Incompetent Mechanics and Impact Wrenches

I'm not holier than thou, 4cylindrfury, and I'm not the best wrench I've ever met. But I'm not a hammer mechanic either. I don't go slamming things down with impact wrenches, especially after cross threading it, and I get tired of coming along behind incompetent fools who do.

One of the things I am, is an engineer. And it's that engineering knowledge that explains why a torque stick cannot work. Has to do with the variability of mass and energy and range of motion in the different impact guns.

By all means, if one has a low end shop with low end mechanics, give them a torque stick and hope for the best. It is better than nothing. But if you want to actually limit torque, do it by hand with a torque wrench.

Having a second tech do a torque test with a click wrench just tells you it wasn't under torqued. Doesn't tell you anything about how far over torqued it might be.

Im done having this conversation - when matched to the correct gun, the sticks do work. Plain and simple. They may not be a great match with EVERY gun, so perhaps you may have a case in SOME scenarios. I will agree to disagree.

With regards to the tone of the conversation, you did come across as sounding holier than thou. However, I dont want to regress back to that old "education" thread, so I will just keep my yapper shut.

I like cars, you like cars, whatever. Im over it

foxtrapper wrote: I'm not holier than thou,

Show me someone who says "I know better, because I'm an engineer", and I'll show you someone is acting holier than thou.

There is science and there is anecdotal evidence. I tend to favor science. There are many tools that exist simply to speed up the job, which is a priority for any shop. Speed tends to beget carelessness. And lets face it, any tech that does 399 brake jobs a year might not be quite as careful as you would be while you are working on your own car.

No professional mechanic cares as much about my car (or my wife's car) as I do. Consequently, I do virtually every maintenance and repair myself.

zomby woof wrote:

foxtrapper wrote: I'm not holier than thou,

Show me someone who says "I know better, because I'm an engineer", and I'll show you someone is acting holier than thou.

Come to class with me for a week, I'll show you a million.

Wow... I can tell by reading all of the posts, some of you haven't ever been paid the "flat rate" way. Come back when you know you either get 18 or 24 min of pay for a job that takes 30 mins. It takes all your time to get the vehicle in the air and the wheels off. So by the time you are putting on the wheels, you are working for free. Then its ever a wonder why, when you visit places that operate on flat rate, you get "hounded" for additional services. It's just a poor person trying to pay the bills.

Now, some would say pay them by the hour instead, but I have seen it first hand that when you do that, the worker produces less and is even sloppier/shoddier in their repair practices.

So which would you prefer?

BTW, I always hand started lugs and then used my 3/8 impact to tighten wheels back on most of the time. The 22mm-7/8" and 15/16" lug nuts involved using my 1/2 instead. I also always stopped 2 hits after the lug stopped turning. In using that yardstick, I have taken wheels back off by hand with very little extra effort needed.

Brian

Hell, I use my impact at home.

foxtrapper wrote: One of the things I am, is an engineer. And it's that engineering knowledge that explains why a torque stick cannot work. Has to do with the variability of mass and energy and range of motion in the different impact guns.

A torque stick can work, if used correctly, and have been proven to be consistent. You explain that it "cannot work" based on your knowledge of physics, but it "can" work based on the torsional stiffness of the bar combined with the impact (key word) loading applied.
I'm an injuneer too...but try not to admit it in public.

Vigo wrote: If you want something done 'the way you would do it yourself' (~right?), do it yourself. A much older and truer line than 'dont use impacts in ways i dont like.'

That's not quite correct. It isn't 'don't use impacts in ways I don't like'. Its more like 'don't use impacts incorrectly'. Like every other tool, there is a correct way and an incorrect way to use them. Starting nuts with an impact, gunning them down and letting the gun bang away until the studs cry for mercy, and not properly cross-torquing are incorrect. This forum, by and large, isn't populated with millionaires who treat their cars like glass candy dishes and get peeved when they try to cheap out and have have the guy at King Tire install new rubber on their Porche, and he doesn't follow the express written instructions of Ferdinand Porsche. This is about a guy who needed tires and got screwed by a hamfisted wrench-turner. Most of us don't have the capacity to change our own tires, it is a trade that requires very expensive machinery (that you then have to store) and is beyond the scope of most grassroots mechanics. Those of us scared or burned enough, sure, we'll take the extra time to take the wheels off and put them back on ourselves, leaving the car stranded on jackstands. But most guys expect a certain minimum level of competancy at a garage, and often, it seems, aren't getting it.

Besides, with the average automotive literacy of this country declining at lightning speed, how scary is it that these wrench gorillas are working on peoples' cars who have no idea what the proper way to torque a wheel nut is, let along someone like us who has a clue?

zomby woof wrote:

foxtrapper wrote: I'm not holier than thou,

Show me someone who says "I know better, because I'm an engineer", and I'll show you someone is acting holier than thou.

