to change a Honda Accord 1988 model timing belt

So then your theory revolves completely around heat distortion?

The only way heat could affect torque is if the bolt screwed itself in
further while it heated, and if its receiving hole did not also grow
longer. Simple elongation will not do anything unless that elongated
material can creep around the threads and stay elongated for evermore.

 

Opinion page taken down pending clarification.

 

I have responded to this point more than once already. Bozo did also, and I
agree with what he said. I don't know what words to use to make it anymore
clear.

I took my web site down.

I don't agree with everything on your site or on the (at least) two
technical, homemade sites to which my web site pages link. But I feel no
need to reproduce battles over minor disagreements when all these sites do
far more good than bad.

If you have a better solution to resolve what I think is a trivial conflict
gone out of control, I will hear it out.

 

Women use the F word less?

;-)

It's not a dumb question. My take, FWIW:

Boys as youngsters are encouraged to explore the workings of mechanical,
electrical, and electronic gadgets more than girls. (With some exceptions.)
Girls quickly become accustomed to not showing curiosity, because it's seen
as unfeminine. It doesn't get them attention the way dressing up and finding
the perfect haircut etc. do. And guys feed this to some extent, though I
doubt it's an entirely conscious thing. E.g. girls on the softball field who
are best remembered by some of the men are the bona fide babes, not the
athletes. (Again there are exceptions.)

Hence many of the women who ultimately do want to do much more with
mechanical, electrical, etc. gadgetry start fiddling with--putting their
hands on--such gadgets at a much later age than men.

The consequence of this is females' less intuitive (so to speak)
understanding of mechanical leverage, circuits, etc. They don't "get" things
as quickly as guys do. I speak not just for myself but from educating
college engineering students, both boys and girls. The difference is very
noticeable. I reached the point where I could quickly discern the gals who
flat out could not imagine certain stress concepts and needed more graphic
or hands on examples to help them understand. (Some of the boys would have
problems and need these aids, too, but it tended to be the girls moreso.)
Supporting this is also an observation from a former, elderly colleague of
mine: The guys weren't even as adept as mastering concepts in the 1990s,
because fewer and fewer were working on cars, the farm tractor, around the
house, carpentry, whatever, and instead were spending more of their boyhood
on computers.

I did some fidgeting with gadgets as a young girl. E.g. I built my own radio
using a relative's old Navy radar basic textbook. I got stuck where it said
to install a "cat whisker." (It was an /old/ textbook!) My relative helped
and said a crystal diode would work fine instead. He got one for me. I put
it in. The radio worked! Very cool, but not something I ever advertised as
having done until I was in my 30s, cause it was, ya know, geeky. I still
remember the weird looking old capacitor I used to tune the radio to
different stations. Granted I got only a few stations.

But I never worked on cars as a kid. I did my first oil change at the age of
23. I had a lot of hands on experience in college, turning a lot of
wrenches, for one, due to the nature of the unusual program I was in. But I
was way behind the learning curve when taking that hands on experience and
applying it in the engineering classroom. The way forces work together was
something that was often obvious to certain boys who were poor at
mathematics (unlike myself). I had to read and reread descriptions in
textbooks, and eventually would devise little desktop experiments, where
possible, to prove, reinforce, and then master a concept to the point I
could teach it or publish it in reputable places. (And I mean that
literally.)

So in a nutshell, if the words describing a technical concept aren't dead on
accurate, I will be more likely than a lot of men to scratch my head and
wonder, say, 'Did he mean this? Or could this phrase instead mean that?'

Not to say my technical writing is perfect.

I'm not asking you to buy any of this. It's just my take, based on years as
an engineering educator yada. In no way do I profess to know as much about
auto repairs and maintenance as many of the regulars here.

 

Hah! You should meet some of the women I know!

 

This bolt must be a special micro-thread indented with a "one-way"
design. This "self-torque" design makes sense since we are not allowed
to oil anywhere else except on the threads. The oiling protects the micro-
threads. Here's an image of a bolt.

http://square.cjb.cc/images/bolt.jpg

Do not oil the the bolt's face or the washer otherwise the mechanism will not work.

