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Old 08-20-2003, 04:20 PM   #1 (permalink)
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Locktite question.

I've been thinking about using Locktite on the steering arm stud and nuts on a d44 or 60 or not. I've been intalling and using them for years and have seen a few failures for a few diffrent reasons. My question is, should you use Locktite on the nuts or not. I've read alot about this here and most everyone says use it, including myself. I'm thinking now it might not be a good idea. I've seen a lot of arms come loose and need retorqued but have never thought they came loose from the stud or nut backing off. When the arm seats, or the studs streach and the nuts need to be retorqued (like allmost all do) you wont be able get the propper torque with Locktite on them so is it really a good idea? Perhaps I'm just not using the propper type of Locktite??? Obviously I'm talking about using Nylock's, lock washers, or some type of self locking fastner with the studs, so it seems the use of Locktite is not only un needed but may cause a problem later.

Just a thought I had and would like some input from the PBB pro's.
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Old 08-20-2003, 04:43 PM   #2 (permalink)
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I put red on my u-bolts and steering stuff. It's a bitch to back off when I need to do repairs, but keeps everything tight. Lots of heat is the only thing I have had luck with getting it loosened up. Blue doesn't lock in that tight, but is better than nothing. Just random info I've noticed, don't know if you can use it.
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Old 08-20-2003, 04:55 PM   #3 (permalink)
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Loose the lock washes for starters. They are not needed. Just another way for people to make mo money IMOP.

As for the loktite affecting your torqe, I went to a class given by ......Locktite. I asked the same question and was told it will increase your actual torqe by 1 to 3 %. Lubricating the threads.

Most stud specs that I've seen call for a light oil on the studs. Works for me.




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Old 08-20-2003, 05:00 PM   #4 (permalink)
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Todd, you're talking about wet locktite. I'm talking about after it's dry.

Hell yeah, Fordyce's gonna be fun. Bring plenty dry clothes.
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Old 08-20-2003, 05:13 PM   #5 (permalink)
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I use toplock (stover) nuts on steering arm studs (d44). Red locktight as well. Not sure how toplocks effect torque initially, but they are definitley secure, especially with red locktight.

If retorquing the nuts, I would need to remove the nuts and clean all the old locktight off the studs, (at least thats how I'd do it) and use new nuts to re-torque properly. Again this is just how I'd do it...top locks really shouldnt be re-used.
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Old 08-20-2003, 05:14 PM   #6 (permalink)
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Yeh, I am because to do it right you need to remove the nut and clean the threads befor you retorqe it. And I live in a perfect world don't you know!

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Old 08-20-2003, 06:02 PM   #7 (permalink)
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Thanks for the input guys but the question still remains....
Should you use Locktite for that application?
Locktite does the same as any type of self locking nut, keeps the nut from turning on the stud. Right? if that's all it does and the nuts are not backing off the studs, should you use it?????
Also consider you can't properly retorque with DRY Locktite on the nuts.
So should you use it?
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Old 08-20-2003, 06:09 PM   #8 (permalink)
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If retorquing the nuts, I would need to remove the nuts and clean all the old locktight off the studs, (at least thats how I'd do it) and use new nuts to re-torque properly. Again this is just how I'd do it...top locks really shouldnt be re-used.


Exactally my point. Why go through all the trouble of removing all the old Locktite if it didn't do a damn thing to begin with? Toplock nuts are sure as hell not going to back off the stud with or without the aid of Locktite so why use it in the first place?

Why turn a simple retorque of a few VERRY important nuts into a big deal?
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Old 08-20-2003, 06:23 PM   #9 (permalink)
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couple of points.....first of all, if the studs are stretching and letting the arm come loose you need to do something besides just retorque. The most accurate way of checking torque on a fastener isn't with a torque wrench, but by measuring bolt stretch. If the studs stretch in use then they effectively have been junked, so to speak, and retorquing doesn;t solve anything.
As far as dry sealant being on the threads, even if there wasn;t dry Locktight you need to have the threads clean and lightly lubed. A fastener without Locktight on it still would need to be taken off, cleaned, and lubed, not just retorqued....assuming the nut was just loose and the stud had NOT stretched.

So, in real life....just tighten the damn thing and go on with it. Hardly no one, except in the aviation field and big time racing teams, torque bolts the way they should be anyway. If the nut coming loose bothers you, and the stud isn;t stretching, get yourself a "safety wire" kit and wire it.
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Old 08-20-2003, 06:28 PM   #10 (permalink)
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I will share a few thoughts.

1) There are many different methods for trying to resist the loosening of bolted joints - each have strengths and weaknesses, and NONE are absoloutely foolproof (though lock-wiring is close)

2) I'm not a big fan of split lockwashers or starwashers in an application such as this - they need to bite into the material to work, and I don;t want them to bite into my steering arms, they don;t realy provide enough loosening resistance in a critical app such as this, and they tend to "squish out" under high clamping force - and high clamping force is exactly what you want in this joint.

