, you can target your purchases, choosing the torque tools you’ll need most often first and purchasing the others as funds become available. Alternatively, you can purchase hand or power torque limiters. These devices fit onto the tools you already have, providing them with the ability to detect and limit applied torque. While torque limiters do not provide the same specificity as torque tools designed for the purpose, they are less expensive and still significantly more effective than tools with no torque control at all.
At the end of the day, what matters most is making sure your customers drive out of the shop in a safe, working condition. If you’re handling fasteners at all—and you will be on almost every repair—the best way to make this happen is by ensuring you put the right amount of torque on each fastener you touch. Whether you do so by using a hand or power torque tool or a regular tool with a torque limiter attachment, we’re here to help.