Can I use an impact to torque nuts and bolts?

A buddy swears I can. I told him it should always be a torque wrench. I know with lug nuts that's the case because uneven torque warps rotors. But what about stuff like pan hard bars or upper struts mounts or suspension pieces? Could I torque them Down with the impact and then follow up with a real torque wrench?

I wouldn't. How do you control the torque of the impact wrench?

And while we are on the subject- learn me torque wrenches. I've bought the Autozone $29.99 "durrrr"-a-last special the last three times I've needed one. They all work fine for about a year (and I store them zero'd). My latest one crapped out so bad it would click at no pressure. And in the higher settings, it was a consistent 10lbs low.

Learn me: torque wrenches<100$.

The Tekton torque wrenches from Amazon seem to be pretty good. I've got a few that are holding up fine. And one guy tested one he bought against a Snap-On and it was just as accurate.

As far as torquing things with an impact, I rarely do it. Only if it's a big bolt where the impact will get it tight enough but is in no danger of breaking it.

I have had great luck with the Harbor Freight ones. Checked them against much more expensive ones now and then and they were fine I have one that is probably 15 years old and never had an issue.

Does craftsman lifetime warranty them?

You stand a very high risk of either overtorquing or undertorquing nuts and bolts using an impact wrench. I've seen three cars lose a wheel on track and every one of them had the lugs tightened with an impact. I discussed that with the mechanic each time and they defended the use of an impact. My reaction is -- clearly something was done wrong! One car lost a wheel twice, sidelining the car for a long time the second time. Some people never learn!

On the torque wrench, a harbor freight one tends to be just as accurate as a snap on. But the snap on is a more pleasant experience. None of them guarantee long term calibration that I know of - it's an instrument that's supposed to be calibrated annually but that costs more than just replacing the harbor freight ones.

Trackmouse wrote: A buddy swears I can. I told him it should always be a torque wrench. I know with lug nuts that's the case because uneven torque warps rotors.

I've never seen that happen in real life.

Wheel torque is critical for a variety of reasons but rotor warping isn't one of them.

I use a torque wrench on my race car wheels and have never lost one!

I rarely use one on my street car, I have an impact wrench I have had for years and can judge the torque I am applying. I have never had a wheel come loose on the street.

I have 2 Impact Torque bars (made by Matco Tools) I used to use at the dealership for lug nuts because managment insisted on torque control. The bars are ~6" long and have the socket built-in with a ground down "extension" area that acts as a spring.

I'd just like to chime in, I've been through 3 of the quarter inch drive inch pound torque wrenches from harbor freight. No click, no noise, no pressure changes, no noticeable difference in torque application at all. If you need inch pounds, get one a little nicer.

Trackmouse wrote: Does craftsman lifetime warranty them?

It depends on the type: the beam-type torque wrenches have a lifetime warranty, the click-type have a one year warranty, at least that's what my local Sears told me when I tried to warranty my broken click-type torque wrench (it was more than a year old).

If you want to use your impact wrench for torquing nuts and bolts you can get torque-limiting extensions, like these:

HF link

These are what most tire stores use I think.

Knurled wrote:

Trackmouse wrote: A buddy swears I can. I told him it should always be a torque wrench. I know with lug nuts that's the case because uneven torque warps rotors.

I've never seen that happen in real life. Wheel torque is critical for a variety of reasons but rotor warping isn't one of them.

I used to have a 2000 Oldsmobile Alero. Within 6 months of having tires rotated by a shop, I'd have pulsing in the brakes and there would be run out in the rotors. After I sold the car I stumbled on a forum (never imagined there would be an Alero forum) and it turns out many people had the same issue.

Yeah, the "torque sticks" give a certain level of confidence in the torque on the lug nut. It's not as precise as a proper torque wrench, but it's better than nothing.

There's nothing on a car that I would be happy torquing with the impact wrench alone.

For things like lug nuts, you can definitely use a torque stick. But use one that limits to around 50% of the torque spec and then finish it with a torque wrench.

