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#101
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WHAT A BOLT IS, AND HOW IT WORKS
TeGGeR® wrote:
> "Elle" > wrote in > .net: > > >> "TeGGeR®" > wrote >> >>> Each wheel has, of course, 4 nuts. Each lug nut was tightened by >>> me to 75 ft lbs back in the summer. Well, I just measured the >>> torque necessary to break them loose just now, in two pound >>> increments on the click-wrench. >>> >>> Guess what? Each one required about 90 lbs to crack free. >> >> For the archives, I think it's important to note that the torque >> wrenches accessible to the ordinary consumer are not supposed to be >> used to measure loosening torque. > > > > > It's not supposed to be used to measure loosening torque because of > the possibility of overloading the mechanism. 90 ft lbs is well > within my wrench's maximum of 150 lbs. > > I started at 75, and worked my way up in 2 lb increments. > > There is no harm done to a torque wrench used in such a manner. > > > --------------------- > > An update to yesterday: I picked up a nail in one tire two weeks ago. > I brought it to a tire place to get the puncture repaired, and > watched while the tire guy used a torque wrench to tighten the lug > nuts. I noticed /all/ the tire guys were using torque wrenches as a > matter of course. of course. not only is it specified by the manufacturer, but more importantly, their liability insurance /requires/ they use torque wrenches. i used to date an accident/injury attorney, and she used to /nail/ poor sob's who couldn't prove they'd used such practices. > > By the pressure he appeared to be applying, I'd /guess/ the force > used was on the order of 100 lbs before the wrench clicked. I did not > ask to see what the setting was. > > When I tried to undo the nust on that particular wheel yesterday, I > reached 100 lbs with the torque wrench, with no apparent movement > visible at the nuts. I then laid aside the torque wrench, for fear of > the very damage you mention. > > I enmded up having to STAND on an extended wrench, and bounce up and > down on it! I weigh 180 lbs, so I must have been applying removal > torque of over 200 lbs before nuts came loose. right side or left side? > > I'm wondering if removal torque increases exponentially compared to > tightening torque once you get closer to maximum tension. > with respect, that's straw clutching. go to a parking lot where there are some big rigs and look at their wheel lugs. see any where there are red rust marks around the nut, particularly ones where the red has streaked radially outwards? that's fretting at the interface, and fretting is movement. if there's movement, there's precession [in lateral loading] and it will either loosen or tighten, depending on the sense of rotation relative to the thread. you think your car lugs were tight? try a nice red-rusted big rig lug nut some time. why don't left side car lugs loosen? because they have a tapered interface, and as you know, tapers impart significantly higher friction. this will prevent rotation if torqued sufficiently. which brings us neatly back to accident/injury attorneys and liability insurance... |
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#102
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WHAT A BOLT IS, AND HOW IT WORKS
"Elle" > wrote in
.net: > "TeGGeR®" > wrote >> "Elle" > wrote >> > "TeGGeR®" > wrote >> >> Each wheel has, of course, 4 nuts. Each lug nut was tightened by >> >> me to 75 ft lbs back in the summer. Well, I just measured the >> >> torque necessary to break them loose just now, in two pound >> >> increments on the click-wrench. >> >> >> >> Guess what? Each one required about 90 lbs to crack free. >> > >> > For the archives, I think it's important to note that the torque >> > wrenches accessible to the ordinary consumer are not supposed to be >> > used to measure loosening torque. >> >> >> >> It's not supposed to be used to measure loosening torque because of >> the possibility of overloading the mechanism. > >> 90 ft lbs is well within my >> wrench's maximum of 150 lbs. >> >> I started at 75, and worked my way up in 2 lb increments. >> >> There is no harm done to a torque wrench used in such a manner. > > I don't agree. Using a torque wrench as you describe puts a lot more > wear and tear on it for each assessment of a bolt's loosening torque > (as opposed to the one-time application of tightening torque). The > wrench "allows" only so many clicks before calibration becomes a > concern. > > Without good calibration, the torque wrench is useless. And how often am I going to do this? Every week? I did this with 16 wheel nuts on one occasion. There is absolutely nothing wrong with using the wrench as I did. Remember that torque wrenches are meant to be used on an hourly basis. Garages use the same wrench every few minutes. What they refer to in the warning is that some people try to use torque