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Old 05-27-08, 06:50 PM   #1
Fissile
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Dry Torque Versus Wet Torque

I assume that when a torque spec is given by a manufacturer, it for dry torque unless wet torque is stated. I almost always use anti-seize compound or loctite when assembling anything mechanical. I assume that applying either product to a fastener makes the fastener "wet" If I use the dry torque spec, will the fastener be over-torqued after applying anti-seize or loctite? If so, by what percentage should torque be reduced from dry torque spec for a "wet" fastener?

Thanks in advance for your comments.
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Old 05-27-08, 07:28 PM   #2
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For what it's worth only, the aviation and automotive industries are standardized on stating "wet" (your term and it is self-explanatory so it's OK) torque specs.

"Dry" tightening a threaded fastener doesn't give consistant torque readings as the mated threads "grind" past each other, so the specs are established by using a lubricant.
alf
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Old 05-27-08, 07:51 PM   #3
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Thanks, that's what I wanted to know.
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Old 05-27-08, 09:06 PM   #4
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Quote:
Originally Posted by old_alfie View Post
For what it's worth only, the aviation and automotive industries are standardized on stating "wet" (your term and it is self-explanatory so it's OK) torque specs.

"Dry" tightening a threaded fastener doesn't give consistant torque readings as the mated threads "grind" past each other, so the specs are established by using a lubricant.
alf
Are you saying when torquing something in the aircraft industry, unless otherwise stated, it's wet torque?
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Old 05-28-08, 12:34 AM   #5
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"For what it's worth only, the aviation and automotive industries are standardized on stating "wet" (your term and it is self-explanatory so it's OK) torque specs." QUOTE.


Please give reference.


Regards,
J T
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Old 05-28-08, 01:26 AM   #6
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threads should not be torqued without lubrication, it just dosnt work. I have never heard of dry torque. even compatible metals like brass and steel still MUST be lubricated to run on each other. If you want to get technical no threads should be tightened dry unless they are a specially manufactured to do so.
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Old 05-28-08, 01:51 AM   #7
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Quote:
Originally Posted by rustguard View Post
... If you want to get technical no threads should be tightened dry unless they are a specially manufactured to do so.
And if you REALLY want to get it right you ignore the torque and go by bolt elongation instead.
Or, you use a lower torque value only intended to take up any slack, then tighten a determined number of degrees from that.
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Old 05-28-08, 07:47 AM   #8
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I'm an aircraft mechanic, and, FWIW, the FAA states, "all torque figures, unless otherwise stated, are given with threads clean and dry."
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Old 05-28-08, 08:41 AM   #9
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"I'm an aircraft mechanic, and, FWIW, the FAA states, "all torque figures, unless otherwise stated, are given with threads clean and dry." QUOTE.


Thank you Sir!

+1

AND, according to the former Premier Industrial, (Supertainium Fastners)

when "wet", reduce torque 40%.


Regards,
J T
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Old 05-28-08, 08:50 AM   #10
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Park Tool's "Basic Thread Concepts."

Should be required reading.....
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Old 05-28-08, 08:53 AM   #11
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Quote:
Originally Posted by UnsafeAlpine View Post
I'm an aircraft mechanic, and, FWIW, the FAA states, "all torque figures, unless otherwise stated, are given with threads clean and dry."
Check me if I'm wrong here, but ... neither is "right" or "wrong," but ... it IS important to know whether the spec given IS for lubed or dry ... because the difference can be significant.