The world would be a better place if you needed a difficult to obtain license, one difficult enough even most professional mechanics don't bother with it, to own an impact gun the will run clockwise.

If you're careful you can do it, only on big bolts, hand starting everything to prevent cross threading and stopping at the first hammer so the fastener is nowhere near fully torqued and can be properly finished off with a torque wrench (or even a well calibrated arm), but that kills a lot of the "advantage" to using the impact in the first place. A drill with a socket adapter would work just as well for assembly if you're doing it right.

Also, you would think the following is really obvious but some people (including those who work in tire shops) don't get it. If you run a bolt/nut on with an impact and the torque wrench doesn't move it afterwards, the fastener is over torqued.

To put it simply, yes you can use it. But there are reasons that the factory specifies a certain torque value for every fastener on a car and you simply will never know what it is without a torque wrench.

Some might be able to use an impact to get closer than others to the proper value, and some fasteners are more critical than others, but if you want to ensure that it is properly torqued, you simply have to use a correctly working torque wrench.

The amount of time it takes to torque a set of lugs relative to the potential amount of time and cost of a failed or mis-torqued fastener reminds me of the old saying, "an ounce of prevention is worth a pound of cure."

At home and the track, impacts take lugs off in mere seconds, zap hand-started lugs until just snug and a torque wrench quickly wraps up the job.

The impact wrench can't measure the torque being applied, so they are best used to tighten fasteners that just need to be tight. Adjustable ones can be turned down so you can finish torquing a fastener that needs a specific measurement.

"Can I use an impact to torque nuts and bolts?"

That's your inner voice saying no.

Whoa. I Never would use an impact on lug nuts. I KNOW rotors warp when you get the torque Values off. Explain to me how they wouldn't???

In reply to Trackmouse:

To accomplish that, you'd have to bend the hub and the wheel. At that point, you'd likely start breaking things.

Rotors tend to warp due to incorrectly bedded pads and that can be exacerbated if the rotor is not straight to begin with, so ensuring the mounting surfaces are clean.

bentwrench wrote: I have never had a wheel come loose on the street.

Funny enough, none of the people I talked to had lost a wheel on track, until they did. An impact is a short cut. You don't need to take short cuts, especially ones that risk your vehicle and safety.

In reply to Trackmouse:

Ok but if you're not comfortable with it on lug nuts because the torque would be wrong and cause problems, then realize it would do the same on other bolts and nuts.

I wonder if there I a different between hub centric versus lug centric. And if one is more susceptible to rotor warping

atm92484 wrote:

Knurled wrote:

Trackmouse wrote: A buddy swears I can. I told him it should always be a torque wrench. I know with lug nuts that's the case because uneven torque warps rotors.

I've never seen that happen in real life. Wheel torque is critical for a variety of reasons but rotor warping isn't one of them.

I used to have a 2000 Oldsmobile Alero. Within 6 months of having tires rotated by a shop, I'd have pulsing in the brakes and there would be run out in the rotors. After I sold the car I stumbled on a forum (never imagined there would be an Alero forum) and it turns out many people had the same issue.

You just proved it for me. If irregular torquing was warping the rotor, the pulsation would be apparent as soon as you got the car back.

More possibly, the rotors were coming loose with the wheels off, debris/rust settled to the bottom, when wheels got reinstalled the debris caused a small amount of runout to occur. A small amount of runout with a flat rotor is not noticable since the pads and calipers can track the rotor. However, over time, when driving with the brakes NOT applied, the pads graze the high spots down, so you get two slightly thinner spots 180 degrees out. THAT will cause a brake pulsation.

Or, more likely, that happens all the time on N-bodies because the rotors rust easily from poor pad composition. GM was still in the mindset of using small brakes with grippy pads, and the brakes regularly get hot enough to go into heavy pad-transfer mode, and the transferred material flakes off and causes hellacious pulsation.

I'm betting the latter, given that you would be able to go more than 6 months between tire rotations (a 4000-6000mi service, max, on a front-driver) so the car either saw a lot of brake-heavy city driving or simply sat a lot, allowing the brakes to rust.