Crank Bolt Tightening Debate, what is the issue?

I just joined this group, and I see a heated "crank bolt tightening debate." This debate has forked into several branches and it is difficult to see what the issue is. It
started before I joined this group, and it is not clear to me what the issue is. Is there a summary?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

you have the correct original title for the original thread it all started with "jim bean" then "tegger' and then the posse's joined
someone has a website dscribing the finer points of bolts
HTH
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

To robm: Go back to the original message and start from there.

Sure is. www.googlegroups.com
Go to Advanced Search, and search in rec.autos.makers.honda for the title of the thread (not including the "Re" part).
Oh, I'll do it for you... <http://groups.google.com/groups?as_q=&num &scoring=r&hl=en&as_epq=&as_oq=&as_eq=&as_ugroup=rec.autos.makers.honda&as_usubject=to+change+a+Honda+Accord+1988+model+timing+belt&as_uauthors=&lr=&as_qdr=&as_drrb=b&as_mind=1&as_minm=9&as_miny 05&as_maxd=7&as_maxm&as_maxy 05&safe=off>

www.boltscience.com
And by the way, it's not a good idea to start new threads regarding another cross-posted thread without cross-posting your new one. Most of the posts in the thread above were posted in rec.autos.makers.honda and only ended up here on account of the cross-posting.
Not everybody checks alt.autos.honda.
--
TeGGeR

The Unofficial Honda/Acura FAQ
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The debate grows out of the observation that crank bolts require several times as much torque to break loose as the specified tightening torque at timing belt changing time. One theory has it that the bolt actually creeps CW with engine operation, while another has it that the bolt doesn't turn and the increase in break-loose torque comes from other phenomena.
It has been the subject of conjecture for some time and only recently flared into active discussion.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That theory has been decisively debunked by a representative of Bolt Science, Ltd. in Great Britain.
The theory also does not explain its opposite in engines that turn so as to LOOSEN the bolt. NObody can explain why, if "creep" exists, those bolts do not come loose in operation. Every time I bring this up, it gets ignored.

This is a well-known and established fact. To deny its existence in favor of discredited conjecture is not wise.
--
TeGGeR

The Unofficial Honda/Acura FAQ
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
TeGGeR wrote:

er, what's the context? "debunked" requires somewhat more analysis than "i got this email". have your bolt science guy post to this group.

no it doesn't! /you/ are ignoring the fact that /other/ bolts use loctite and/or locking washers!!!

other phenomena /do/ exist. we've already discussed them: rust, localized adhesion, etc., but they do /not/ account for an increase in torque within a period of 24 hours as per my crx! and proven galling is as plain an evidence of lash as you will /ever/ see. and once we've estblished that lash exists, there is no "discredited conjecture".
the fact that you mistook bolt washers for pulley wheels doesn't strengthen any argument that you can interpret the evidence correctly.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
TeGGeR wrote:

Okay, not saying either theory is accurate, but there's a simple explanation for this *If* "creep exists": since rotation of the pulley is limited by the splines/key, and it only tweaks a tiny amount under rotation, the bolt would only loosen as long as it's tight enough that the friction between the bolt and the pulley overcomes the rotational torque. Once the bolt is loose enough that it "slips" against the pulley, it won't loosen any more.
--
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 0545-0, 11/07/2005
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He didn't debunk it. He said there was no net rotational movement and did not explain it or rebut the theory. That's his opinion. He is, on the other hand, drawing from some experience, so I don't disregard what he said.

to
do
ignored.
Rotation of the pulley /around the crankshaft/ is so limited to the angular lash in the key or splines.
Rotation of the bolt is not so limited. If it's loose, and the friction between its threads and the crankshaft's female threads is small enough, it can turn freely and without limit from the key or splines.
The crankshaft/pulley/bolt assembly move as one only as long as the axial load in the bolt is high enough to maintain clamping.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Matt Ion wrote:

tegger kindly forwarded me the email, and the boltscience guy says no NET rotation movement - which is true for the pulley because the woodruff. but it still lashes and those lashes create impuse, which in this case happens to be in the tightening direction.
it's also worth noting that, apart from the bolt locking methods commonly used in "loosening" applications, most pulley wheels on "loosening" engines incorporate rubber insulators - ostensively for harmonic balancing - but these also substantially mitigate lash momentum.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

/My/ theory ;-) emphasizes the crankshaft turning faster than the bolt turns (at times, possibly consistent with what Burt has written about impulses acting upon the pulley due to inertial/centrifugal forces, which then imposes forces upon the bolt head, etc.), with the result that the bolt advances deeper into the crankshaft. But bolts can advance without actually turning.
In other words, there is at times some relative motion between crankshaft female threads and bolt male threads.
I think, but am not sure, that Jim calls this "precession." I call it simply 'male and female threads working per their design when sufficiently loosened.'

flared
Ha good choice of words.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It appears that the threads don't bind and free to move. But I can see that the face of the bolt takes on a lot of stress, sometimes scratched beyond recognition on some cars. I also believe that the pulley is expanding, caused by the centrifugal force which squeezes the face of the bolt. I can't explain this without a drawing. See this same page again but scroll to the bottom.
http://square.cjb.cc/bolts.htm#centrifugal
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

crankshaft
that
can't
bottom.
You say at the above site:
"This image shows what the power of centrifugal force can do. It can squeeze the bolt to the point where the bolt can get pretty tight."
I am not sure what you're saying. My view: The pulley has centrifugal forces acting on it. If the bolt were absent, the pulley would fly off the crankshaft. With the bolt present and reasonably tight, the pulley is pushing against the underside of the bolt head. This pushing doesn't "squeeze" the bolt. It stretches it. The stretching reduces the bolt diameter a bit. The smaller diameter makes it "looser." Hence with, say, momentary impulses, the crankshaft will turn a bit faster than the bolt, resulting in relative motion between the two.
The boltscience.com guy first said "the screwing in theory is somehat improbable." I don't know if he was talking about the notion that precession was behind this alleged rotation, or something else. (Again, I completely reject the precession theory. Tegger had by accident assumed it was part of my theory when he wrote boltscience.com.) In his second email, the boltscience.com guy said, "There is no net rotational movement."
I am not sure he is correct. He might be. Physics-engineering wise, I think it's valid to hypothesize, using simply Newton's laws, that high enough pulley rotational speeds and sudden changes in them could certainly tear that bolt head right off or rip the bolt right out, destroying the male and female threads. Not that the RPM ever gets /that/ high. Also, there are other limiting factors. I am only attempting to indicate the forces at work here. I don't know if they are large enough to do what I propose.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Elle wrote:

That's not centrifugal force causing the pulley to come off...
--
avast! Antivirus: Outbound message clean.
Virus Database (VPS): 0545-1, 11/09/2005
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://groups.google.com/group/alt.autos.honda/browse_thread/thread/99b1b0379862d91e
Thank you; this tells very nicely what the issue is.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.