|
crank bolt tightening debate
this afternoon, i went to my favorite junkyard and bought two crank
bolts. one from an 91 civic, one from a 92 civic. i'm going to post the pics later this evening, but the observations are these: _91_ * eyeball=poppingly hard to shift - had to get a fulcrum and bounce full bodyweight at the end of a 18"x3/4" breaker bar. * no evidence of loctite. * clear fretting damage on the mating surface between the washer & the bolt head. * no evidence of corrosion. [i'm in california] * pulley wheel locked with single woodruff key. _92_ * it was definitely snug, but i could remove with one hand. * bolt thread clearly loctited. * no evidence of fretting. * no evidence of corrosion. * pulley wheel splined /and/ woodruffed. now, we all know what loctite does - it binds threads so they don't move. no movement means no possible further tightening. loctite also means a bolt is hard to remove compared to its fastening torque. conclusions: 1. there is /definitely/ lash in the 91 pulley wheel - something that honda evidently felt needed to be addressed with the addition of a splined interface for the 92. [splines don't eliminate lash, but help mitigate it.] fretting [or lack thereof in the case of the 92] is as clear an evidence of lash as you can get. 2. loctite /prevents/ further tightening of the bolt! hence the 92 was much easier to remove, despite the loctite's binding function. the reduced lash would help in this regard also. time to get out the camera... |
Re: crank bolt tightening debate
jim beam <nospam@example.net> wrote in news:jY2dnf6UQMdVmPHeRVn-
sQ@speakeasy.net: > this afternoon, i went to my favorite junkyard and bought two crank > bolts. one from an 91 civic, one from a 92 civic. i'm going to post > the pics later this evening, but the observations are these: <snip> Jim: Properly tightened, that bolt does NOT allow any sort of movement. It /cannot/, and it /does not/. Period. Full stop. End of story. You may be an electronics whiz, but you are clearly no mechanical engineer. The pulley and the pulley bolt do NOT move in use, and the bolt absolutely does NOT rotate so as to "tighten" after initial torque. If you choose to believe that the bolt tightens more through rotation after initial tightening torque, then you are misleading yourself and everyone who reads your posts. There are many reasons why some crank bolts are difficult to remove. Rotation after initial tightening torque is *NOT* one of them. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: crank bolt tightening debate
"TeGGeR®" <tegger@tegger.c0m> wrote in message news:Xns9704E5085404Etegger@207.14.113.17...
> Jim: Properly tightened, that bolt does NOT allow any sort of movement. It > /cannot/, and it /does not/. Period. Full stop. End of story. > The pulley and the pulley bolt do NOT move in use, and the bolt absolutely > does NOT rotate so as to "tighten" after initial torque. If the bolt doesn't move then locktite would have been recommended, but instead they recommend oil. http://square.cjb.cc/images/oilgood.gif > If you choose to believe that the bolt tightens more through rotation after > initial tightening torque, then you are misleading yourself and everyone > who reads your posts. Not observing the different variety of bolts manufactured is misleading. Patents are create for almost everything, possibly including the tap and die used on self-tightening bolts. > There are many reasons why some crank bolts are difficult to remove. > Rotation after initial tightening torque is *NOT* one of them. Most of these crank bolts show no signs of wear, crystalization, bonding or rust. However there is a slight wear on the face of the bolt which probably suggest that it's moving. |
Re: crank bolt tightening debate
"jim beam" <nospam@example.net> wrote in message news:jY2dnf6UQMdVmPHeRVn-sQ@speakeasy.net...
