Does anyone know of real data to show air ratchets can be calibrated close enough to be within tolerances to a given setting for lug nuts? I have on several occasions walked out of tire shops that insist that their air-driven lug wrenches are calibrated. I have cast aluminum wheels which I believe are susceptible to over-torquing damage. I now deal only with a garage that hand torques. I can?t believe that air wrenches that are repeatedly dropped around the shop could ever remain in calibration, even if they once were.
Most Of These Shops Use “Torque Sticks” On Their Impact Wrenches. That Come In Differnt Ft. Lb. Measures. These Are Supposed To Be Quite Accurate.
Here’s A Link.
Thanks CSA, this helps. While I’ve seen some garages use these, I never undestood the principal behind their design. Also, I’ve noticed that not every garage uses them. Need to be more vigilant.
Redundance is a pet peeve of mine but so is the missplaced dependence on those stix. Some people seem well suited to doing mechanical repairs. It seems one of my few talents is repairing things mechanical. Neither myself nor any of my long time employees use the styx that have been put away for years. We don’t have a problem with broken studs or cracked wheels or wheels falling off and the vast majority of work done here is on fleets and regular, long time customers. Nascar uses impacts wrenches to change the tires and immediately launch to drive in excess of 150mph. And the difference in Nascar lug studs and OE studs is the tapered tip to speed up getting the nut threaded.
First, a few basics…
All tools, including torque wrenches, impact guns, and torque sticks can “go out of calibration” or tolerance by use-- even careful use.
Second, fasteners, like nuts and bolts, work on “tension” between the nut and the bolt (or wheel stud) causing the threads on each to strech, causing tension between each to create a “tight fit” There are some fasteners, like cylinder head bolts, that can be used only once because once the threads have “streched” they cannot be used again safely and reliabily.
Wheel studs and lug nuts are inteded to be re-used, but with care. Most shops use impact guns to remove wheel lug nuts and bolts due to the fact that they are often “siezed” due to corrosion, mis-installation by a previous technician, or wear. For expedience, some shops use impact wrenches to install the fasteners as well.
So, what’s the best practice?
Make sure the wheel studs and lug nuts are clean, coated with a light coat of “anti-seize” compound, and can be fitted to each other with litte or no “seizure” by hand installation. Then, according to OEM wheel tightening patterns, tighten the lug nuts or bolts equally around the wheel pattern. Check torque with a torque wrench. Road test. Check again. New fasteners and old fasteners will always have different characteristics when tightened and loosened over time. If you notice any “sticking” or “seizing” replace the suspect stud or nut immediately.
If you’re worried about wheel damage, etc. Do it yourself.
In close to 40 years in the biz never once did the “air tool calibration man” ever show up. I can see issues with mistakes dealing with the air pressure input to the tool, the variable setting at the tool, wear on the tool and socket selection affecting the tools output.
That being said not one manager or Foreman ever came down on me for using an air tool to tighten a wheel, torque stick or not, now leaving a wheel loose guaranteeded a visit from management.
I took it upon myself to hand torque alloy wheels, with steel the torque stick and a gun with the proper “feel” worked out well. Don’t like my hand torquing, well you can always fire me.
This has been a pet peeve of mine for years. I always insist on hand torqueing, and have had to ask them to do it again properly numerous times. They are mostly in a hurry, and after the “click” will give it another pull/push or two, I guess to insure against under torqueing. The personnel tire installers) at tire shops are not mechanics, and probably not trained adequately.