Quoting ParkTool (which I'm presuming is pretty well geared to the bicycle industry ):

Quote:
Originally Posted by ParkTool
There is resistance to turning the bolt, as the fastener gets tighter. Some resistance comes from friction and rubbing between the internal and external thread surfaces. Because of this, it is common to prepare the threads with lubrication. This can take for form of liquid lubrication, grease, or an anti-seize compound. Even liquid thread-lockers provide some lubrication during tightening. As a simple rule of thumb, if the thread size is small, such as a derailleur pinch bolt, a liquid lubricant is adequate. If the thread is large or the torque relatively high, such as a pedal thread or bottom bracket, use a grease or anti-seize compound. There are situations, however, where a manufacturer may recommend no lubrication on the fastener. If is useful to lubricate the threads and under the head of the bolt, especially when the bolt head is turned during tightening.
My philosophy is: if it doesn't say fasten it dry, I give it some sort of lube/theadlocker/anti-seize/grease, in line with Park's recommendation.
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Old 05-28-08, 08:59 AM   #12
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Originally Posted by neil0502 View Post
My philosophy is: if it doesn't say fasten it dry, I give it some sort of lube/theadlocker/anti-seize/grease, in line with Park's recommendation.

I would concur with that. Park is the industry standard.
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Old 05-28-08, 09:07 AM   #13
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"And if you REALLY want to get it right you ignore the torque and go by bolt elongation instead.
Or, you use a lower torque value only intended to take up any slack, then tighten a determined number of degrees from that." QUOTE.


+1

The truth be known, the above is a "true value test", for fastner clamping effect,

"torque readings", as we know them are "old-fashioned", and actually inaccurate!


Regards,
J T

PS

Of "coarse", here I sit with 3/8" and 1/2" Snap-on click type torque wrenches!
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Old 05-28-08, 09:25 AM   #14
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Quote:
Originally Posted by J T CUNNINGHAM View Post

Of "coarse", here I sit with 3/8" and 1/2" Snap-on click type torque wrenches!
Those are just going to mess you up ... you poor thing.

I'll PM you my mailing address, and -- because I'm a generous and caring guy -- allow you to send them to me ... so you never have to be confused, mislead, or distracted by them again
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Old 05-28-08, 10:18 AM   #15
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"so you never have to be confused, mislead, or distracted by them again." QUOTE.

Actually, I now use them as hammers, after having molded "lead heads", on them.

(ROTFLMAO)


Regards,
J T
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Old 05-28-08, 10:21 AM   #16
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FWIW, I rarely use a TW on bikes, but I always make sure all threads are perfectly clean and oiled.

On my car, I always use a TW with cleaned and oiled threads set to the recommended torque (which are DRY torques in all the books I have) and I have never had a fastener break, strip, a component come apart or had a leak from any cover or sump. Everything comes apart very easily with oiled threads.
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Old 05-28-08, 11:25 AM   #17
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I'm pretty sure the automotive references i've used are for "clean and dry" threads unless it is marked as wet or lubed. Also, the torque difference between dry vs. wet is dependent on the type of lube/oil that is used. I have a book that has a chart for dry vs. wet for various lubricants, i'll try to find it tonight. IIRC, the book is "Engineer to Win" by Carroll Smith.
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Old 06-02-08, 10:36 AM   #18
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in Australia, I have never come across the term dry torque. I searched australian web pages by entering "dry torque" in google and came up with 12 listings and only 2 of these were to do with dry torque upon removing the exclamations i found a set of genie installation instructions that gave both dry and wet. Genie is an american brand. upon searching american web pages, yes dry torque was commonly referred too. obviously australian standards are different to usa. I have been taught that torquing bolts un- lubricated produces inconsistent results. and I still believe from my experience that threads are always best tightened lubricated. If you have experienced what happens when threads 'pick up' you will know why. And as for genie suggesting that people should put bolts in a chassis underneath a car dry is a joke, because cars drive through water and I havnt seen any stainless suspension bolts on a car yet. I would like the author round when ive been underneath a few cars undoing 'dry' bolts. And as for setting torques by stretch or degrees, well thats fine when its all been worked out for you by the manufacturer, but not so practical in the jobbing workshop. Sounds a lot more like an engineer talking than a mechanic. No offense engineers usually get paid more.