> this afternoon, i went to my favorite junkyard and bought two crank > bolts. one from an 91 civic, one from a 92 civic. i'm going to post > the pics later this evening, but the observations are these: > _91_ > * eyeball=poppingly hard to shift - had to get a fulcrum and bounce full > bodyweight at the end of a 18"x3/4" breaker bar. > * no evidence of loctite. > * clear fretting damage on the mating surface between the washer & the > bolt head. > * no evidence of corrosion. [i'm in california] > * pulley wheel locked with single woodruff key. > _92_ > * it was definitely snug, but i could remove with one hand. > * bolt thread clearly loctited. > * no evidence of fretting. > * no evidence of corrosion. > * pulley wheel splined /and/ woodruffed. > now, we all know what loctite does - it binds threads so they don't > move. no movement means no possible further tightening. loctite also > means a bolt is hard to remove compared to its fastening torque. > conclusions: > 1. there is /definitely/ lash in the 91 pulley wheel - something that > honda evidently felt needed to be addressed with the addition of a > splined interface for the 92. [splines don't eliminate lash, but help > mitigate it.] fretting [or lack thereof in the case of the 92] is as > clear an evidence of lash as you can get. > 2. loctite /prevents/ further tightening of the bolt! hence the 92 was > much easier to remove, despite the loctite's binding function. the > reduced lash would help in this regard also. > time to get out the camera... As I suspected. I've created a page just to explain my reasoning check it out here. http://square.cjb.cc/bolts.htm |
Re: crank bolt tightening debate
TeGGeR® wrote:
> jim beam <nospam@example.net> wrote in news:jY2dnf6UQMdVmPHeRVn- > sQ@speakeasy.net: > > >>this afternoon, i went to my favorite junkyard and bought two crank >>bolts. one from an 91 civic, one from a 92 civic. i'm going to post >>the pics later this evening, but the observations are these: > > > > <snip> > > > > Jim: Properly tightened, that bolt does NOT allow any sort of movement. It > /cannot/, and it /does not/. Period. Full stop. End of story. i've just emailed you the photo evidence. if you host it, we can all discuss it. > > You may be an electronics whiz, but you are clearly no mechanical engineer. i'm no electronics guy and no engineer. i'm an [ex] metallurgist. and metallurgists spend a big proportion of their time sorting out the screw-ups the engineers make because half of them don't know what they're doing and were asleep in materials 101 or are too egotistical to bother to ask. > > The pulley and the pulley bolt do NOT move in use, and the bolt absolutely > does NOT rotate so as to "tighten" after initial torque. check your email. i've just sent you the galling evidence. it's a perfect textbook example. > > If you choose to believe that the bolt tightens more through rotation after > initial tightening torque, then you are misleading yourself and everyone > who reads your posts. the loctited bolt/splined pulley does not move. the torque-only bolt/woodruff-only pulley does. the galling proves it. > > There are many reasons why some crank bolts are difficult to remove. > Rotation after initial tightening torque is *NOT* one of them. except that we have the photo evidence to prove to the contrary! |
Re: crank bolt tightening debate
Burt S. wrote:
> "jim beam" <nospam@example.net> wrote in message news:jY2dnf6UQMdVmPHeRVn-sQ@speakeasy.net... > > >>this afternoon, i went to my favorite junkyard and bought two crank >>bolts. one from an 91 civic, one from a 92 civic. i'm going to post >>the pics later this evening, but the observations are these: >>_91_ >>* eyeball=poppingly hard to shift - had to get a fulcrum and bounce full >>bodyweight at the end of a 18"x3/4" breaker bar. >>* no evidence of loctite. >>* clear fretting damage on the mating surface between the washer & the >>bolt head. >>* no evidence of corrosion. [i'm in california] >>* pulley wheel locked with single woodruff key. >>_92_ >>* it was definitely snug, but i could remove with one hand. >>* bolt thread clearly loctited. >>* no evidence of fretting. >>* no evidence of corrosion. >>* pulley wheel splined /and/ woodruffed. >>now, we all know what loctite does - it binds threads so they don't >>move. no movement means no possible further tightening. loctite also >>means a bolt is hard to remove compared to its fastening torque. >>conclusions: >>1. there is /definitely/ lash in the 91 pulley wheel - something that >>honda evidently felt needed to be addressed with the addition of a >>splined interface for the 92. [splines don't eliminate lash, but help >>mitigate it.] fretting [or lack thereof in the case of the 92] is as >>clear an evidence of lash as you can get. >>2. loctite /prevents/ further tightening of the bolt! hence the 92 was >>much easier to remove, despite the loctite's binding function. the >>reduced lash would help in this regard also. >>time to get out the camera... > > > As I suspected. I've created a page just to explain my reasoning > check it out here. > > http://square.cjb.cc/bolts.htm that's bunk. you're citing rolled vs. cut threads as evidence of some kind of ratchet mechanism? no. threads are rolled for fatigue resistance - rolling has nothing to do with ratcheting. oh, and yes, i /have/ looked at plenty of bolts under microscopes, thanks. |
