Steps for Initial Tightening with an Impact Wrench

To use an impact wrench for tightening bolts or nuts, which applies torque through rapid rotational blows rather than continuous force, you position the socket over the fastener and gently squeeze the trigger, starting with light pressure.

While an impact wrench can rapidly tighten fasteners, it is not a tool designed for applying precise torque. Achieveing a specific torque value typically requires a calibrated torque wrench. Impact wrenches are best used for quickly loosening stubborn fasteners or running them up to a snug fit before final torquing with a different tool.

Steps for Initial Tightening with an Impact Wrench

Using an impact wrench to run a fastener up to a snug position involves a few simple steps:

1. Select the Correct Socket: Choose an impact-rated socket that perfectly fits the nut or bolt head you are working on.
2. Position the Socket: As shown in the reference, position the chosen socket securely over the fastener. Ensure it is fully seated to prevent stripping.
3. Engage the Tool: Make sure the impact wrench is set to the forward (tightening) direction.
4. Gently Squeeze the Trigger: Start with light pressure on the trigger. This allows the tool to begin turning the fastener without immediately applying full impact force. This is especially important when initially engaging threads.
5. Increase Pressure (Gradually): As the fastener starts to turn and resistance builds, you can gradually increase pressure on the trigger. The tool will begin to deliver impacts, rapidly turning the fastener.
6. Stop Before Full Torque: Crucially, stop using the impact wrench once the fastener is snug or reaches a point where it just starts to resist turning further. Do not attempt to use the impact wrench to achieve a specific, final torque value, especially on critical components like wheels, engine parts, or suspension.

Why Impact Wrenches Aren't for Precise Torquing

An impact wrench delivers torque in pulses or impacts. The amount of torque delivered depends on several factors, including:

• Trigger pressure and duration
• Battery charge level (for cordless models)
• Air pressure (for pneumatic models)
• Condition of the tool
• Condition of the fastener and threads
• Speed of the tool

Because these factors are difficult to control precisely, the final torque applied by an impact wrench can vary significantly. This makes it unreliable for applications where a specific torque specification is required for safety or proper function.

How to Achieve Precise Torque After Using an Impact Wrench

For any application requiring a specific torque value (e.g., lug nuts on a car, bolts on an engine component), the correct procedure is:

1. Use the impact wrench to quickly run the fastener up until it is snug.
2. Stop using the impact wrench.
3. Switch to a calibrated torque wrench.
4. Use the torque wrench to tighten the fastener to the exact specified torque value. Follow the correct tightening pattern (e.g., star pattern for wheels) and sequence if applicable.

In summary, while you use an impact wrench by positioning and squeezing the trigger gently at first, it's a tool for speed and power in tightening and loosening, not for achieving precise torque specifications. Always finish critical fasteners with a proper torque wrench.