3) I see no advantage to liquid or paste threadlocking compound over other "positive retention" methods (such as nylock or stover nuts) unless you can;t use a nylock or stiver nut - for instance on the srud in cast knuckle, or if using a 60* tapered seat nut that doesn;t also come in "positive retention" flavour.

4) In either app (44, 60) you really, really should be using something with a taper - either taperd cone washers or tapered seat nuts on the studs - my arguments for which appear here:

http://www.pirate4x4.com/tech/billav...OTT/index.html

5) If a bolted assembly is loosening without stud or nut backing off (how can you be sure without using safety wire?) then something is not right in the design of the joint and you need to correct that at the source - no manner of "positive retention" device is going to cure that. Think about it for a second.

6) torquing and retorquing - it's a can o worms. depends if you believe in perfect theory, common sense, or booty fab! Ideally, you wouldn;t use either stud or nut again - much the same way as ring gear bolts and many engine critical fasteners should never be re-used. Common practice in aerospace too. Install, torque (or measure stretch) and if it llosesns, remove and replace. Middle ground - install with clean dry threads, using tapered interface, and a mechanical lcoking device (stover type would be my choice), re-torque as necessary - if loosening is frequent - find out why and correct. Booty - use whatever you;ve got, hammer it on with an impact and lots o thread locker, if it llosens, just crank it down! All 3 methods can work
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Old 08-20-2003, 06:47 PM   #11 (permalink)
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I prefer to use Belleville Spring Washers and Anco style locking nuts on mine. Easy to assemble and disassemble as needed with no problems so far with loss of torque on the connection.
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Old 08-20-2003, 06:54 PM   #12 (permalink)
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I just got done going through some similar stuff at work.

It was a very high vibration application where we were having problems with loctited assemblies coming apart, primarily due to human error in applying it.

We did several studies on breakaway and prevailing torque with different methods of applying loctite.

We found that application of loctite can cause a LOT of variation in breakaway and prevailing torques on fasteners. The torques applied were always higher than clean threads, but the amount of "drag" induced on the threads by the loctite was very inconsistent.

Once the bolts had loctite applied to them a second time without cleaning in between, it got even worse. I don't know if you know much about statistics, but we were seeing std deviation values of about 30-40% of the averages on a lot of the torque figures.

The main problem I'd see with your application is the nylock. There isn't much info on any reactions between the insert and the loctite, especially when you are talking about non-milspec hardware where the insert could be made out of anything under the sun.

Also, once a nylock backs off and you retorque it, you're cooked. You are not going to get anywhere with it from there out.

I'd recommend using either Red or Green loctite with a stover nut, just plan on having to use some heat to disassemble the stuff, and clean up the male and female threads with acetone or MEK before re-applying the loctite when you are doing repair work.

If you can find green loctite, (Loctite 635) it is good stuff, intended for gap filling on press-fit applications, and it REALLY locks threads.

Also, remember that with loctite you start to setup in about 10 minutes, so you need to be done tightening it by then, but it won't fully cure at room temperature for 72 hours, so don't think that the loctite you applied at 10pm friday night while checking out your steering is going to be holding your shit together at 8am saturday when you hit the trails.
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Old 08-20-2003, 07:27 PM   #13 (permalink)
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Great info...Loctite also makes a Green 609. We call it Green death because you can't hardly get it off. They also have a primer for loctite.

Permatex (according to there tech people) say it should be applied to the nut or hole in case of a stud. and not to the bolt.
They also say just to use a very small drop not coat the nut. More is not better.
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Old 08-20-2003, 07:47 PM   #14 (permalink)
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Interesting

From a mechanical standpoint Like HVAC etc. We only use red locktite for high vibration devices. The reason being most of the fasteners are rarely even grade 5 and break easy when torque is applied.

At home and on my rig I use anti-seize more than loctite and Stover nuts, or Nylocks where needed.. I agree if your realy worried drill it and wire it..
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Old 08-21-2003, 11:20 AM   #15 (permalink)
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A key question others have brought up is what is permitting that loosening in the first place? The stud/knuckle, the bolt/stud, or the stud itself?

In my experience steering studs are not torque-to-yield (TTY) like a cylinder head bolt -- I can re-use knuckle studs through many torque cycles without having loosened nuts ...but some folks are MUCH harder on their equipment, and they may be forcing the studs to yield with their 'wheeling (or their hydro steering), more than with their torque wrenches. If that's the case, then no amount of loctite or star washers is going to help -- it might be time to look to better fasteners or more of 'em (Dedenbear's knuckles).

What works for me is red loctite to seat the stud into the knuckle and no loc-tite on the nut. Once the bottom stud threads are seated in the knuckle, the top threads are wire-brushed clean and blasted clean of any grit with WD-40, then dried with a towel. I torque the nuts to spec with a torque wrench, and check 'em when I get home with the same wrench. Break-away torque is higher than the spec, so if the nut moves at all on the torque-check, it comes all the way off for inspection, as do its partners (this happens at least once a season for winter inspection, and sometimes more often if I choose to pull the knuckle off the axle for joint replacement). I'm super-conservative about steering, though... with me, my wife, and our dog in the truck rolling down the highway, I'm not taking chances.