wrenches as breaker bars, since they are long and provide lots of leverage. In use, the wrench's maximum torque can thereby get drastically exceeded. <snip> > > The thread mating surfaces are closer together at higher axial loads. > So static (as opposed to dynamic) friction effects should prevail > increasingly more the closer one gets to the maximum allowable axial > load in the bolt. In addition, surface conditions can vary a lot due > to wear, how lubricant was applied, temperature, even the manner in > which the bolt was tightened. The variability of surface conditions > from one tightening to the next should increase the unpredictability > of loosening torque at higher axial loads. > > By contrast, at lower loads, the thread mating surfaces are farther > apart, There is no gap between mating threads when the bolt is tight, no matter how much/little tension is present. When the bolt's threads ride up the incline, the threads are squeezed together with more pressure as tension on the bolt's shank increases, but the the threads can not get any /closer/ together. "Embedment" after final tightening torque DOES occur, and results in a reduction in bolt tension (not the same as torque!) of about 5-10%. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#103
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WHAT A BOLT IS, AND HOW IT WORKS
"TeGGeR®" > wrote in message ... > scott > wrote in > : > >> Remember >> that loud click as the bolt came loose? That was it.(Experienced it, >> Paid for it. $40 to recalibrate wrench.) > > > Yeah, but all my bolts came loose slowly. At 88 lbs, the wrench clicked. > At > 90 lbs, they turned, slowly, easing their tension gradually. No snaps, > crackles or pops, no sudden-ness anywhere. Most torque wrenches are designed to measure dynamic torque accurately, not static. Is yours different? |
#104
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WHAT A BOLT IS, AND HOW IT WORKS
"TeGGeR®" > wrote
> "Elle" > wrote > > "TeGGeR®" > wrote > >> "Elle" > wrote > >> > "TeGGeR®" > wrote > >> >> Each wheel has, of course, 4 nuts. Each lug nut was tightened by > >> >> me to 75 ft lbs back in the summer. Well, I just measured the > >> >> torque necessary to break them loose just now, in two pound > >> >> increments on the click-wrench. > >> >> > >> >> Guess what? Each one required about 90 lbs to crack free. > >> > > >> > For the archives, I think it's important to note that the torque > >> > wrenches accessible to the ordinary consumer are not supposed to be > >> > used to measure loosening torque. > >> > >> > >> > >> It's not supposed to be used to measure loosening torque because of > >> the possibility of overloading the mechanism. > > > >> 90 ft lbs is well within my > >> wrench's maximum of 150 lbs. > >> > >> I started at 75, and worked my way up in 2 lb increments. > >> > >> There is no harm done to a torque wrench used in such a manner. > > > > I don't agree. Using a torque wrench as you describe puts a lot more > > wear and tear on it for each assessment of a bolt's loosening torque > > (as opposed to the one-time application of tightening torque). The > > wrench "allows" only so many clicks before calibration becomes a > > concern. > > > > Without good calibration, the torque wrench is useless. > > > > And how often am I going to do this? Every week? I did this with 16 wheel > nuts on one occasion. > > There is absolutely nothing wrong with using the wrench as I did. Wow. You do dig in. I am happy to agree to disagree. > Remember > that torque wrenches are meant to be used on an hourly basis. Garages use > the same wrench every few minutes. I am confident that garage torque wrenches tend to be far more out of calibration than the average home DIYer. If you think differently, whatever. The number of clicks counts. > What they refer to in the warning is that some people try to use torque > wrenches as breaker bars, since they are long and provide lots of leverage. > In use, the wrench's maximum torque can thereby get drastically exceeded. > > > <snip> > > > > > > > > The thread mating surfaces are closer together at higher axial loads. > > So static (as opposed to dynamic) friction effects should prevail > > increasingly more the closer one gets to the maximum allowable axial > > load in the bolt. In addition, surface conditions can vary a lot due > > to wear, how lubricant was applied, temperature, even the manner in > > which the bolt was tightened. The variability of surface conditions > > from one tightening to the next should increase the unpredictability > > of loosening torque at higher axial loads. > > > > By contrast, at lower loads, the thread mating surfaces are farther > > apart, > > > > There is no gap between mating threads when the bolt is tight, no matter > how much/little tension is present. The bolt threads and female side threads are perfect, eh. We disagree. > When the bolt's threads ride up the incline, the threads are squeezed > together with more pressure as tension on the bolt's shank increases, but > the the threads can not get any /closer/ together. It's not so black and white, like an "on/off" situation. But you believe what you want. I gave you a theory that supports your idea. Throw it out. I don't care. |