I don't believe foxtrapper said that. And neither did I, when I mentioned my engineering credentials earlier. We both simply stated, "Here's some knowlede, based on my years of training an experience, that explains why such-and-such" is the case. That's not being holier than thou. That's using our knowledge to help those who might not possess that knowledge.

Look at it this way: we had to cull through years (10, in my case) of college education, scores of books, and countless problems and formulae and experience to provide this information to the community for free. And, of course, you are free to ignore and discard it, or learn from it, as you see fit.

Then get your head out of your butt, and read his posts referring to people who don't believe him as morons, moron shops, and low end mechanics.

All I can say is: I wish I had a nice cordless impact wrench for changing tires efficiently when I get the race car to the track.

As with any tool, it is up to the operator to use it properly.

zomby woof wrote:

Jensenman wrote: Most wheels are around 85 foot pounds, there are some (old Isuzus, for instance) which require 65 foot pounds.

44 lb/ft for Geo Metro

We wuz talking about cars.

Right here is an excellent argument for torque sticks. That way Billy Bob has way less chance of overtorquing lug nuts or bolts.

I'm all for doing it faster. Believe me, the manufacturers screw techs every day with warranty flat rate because some shiny happy person with a green eyeshade told the board 'if we can cut 6 minutes off what we pay for the average warranty repair for this piece of E36 M3 we build then more of you can fly Lears to Washington to beg for tax money bailouts' and I like seeing the little guy come out on top occasionally.

But doing it faster is no excuse for tearing stuff up. So that's why I have the lug nut zero tolerance policy.

foxtrapper wrote: Torque sticks are for moron shops only. They don't work well and are generally forbidden by sanctioning bodies like the FAA and such. Don't know of any reputable shop that uses them.

now you're tarring everyone with a dirty brush when you don't know 99.99% of them... your experiences are what they are... just don't accuse others with out knowledge.... to me that borders on ignorant....

one of the most well thought of shops in my area ALWAYS use torque sticks... then re-torque with torque wrench... (after looking up the proper torque for the vehicle )

that's also the way I change my own at track days and a-x's... so I really hope you're not calling me and all the others that do it this way .. morons.... not very nice on your part

Torque stick only works right with an actual hammer/anvil type of impact wrench. It works because at a certain amount of torque the stick will bend every time the hammer hits, then spring back in between hits. Imagine pushing a car via a spring mounted to the rear bumper. Push consistently and the car moves, smack it with a hammer and the spring absorbs the energy, the hammer bounces off, and the car sits still.

If you use it with a motor-type of wrench or a breaker bar it's just a bendy extension.

I'm only 3/4 of an engineer, and it makes perfect sense to me.

Nah, the fact that you do sloppy work and usually get away with it doesn't make it right, and doesn't preclude someone from observing that it's a poor way to do a job.

What's sloppy? What did i say about being sloppy? See, here's the thing about people who work in repair, and people who dont. People who work in repair know when something works and when it doesnt based on experience. The smart ones start out working straight out of the CYA manual and then gradually parse all the bullE36 M3 and work down to what's about the car and whats about the courts. People who DONT work in repair take whatever method sounds most professional to them, and assume that it is best, and never go out of their way to find out otherwise. I dont think you can look at a guy zipping something down with a impact and say that that is sloppy. There's a very good chance that that guy just fulfilled 100% of the real-world requirements of that task without using a torque wrench. Even if you then put a torque wrench on that fastener and find out its + or - 10%, that STILL doesnt mean you proved his method wrong. ONLY if something actually ceases to function properly and you can PROVE that that margin of variance contributed to a failure can you say that that tech is at fault, and in my experience thats VERY rare.

You may not care if a customers wheel wobbles when it leaves your shop, or if their brakes now pulse because you bent their rotor.

I would care if it ever happened and i knew it was my fault. So far that hasn't happened.

Look im not saying there aren't idiots in the trade who use impacts to completely screw up tasks involving fasteners. But, i dislike seeing the people and the tools lumped together in the same category. You can dislike people being idiots when they use tools. You can dislike using certain tools for certain tasks. But once you insinuate that someone is an idiot or sloppy for a using a certain tool for a certain task, you're crossing into the realm of preaching with an assumed authority that no one else has to recognize.

Im not accusing any one person here of doing that (i might have missed it) but im just saying those kinds of generalizations are not an easy sell and you're likely to annoy anyone who feels like they're on the wrong end of your stereotyping.

Im not defending idiots who do things that immediately result in breakage and irrefutable bad effects. Im saying it's bad to assume that you can extrapolate from those people to say that NOONE should use a certain tool for a certain task.

So basically what im saying is that the torque issue and the crossthreading issue are different, and in either case it wasnt the tool's fault.

Salanis wrote: All I can say is: I wish I had a nice cordless impact wrench for changing tires efficiently when I get the race car to the track.

try this one... it's worked well for me for several yrs

That's not quite correct.

How can you look at what you quoted and say that that is not correct? 'Incorrect' is not the word i would choose for disagreeing with that statement. Disagreement does not equal Incorrect.

