Best is a relative term. When you’re choosing a torque wrench or a line of torque wrenches for your automotive business, the best torque wrench isn’t necessarily the one that’s earned the most blue ribbons. It isn’t the most precise torque wrench ever created or the one that generates the most force. Rather, it’s the one that fits your needs.
So, when deciding which torque wrench is ideal for your company, consider what you’ll be using it for. How much torque will the wrench need to produce? How precise will it need to be? How low must the cost be for you to generate a return on your investment? By answering these three questions, you’ll be able to determine the best torque wrench for your automotive business.
Torque Requirements for Common Automotive Fasteners
First things first: how much torque do you need? Here’s a rundown of the torque needs you’ll commonly encounter in the automotive world:
- Very Light Duty
- Very light duty automotive torque applications range from 15-75 ft.lbs.
- This range covers common maintenance needs such as spark plugs, oil drain plugs, valve cover bolts, and similar fasteners.
- Light Duty
- Light duty automotive torque applications range from 30-150 ft.lbs. Most automotive repairs fall into this range. In other words, without a torque wrench in this range, you won’t be able to complete the majority of automotive repairs.
- Common repair needs within this range are head bolts, lug nuts, and caliper bolts.
- Moderate Duty
- Moderate duty automotive fasteners require between 50 and 250 ft.lbs. While fewer fasteners fall into this range than light duty fasteners, those which do are critical applications.
- Some of the common automotive fastening applications within this torque range are axle bolts, hub bolts, and bolts on installed trailer hitches.
- Heavy Duty
- Heavy duty automotive bolts require between 120 and 600 ft.lbs of torque.
- Common applications include driveline components and bearings, as well as much of the work involved in transfer cases and differentials.
- Very Heavy Duty
- Very heavy duty automotive fasteners require between 200 and 1,000 ft.lbs of torque, or even higher amounts.
- Applications include camshaft sprockets and harmonic balancers. Many off-road vehicles or performance racing vehicles will require torque applications in this range as well.
The type of automotive work you do will dictate the wrench you need. If you’re primarily focused on oil changes and tune-ups, you will likely only require light or very light duty torque wrenches. If you market yourself as a shop specializing in heavier duty repairs, such as rebuilding engines or transmissions, or handling structural repairs like axle or hub work, you’ll need a heavier wrench.
Capabilities of Torque Wrenches Used in Automotive Repair
Different types of wrenches administer different amount of torque. There are two primary types of torque wrenches used in automotive repair: hand and pneumatic wrenches. Within these, there are a few subcategories. Hand wrenches can be either click, break-over, or cam-over, while pneumatic wrenches can be powered by a continuous or discontinuous drive. However, only discontinuous drive pneumatic tools, otherwise known as pulse tools, generate enough torque to be useful in the automotive industry. For all of these wrenches, keep in mind that it is critical to properly care for and regularly calibrate them in order to maintain good working order.
Here’s a brief description of the capabilities of the different types of torque wrenches.
- Hand Wrenches
- Click Wrenches: The simplest and least expensive of the torque wrenches, click wrenches limit torque by informing their operator when the proper torque is achieved with an audible “click” sound. As these wrenches rely on the operator to limit the torque applied, they are less precise than other types of torque wrenches. However, they are capable of delivering far more torque than any other type of hand torque wrench, ranging from 18 lbf.in to 2,212 ft.lbs of torque. Click wrenches are a fantastic choice for automotive mechanics due to their versatility and price.
- Break-Over Wrenches: While break-over wrenches are more expensive than click wrenches, they limit torque with significantly more assurance. When the proper torque is reached, the wrench will “break,” preventing the operator from delivering too much torque. As such, break-over wrenches are more appropriate than click wrenches for applications requiring precise amounts of torque. However, the break-over action limits the amount of torque the tool can deliver, cordoning the torque range of most break-over wrenches to between 25 ozf.in at the low end and 147 lb.ft at the high end.
- Cam-Over Wrenches: Cam-over wrenches deliver similar amounts of torque as break-over wrenches, from 2-90 lb.ft, and they limit torque at least as effectively by “slipping,” or disengaging, when the proper torque is reached. Cam-over wrenches are typically higher in price than break-over and click wrenches. The benefit of cam-over wrenches in the automotive industry is ergonomic. As they do not require as large of a range of motion as break-over wrenches do, they are better suited for the tight spaces mechanics often work in.
- Pneumatic Wrenches
- Discontinuous Drive: Discontinuous drive or “pulse” wrenches use pressurized air to deliver precise bursts of radial force to fastener heads. When proper torque is achieved, the wrench disengages either its hydraulic pulse unit or air supply, preventing the operator from over-torquing. Capable of delivering up to 332 lb.ft of torque, these tools can handle most automotive applications. The major disadvantage of pulse wrenches compared with hand tools is the initial investment required, which is significantly higher for pulse tools. However, pulse tools deliver torque much more rapidly than hand tools, rendering it possible for high-volume shops to justify their investment with increased capacity.
To summarize, click wrenches deliver the most torque for the lowest cost, rendering them ideal for most automotive applications. Cam-over and break-over wrenches cannot deliver as much torque, but they limit torque more precisely, making them necessary for more critical fasteners, such as head bolts or calipers. Finally, pulse tools are as accurate as cam or break-over wrenches and deliver high torque loads at rapid speeds, for a higher price. Their cost makes them most effective when they can generate a return by increasing a shop’s production capacity.
Which type of wrench is the best for your automotive business? Now you can answer the question for yourself.
