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question for ASME types
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After the last round of posts here regarding torqueing bolts and thread
lubricants, I've been pretty liberally using anti-seize compound (Permatex,
silver paste in a tube) on all critical bolts as well as any steel bolts in
aluminum threads.
The only problem I've run into is when I put the anti-seize on the threads of a
bolt which uses a locking nut. Not sure how best to describe this type of nut,
but on my YZ's they are typically on the rear axle, the brace that connects the
cylinder to the upper frame, and the motor mounting bolts. The nut normally has
a washer-sized base on the contact edge, and the opposite edge has a pair of
"teeth" that must bite into the threads (?).
I noticed some corrosion on the motor mount bolts that use this type of nut, and
now when I try to torque it (69 N-m) it feels like the bolt is getting ready to
shear, and my calibrated arm muscle is telling me I'm way past 69 N-m. I first
noticed this on the frame to cylinder brace a couple months ago after a top end
replacement, and thought my torque wrench was bad. Now I've got a new torque
wrench, and I'm still having this same problem.
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I don't understand what the problem is with the torque
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Last night, I just couldn't grok what you were saying. I realize you're thinking
of a beam-type wrench. I was using a clicker, so I have no way of knowing how
much torque is being applied until it clicks. I'll try it with my beam wrench.
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NASA did a study of bolt tension accuracy vs. torque techniques years
ago.
I don't remember the exact numbers but these are close:
strain gaged bolt = 5%
finger tight then number of turns - 15%
Clicker type wrench in calibration - 15%
Clicker type wrench out of cal - 30%
beam type wrench (typically not calibrated) - 20%
experienced mechanic - 15%
Trust your arm, as long as you got the experience on somebody else's
machinery.
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We could have a calibrated arm contest in Idaho!?
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Good idea.
The other day while camping, I was talking to a rider from MI that was
out to ride with Bill Dart and the HSMC. I wish I could remember his
name, he's the guy manufacturing the DB Snorkel.
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The guy i know from dBsnorkle is Syd, is it that guy?
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Yes, thanks. Got a last name?
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We were discussing trials tires. I asked what pressures he was
running. He didn't know and as he went for a tire gauge I used my
calibrated hands to put the sqeeze test to his tires. I guessed 8psi
rear, 12 front.
I was spott on the rear, one pound off on the front. (11psi)
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*****************************************************************
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I'd figured on trying that too, although I think the possibility of unintended
consequences is a bit high. I have this feeling I'll be wishing I'd just tossed
the things and gone to bed...
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If you break a motor mount on purpose, what could go wrong? Just
don't smash your fingers.
Go fast. Take chances.
Mike S.
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wrenches, both old and new. Are you getting readings
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just how embarassed would a teenage girl be if you dropped
her off at school in one of these?
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that look way too low when your calibrated arm (trust
your arm) is saying "that's too tight"????
Lube will make the required bold torque be lower.
The objective in tightening a bolt is getting the correct
bolt tension, not the correct torque. Torque is just
an easy way to measure bolt tension..... except that
it's not exactly a measure of bolt tension....except
it's the best thing ya got usually.
So is my first paragraph what is happening?
Go fast. Take chances.
Mike S.
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Any clues?
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Well, now that I have power again, I can post. Did you know that 69
Newton meters is = to 508.9 ft/lbs. I think your manual is has a
misprint. I have to be honest and tell you that I do not use a torque
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so is it righty tighty for ripping heads off?
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john
What is green and skates? Peggy Phlegm.
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wrench on motor mount bolts. I just make sure they are good and
tight.
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I read your other post, this is understandable.
69 N-m = 610 inch-lbs
= 50.8 ft-lbs
Yeah, I LOVE torque wrenches though. There's something odd going on with these
lock nuts and the anti-seize, regardless of torque wrench or not. It feels like
I could keep tightening until something snaps.
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Yes, because as it has already been pointed out antiseize is a
lubricant. The bolt is a spring. Torque on a nut is only an indirect
means of measuring the tension in the bolt. Lubricated nut produces more
tension for the same or less torque.
Look for the torque coefficient "k" on the data sheet for your antiseize
compound. For example:
0703.pdf
Use k=0.20 for clean steel-on-steel approximation.
If your antiseize has k=0.11 and torque is specified at 50 ft-lbf then
use (0.11/0.20)*50 = 27.5 to produce the same tension in the bolt as
unlubricated 50 ft-lbf.
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Mike Baxter --------------- "All GasGas, All The Time"
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Wishing you many grape popsicles,
Tami-
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You mean, like, "why I oughta POUND you" ??
Always thought that was a pretty good threat.
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2005 GasGas EC300, 2000 GasGas EC300, 1997 GasGas JXT270
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Mike,
Move your decimal point 1 to the left. It is 50.98 ft/lbs.
