Changing Tire

[75thRanger]

Had to change a tire on my truck ( F250) yesterday and used my Kobalt 24V Impact Wrench for the first time. What a difference! Makes me wonder why I didn't buy one long ago. The farm roads around here are tough on tires.

I wasn't on a public road so no problems there but I have done it on an Interstate before and that was a very unpleasant experience. The impact makes it a much faster job.

It also requires Impact Grade sockets (they're black) . The standard sockets will not tolerate the torque it generates. Kobalt says it has break loose torque of 650. I know I just had to touch the trigger to break loose my lug nuts. I torque them at 155. I could see myself on a NASCAR pit crew.

I had to experiment a bit to get the right tightening torque. It will easily over torque but it's not difficult to get it right. I checked with my torque bar and then loosened again to determined how long to hold the impact trigger after the nut had been run up to wheel.

[Brian B-P]

Originally Posted by 75thRanger

I had to experiment a bit to get the right tightening torque. It will easily over torque but it's not difficult to get it right. I checked with my torque bar and then loosened again to determined how long to hold the impact trigger after the nut had been run up to wheel.

That's not likely to be a very accurately reproducible torque application method. Even with a perfectly consistent "extra running time", the torque will depend on the internal tool speed, which will vary with battery voltage. It's somewhat comparable to turning the air adjustment on a air-powered impact wrench, which doesn't work well enough for critical fasteners. I suppose that leaves the question of how critical wheel nut torque is...

A better and easier method is to use a torque-limiting impact extension bar (or "torque stick"), which is designed to flex with the impacts and effectively limit the applied torque; when the nut stops turning, it's done. They are sold in sets, each bar calibrated for a different torque. I use an inexpensive set from Princess Auto... and I usually still complete torquing manually.

[Centex]

Yep, my first cordless impact wrench was an instant 'spoiler' (why did I put this off for so long??). It's always in the truck with me, even in the workshop I love being free-of-the-hose ... my compressor is getting a lot less use lol.

But I'm still olde skool on the installation-end of projects ... it's 'stop short with the impact' and strictly the manual torque-wrench for me.

[Iowa Dave]

I have a two torque setting Milwaukee 18 volt. I put it on the slow light torque and run the nuts on. As sit as they seat, I stop. Then I get out the torque wrench them from there in a star pattern. But I sure do like the break-free take off power. I’ve changed a number of trailer hitch balls and taken apart some long frozen nuts with ease. I have a good set of older Craftsman impact sockets (deep well) and a new set of Sunex metrics that work fine too. I only needed the 21’MM but got the whole set,1/2inch, for under $50. From Acme Tools on line.
Iowa Dave

[75thRanger]

I did the tighten, loosen drill 5 or 6 times and was too tight each time. I backed off the nut with my torque bar about 1/4 turn and tighten back the same 1/4 and the torque 'clicked' in. So I'm so close I don't think it matters.

I've read that over torque will have some negative affect on the brakes. I haven't the foggiest why.

Hopefully this will be a seldom used tool so I'll forget what I did anyway.

[Brian B-P]

Originally Posted by 75thRanger

I've read that over torque will have some negative affect on the brakes. I haven't the foggiest why.

The drum can be warped, especially by uneven excessive torque. I would be more concerned about stud damage (I had one wheel stud on a car cracked by an idiot with an air impact at an alignment shop), and simply making the nuts difficult to get off later.