I'm new to DIY auto mechanic stuff, and I just bought a Hercules 1/2" compact impact wrench (HCB84B2) mainly to get lug nuts off the car. I know you're not supposed to use impact wrenches to put the lug nuts back on, but... The tool advertises having 4 modes, including an "Auto" mode; as described in the manual:

Set Mode:

Push Speed Selection Button to cycle through 4 modes.

I - 0-1000 RPM and 0-1300 IPM

II - 0-1600 RPM and 0-1900 IPM

III - 0-2000 RPM and 0-2800 IPM

Auto - Forward: Tool stops within a few impacts when driving small, self-tapping metal screws.

Auto - Reverse: Tool stops once impacting has stopped.

So my main question is, can I use the Auto (forward) mode to safely get the lug nuts on, and then finish torquing them to proper spec (88 ft. lbs.) with my torque wrench?

I don't quite understand what "stops within a few impacts" means in terms of how torqued the lug nuts will be using that Auto mode. Alternatively, do you think I could safely use the lowest setting to get the lug nuts snug, again finishing with the torque wrench?

I'll take any other tips/advice you might have! I've never taken the wheels off before, and I'm about to do a full brake job. Excited! Thanks

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1 Answer 1


Bottom line is, you can pretty much use your tool the way you want to use it.

The real question is, should you? Basically, no you shouldn't. Even in the Auto-Forward mode, it would be way too easy to over torque the lug nuts. This isn't good for the lugs, nuts, or rim. It's a much better practice to just tighten by hand, then torque them while the wheel is on the ground.

  • 1
    This is the correct answer. Personally, I use an old plastic faucet tool to spin the lug nuts on by hand while in the air, which is simple and fast. You could get the same results using a short extension and socket to spin them on by hand then torque on the ground. Commented Feb 19 at 19:21

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