It isn't 'don't use impacts in ways I don't like'. Its more like 'don't use impacts incorrectly'. Like every other tool, there is a correct way and an incorrect way to use them.

I dont believe there is a correct and incorrect way to use every tool. I DO believe that there are countless instances of arbitrarily assuming to have the authority to christen things correct or denounce them as incorrect. I dont think you can say with any authority 'dont use an impact to start fasteners or you are automatically wrong'. I DO think you can say 'dont ruin fasteners WHILE starting them with an impact or you are automatically wrong.' < THAT statement doesnt omnisciently assume a perfect correlation between the tool and the result.

wbjones wrote: try this one... it's worked well for me for several yrs

I have this one as well. After some initial pains - it seemed to take a few uses to 'break in' and reach full power - it has proved surprisingly powerful and holds a charge well.

This reminds me of learning to bowl from my Dad. He was a lifetime 195 average bowler--before synthetics, and such. Even has a patch from the ABC for making the 7-10 split in competition. Never rolled a 300 though. Too bad cause he deserved to. Anyway, I never rose to the level he did. One thing he always said regarding skill however (which certainly came from elsewhere) was, "a poor workman blames his tools." I.E., accept responsibility if you screw up or do poorly. Problem is most young guys going into the trade have no training and are left to learn on YOUR vehicle. I've taught at tech, I've done SEARS, independents, and the dealership as a tech. Starting a lug nut (or worse a lug stud--I'm looking at you VW) with a gun is bad practice. Only by hand can you truly know that the lug has started correctly. Using the gun to run 'em down is acceptable. Torquing with a wrench is best practice. Torque sticks do work, but the tech has to have set his gun for the stick. It only takes one unhappy customer to learn---or else you don't care.

As for the left hand vs. righthand thread mistakes--don't be upset if you don't give fair warning to the shop or technician--you are merely contributing to the possible bad outcome.

Enough said. I'm going to bed!

The shop I started in got a GSA contract to build several small 2 wheel trailers. We had one of the trained monkeys installing the wheels on the first one off the shop floor. She used my gun, didn't bother to check (maybe didn't know about) the torque knob and started the nuts by hand (at least she got that right) and ran 'em down with the gun. Then went around the pattern one more time and called it a day. I gave her my 18" breaker bar and had her see if she could break any of the nuts loose. Nope, she couldn't. I doubt I would've been able to. Then I had her use the gun to loosen them all and try again, this time letting the gun hammer only twice. THIS time she could loosen the nuts with the breaker bar, and when she was done, at last she understood that maybe sometime someone would have to change a tire with a hand tool instead of an air wrench.

I don't currently have a decent air system, so any tire work I do is with a 4-way wrench. Maybe it's just as well. Don't have to worry about keeping an air wrench in good repair this way.

unevolved wrote:

zomby woof wrote:

foxtrapper wrote: No one should ever use an impact gun to run nuts down

Nonsense. I do it all the time, and have never ruined a thread.

Wrd. Like most things, it's OK in moderation. I've used one many a time, but only after I've hand-threaded the nuts, and I have the impact turned all the way down. I measured it once with an impact, I think it was about 55-60 lb/ft worth. It's a huge timesaver on cars with extended studs and deep lug mounting faces.

It's not a moderation thing, it's simply when it's ok and when it's not. Not all wheel studs are created equal. Some have a section without threads that will align the nut before it gets to the threads, while other simply are the end of a bolt.

Of the below pictures the first one is perfectly acceptable to use an impact to install lug nuts. And the second, is not. Most tire people (no offense to anyone) just simply don't pay enough attention to even realize there are different style wheel studs.

Most tire people (no offense to anyone) just simply don't pay enough attention to even realize there are different style wheel studs.

I can totally agree with that.

There's a local tire shop near where i grew up in south texas called Flores Tire. Ive been going there for about 10 years, and most of the same guys are still there. Age seems to range from 30-60 with 1 or 2 young guys coming and going and the regulars being the middle aged guys.

Now, there's some undesireable socioeconomic factors here that are keeping 40+ y/o guys changing tires. But, on the other hand, i trust those guys to know how not to break stuff, and i dont even speak the same language as them (yet).

To most people (including the tire-changing business employers!), tire-changing is an entry-level job that you do because you have to and then move on to something that pays better. That's why crappy work is so common. If you paid someone enough that they stayed in the job because they wanted to instead of resenting their position, broken stuff would be less common, but then it would cost more than $2 in labor charges to unbolt a tire from the car.

I think its interesting that noone is complaining about the fact that it doesnt say anywhere that you have to have the tools and ability to change a lug stud to run a tire-changing business.

Walmart may have a great policy concerning the application of lug nuts, but they refused to properly air up a trailer tire for me last year, even after I showed them ON THE SIDEWALL of the tire they had just installed that the max pressure was 60+ psi. They would not put more than 35 psi into the tire. So, I paid, drove to a nearby gas station and filled the tire the rest of the way.