torque wrench vs impact wrench

travis.diller

travis.diller

Adventurist
All too often I see people using a impact wrench tightening down lug nuts. This is a very easy way to break or at least weaken your wheel studs. You should ALWAYS use a torque wrench. You can even break them by hand. The FSM for my Tacoma specifies 85ft lbs on lugs. It is possible to turn them a lot more than that but the Toyota gods say 85. As a rule of thumb I only use my impact wrench to loosen stubborn nuts and bolts. You can use it to turn things up until it stops free spinning, when it makes its first "impact" it means its time to get out the torque wrench. It seems humorous to me that the gods have torque specs for everything, but they do. I have a fairly inexpensive torque wrench ($90) they are not cheap and you get what you pay for. I got the half inch drive so I can always step down. There are three types, dial indicator (used for precise measurement, I use them on submarines, we don't want anything breaking down there.), mechanical indicator (dumbed down not very accurate) and snap type(set the desired torque and turn til it snaps) this is the type I have. So do yourself and your truck a favor and invest in one! Also, no lateral extensions allowed (cheater bars, pipes) you can only extend straight down from the drive portion without using one of these equations to correct your torque.
http://www.motorcraftservice.com/ren...la_main_en.asp
Good luck and happy wrenching!
 
Good post Travis. I learned long ago the importance of properly torquing fasteners. I now use three click-type wrenches: one for lbs/in, one for lbs/ft up to 75, and one for lbs/ft to 250. All of the wrenches require a calibration certification when doing professional work. I haven't used an impact wrench in years, destroyed too many fasteners too quickly.

-Andy
 
I like to use an impact gun on oil pan drain plugs. Run'm on full power! I hate little drips of oil in my drive way. A technician at Valvoline quick change showed me how:)
 
Al Swope said:
I like to use an impact gun on oil pan drain plugs. Run'm on full power! I hate little drips of oil in my drive way. A technician at Valvoline quick change showed me how:)
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weird, see at jiffy lube they just don't put the differential fill plug back in, then you don't have to worry about the whole breather thing.
 
Al Swope said:
I like to use an impact gun on oil pan drain plugs. Run'm on full power! I hate little drips of oil in my drive way. A technician at Valvoline quick change showed me how:)
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You must have been the one to teach my nephew that trick. He dispatched an oil pan on his XJ and then the trans pan on his grandmother's Subaru.:eek:

-Andy
 
travis.diller said:
I don't think he is being sarcastic. :lightbulb
I like to crossthread lugnuts, it holds them on really well.
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Cross-threaded is tighter than Lock-tite.

I do not use a torque wrench on lug nuts. I use the tool that I'm going to use to remove the lug nuts while in the field should that need to happen. That way I know that the tool used to put them on will also remove them. All of my lug studs get a thin slathering of anti-seize so that rust in the threads is not a problem. Been doing it this way for nearly two decades and it works for me.
 
ntsqd said:
Cross-threaded is tighter than Lock-tite.

I do not use a torque wrench on lug nuts. I use the tool that I'm going to use to remove the lug nuts while in the field should that need to happen. That way I know that the tool used to put them on will also remove them. All of my lug studs get a thin slathering of anti-seize so that rust in the threads is not a problem. Been doing it this way for nearly two decades and it works for me.
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85-90 ft/lbs is easily removed with a standard lug wrench or even a 1/2" drive ratchet. Ditto on the anti-seize, only need to do it once.

-Andy
 
I was taught years ago to not use antiseize on lug bolts. So I don't. I use the impact to loosen the lug nuts during tire rotation (every 5000 miles) I do use MY impact gun, with my air compressor set at 90 psi to tighten the lugs initially (after carefully starting them by hand). Set on "2" my impact puts down a whopping 70 ft/lbs on a lug nut. Then I go around with the torque wrench and finish.
 
We aren't allowed to use antiseize on submarine work because it its actually corrosive over time. I just use the red sticky grease works fine by not letting any rust grow.
 
travis.diller said:
We aren't allowed to use antiseize on submarine work because it its actually corrosive over time. I just use the red sticky grease works fine by not letting any rust grow.
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Luckily you don't have to change the tires that often.
Seriously, that's a change over the Ustafish. Anti-sieze had its (legitimate) places there/then.
 
Great post, Travis. I agree, once threaded fasteners pass their tensile strength from over tightening they break down and become weaker. Also stretched/rolled threads are hard to loosen when needs be.
 
Grumps said:
85-90 ft/lbs is easily removed with a standard lug wrench or even a 1/2" drive ratchet. Ditto on the anti-seize, only need to do it once.

-Andy
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The point is that they went on with the tool that I'll need to take them off in the field. I get the value of torquing critical fasteners, it's not like I don't torque con-rod bolts and head bolts but I don't have to remove those nearly as often and I've never had to remove them in the field. Lug nuts I do on occasion have to remove in the field and more than once I've had lug nuts that were torqued on that I couldn't remove with the tool that rides in the vehicle. Fortunately those instances were not in the field. So, I know that they went on with the tool that I have and I know that the threads have not corroded together since they went on. That gives me the confidence to know that I can get them off if I have to.

