Best Torque Wrench
Torque wrenches are precision instruments, used to ensure that nuts and bolts are properly tightened in automotive engines, aviation and industrial applications. They provide a means of measuring the amount of force applied to the fastener, in order to tighten it. Without this measurement, there is no sure way of verifying that these fasteners have been properly tightened.
If you’ve ever tightened up something just finger tight on your car engine and then forgotten about it; you probably have experienced the bolt or nut loosen up fairly quickly when the car was started. Since there is no opposing force to cause the nut or bolt to remain tightened, it is easy for it to become loose. However, a properly tightened bolt or nut won’t come loose, even after many hours of operation.
The way that nuts and bolts work is that when tightened they put pressure, called “clamping force,” on the items they are holding together. As those items are more massive than the hardware holding them together, they push back, actually stretching the bolt microscopically. It is this stretching which prevents the bolt from coming loose. The stretching is like stretching a spring, allowing the bolt head and the nut to maintain pressure on the sides of whatever they are holding.
There is a strong element of friction involved in fastener holding power. The friction between the head of the bolt or the side of the nut and the object they are holding, prevent the bolt head or nut from turning. As long as there is enough clamping force to maintain that friction, they won’t budge.
While tightening fasteners to the proper torque is the way that we ensure that there is enough clamping force, this clamping force can change due to the type of finish on the fasteners and whether or not the fasteners have been previously used. The threads of a nut and bolt pair which has been tightened and loosened a number of times (without rusting) become somewhat polished by the pressure. This will increase the amount of clamping force applied each time, if tightened to the same torque.
Nevertheless, the torque values which are used for nuts and bolts take into account the type of material used in the fastener, the hardness of that material and any surface coating. Engineers use pre-calculated tables, which take all of those factors into account, when specifying the proper torque to be used.
Most torque wrenches today are “click type” wrenches, meaning that they make an audible click when the fastener is tightened to a pre-determined torque. The torque desired can be set electronically, with a mechanical digital readout or with a vernier, depending upon the design of the torque wrench. Generally speaking, the electronic ones are considered the best, as they are the easiest to set and work with. Vernier calipers require knowing how to work with a vernier.
Torque wrenches which have a dial or needle and gauge aren’t really torque wrenches, but rather torque meters. While it is possible to use them to tighten a fastener to the right torque value, it is extremely hard to do so accurately.
Torque is measured in foot-pounds or inch-pounds. Conversion from foot-pounds to inch-pounds is simple; all you have to do is multiply the foot-pounds by 12. One foot pound is one pound of pressure applied over a lever, where the force is applied one foot form the fulcrum or rotational point. So, if you have two torque wrenches, one that is one foot long and the other that is two feet long, and apply the same amount of pressure, the actual torque would be different. That one pound of force would become two ft-lbs of torque with the two foot long torque wrench.
When selecting a torque wrench, it is important to verify that he tool will cover the entire torque range that you will be setting. A torque wrench that has a maximum torque value of 120 ft-lbs. won’t do you a bit of good, if you have to torque a nut to 150 ft-lbs. Having all torque ranges you need may require having more than one torque wrench, although it is possible to get one torque wrench which will cover all needed torque values for working on a car engine.
Best Torque Wrench Overall:
Torque wrenches are used in a variety of situations where the tightness of fasteners is critical to the operation or safety of the equipment. By accurately measuring the amount of force used to tighten the bolt or nut it is possible to ensure that it is properly installed in such a way that the spring action of the steel or iron beneath the bolts head will prevent it from backing out.
It is this spring tension, which is referred to as clamping force, that makes any bolt work. Without it, a bolt will eventually vibrate loose. Since we cant directly measure the clamping force being applied, we instead measure the amount of force being used to tighten the bolt, as a certain amount of tightening will produce a certain amount of clamping force. The torque wrench allows us to make this measurement.
Most torque wrenches are accurate to within 3% of the value set. That makes the torque wrench itself more accurate than the clamping force that is being applied. The torque wrench only measures the amount of force applied to tighten the bolt, it cant measure the friction, lubrication or any of the other factors which affect the clamping force.
