crank bolt tightening debate

"Matt Ion" > 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.

"Elle" > wrote in message t...
> "jim beam" > 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

"Burt S." > wrote in
m:

> "TeGGeR®" > wrote in message
> ...
>
>> 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/

Matt Ion > 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/

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

"Michael Pardee" > wrote
> What muddies the comparison is that the cars were both old enough to have
> been through at least one timing belt change,

I was figuring they were junked cars, so their age and mileage might have
been quite low. One Honda Civic vintage early 1990s I saw in a junkyard last
year had only 5500 miles or so on it. Pretty well stripped, so I figure it
had been there awhile.

Maybe Jim will give the odometer readings next time.

> 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.)

Sure.

> I'm completely undecided on this debate.

This is a healthy position in which to be, AFAIC.

TeGGeR® wrote:
> Matt Ion > 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.

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.


---
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 0544-8, 11/04/2005
Tested on: 11/6/2005 9:28:49 AM
avast! - copyright (c) 1988-2005 ALWIL Software.
http://www.avast.com

jim beam wrote:
> lower res pics are he
>
> http://www.snapfish.com/thumbnailsha...72/t_=36454773
>

ok, let's try this instead:

http://www.flickr.com/photos/38636024@N00/

jim beam > wrote in
:

> TeGGeR® wrote:

>>
>> 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.


The pics are he
http://www.tegger.com/hondafaq/misc/...m_pulley_pics/


>
>>
>> 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.



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.



>
>>
>> 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!
>
>



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.



--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

Matt Ion > wrote in
news:x3rbf.424095$1i.286090@pd7tw2no:

> TeGGeR® wrote:
>> Matt Ion > 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.
>
> 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.


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.



--
TeGGeR®

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/