How do I choose and use a motorcycle torque wrench?

In motorcycle mechanics, there are two schools of thought: those who tighten with a blue vein and those who use a torque wrench. Clearly, one method is better than the other. Whether it's a brake caliper, a wheel axle or even a simple drain plug, precise torque is recommended. So, the torque wrench: gadget or essential tool? How do you choose and use it? Our team answers these questions:

Is the whole torque thing just a big hoax? A vain attempt by the tool lobby to sell its products? Nonsense! In fact, anyone who has ever screwed up a thread suddenly realizes the importance of proper torque.

A nut that isn't sufficiently tightened will unscrew with vibration. In the best case, you lose a piece of fairing. In the worst case, a wheel. Excessive torque? The risks are many. The main one is to damage a thread. But you can also bend a stud or pinch a gasket. Brake caliper bolts, drain plugs, wheel axle nuts - there's no shortage of parts on your bike requiring precise tightening.

But what is torque, anyway?

It's simply a force (in Newton) multiplied by a lever arm (in meters). This value is therefore expressed in N.m ( Newton.meter). You can also find a second unit: the metre-kilogram-force. The conversion rule is simple: 1 mkg = 9.81 Nm. And unless you're tinkering with your bike during a spacewalk on the moon, this correspondence is still valid.

In life, we're confronted with decisive decisions that will have an impact on the rest of our lives. Carapuce, Salamèche or Bulbizarre? The same applies to the choice of torque wrench: there are three types.

Direct-reading torque wrench

The low-tech par excellence. When you turn the wrench, a dial tells you the torque you're at. It's purely mechanical. No batteries, no frills, it's simple, affordable and effective. The only hitch? It 's not always possible to keep your eyes on the dial during operation. This can lead to unwelcome gymnastics and inaccurate readings.

Electronic torque wrench

Also known as the digital torque wrench, this is the digital evolution of the previous model. Again, it's a direct reading in the sense that the torque value is displayed on a screen. Except that everything is electronic: sensor, display, setting, etc...

How does it work? You set the torque setpoint using buttons, then force it until it beeps. The undeniable advantage over the mechanical version is that you don't have to look at the dial.

Trigger torque wrench

Probably the most widely used torque wrench. The desired torque is set by turning the handle up or down according to a scale on the handle. Then, once the set point has been reached, a click is heard. You hear it, and feel it in your hand. Robust, with no batteries or fuss, this model is as reliable as it is durable.

Our selection :

----> JMP 3/8" 20 - 110 Nm torque wrench

----> EXPERT torque wrench 1/2" 20-100 Nm

----> FACOM torque wrench 1/2'' 20-100 Nm

Now that the introductions have been made, it's time to choose the key that will accompany you during your carnal moments with your bike. Here are the criteria for your choice:

Key type

Direct-reading, electronic or trigger-operated: it's a matter of taste and feeling. Purists will prefer mechanical models, while aficionados of fine-tuning will opt for a digital model.

Operating range

This is THE decisive criterion. Torque wrenches are designed for a certain range of torques, from 10 to 50 N.m. for example. Okay, so what? It's important to know what you need. Generally speaking, on a motorcycle, you'll be tightening nuts between 10 and 100 N.m. This applies to the basic maintenance of your bike, such as drain plugs, spark plugs, wheel axles, brake caliper nuts, etc...

Be careful, though: when you start getting your hands into the engine, some parts require much greater tightening effort. For example? The flywheel, the clutch bell or even chassis components such as swingarm axles or fork crowns. Torques can reach up to 130-150 N.m. So it's up to you to target your needs.

For general maintenance? From 10 to 90-100 N.m, that's fine. For open motor operations? Then you'll need to go up to 150 N.m.

Tightening precision

Here, the adage "who can do more, can do less" is no longer valid. What does this mean? Well, the greater the operating range, the less precise the wrench will be at low values. For example, a wrench ranging from 10 to 200N.m offers you great versatility, but is only moderately accurate (especially when tightening between 10 and 50N.m). So it's important to remain humble, target your needs and don't necessarily opt for the biggest wrench. And yes, size isn't everything.

Dual threads

Some nuts, studs and screws have reversed threads. They tighten counter-clockwise. This is particularly true of certain rotating parts. So what happens? If your grinding wheel has these left-hand threads, then you need a torque wrench that can work in both directions.

Budget

Here, it's a question of compromise between expected quality, your use, the type of wrench, precision and operating range. We can only recommend that you opt for a quality model, offering the right range of tightening torques you need.

Using a torque wrench isn't rocket science. However, to avoid any blunders that could end up with a thread in the jug, let's take a look at the procedure:

1- Determine the right torque

All you have to do is pore over the sacrosanct Revue Moto Technique to find the right torque. If you don't have the manual for your bike, you'll find that the groups and forums on the Internet are a mine of information on this subject.

2-Setting the setpoint

For direct-reading models, the question doesn't arise. The information is displayed in real time on the mechanical dial. For digital versions, all you have to do is play with the buttons to set the expected torque. And what about trigger keys? It's a little more complicated. In fact, you first need to unlock the safety device at the end of the handle, turn the handle to adjust the set point, and then relock the system in the "locked" position to prevent the wrench from getting out of adjustment when you manipulate it.

3-Re-tighten the nut or screw in question

The torque wrench should be considered as a measuring tool. It should therefore be reserved for the final stage of exact torque setting. What's involved? Start by tightening the component in question, using your good old ratchet wrench.

4-Setting the torque

Make sure the wrench is in the right position: tightening or loosening. Then, using the appropriate fitting, put it in place and apply continuous force. And stop tightening as soon as you hear the signal (electronic beep or mechanical click, depending on the model). What to avoid? Jolts that could distort the measurement.

Tighten a little more, "just in case".

No, no, when you hear the signal, stop. A screwed-up net happens faster than you think. The pleasant 30-minute overhaul turns into a two-hour rescue operation.

Use an extension cord or universal coupling

Any additional element can distort the measurement, so keep the configuration as simple as possible: wrench + adapted socket. "Less is more", as the saying goes.

Using a torque wrench to loosen a stubborn nut

Think of your wrench as a measuring tool. It's precise, calibrated and doesn't like to be hit. Wouldn't you think of using a caliper to tighten a 13" nut? Well, it's all the same. Impact wrench, impact screwdriver, grinder, plasma cutter: there's no shortage of solutions to get rid of a seized bolt.

Treat your torque wrench like a low-grade socket wrench

Like any measuring tool, you need to take good care of it, avoid dropping it or bathing it in drain oil. Incidentally, you should also avoid using it to energetically stimulate the prefrontal cortex of your mechanic's assistant.

Well, I hope we've convinced you of the merits of the holy torque wrench. Much more than a gadget, it's an indispensable tool for ensuring optimum tightening. So, what's your next workshop? Brake caliper rebuild, spark plug check or engine oil change? It's up to you!