Re: crank bolt tightening debate
"jim beam" <nospam@example.net> wrote
> Burt S. wrote: > > "jim beam" <nospam@example.net> wrote > >>this afternoon, i went to my favorite junkyard and bought two crank > >>bolts. one from an 91 civic, one from a 92 civic. i'm going to post > >>the pics later this evening, but the observations are these: > >>_91_ > >>* eyeball=poppingly hard to shift - had to get a fulcrum and bounce full > >>bodyweight at the end of a 18"x3/4" breaker bar. > >>* no evidence of loctite. > >>* clear fretting damage on the mating surface between the washer & the > >>bolt head. > >>* no evidence of corrosion. [i'm in california] > >>* pulley wheel locked with single woodruff key. > >>_92_ > >>* it was definitely snug, but i could remove with one hand. > >>* bolt thread clearly loctited. > >>* no evidence of fretting. > >>* no evidence of corrosion. > >>* pulley wheel splined /and/ woodruffed. > >>now, we all know what loctite does - it binds threads so they don't > >>move. no movement means no possible further tightening. loctite also > >>means a bolt is hard to remove compared to its fastening torque. > >>conclusions: > >>1. there is /definitely/ lash in the 91 pulley wheel - something that > >>honda evidently felt needed to be addressed with the addition of a > >>splined interface for the 92. [splines don't eliminate lash, but help > >>mitigate it.] fretting [or lack thereof in the case of the 92] is as > >>clear an evidence of lash as you can get. > >>2. loctite /prevents/ further tightening of the bolt! hence the 92 was > >>much easier to remove, despite the loctite's binding function. the > >>reduced lash would help in this regard also. > >>time to get out the camera... > > > > > > As I suspected. I've created a page just to explain my reasoning > > check it out here. > > > > http://square.cjb.cc/bolts.htm > > that's bunk. you're citing rolled vs. cut threads as evidence of some > kind of ratchet mechanism? no. I agree with Jim that, upon vibration, the cut of the threads does not tend to tighten the bolt. Your Figure 3, Burt, doesn't show anything different from a coarse thread cut. The threads are helically cut on both coarse and fine thread designs, of course, so back-and-forth vibrating forces will tend to have the same effect on both, absent other forces being at work. So far I think the rest of the site has much to offer. I would suggest 1. Making sure you use the right units for torque. The units for torque in automobile manuals are conventionally given as ft-lbs or newton-meters in manuals. I realize English is not your first language, so maybe something got lost in translation here. 2. From my reading, "momentum force" is not a commonly accepted way of characterizing the forces acting on the pulley under normal car operating conditions. Inertial force is okay, being one way of saying centrifugal forces are what mostly tend to push it off the crankshaft. (Recognizing, for the physics-inclined among us, that whether it's accurate to call the effects of centripetal forces "centrifugal forces" depends on what frame of reference is used. What "centrifugal force" means in practical, hands-on applications is well-understood, so I'm using it.) 3. Your wording is not perfect, but then rarely is mine. I can understand your other points and tend to agree with them. I think it is particularly noteworthy that oil is supposed to be used, /not/ something like Loc-Tite, on the threads. For now, I agree the purpose is to ensure that the bolt and shaft threads can move relative to each other upon commencing operations. 4. I want to look further into your hypothesis about what causes that loud crack when the bolt frees. I think you're right that it may be due to release of a large axial load in the bolt and so is a sonic boom(?). If it is a sonic boom, then that does tend to suggest that the pulley bolt is in fact under very high axial load. It's not, like Tegger has been contending, merely the galling of female and male threads against each other, essentially adhering one to the other. 