Which ultimately tightens itself once properly torque. The recommended torque
is required to make the "one way" thread to work. If not torqued correctly the
the mechanism will fail and the pulley will fall out. Otherwise they'd probably
recommend a cotter pin or stake-in lock (found in tie rod, AT clutch, wheel
hub ends, and etc.)

The momentum difference from the alternator, AC etc. and the transmission
will allow the pulley to move back and forth, unless the pulley is torque to 300lb.
The back and forth pulley movements aid the "one way" threads which ultimately
"self-torque" itself under different conditions. The bolt will continue to tighten
(screw in in) probably beyond 300lb until pulley stops sliding back and forth.
How much it tightens differs in various driving styles, transmission shift harshness
or various climates.

If the bolt doesn't tighten itself on a part that has a potential for play then their
is a potential for the bolt to unwind. Either stake it, castlenut/cotter pin it or in
this case use a one-way threaded bolt.

 

I googled using a number of different keywords and turned up only a few (and
I do mean no more than two) posts to Usenet that talk about such a bolt. The
posts were in automotive or motorcycle newsgroups.

I even searched the academic literature. Nothing's turning up.

Do you have a citation, online or offline, to back up your assertions below?
(I don't reject them. I'd like to see a tad more support for them.)

I agree the unusually fine thread pitch (even smaller than the standard fine
thread pitch) combined with the loads on and temperature variations of the
crankshaft, bolt, and pulley must have everything to do with why this bolt
tightens so.

I remain a little troubled at the axial load in the bolt implied by such a
torque. But I suppose if you are correct below, that it's possible that this
microthread design means that a certain torque correlates even less than
usual to axial load.

not work.

T wrote

 

They also produce a variety of versions: Quote:

"The Shimmie has been used in Japan for...Railways, earthquake proofing of
buildings, and in reconditioning of airplanes are just some of the applications."
The Shimeru (Japanese term) is a device that can self- tighten nuts and bolts,
keeping torque in tact. For example, wooden structures often contract as
the wood dries with the passing of time, and gaps appear between the wood,
nuts and bolts. Metal can expand and contract with variations in temperatures,
causing bolts to loosen over time [or in areas] that experience strong vibration
and extreme temperature changes... "

"The SHIMMIE device will tighten automatically when any contraction or
expansion occurs thus the cost of maintenance, is greatly reduced, and
safety and structural integrity are maintained. The SHIMMIE may hold up
to strong vibrations, so damage from earthquakes, hurricanes or high
vibration areas are greatly reduced. The SHIMMIE can be produced in
various sizes, materials and preset torque..." - SPACE COAST
TECHNOLOGY

Read more.

http://its-mart.com/moreinfoshimmie.htm

Other citations:

"...Patented Self-Retaining Nut And Bolt..."

http://www.boltscience.com/pages/references.htm

 

What's here (pictured at http://its-mart.com/HOWTOUSESHIMMIE.HTM ) bears
no resemblance to the pulley bolt.

Furthermore, this device was patented only in the last several years.

Mere mention of a phrase is not a citation.

Where did you first hear the description (or one like it) that you posted
earlier?

Or is it a guess of yours?

 

The company produces a variety of self-locking bolts, some patents extending
further back. Their Japanese partner website is down so as their PDF's.

I am merely citing (quoting) a phrase that may possibly explain the
theory by a reputable site.

I stated my beliefs and explained how it works. No claims made. These are
educated guesses that will eventually require an experiment to unravel the
mystery. I've seen these bolts in mills and laths or AC generators. Sometimes
even finding them on seized (one-way) portable jacks. Like every theory, it
has to be repeatedly be shown in an experiment. Try this experiment with
a new bolt:

Exper 1.) Coat the threads with oil and precisely mark bolt and the pulley.
Torque the bolts to spec. Turn the AC on and give it some harsh transmission
shifts for an undefined time and rpm.

Exper 2.) Coat the face of the bolt and washer with oil and degrease the
threads and precisely mark bolt and the pulley. Torque the bolts to spec.
Turn the AC on and give it some harsh transmission shifts for an undefined
time and rpm.

(Don't just put the bolt under a microscope since the crank bore may have
been specially tapped.)

Explain the results. The bolt should move at least 1/200th of a millimeter on
experiment 1 but not much on experiment 2. Use a flash camera with 3-
megapixels and share your results.