If your torquing or installing bolts dry without a reason its second rate work. am i guilty yes. have i ever used olive oil cause im too lazy to walk out to the shed- yes.
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Old 06-04-08, 05:52 PM   #19
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I was surprised to find this online, but here's the page i was referring to in Google Books:

Engineer to Win, page 138 (Carroll Smith)

as you can see, even changing the lube has a fairly significant effect on the pre-load of the bolt vs. the applied torque.
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Old 06-04-08, 08:10 PM   #20
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"Premier, whose threaded fastners are junk, ......." QUOTE.


I am deeply disturbed by what Carroll Smith has written, in that what he maintains as

"The Gospel According To Carroll Smith", has also been stated by Premier Fastner (now

Lawson Products) for years, and he claims that they are POS! He is most certainly correct

when he writes of the high cost of anything purchased from Premier, I however have

always found their products to be the best-of-the-best available. The "Supertainium", line

of fastners was to be used as a fastening system, with each part of that system engineered

to form a total positive clamping force just as he mentions they should.

Mr Carroll Smith, and his "trashing", of Premier Industrial Corp's "Supertainium", brand, has put

himself at odds WITH WHAT HE HIMSELF PROCLAIMS!


Regards,
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Old 06-11-08, 04:05 AM   #21
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.. as for setting torques by stretch or degrees, well thats fine when its all been worked out for you by the manufacturer, but not so practical in the jobbing workshop.
Well, stretch is fairly rare, the pieces have to be quite large before stretch can be measured in a reasonable manner. But angle is dead simple, and people are usually better at estimating angle than torque anyhow.
And If I'm going by the service manual then following torque recommendations or angle recommendations are pretty much the same thing.

But yeah, if I'm winging it and only working from bolt sizes then torque is more useful.
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Old 08-06-08, 10:04 PM   #22
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I was surprised to find this online, but here's the page i was referring to in Google Books:

Engineer to Win, page 138 (Carroll Smith)

...
Excellent, excellent stuff!

Thx. This clears up some stuff I've wondered about for years!

I'm going to buy this book and put it on the shelf right next to Jobst Brandt's Bicycle Wheel book.

+1000
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Old 08-06-08, 10:53 PM   #23
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http://www.morbark.com/service/belttorque.pdf

Note the info at the bottom of the chart. Clean dry threads. Reduce torque values by 10% for lubricated threads.

Here's another one. Consider waxed to be the same as Never Seize, oil or grease. Note the drop to almost 1/2 the dry torque for lubed 1/4 inch bolts which are very close to our 6mm bolts.

http://www.portlandbolt.com/technica...que-chart.html

The aerospace industry may lubricate their fasteners or it may not (I'll have to ask my buddy that has worked with on planes and heli's most of his working life) but I have yet to see anything in the automotive or motorcycle world outside of the internals of the engine, transmission or rear end where the fasteners are lubricated. All the chasis and suspension stuff is done up dry other than whatever residue is left from the bolt factory. And I have yet to see a mechanic oil or lube those bolts before replacing them. In a perfect world yes. But in reality it just doesn't happen when time is money.

Unless a torque chart specifies that the values are for lubricated threads you can bet it's based on clean dry threads. But since nothing on our bicycles should be left dry you can reduce any spec'ed torques by 10 to 15% unless the write up specifies oiled or greased. The fact that many of our screws are going into alloy parts means that you want to further reduce the torque in most cases unless you're working with the spec from the part maker. A lubricated bolt can quite possibly strip out threads if you try to draw it in to the dry spec torque value intended for anchoring in steel threads. You may get away with it once or twice but aluminium fatigues sooner than steel and that third time you may be suddenly looking at a helicoil job.
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Old 08-07-08, 01:47 AM   #24
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concerning bolt threads, what are good candidates for Loc-tite , blue or red. On a bike

I mess around with hobby R/C cars, and Loc tite is almost a must when bolting anything to the frame, especially engine mounts. Normally i will heat the frame to remove a engine mount..but i have only replaced two motors, i try to keep things simple.

thanks
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