Torquing is to be done with dry threads - applying anti sieze or
oil/grease will prevent proper measurement and will likely result in
overtorqued fasteners.
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Usually done with dry threads...
I used antisieze on lug nuts on my truck when I wasn't thinking and
used a torque wrench to apply the 110 ft/lbs. they needed. Snapped
a 9/16" stud...
I knew all that training as and aircraft mechanic/engineer would come
in handy....just gotta remember to use it.
- Idaknowitall "ya right..."
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Cool website. I looked for 20 minutes, and couldn't find the above info about
dry threads.
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The info about dry threads comes from my training and many years as a
mechanic.
But if you look here:
You will see there are ways to compensate for lubricated threads.
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"Notice that the torque required for a lubricated fastener is LESS THAN
HALF that of an unlubricated fastener"
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No, it depends a lot on exactly what antiseize product you are using. I
posted this link a moment ago where the torque coefficient of Loctite's
products vary from 0.11 to 0.18 while convention says a dry steel on
steel is 0.20. If lubricated k=0.10 then one would use half the torque
to produce the same bolt tension. If k=0.15 one uses 0.15/0.20 = 3/4.
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Hmmm. The NASA Fastener Design Manual gives K=0.15 for steel on
steel.
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I did say in a different fork of this thread that 0.20 was an
approximation. Have seen it listed in other places. As for NASA, they
rarely assemble anything dirty, most always new bolts in new threads.
The Loctite link quoted above listed 0.18 for one of their antiseize
products. Antiseize plus threadlocking properties in one product? :-)
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I guess what is important to this conversation is that lube changes
the torque required to achieve the same bolt tension. Without
doing a bunch of research into the application, it's hard to know
exactly how.
Trust your arm.
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Problem is that what you are feeling with your "arm" is the bolt and/or
threads yielding. "Tight as it will go" is rarely the best. The bolt
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An inexperienced mechanic, yes. An experienced mechanic has
done enough bolts on other's equipment, and yielded them, that he
stops just short of yield now that he knows what he's doing. He
can feel the inflection in the stress/strain curve. And for a typical
application, you want bolt preload just short or right at yield.
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ZAMM.
Become one with the metal.
-Jeff Deeney- DoD#0498 NCTR UTMA BRC COHVCO AMA
'99 ATK 260LQ-Stink Wheels '94 XR650L-HellSickle
We don't stop riding because we get old, we get old because we stop riding.
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Agreed.
As you seem to know, it's way more complicated than we've let on
For starters, the first thread carries more of the preload than the
second
than the third and so on. Friction coefficient is important. Bolt
materials change so that the bolt's yield strength changes. Thread
form is important.
All of those things matter less to a trained arm. They matter a
lot to a torque wrench. A good mechanic will get it tight enough
without breaking stuff, usually, on normal non-critical applications
like a motorcycle bit. After all the other factors affecting bolt
torque
are added up, he'll still get it just short of yield, where it belongs.
Go fast. Take chances.
Mike S.
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Amen to what?
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Dunno, wasn't me.
I didn't mean for you to break the bolt on the bike.
Take it off, put it through something (a bunch of bigger nuts?)
and break it there. I think you do want to know why the
bolts are feeling funny, if there is an easy way to figure it
out.
Sorry for the confusion.
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Go fast? Take chances? Don't smash fingers? Toss 'em & go to bed?
As far as what could go wrong, well, for starters, let's say the nut strips the
threads, which then become fused to the nut itself, which is now locked onto the
bolt held in place by 4 or 5 threads that didn't shear off. The only way to get
the bolt out now is to drill it out (it's a roughly 10mm dia. bolt). The drill
slips, and gouges a hole in the right side crankcase. This causes oil to drip
out onto the red hot drill bit, which starts smoldering. The fumes cause me to
pass out, and I fall over backwards hitting my head on the concrete floor. I
wake up in a bathtub full of ice, and I'm missing one kidney.
I think I'll just toss them out.
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That'll woirk.
Go fast. Take chances.
Mike S.
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will only hold the load plus its preload. The more preload the less
available to hold load in tension.
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Go fast. Take chances.
Mike S.
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Years ago, my "clicker" torque ratchet rusted or something and was
torqueing way over its setting & snapped a couple (fork) pinch bolts on
my '96 XR250R. After cleaning up the threads & getting new bolts, I
have always used anti-sieze on those bolts and torqued them per the
manual.
Thanks for posting te above link - I learned something very useful
today.
So, is a good rule of thumb to use half the torque when tightening a
bolt with anti-sieze?
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I think you have to use the rule of 72.
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I was just referencing the fact that I have seen very few manufacturers
that want lubrication used on torque sensitive fasteners.
- Craig
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- Rock Hardly
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