 

interesting...

now if THIS doesnt "muddy the water" i dunno what will

a one way threaded bolt that relies on the pulley moving to tighten
it... whoda thunk it?

 

WHAT A BOLT IS, AND HOW IT WORKS
--------------------------------

1) A bolt's sole function on earth is to serve as a clamp. Its job is to
keep two or more things from moving relative to each other. That's it.
Nothing else.

2) A bolt works /only/ because one thing happens: Its shaft rides up an
incline formed by helical threads, and the shaft thereby gets "axially
loaded" (stretched) in the process.

3) The one-and-only purpose of helical threads is to impart that "axial
loading" (stretching). Axial loading IS what gives the torque (clamping
pressure) necessary to hold the bolt's clamped parts in place, and the only
thing that keeps it from eventually backing off again. And the only way the
bolt can ride up the threads is if it rotates.

To sum up: Rotation + stretch = torque.
If no incline, then no rotation, no stretching, and therefore no torque.

The sentences above are as fundamental to the concept of a bolt (or screw)
as air is to life on earth. It is why the idea of a bolt can exist in the
first place. If the sentences above are /not/ true, then the very concept
of a bolt cannot exist.

If, as some have contended, the bolt stretches/distorts with heat but does
NOT rotate, then it has not ridden up the incline, cannot impart additional
stretch to itself, and thus cannot apply additional torque. In order to
permanently stretch, it would have to skip threads, and jump up to the next
rotation of the helix. I think we all would agree this does not happen.

If the bolt DOES rotate, then this should be readily apparent by placing a
paint mark that crosses the bolt head and the pulley, or the pulley and the
crankshaft. I GUARANTEE to you that bolt will not have rotated, and neither
will the pulley.

If the bolt has somehow rotated only on its shank, and not at its head,
then you have torsional loading (twisting), which is something that is
death to fasteners and is never allowed to happen, because a bolt that is
allowed to twist will eventually snap.
(In some rare, low stress cases, such as a bicycle brake, the bolt can be
constructed so as to allow a small degree of bending. Also, some bolts can
be specially constructed to allow shear forces, such as in a movable clevis
joint. A clevis joint is loose by design though, so not applicable to this
discussion.)

A bolt, especially one used in a high-stress automotive application, cannot
be allowed to deal with anything more than stretch. It cannot undergo
torsion, shear, or bending. The parts it is clamping are supposed to deal
with that load. It is critical, imperative, fundamental to the function of
any bolt, that it clamp with enough force to prevent its clamped parts from
moving relative to each other. If the clamped parts should start moving
relative to each other or to the bolt, the joint has failed, and soon the
bolt will also. Or it will come out.

In the case of a Honda crankshaft pulley, the pulley itself is located by a
Woodruff key. This key resists most of the torsional forces imparted by the
crankshaft and the engine's accessories. The rest of the resistance is
donated by the crankshaft pulley bolt. If the crank pulley bolt is not
tight to the point where no relative movement is possible, the Woodruff key
will get hammered flat from constant shock loading, and/or the bolt will
eventually come out. The bolt will not work as a clamp if it is
insufficiently tightened, even if it "looks" like it's tight enough.

So why are crankshaft pulley bolts so hard to remove when they've been
tightened properly?

1) Corrosion around the perimeter of the bolt head and washer. When a
clutch disc seizes to its flywheel, it's not held by very much pressure,
but it is held enough that you won't be able to free it without some
effort. Same thing happens with that ring of rust. It's not holding by
much, but getting the seal to break takes effort. The more rust, the more
effort needed.

2) Breakdown of the friction stabilizer coatings on the bolt. High-stress
bolts are coated with materials ranging from cadmium to Teflon. These
coatings make actual friction more predictable, so the engineers have
better control over actual bolt stretch in the real world. When these
coatings break down, as they can with time and heat, friction will tend to
increase.

3) "Embedment", which is when the thread mating surfaces deform with time
and vibration, and mesh more closely together at a microscopic level.
Embedment, believe it or not, actually results in BOTH a slight /decrease/
in actual bolt tension as well as an /increase/ in removal torque.

