good point about "all causes". i don't know all causes either, but i am
however trained to observe carefully, and from that the following facts
1. there is angular galling under the bolt head. that's hard evidence
of some rotation.
2. the rotation direction on the crank is such that the bolt would
tighten against a "stationary" pulley wheel.
3. the apparent pulley bolt torque increases from ~120 ft.lbs to
~300ft.lbs in ~30 miles.
i also know from other research that bolts can tighten. now, the dots
on this may not all be joined, but an outline appears to be there.
That's properly qualified and so reasonable, AFAIC. It's an
outline, but nothing certain as yet.
I am interested in point 3 above. I remember your mentioning
some months ago that you had generally evaluated the
tightness after torquing to spec and then driving briefly.
Did you redo this experiment a few times, estimating as best
you could the torque necessary to free the bolt each time?
I am still not willing to remove my Civic's pulley bolt more
than is necessary--too lazy and I don't like putting wear
and tear on such an expensive bolt with super fine threads,
and so more susceptible to stripping in my estimation, at
that. Admittedly that might be overworry on my part.
I will say that in 2004 when I first got some experience
with my 91 Civic's pulley bolt that the first time I broke
it free (some three years after it was last removed)
demanded, from memory, notably more force than the next few
times I freed it. (I spent a few weeks researching and
preparing to replace the front crankshaft seal blah blah,
and so ended up freeing the bolt I think maybe four times
algother during this period.) I did not try to estimate the
torque to free it after the first removal, since I was kinda
Why is it again that you feel the abrasion beneath the bolt
head could not occur while torquing the bolt to spec with
the pulley fixed?
yes, best estimate #'s. i've done it twice on the 91 crx and twice on
the 89 civic. pretty much the same tightening experience on both. i
will say though, second release was not /quite/ as high as first. full
body weight at 18" = 300ft.lbs for second release, near enough. first
release requires a little "bounce" of that weight, so what's that? 330?
not 400 though.
it's not delicate. pitch is 1.25mm, so not that fine.
sure, but it sure is tighter than the torque-wrenched tightening that
there will be some abrasion on simple tightening, but that's usually
really superficial. comparison between two identical bolts, one from a
splined/loctited pulley wheel and one from a single woodruff/no loctite
show that the latter is abrading substantially and therefore lashing,
the former is not. this is consistent between junkyard hondas i've
inspected of the splined/unsplined eras. the type of galling is also
inconsistent with that seen from large angle rotation - it definitely
appears to be lashing within a limited range.
I think it's hard to estimate the effect of bounces. A
person jumps say six inches, s/he accelerates to a certain
velocity. Whatever s/he hits decelerates the person from
that velocity, producing the force that is higher than mere
body weight, as I trust you and others here are aware.
Surely your bouncing is less than around 550 ft-lbs., but I
base this number only on general reports of how much torque
is needed to free the bolt, not any rough physics
calculations involving body deceleration, and so force
applied, by the breaker bar.
I am not troubled by the second release being a bit easier.
Goes towards arguing that years of heat and load cycling do
contribute to the tightness.
It's delicate to me, though maybe not because of the fine
pitch. Maybe it's the fatigue it sees.
I have a vague recollection that the bolt is supposed to be
replaced every so often.
That might be something to expect. IIRC, one important point
(of many) Tegger has brought up on this subject is that the
torque to free can vary quite a lot from the torque to
tighten, even if it was just a few moments before that the
bolt was tightened. I believe plenty of sources back this
It's a very inexact science, though, like many sciences,
with high reliability. Torque does not directly,
formulaically correlate to clamping strength. Or, rather,
formulae used to determine clamping strength from torque are
crude estimates. There is just so much at play: Dry surface
age and so condition, lubricants, torque wrench
inaccuracies, material differences from one bolt to the
rotating engines, also. Our Volvo took much more than the spec'd 190 ft-lbs
the first time I changed the timing belt. I had a floor jack under the 9
inch socket handle and the tires had started to come up off the ground
before the bolt moved. When the harmonic balancer failed a few months later
it took much less. With the second timing belt change it was back to its
interesting. do you have any thoughts on the fact that it has an
"harmonic balancer" also? they do a lot to reduce rotational inertia
which might tighten a bolt in one direction, but loosen in another. for
a balanced crank and flywheel, there's really isn't a lot something low
mass like this can achieve vibrationally. besides, hondas run
successfully without them, so i wonder about its actual purpose.
occasionally (the first lasted about 150K miles). For those trying to
picture this device, imagine your crank pulley with a strip of rubber
running the circumference and bonding the pulley part to the core. The
rubber eventually shears....
For whatever reason, the B230 engine has a harmonic balancer - also called a
harmonic damper... not sure which term is official - while the very similar
B23 engine has a conventional pulley. Hmm.
Successful? What about the galling on the crank bolt head you've
talked about. That could've been caused by the torque pulsation of the
Take for instance, when ever I do a brake lathe without the vibration
damper on the brake disc there is a wave effect on the surface. On
the crankshaft, these wave (oscillating) effects can transfer eat up the
transmission gears or various parts.
After 375k I've done a bunch. It was a bitch the first time and it was a
bitch the most recent time. In all cases the usual 250ish foot-pound
impact wrench on a quarter-inch hose wouldn't budge it, though I wasn't
willing to spend all day on it before breaking out the big guns.
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