crank bolt tightening debate

"jim beam" > wrote in message
...
> ok, let's try this instead:
>
> http://www.flickr.com/photos/38636024@N00/
>
I still dunno. I've seen galled steel flat washers and bolt heads various
places before (but I don't recall where they have been), so I wouldn't have
thought it was unusual. I would speculate that the torque we need to apply
to break crank bolts loose isn't being directed to the threads but to the
head, where the galled surfaces are responsible for the excessive
break-loose torque. Pure speculation, though.

Usually crank bolts (Honda or otherwise) need to loosen a quarter turn or so
before they come free, and then there is no evidence of the threads
galling - leading me to the speculation of the galled head and washer
surfaces being the key. That would also be consistent with the observation
that the break-loose torque goes up over the years, if engine heat and/or
vibration is important in the development of the galling.

I don't think we have enough to work with to come up with a definitive
answer.

Mike

"Michael Pardee" > wrote
> "jim beam" > wrote in message
> ...
> > ok, let's try this instead:
> >
> > http://www.flickr.com/photos/38636024@N00/
> >
> I still dunno. I've seen galled steel flat washers and bolt heads various
> places before (but I don't recall where they have been), so I wouldn't
have
> thought it was unusual. I would speculate that the torque we need to apply
> to break crank bolts loose isn't being directed to the threads but to the
> head, where the galled surfaces are responsible for

You mean they are a result of?

Galled refers to a surface that has been rubbed by something else.

> the excessive
> break-loose torque. Pure speculation, though.
>
> Usually crank bolts (Honda or otherwise) need to loosen a quarter turn or
so
> before they come free,

Are you sure you're not referring to the roughly quarter turn of typically
1/2-inch drive extension tool windup that occurs?

'Cause that will rotate about 45 degrees at 300 ft-lbs of torque. If more
torque is required to breakloose the bolt, then even more angular deflection
occurs. But it's not the bolt turning.

> and then there is no evidence of the threads
> galling - leading me to the speculation of the galled head and washer
> surfaces being the key.

Are you saying you think the head and washer are adhering, and that's why
the breakloose torque is so high?

> That would also be consistent with the observation
> that the break-loose torque goes up over the years, if engine heat and/or
> vibration is important in the development of the galling.

> I don't think we have enough to work with to come up with a definitive
> answer.

Quite right.

TeGGeR® wrote:
> 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/

thanks dude - appreciate it.

>
>
>
>>>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.

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.

>
>
> 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.

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.

>
>
>
>
>>>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.

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/...her_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.

Michael Pardee wrote:
> "jim beam" > wrote in message
> ...
>
>>ok, let's try this instead:
>>
>>http://www.flickr.com/photos/38636024@N00/
>>
>
> I still dunno. I've seen galled steel flat washers and bolt heads various
> places before (but I don't recall where they have been), so I wouldn't have
> thought it was unusual.

it's not - because bolts move! that's why there's a whole industry
dedicated to the production of locking mechanisms for threaded fastners.
usually, we only care about the ones that loosen because they are more
likely to cause the failures.

> I would speculate that the torque we need to apply
> to break crank bolts loose isn't being directed to the threads but to the
> head, where the galled surfaces are responsible for the excessive
> break-loose torque. Pure speculation, though.
>
> Usually crank bolts (Honda or otherwise) need to loosen a quarter turn or so
> before they come free, and then there is no evidence of the threads
> galling - leading me to the speculation of the galled head and washer
> surfaces being the key.

which is consistent with lash of the pulley wheel!

> That would also be consistent with the observation
> that the break-loose torque goes up over the years, if engine heat and/or
> vibration is important in the development of the galling.

that's part of it, but ultimately, as we can see from the skid marks on
the underside of the washer, the bolt is still free to turn. the
question is, at what torque. once it is turning, that sob is still in
there /way/ tight, and way tighter than when torquing to fastening spec.

>
> I don't think we have enough to work with to come up with a definitive
> answer.

depends if we've spent time doing this kind of work before!

>
> Mike
>
>

"TeGGeR®" > wrote in message ...

> 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.

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.

> 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.