5. OTOH, I think galling does play a role. One need only consider some of the exhaust bolts that become so hard to remove. Many of them are fine threaded (not sure if they're super-fine, non-standard fine threads or not). Fine threads are used to minimize the likelihood of the bolts vibrating free during operation. The greater surface area contact between male and female threads is what holds fine threaded applications more tightly together than coarse threads. But unlike the pulley bolt, the exhaust bolts don't have a rotating mass attached to them. The exhaust bolts also get very hot, though, and they also vibrate while they're hot. Heat cycling--temperatures being alternately raised and lowered, causing the metal to expand and contract and fill in whatever microscopic gaps there are between male and female thread surfaces--may play a huge role, as I believe SoCalMike, for one, proposed. So the exhaust bolts seize up principally due to galling. (Not sure they're all so terribly exposed to, say, gases of combustion causing corrosion, though. Temperature may cause foreign materials on the bolt to crud up the thread surfaces, OTOH.) The exhaust bolts are all I believe notably smaller in diameter than the pulley bolt. Is the torque required to loosen these exhaust system bolts in some proportion to the pulley bolt torque? I couldn't say with certainty. In sum, right now I personally can't rule out either a highly axially loaded bolt or galling due to massive heat cycling causing that loud "crack" when one frees the pulley bolt. 6. At the bottom of your site, I do not think your explanation of why the loosening torque is often higher than the tightening torque is accurate. I agree with boltscience.com , Tegger, and Scott that the main reason the loosening torque is higher is the difference between the dynamic coefficient of friction and the static coefficient of friction. The static coefficient is higher. > threads are rolled for fatigue > resistance - rolling has nothing to do with ratcheting. oh, and yes, i > /have/ looked at plenty of bolts under microscopes, thanks. Jim, re your current investigation: All you noted is interesting. For me, the fretting on the one car's bolt-washer mating surfaces is particularly so. I would hypothesize that the 92 vehicle hadn't been in operation long with the loc-tited bolt. Also, if it had continued to run for some time, it was at higher risk of the pulley bolt coming undone, since no oil was used to facilitate relative (tightening) motion between female and male threads, leaving the vibrations/pulsing of the pulley against the bolt head to potentially overwhelm the system, vibrate free the bolt, and so knock the pulley free of the crankshaft. I hope you bring "pillows" to the yard when you're jumping up and down on that 1.5 foot breaker bar. ;-) I may take pictures in a few weeks if I free up my Civic's pulley bolt during a tire rotation, and the safety engineers among us can have at it. :-) This remains an interesting academic debate, for bona fide engine enthusiasts (pity the poor soul who comes here lately just wanting to know whether he should change the washer for his oil drain plug at every oil change!). I trust others here are wise enough to keep the boxing gloves off and attend to them. I for one put my web site back up, and it does have some changes reflecting some of the discussion here, FWIW. Elle Still an amateur learning much from those with specialized experience! |
Re: crank bolt tightening debate
Hmmm, not to add to the confusion, but...
I don't know how much relevance this has to crankshaft pulley bolts, but on every table saw or radial-arm saw I've ever used, reverse-threaded nuts are used to hold the blade on the threaded shaft, because the clockwise (looking at the shaft) rotation of the blade would cause a nut with a normal thread to come loose and spin off. And yes, they do tighten up, with very little use. --- avast! Antivirus: Outbound message clean. Virus Database (VPS): 0544-8, 11/04/2005 Tested on: 11/5/2005 10:36:31 AM avast! - copyright (c) 1988-2005 ALWIL Software. http://www.avast.com |
Re: crank bolt tightening debate
|
Re: crank bolt tightening debate
Since the below requires some kind of login, then if you send me the
photo(s), I would be happy to post it as a query topic on the "Queries" page of my site. Email: honda.lioness@earthlink.net "jim beam" <nospam@example.net> wrote > lower res pics are here: > > http://www.snapfish.com/thumbnailsha...72/t_=36454773 > |
Re: crank bolt tightening debate
"Matt Ion" <soundy@moltenimage.com> wrote in message news:ZY6bf.419264$tl2.287104@pd7tw3no...
