How to use a torque wrench correctly

Are you worried about overtightening or undertightening bolts and nuts, causing damage? Don't let guesswork dictate the correct tightening force! A torque wrench is the ideal tool to help you precisely control the tightening torque. With an automatic shut-off mechanism when the set torque level is reached, a torque wrench helps you avoid overtightening or undertightening, which is extremely useful when repairing cars or machinery.

Adjusting and using a torque wrench is very simple, and in this article, Tiptory will guide you step-by-step from setting up and using to maintaining a professional torque wrench. Keep reading to become a "perfect" repairman with a torque wrench!

Things to know when using a torque wrench

1. Loosen the locking knob at the end of the torque wrench.

2. Rotate the handle so that the top edge of the handle aligns with the nearest torque mark on the wrench.

3. Rotate the adjustment knob on top to select the desired torque value, aligning it with the vertical mark on the wrench. Add the number on the knob to the number on the wrench body to determine the total torque.

4. Use a torque wrench to tighten the nut or bolt until you hear a "click" or feel the wrench stop moving.

Part 1: A beginner's guide on how to properly adjust a torque wrench.

Step 1: Loosen the locking knob at the end of the handle.

• Look for the metal or plastic locking knob at the end of the torque wrench handle—it's usually a different color for easy identification.

• Turn the locking knob counterclockwise by hand to loosen it.

• There's no need to disassemble the knob; just loosen it until the handle rotates smoothly.

Step 2: Identify the torque markings on the wrench.

• Look above the handle to see the horizontal lines on the wrench body — usually spaced 10 or 20 force units (foot-pound or kg·m).

• The knob at the end of the handle has smaller vertical markings, increasing in increments of 1 unit of force.

Note:

• "Foot-pound" (lb·ft) and "kilogram-meter" (kg·m) are units of measurement for tightening force – indicating the force applied over a distance.
  For example: 1 lb·ft = 1 pound of force applied over a distance of 1 foot.

• Wrenches usually have both units marked on them. If they are on the same mark, the smaller number is the foot-pound, and the larger number is the kilogram-meter.

Step 3: Adjust the handle to the nearest torque setting.

• Hold the wrench handle with your non-dominant hand to keep it stable.

• Use your dominant hand to turn the handle:

  • Rotate clockwise to increase tightening torque.

  • Turn counterclockwise to reduce torque.

• Stop when the top edge of the handle aligns with the nearest horizontal line indicating the force you need.

For example:
If a tightening torque of 145 lb·ft (20 kg·m) is required, rotate the handle until it aligns with the 140 lb·ft (19 kg·m) mark.

Note:

• Some wrenches have handles that slide up and down instead of rotating.

• If using an electronic torque wrench, simply press the increase/decrease buttons on the screen.

• Each type of wrench has a different adjustment method — please refer to the instruction manual that comes with it.

• Check your car or bicycle owner's manual for the exact torque required — there is no one-size-fits-all method.

Step 4: Turn the knob on the handle to adjust precisely.

• Once you've turned the handle close to the desired torque level, look at the numbers on the knob at the end of the handle .

• Turn the knob clockwise to increase the force , or counterclockwise to decrease the force .

• Stop when the number on the dial aligns with the vertical mark on the wrench handle.

For example:
You need a torque of 145 lb·ft (20 kg·m), and the handle is set to 140 lb·ft. At this point, simply turn the knob to 5 lb·ft .

Note:

• On some types of wrenches, this knob operates independently of the handle; you can turn it directly without turning the entire handle.

Step 5: Add the two values ​​to determine the total tightening torque.

• After adjusting the handle and knob, add the two numbers :

  • The numbers on the wrench body (the position of the handle is currently aligned)

  • The numbers on the rotary knob (aligned with the vertical line)

For example:
If the handle aligns with the 140 lb·ft mark and the dial shows 5 lb·ft , the total tightening torque is 145 lb·ft (equivalent to 20 kg·m).

Step 6: Tighten the locking knob to secure the torque level.

• Hold the wrench handle with your non-dominant hand to avoid misaligning the setting.

• Using your dominant hand , turn the lock knob clockwise until it is fully tightened.

Once the knob is tightened, the tightening torque cannot be changed until you loosen the knob again.

Part 2: How to safely use a torque wrench to tighten nuts/bolts

Step 1: Attach the socket to the torque wrench.

• Choose a socket that matches the size of the nut or bolt you need to tighten.

• Insert the socket into the wrench head until you hear a " click "—this indicates a secure fit.

• If the tightening location is difficult to reach, you can attach a socket extender before attaching the socket head.

Note:
Torque wrenches come in various sizes — measure the square end of the wrench to select the correct socket size.

Step 2: Tighten the nuts or bolts by hand before using a torque wrench.

• Insert the screw or bolt into the correct position on the thread.

• Turn it clockwise by hand until it can't be turned any further.

Warning:
Don't use a torque wrench right from the start.
Because torque wrenches are very powerful, if the threads aren't properly engaged, you can damage them immediately.

Step 3: Place the socket head of the wrench onto the nut or bolt.

• Hold the wrench handle with your non-dominant hand.

• Use your dominant hand to insert the socket into the correct position on the screw or bolt .

• Make sure the socket fits snugly , without being loose or rotating freely.

Note:
If the socket head rotates but doesn't grip the screw, you need to switch to a smaller socket head .

Step 4: Tighten the nuts or bolts with a torque wrench.

• Turn the handle clockwise to begin tightening.

• Most torque wrenches have a self-returning function, so you don't need to remove them after each turn — just return the handle to its original position (counterclockwise) to continue tightening.

• If the wrench cannot be turned in the opposite direction , remove the socket head and put it back in place.

Note:

• If you hear a "click" or "snap" sound when returning the handle, it means your wrench has an automatic return function.

• Torque wrenches are only for tightening , not loosening.

Step 5: Stop tightening when the wrench makes a "click" sound or stops rotating.

• When the wrench starts making a "clicking" sound or feels harder to turn , it means you've reached the correct torque.

• If you hear a "click" sound when turning it counterclockwise , that's normal.

• Never tighten further after hearing a "click" or feeling resistance, as this may damage the screw, bolt, or wrench.

Part 3: How to maintain torque wrenches to ensure long-lasting accuracy

Step 1: Reset the wrench to zero after use.

• After tightening, turn the adjustment knob on the handle to the 0 position .

• This helps protect the accuracy and lifespan of the wrench , preventing calibration deviations from prolonged storage.

Step 2: Note the importance of cleaning nuts and bolts before tightening.

• Before tightening, wipe away any rust or dirt from the nuts and bolts with a cloth or rag.

• If the rust is stubborn, use a wire brush to scrub it off.

• Rust and dirt can reduce the grip of the socket head, damaging the torque wrench over time.

• Do not lubricate the torque wrench, but you can spray WD-40 or a degreaser on the nuts and bolts to clean them before attaching the wrench.

Step 3: Torque wrench maintenance: Periodic calibration

• Torque wrenches should be calibrated at least once a year or after approximately 5,000 "clicks" (tightening cycles).

• You can calibrate it yourself if you have experience, but it's best to have a mechanic or professional do it.

• Calibration costs typically range from $25 to $75 .

• Without proper calibration, wrenches can inaccurately measure torque, leading to damage or safety hazards.

• If you work continuously every day, 5,000 clicks might be reached after 8-10 months. If you use it less frequently, a year is a reasonable time for calibration.

Author: Audra Fordin .