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

"Elle" > wrote in message
.net...
> "Michael Pardee" > wrote
>> I still dunno. I've seen galled steel flat washers and bolt heads various
>> places before (but I don't recall where they have been), so I wouldn't
> have
>> thought it was unusual. I would speculate that the torque we need to
>> apply
>> to break crank bolts loose isn't being directed to the threads but to the
>> head, where the galled surfaces are responsible for
>
> You mean they are a result of?
>
> Galled refers to a surface that has been rubbed by something else.
>
>> the excessive
>> break-loose torque. Pure speculation, though.
>>
No, I'm uncertain if the galling is the result of other movement (either in
torquing or in service) and that the galled surfaces are producing the
excessive break-loose torque. I've dealt with galled threads before, and
crank bolts just don't feel that way - once they back off a bit they always
have been smooth for me. Disclaimer - I've only done a handful of crank
bolts, not dozens or hundreds like pros encounter.

>> Usually crank bolts (Honda or otherwise) need to loosen a quarter turn or
> so
>> before they come free,
>
> Are you sure you're not referring to the roughly quarter turn of typically
> 1/2-inch drive extension tool windup that occurs?
>
I have never used extensions - really! The impact socket rotates an
estimated 1/4 turn before it takes off. I always watch it, trying to will it
to turn ;-) I've never really kept track of how far it rotates to reach
torque specs when tightening.

> 'Cause that will rotate about 45 degrees at 300 ft-lbs of torque. If more
> torque is required to breakloose the bolt, then even more angular
> deflection
> occurs. But it's not the bolt turning.
>
>> and then there is no evidence of the threads
>> galling - leading me to the speculation of the galled head and washer
>> surfaces being the key.
>
> Are you saying you think the head and washer are adhering, and that's why
> the breakloose torque is so high?
>
That's where I'm heading, but I don't really know if that's right. My
opinion is still in freefall on this.

>> That would also be consistent with the observation
>> that the break-loose torque goes up over the years, if engine heat and/or
>> vibration is important in the development of the galling.
>
>> I don't think we have enough to work with to come up with a definitive
>> answer.
>
> Quite right.
>
>

"Michael Pardee" > wrote
> "Elle" > wrote
snip
> No, I'm uncertain if the galling is the result of other movement (either
in
> torquing or in service) and that the galled surfaces are producing the
> excessive break-loose torque. I've dealt with galled threads before, and
> crank bolts just don't feel that way - once they back off a bit they
always
> have been smooth for me.

I suspect this is the consensus, and I think it's a good point to throw in
the mix: Galled bolts are hard to free for a number of turns after the
initial breakloose. This hasn't happened in the maybe three times I've
loosened my 91 Civic's pulley bolt.

> Disclaimer - I've only done a handful of crank
> bolts, not dozens or hundreds like pros encounter.



> >> Usually crank bolts (Honda or otherwise) need to loosen a quarter turn
or
> > so
> >> before they come free,
> >
> > Are you sure you're not referring to the roughly quarter turn of
typically
> > 1/2-inch drive extension tool windup that occurs?
> >
> I have never used extensions - really! The impact socket rotates an
> estimated 1/4 turn before it takes off.

Okay.

And no surprise about the impact wrench you're using. It's a popular method,
by all reports here.


> > Are you saying you think the head and washer are adhering, and that's
why
> > the breakloose torque is so high?
> >
> That's where I'm heading, but I don't really know if that's right. My
> opinion is still in freefall on this.

Okay.

Aside: If the thread's bolts are seized, I remain baffled at why the bolt
head doesn't shear off the way they commonly do on certain suspension bolts.

> == 3 of 5 ==
> Date: Sat 5 Nov 2005 16:42
> From: "Elle"
>
snip
>
> 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 are irrelevant as long as the quantities
are correct.


> 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.
> Frommy reading, "momentum force" is not a commonly accepted way of
> characterizing the forces acting on the pulley under normal car operating
> conditions.


Normal operating conditions or not, a moment of force
is commonly called torque.


> 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.)


Whatever that is, it is beyond me to see any relevancy
to the bolt tightening debate.


> 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.


What would this be good for - the bolt should remain
lose "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.


It's not the greater surface area that "holds fine
threaded applications more tightly together," it is
the smaller lead (the pitch in a simple bolt).
<http://www.efunda.com/designstandards/screws/faste
ners_intro.cfm?search_string=thread>


> 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


Galling is abrasion and fusion caused by friction,
not 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.

"karl" > wrote
> > Date: Sat 5 Nov 2005 16:42
> > From: "Elle"
> >
> snip
> >
> > 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 are irrelevant as long as the quantities
> are correct.

If someone else would like to address this gentleman's comment above and his
other assertions, then please be my guest.

snip for brevity

"Elle" > wrote in message
.net...
> Aside: If the thread's bolts are seized, I remain baffled at why the bolt
> head doesn't shear off the way they commonly do on certain suspension
> bolts.
>
>
That's a good point.

Mike