#105
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WHAT A BOLT IS, AND HOW IT WORKS
"Elle" > wrote in
.net: > > The number of clicks counts. There is only one click. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#106
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WHAT A BOLT IS, AND HOW IT WORKS
"TeGGeR®" > wrote
> "Elle" > wrote > > The number of clicks counts. > > > There is only one click. The torque wrench has only about so many clicks in its life before its calibration becomes too far off to be useful. Your measurement of breakloose torque requires several clicks per measurement. |
#107
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WHAT A BOLT IS, AND HOW IT WORKS
"Elle" > wrote in
.net: > "TeGGeR®" > wrote >> "Elle" > wrote >> > The number of clicks counts. >> >> >> There is only one click. > > The torque wrench has only about so many clicks in its life before its > calibration becomes too far off to be useful. > > Your measurement of breakloose torque requires several clicks per > measurement. > > > There is only ONE click. You've never actually used a click-type torque wrench. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#108
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WHAT A BOLT IS, AND HOW IT WORKS
"TeGGeR®" > wrote
> "Elle" > wrote > > "TeGGeR®" > wrote > >> "Elle" > wrote > >> > The number of clicks counts. > >> > >> > >> There is only one click. > > > > The torque wrench has only about so many clicks in its life before its > > calibration becomes too far off to be useful. > > > > Your measurement of breakloose torque requires several clicks per > > measurement. > > > > > > > > There is only ONE click. You proceeded in 2 ft-lb increments. Are you saying you don't let it click after each increment. > You've never actually used a click-type torque wrench. Right. And I lie about my 91 Civic averaging 40+ mpg. And I lied about Grade 8 bolts being available at popular hardware stores. And what I said (with others) about clogged PCV valves reducing fuel mileage is a lie, too. All these things you said were lies, and you were shown wrong. Torque wrenches do not stay calibrated forever. One crude measure of when one requires calibration is how many clicks it's seen. |
#109
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WHAT A BOLT IS, AND HOW IT WORKS
"Elle" > wrote in
.net: > "TeGGeR®" > wrote >> "Elle" > wrote >> > "TeGGeR®" > wrote >> >> "Elle" > wrote >> >> > The number of clicks counts. >> >> >> >> >> >> There is only one click. >> > >> > The torque wrench has only about so many clicks in its life before >> > its calibration becomes too far off to be useful. >> > >> > Your measurement of breakloose torque requires several clicks per >> > measurement. >> > >> > >> > >> >> There is only ONE click. > > You proceeded in 2 ft-lb increments. Are you saying you don't let it > click after each increment. Of course I did. Tht's the only way I knew it passed that figure without breaking loose. After the click, you can keep turning if you like, and the wrnch will apply torque to the bolt, but that would be pretty stupid. > >> You've never actually used a click-type torque wrench. > > Right. <snip> Well, have you? -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
#110
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WHAT A BOLT IS, AND HOW IT WORKS
Elle wrote:
> "TeGGeR®" > wrote > >>"Elle" > wrote >> >>>"TeGGeR®" > wrote >>> >>>>"Elle" > wrote >>>> >>>>>The number of clicks counts. >>>> >>>> >>>>There is only one click. >>> >>>The torque wrench has only about so many clicks in its life before its >>>calibration becomes too far off to be useful. >>> >>>Your measurement of breakloose torque requires several clicks per >>>measurement. >>> >>> >>> >> >>There is only ONE click. > > > You proceeded in 2 ft-lb increments. Are you saying you don't let it click > after each increment. > > >>You've never actually used a click-type torque wrench. > > > Right. And I lie about my 91 Civic averaging 40+ mpg. And I lied about Grade > 8 bolts being available at popular hardware stores. And what I said (with > others) about clogged PCV valves reducing fuel mileage is a lie, too. > > All these things you said were lies, and you were shown wrong. come on kids, play nice or don't play at all. > > Torque wrenches do not stay calibrated forever. One crude measure of when > one requires calibration is how many clicks it's seen. actually, it's not that crude. clicking torque wrenches that get regularly used in factory assembly work get recalibrated based on usage. |
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