> Hmmm, not to add to the confusion, but... > I don't know how much relevance this has to crankshaft pulley bolts, but > on every table saw or radial-arm saw I've ever used, reverse-threaded > nuts are used to hold the blade on the threaded shaft, because the > clockwise (looking at the shaft) rotation of the blade would cause a nut > with a normal thread to come loose and spin off. And yes, they do > tighten up, with very little use. Same thing on my angle grinder, my right hand and left hand radial arm saw. The bolt/nut are screwed in the opposite direction of the spinning blade. Even finger tight the bolt/nut will tighten (spin inward) over time. This is caused by (my theory) the force of acelleration of the motor is stronger than the inertial mass of the blade. Another words, the blade wants to sit still. Now, if you look at the face or washer of the bolt you realize that it has a greater surface area contact than on the other side of the blade. The greater surface area (should not be oil or otherwise the bolt won't tighten) is actually moving. However, the threads should be oiled to prevent galling. I believe the same principle is used on the crank pulley. |
Re: crank bolt tightening debate
"Elle" <honda.lioness@nospam.earthlink.net> wrote in message news:bi5bf.5$c_1.4@newsread3.news.pas.earthlink.ne t...
> "jim beam" <nospam@example.net> wrote > > that's bunk. you're citing rolled vs. cut threads as evidence of some > > kind of ratchet mechanism? no. Jim, I don't cite rolled vs. cut threads as evidence of some kind of ratchet mechanism, the images were simply not well drawn. I was citing the mechanisms that cause the bolt to wind inwards caused by they way the bore is tapped and the effects of the pulley. > I agree with Jim that, upon vibration, the cut of the threads does not tend > to tighten the bolt. Your Figure 3, Burt, doesn't show anything different > from a coarse thread cut. The threads are helically cut on both coarse and > fine thread designs, of course, so back-and-forth vibrating forces will tend > to have the same effect on both, absent other forces being at work. > So far I think the rest of the site has much to offer. > I would suggest > 1. > Making sure you use the right units for torque. The units for torque in > automobile manuals are conventionally given as ft-lbs or newton-meters in > manuals. I realize English is not your first language, so maybe something > got lost in translation here. > 2. > From my reading, "momentum force" is not a commonly accepted way of > characterizing the forces acting on the pulley under normal car operating > conditions. Inertial force is okay, being one way of saying centrifugal > forces are what mostly tend to push it off the crankshaft. (Recognizing, for > the physics-inclined among us, that whether it's accurate to call the > effects of centripetal forces "centrifugal forces" depends on what frame of > reference is used. What "centrifugal force" means in practical, hands-on > applications is well-understood, so I'm using it.) > 3. > Your wording is not perfect, but then rarely is mine. I can understand your > other points and tend to agree with them. I think it is particularly > noteworthy that oil is supposed to be used, /not/ something like Loc-Tite, > on the threads. For now, I agree the purpose is to ensure that the bolt and > shaft threads can move relative to each other upon commencing operations. > 4. > I want to look further into your hypothesis about what causes that loud > crack when the bolt frees. I think you're right that it may be due to > release of a large axial load in the bolt and so is a sonic boom(?). If it > is a sonic boom, then that does tend to suggest that the pulley bolt is in > fact under very high axial load. It's not, like Tegger has been contending, > merely the galling of female and male threads against each other, > essentially adhering one to the other. > 5. > OTOH, I think galling does play a role. One need only consider some of the > exhaust bolts that become so hard to remove. Many of them are fine threaded > (not sure if they're super-fine, non-standard fine threads or not). Fine > threads are used to minimize the likelihood of the bolts vibrating free > during operation. The greater surface area contact between male and female > threads is what holds fine threaded applications more tightly together than > coarse threads. But unlike the pulley bolt, the exhaust bolts don't have a > rotating mass attached to them. The exhaust bolts also get very hot, though, > and they also vibrate while they're hot. Heat cycling--temperatures being > alternately raised and lowered, causing the metal to expand and contract and > fill in whatever microscopic gaps there are between male and female thread > surfaces--may play a huge role, as I believe SoCalMike, for one, proposed. > So the