Torque is expressed in foot-pounds (ft/lb) or inch-pounds (in/lb) of force. Twelve inch-pounds of torque is equal to one foot-pound. There is also a metric torque value, which is measured in newton-meters. Most torque wrenches sold in the United States use a foot-pound scale, although they will have a newton-meters conversion on them as well.
The major differences between a low-cost torque wrench and a high cost one are quality and durability, as well as operator comfort. There is very little difference in the accuracy of one torque wrench over another.
Many torque wrenches today are digital, replacing the older torque wrenches which were set with a vernier scale. While the digital ones arent any more accurate than the others, they are much easier to use and set. This is an advantage, especially for those who dont use them often.
No torque wrench should ever be used to loosen a bolt or nut. While most have a ratcheting head and appear to be like a large ratchet, it is very easy to damage one when using it in reverse to loosen a nut or bolt. When done using the torque wrench, it should be set back to zero so that the spring mechanism inside it doesnt become permanently stretched, ruining the accuracy of the torque wrench.
As a company that specializes in torque wrenches, CDI Torque makes some of the best around. This digital model is extremely easy to use, with a 15 degree flex head and 27 inches of overall length. Read Full Review
GearWrench, the company who has impressed us all with their ratcheting box-end wrenches has expanded their product line into many other tools. This digital torque wrench is high quality and easy to work with. The three LED system lets you know when you're getting close to the right torque and even when you go over. Read Full Review
Snap-on's reputation for quality makes them a clear choice for this list. This digital torque wrench allows adjustment in 0.1 ft/lb torque increments for those times when you need extreme accuracy. Read Full Review
A split-beam wrench, like this one from Precision Instruments has some real advantages. Not only is it easy to set, but doesn't have to be returned to zero between uses. Read Full Review
The ratcheting click type TW-6 torque wrench by Park tool is the best overall torque wrench for one simple factor quality. It has all the benefits of a higher end torque wrench for a much lower price. Read Full Review
Best Budget Torque Wrench:
Choosing a torque wrench can be tricky, as the mechanism which makes it work is hidden from view. Not only that, but because it is hidden from view, the finish on the critical parts doesnt give one great confidence in the workmanship.
Since you cannot see the mechanism, you must go by external references; most specifically, the smoothness of the micrometer adjustment mechanism. I say that because I dont believe in using needle type torque wrenches. Why? Because the needle type torque wrenches are much too hard to read, and way too easy to misread; especially when you are trying to put 80 pounds or so of torque on them. For the few dollars more, you can have a click type micrometer torque wrench that will be much more accurate, and much easier to read.
Another important point to keep in mind is that, unless you are planning on buying more than one torque wrench, its a waste of time to buy a 3/8 drive torque wrench. A 1/2 drive torque wrench will allow you to work on a much greater range of torques.
Two things you need to know about micrometer torque wrenches. First of all, dont use as a big ratchet, in order to loosen bolts. Even though they typically come with a reversible ratchet head; this is an almost guaranteed way to break the torque mechanism. Secondly, release the tension on the torque mechanism before storing it, so it doesnt lose calibration. You do this, by returning the torque to zero.
For the purpose of this list, Ive defined budget torque wrenches as being tools that are available for less than $100.
While I have rated these wrenches from #1 to #5, I will have to say that the difference between numbers 3 to 5 is minimal.
The torque range on this tool is very impressive, allowing you to set torques up to 250 foot-pounds. With that type of torque range, it's no wonder that it has a 25 inch long handle. Read Full Review
Craftsman's reputation for quality shows on this torque wrench. It's the only budget priced torque wrench I've seen that has a rubberized handle. I like that for the better grip it gives you, especially when your hands are greasy. Read Full Review
K-Tool is another brand you'll commonly find at auto parts stores. While there's nothing particularly outstanding about them, they provide years of service to the do-it-yourselfer. Read Full Review
Sunex brags of plus or minus 3% accuracy on this tool. That's better than anyone else's. That tells me that they have a lot of confidence in their quality. Read Full Review
MIT or Tekton provides their torque wrench in a kit, complete with a 5-inch extension and a 1/2-inch to 3/8-inch adapter. That's the only budget torque wrench that does. All the others only have the wrench. Read Full Review