Much of the information above comes from the Web site
www.boltscience.com , which is run by Bolt Science Limited, a consulting
firm in Great Britain.
The rest comes from a series of emails between me and an individual at Bolt
Science Ltd., and some conversations with my mechanic, who has owned his
own shop since the early '80s, and has some thirty years of experience as a
licensed mechanic specializing in Japanese cars.

Finally, there is no such thing as a "one way" thread in a bolt that is
intended to be removed and reinstalled.

 

There is no such thing in a bolt intended to be removed and reinstalled.

The jpeg provided by Burt shows absolutely nothing except a fuzzy bolt.

 

Dunno.

Burt, I am not convinced that the pulley bolt's threads are cut such that
the vibrations of the back and forth motion of the pulley tighten it. I am
not finding anything of this nature described on the web, and it doesn't
exactly pass the common sense test. I don't have a good bolt textbook,
either, so my engineering texts treat this only generally. (Usual
disclaimer: No engineer knows anything special, anyway.)

However, Burt, your discussion of how much force the pulley applies to the
bolt head during operation does provoke thought. If that bolt weren't there,
that pulley would go flying off, right? So of course the pulley exerts a
force, and surely a sizable one, on the underside of the bolt head. (I think
Tegger and Jim touched upon this reality, too. I was a little focused on
stretching by thermal effects and should have considered stretching by
mechanical effects.)

The question to me is whether then the force is enough to stretch the bolt.
If so, then of course since stretching a bolt is a known means of reducing
its diameter, then the crankshaft will tend to screw up on the bolt. (Note
for total newbies: Industry uses hydraulic devices to literally stretch
certain bolts, screw them into place, then release the hydraulic pressure,
all to achieve a certain force.)

Once the crankshaft stops rotating, the bolt stretching ceases, the bolt
length collapses as much as the thread engagement allows, and it will have a
higher axial load in it, translating to a higher torque to free the bolt.

The higher torque won't necessarily translate to axial loads that are
standard, since the threads of the pulley bolt are non-standard in at least
one way: Super fine threads.

Burt, I don't want to buy a new pulley bolt, and I want to minimize taking
my Civic's bolt off and putting it on. I may free it in the next month or
so, when I have a tire rotation to do, torque it to spec, paint a line
across pulley and bolt, then monitor the line.

 

I'm in the middle of my front brakes as I type (by candlelight, so to
speak; it's so romantic...)

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.

No corrosion, no friction coatings to break down, little time, and still a
20% increase in torque needed to release.

Now what happens to that crank bolt? It's undisturbed for years, suffers
rust, and is done up to almost twice the torque figure. No wonder thay're
so hard to undo.

 

You also need to consider the difference between static and dynamic
coefficients of friction, which could account for at least some of your
difference in torques. If you have a sensitive beam style torque wrench you
can see it if you watch carefully. Torque a bolt, stop moving the wrench ,
and tighten it further. It will take more torque to start it moving, but
once it is moving, torque decreased as long as it is moving. WARNING do not
loosen torqued fasteners with a click style torque wrench, when you see
this difference in a loosening direction, the sudden change in torque as it
starts to move can impart enough of a jolt to the torque wrench that it may
be damaged. Remember that loud click as the bolt came loose? That was
it.(Experienced it, Paid for it. $40 to recalibrate wrench.)
Keep up the good work, T!
Scott

 

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.

Kinda odd, actually. You get bolts that are rusted in place, and when they
finally (sharply) let go, they can send a shock wave through your fingers
that you'll still feel days later. *My* wheel nuts are never like that.

 

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.

I'm not saying your measurements are necessarily wrong. They sound
reasonable and not inconsistent with the reality that loosening torque tends
to be a little higher (according to boltscience, among others) than
tightening torque, due to the differences in dynamic friction (while
tightening) vs. static friction (while loosening).

I am saying from my reading, this is inappropriate use of a tool, leading I
suspect either to incorrect measurements, abnormal wear and tear on the
torque wrench, or both.

 

go to this link and click on the "safety" icon, where they say not to break
fasteners loose with a torque wrench
It probably was in the manual, and I try to read it all, but I sure didn't
remember it when it counted. But on the bright side, it only cost me $40
and I didn't damage the customer's machine.

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=55265&group_I
D=954&store=snapon-store&dir=catalog

 

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.

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.

I'm wondering if removal torque increases exponentially compared to
tightening torque once you get closer to maximum tension.