exhaust bolts seize up principally due to galling. (Not sure they're > all so terribly exposed to, say, gases of combustion causing corrosion, > though. Temperature may cause foreign materials on the bolt to crud up the > thread surfaces, OTOH.) The exhaust bolts are all I believe notably smaller > in diameter than the pulley bolt. Is the torque required to loosen these > exhaust system bolts in some proportion to the pulley bolt torque? I > couldn't say with certainty. In sum, right now I personally can't rule out > either a highly axially loaded bolt or galling due to massive heat cycling > causing that loud "crack" when one frees the pulley bolt. Galling is possible on the exhaust bolt since they don't require lubricants. Once locked together you will notice the extreme "snap" upon release. O2 sensor are one the parts that can benefit from the anti-seize compound to prevent galling. On some areas on the exhaust system, self locking nuts are used instead. > 6. > At the bottom of your site, I do not think your explanation of why the > loosening torque is often higher than the tightening torque is accurate. I > agree with boltscience.com , Tegger, and Scott that the main reason the > loosening torque is higher is the difference between the dynamic coefficient > of friction and the static coefficient of friction. The static coefficient > is higher. Good work for showing what I should fix. I probably have to add better sketches to visualize a theory and avoid further confusions. Several sections are fixed based on your input and others not pertaining to the crank bolt is eliminated. < snip> -- http://square.cjb.cc/bolts.htm |
Re: crank bolt tightening debate
"Burt S." <BurtSquareman@none.com> wrote in
news:nQ_af.9785$7h7.4308@newssvr21.news.prodigy.co m: > "TeGGeR®" <tegger@tegger.c0m> wrote in message > news:Xns9704E5085404Etegger@207.14.113.17... > >> Jim: Properly tightened, that bolt does NOT allow any sort of >> movement. It /cannot/, and it /does not/. Period. Full stop. End of >> story. The pulley and the pulley bolt do NOT move in use, and the >> bolt absolutely does NOT rotate so as to "tighten" after initial >> torque. > > If the bolt doesn't move then locktite would have been recommended, > but instead they recommend oil. As I said before, the il is a crude friction stabilizer. It is common for high-stress bolt situations to specify friction stabilizers, either as a coating, or as user-applied materials. > > http://square.cjb.cc/images/oilgood.gif > >> If you choose to believe that the bolt tightens more through rotation >> after initial tightening torque, then you are misleading yourself and >> everyone who reads your posts. > > Not observing the different variety of bolts manufactured is > misleading. Patents are create for almost everything, possibly > including the tap and die used on self-tightening bolts. The bolt on your crank pulley is NOT "self tighetening". > >> There are many reasons why some crank bolts are difficult to remove. >> Rotation after initial tightening torque is *NOT* one of them. > > Most of these crank bolts show no signs of wear, crystalization, > bonding or rust. However there is a slight wear on the face of the > bolt which probably suggest that it's moving. > > Whatever the cause of the face wear (the face isn't oiled, remember), it isn't moving. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: crank bolt tightening debate
Matt Ion <soundy@moltenimage.com> wrote in
news:ZY6bf.419264$tl2.287104@pd7tw3no: > Hmmm, not to add to the confusion, but... > > I don't know how much relevance this has to crankshaft pulley bolts, but > on every table saw or radial-arm saw I've ever used, reverse-threaded > nuts are used to hold the blade on the threaded shaft, because the > clockwise (looking at the shaft) rotation of the blade would cause a nut > with a normal thread to come loose and spin off. And yes, they do > tighten up, with very little use. Totally different application. Honda is just about the only manufacturer whose bolts run in a tightening direction. Everybody else has bolts that run in a LOOSENING direction, and these DO NOT COME LOOSE IN USE. Everybody elses' bolts are the same as Honda's, and are torqued to similar tensions. -- TeGGeR® The Unofficial Honda/Acura FAQ www.tegger.com/hondafaq/ |
Re: crank bolt tightening debate
What muddies the comparison is that the cars were both old enough to have
been through at least one timing belt change, so we don't know how diligent the mechanics were about retightening to the spec'd torque. It could be that the one who loctited the bolt also wimped out on the torque, relying on the loctite to hold the bolt. (Not good practice, but it happens.) I'm completely undecided on this debate. Mike |
| All times are GMT -4. The time now is 02:13 AM. |
© 2024 MH Sub I, LLC dba Internet Brands