crank bolt tightening debate

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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...
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<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.
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If the bolt doesn't move then locktite would have been recommended, but instead they recommend oil.
http://square.cjb.cc/images/oilgood.gif

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.

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.
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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.
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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.
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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.
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TeGGeR® wrote:

The difference is, sawblades are not splined or keyed, so they can turn (and tighten) indefinitely. Splining or keying the pulley WOULD mitigate this effect.
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That's one difference. Also the automotive pulley bolts are to be torqued to such a figuure as to prevent movement. Your saw blade nuts/bolts are just snugged by hand to an unknown torque, and are meant to be repeatedly removed and replaced.
I restate: "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." Nobody can explain why this is, if it's assumed that the pulley and bolt can move relative to the crank.
And even on a Honda, a pulley bolt insufficiently tightened (as little as 20 lbs short of the proper figure), will eventually result in a bolt that *FALLS OUT*. Talk to any mechanic familiar with this subject.
The damned assembly is SOLID in use when properly assembled. Nothing anybody says here will change that fundamental fact.
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Spines can reduce or eliminate movement if the spines channels are tapered. This is noticeable when you will require a gear puller to remove the pulley. But woodruff key aren't and they can produce play, or movements. I once removed a crank bolt (1988 at 180k miles) with a key. The face of the bolt is pretty worn from movements. Unlike a radial-arm saw the inertia from the weight load on the pulley develops in both directions but the bolt has to move in one direction so the woodruff key is used.

What do you mean?... Honda have made motors than spin clockwise and counterclockwise. And the crank bolts are always Lefty Lucey and Righty Tighty.
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snip
snip
Mitigate? Splining precludes rotation!

I agree, everything else is rubbish.
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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.

The bolt on your crank pulley is NOT "self tighetening".

Whatever the cause of the face wear (the face isn't oiled, remember), it isn't moving.
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TeGGeR® wrote:

i've just emailed you the photo evidence. if you host it, we can all discuss it.

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.

check your email. i've just sent you the galling evidence. it's a perfect textbook example.

the loctited bolt/splined pulley does not move. the torque-only bolt/woodruff-only pulley does. the galling proves it.

except that we have the photo evidence to prove to the contrary!
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The pics are here: http://www.tegger.com/hondafaq/misc/jim-beam_pulley_pics /

Unfortunately, the pics aren't really evidence of much other than this: You've taken photos of a pulley from an unknown car with an unknown history given unknown servcicing by persons of unknown competence.
These pics are strongly suggestive of a pulley having been installed at some point with no Woodruff key, or otherwise installed incorrectly. I can assure you a pulley properly installed will not gall that way.

A properly tightened joint dowes not rotate. Your pictures do not prove anythng one way or the other because we do not know the car's history.
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TeGGeR® wrote:

thanks dude - appreciate it.

on the one hand, it's healthy to be skeptical. on the other, i've done enough failure analysis on enough machinery to know what i'm looking at. i can also deduce something of the service history based in what i see.

sorry, but i'm the guy that took it off. and if you can't accept that the pictured galling happened with the key installed, then we have a debate beyond the tech arena. the woodruff key, the pulley wheel and the crank keyway were all in perfectly acceptable condition, although there was evidence of lash - much like the lash evident on the splines of a driveshaft. there was no evidence of the pulley wheel ever having been spun out.

without the woodruff, the pulley would absolutely rotate. the more the bolt was torqued, the more difficult it would be to turn, but saying it won't & can't move is like denial of elasticity.
regarding the 91 vehicle's history, i know that it had been relatively well serviced. it had 220k miles. and that pulley bolt had been removed 3 times. you can't see it from the pic, but the skid mark at 2 o/c on the l/h bolt's washer in this pic:
http://www.tegger.com/hondafaq/misc/jim-beam_pulley_pics/both_washer_u-side.jpg
it has 3 of those skidmarks, coinciding with the keyway, one for each removal. the galling evident on the other side of the washer is not what you would see from 3 removals. not by any stretch.
the 92 bolt otoh, you can see the evidence of one removal [evident from the keyway mark] on the bolt, by me. the bolt side of that washer shows some minor skid evidence, but as you can see, it's not impacted the plating and there's no evidence of galling whatsoever.
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Very well said.
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TeGGeR® wrote:

That is right; anything else is rubbish.
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As I suspected. I've created a page just to explain my reasoning check it out here.
http://square.cjb.cc/bolts.htm
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Burt S. wrote:

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.
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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.

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!
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wrote> > that's bunk. you're citing rolled vs. cut threads as evidence of some

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.

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.

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>
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