If you really want to get into torquing in depth you need to know not just the torque value, but also what the thread condition is supposed to be for that torque value. Dry bare steel, dry plated steel, lubed with wax, lubed with anti-sieze, lubed with 30wt oil, rusty, or what? Lube is not lube, each will cause a different loading in the fastener with the same applied torque. If the torque value is near the yield point of the fastener then you really, really need to know what the thread conditions are supposed to be for the supplied torque value. By using anti-seize on the threads (a little does go a very long ways) I wouldn't use the OE torque spec even if I were inclined to torque the nuts. Doing so would yield the studs from excessive tension and cause them to fail.

Some people insist on pre-failing new lug studs by pulling them in with a nut on their threads. I see the appeal, don't do it. Drive them in with a hammer or a press, don't pull them in.

If the anti-seize being used is corrosive to the hardware its the wrong anti-seize. Which I find hard to believe, that its corrosive to the hardware. What I do think the problem is that some exotic and semi-exotic hardware have very specific anti-seize requirements. Use the wrong stuff and you create a very, very big problem. Safer to just not allow that failure mode.
 
ntsqd said:
If you really want to get into torquing in depth you need to know not just the torque value, but also what the thread condition is supposed to be for that torque value. Dry bare steel, dry plated steel, lubed with wax, lubed with anti-sieze, lubed with 30wt oil, rusty, or what? Lube is not lube, each will cause a different loading in the fastener with the same applied torque. If the torque value is near the yield point of the fastener then you really, really need to know what the thread conditions are supposed to be for the supplied torque value. By using anti-seize on the threads (a little does go a very long ways) I wouldn't use the OE torque spec even if I were inclined to torque the nuts. Doing so would yield the studs from excessive tension and cause them to fail.

e.
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There are special lubricants that aren't corrosive. It is simular to anti seize but not as corrosive. I don't recall the brand name but it's out there. We also looked at and used it on the face. Not only the face of the nut but the mating face on the part.
Torque wrenches aren't that expensive or big that they can't be carried out in the field. What I do is change out to the spare and torque the lugs at the next convenient spot, (usually at home)
 
DesertFront said:
There are special lubricants that aren't corrosive. It is simular to anti seize but not as corrosive. I don't recall the brand name but it's out there. We also looked at and used it on the face. Not only the face of the nut but the mating face on the part.
Torque wrenches aren't that expensive or big that they can't be carried out in the field. What I do is change out to the spare and torque the lugs at the next convenient spot, (usually at home)
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Molykote has several types of antiseize
 
DesertFront said:
There are special lubricants that aren't corrosive. It is simular to anti seize but not as corrosive. I don't recall the brand name but it's out there. We also looked at and used it on the face. Not only the face of the nut but the mating face on the part.
Torque wrenches aren't that expensive or big that they can't be carried out in the field. What I do is change out to the spare and torque the lugs at the next convenient spot, (usually at home)
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Not that it isn't so, but I've never, ever (prior to this thread) heard of anti-seize being corrosive. Its intended purpose is exactly contrary to that. Use the wrong type on something even semi-exotic and yeah, I can see problems. Like nickel based on SST, that would be bad (I use lead or silver based).

Its 3:12AM, you're on the side of the road somewhere between San Iggy and Vinzcaino on Mex Hwy 1 and it can't quite make up its mind whether to rain on your tire changing or not. Or its 5:09PM on the 405 in the Sepulveda Pass on a Thursday. In neither case am I going torque those lug nuts even if I happen to have a torque wrench with me. I'm going to curl my pinky finger under the finger next to it and pull on the lug wrench to the same amount of pain for each nut and call it good enough. And if that will get me home - which it has been doing for the last 25+ years, why is it not good enough to just leave that way?

There's being prudent and cautious, and then there's being realistic. Next time you're in a company mandated Safety Meeting ask yourself how much of the former and how much of the latter is being presented to you. Knowing that the tool that tightened the lug nuts is in the truck and can get them loose is realistic to me. Carrying a torque wrench for the lug nuts is not.
 
travis.diller said:
We aren't allowed to use antiseize on submarine work because it its actually corrosive over time. I just use the red sticky grease works fine by not letting any rust grow.
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They use Molykote P-37 Antiseize Paste on Hull Gland nuts all the time on Subs.


There are different types of Antiseize for different types of material. The problem with using Antiseize on lug nuts is that it CAN cause an increase in axial load. Since antiseize reduces the friction between the bolt and nut, when you torque your lug nut down it can actually increase the torque than the OEM design. In some areas, you can actually find where they have recommended a reduction in the torque value to lesson the chance of axial load. Personally, I don't believe this is neccessarily in a vehicle that is not designed on exact tollerances. I think the benefit of using anti seize on lug nut studs outweigh any concerns of problems it may cause. I do think it is a good idea to apply the anti seize very sparingly to the lug studs, and to try to not get any anti seize on the contact point between the end of the lug & where it seats in the rim lug recesses.
 
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