Post-run torque checks the way I do 'em pretty much rule-out stover, nylock, or similar one-shot solutions, unless you're game to replace them each run. Fine if you've got Camo's budget...

IMHO, loctite is a great idea on the bottom, where the stud hits the knuckle, but a bad idea up top, unless you really do remove and clean it all off each time you move the nut (crusty, dried-out loctite throws off subsequent torque if you don't clean it entirely). That's not something I want to do in the midst of a trail repair -- I'm willing to make a few strokes with a wire brush, but not sit there for 15 minutes cleaning the old loctite.

BTW, 635 Green and Loctite Primer is nigh on impossible to remove. If you lay that into the bolt/stud interface up top, you'll back the stud outta the knuckle before you ever get that nut to break free!

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Old 08-21-2003, 11:39 AM   #16 (permalink)
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Thanks for all the info guys!!!

Quote:
5) If a bolted assembly is loosening without stud or nut backing off (how can you be sure without using safety wire?) then something is not right in the design of the joint and you need to correct that at the source - no manner of "positive retention" device is going to cure that. Think about it for a second.
This is exactally what I'm talking about.


I agree with what most of you had to say, but like I said I've installed quite a few of these over the years and have seen alot, actually most come loose (i'm talking about just a little loose, and not freequent) after the initial install and require a retorque. At least one retorque, after that they are seated and good to go. If you use Locktite you can't (without a bunch of work) get a propper retorque on the studs, so why use it in the first place?

Say you're out on the trail and do a bolt check while at camp, the nuts are Locktited and wont turn but the joint has, for whatever reason, lost some of the clamping force. If you put a wrench on the bolts they will feel tight but are not, so you wheel on and the arm breaks off. It not only doesn't do a bit of good to be there in the first place but can actually screw you later on. This is why I think it's a real bad idea.

Most of the replys are saying not to use it on the nut/stud, that's what I was thinking. Allmost every post I'd read on this in the past was people saying don't forget the Locktite, I think it's actually a real bad idea, and can guarantee it wont be used by me on that application again.

Thanks again for the input and confirmation of my thoughts.
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Old 08-21-2003, 11:42 AM   #17 (permalink)
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just some random locktight tech that doesnt have much bearing on this thread.

Locktite has a shelf life of 1 yeah acorrding to the manufacturer. We had to recall 1000's of parts a few years back because of locktite failure.

just an FYI
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Old 08-21-2003, 04:36 PM   #18 (permalink)
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Jasonmt - pics? links? I've learned to really respect your judgement on hardware!

Randii - before I debate you (for fun ), define torque-to-yield please.

Loctits actually have a very good website withh all kinds of product brochures in pdf - well worth a read. Their tech support is good too - and they are not afraid to tell you what their products are not suitable for.

mrtwstr - in the end - it is the same argument as greasable or sealed u-joints. Greasable u-joints (from a longevity / service life point of view - absolute strength is another matter) ARE better as long as you ACTUALLY maintain them regularly. If you don;t , or don;t ALWAYS - then "sealed" are better.

Same here - clean, dry, torqued to spec are prob better, as long as you do ACTUALLY always check them. If not, you're prob better off with some kindof positive retention.
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Old 08-21-2003, 06:25 PM   #19 (permalink)
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Quote:
Originally posted by BillaVista
Jasonmt - pics? links? I've learned to really respect your judgement on hardware!

here is just one link to belleville washers http://www.valleyspring.com/discchar.html

i use them all the time at work to fasten large pieces of electrical switchgear together. ive never thought about using them for other applications. but i have now

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Old 08-21-2003, 06:45 PM   #20 (permalink)
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http://www.lok-mor.com/pn-loc.html

These are commonly used as structural fasteners and on flanges on vibrating services. I like them because they have no effect on the torque applied to the stud unlike a stover or nylock nut. The locking pin is also an excellent visual indicator.



http://www.raymondasia.com/cat_belleville.htm

http://asp.raymondasia.com/belsprhl.asp

As stated above these are common to many electricians who work with large buss bars/switch gear etc. But they are also common on vibrating service pressure pipe at equipment connections.

Belleville washers apply a clamping force to the bolted connection when they are deflected from their normal cone shape to the flat position. Many different clamping loads are available from various manufacturers. In my case I use high rate models that develop approx 12,000#’s of clamping force to match the 12,000# I am getting from torquing the 9/16” grade 8 studs in my D-44 arms to 75% of the tensile strength. If the nut or stud backs off the Belleville washers still be applying a clamping force until the nut/studs back off enough that the washers return to their unloaded position. Because the washers develop a similar clamping force as torquing the studs you can also get away from the use of a torque wrench and simply tighten them until they are flat. Mostly just overkill in my application but I have never had a problem with mine loosing torque.
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Old 08-22-2003, 02:51 PM   #21 (permalink)
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Contestant (Randii): Alex, I'll take Fastener Trivia for $250, please...
Trebek: Normal fasteners are intended to be loaded in elastic tension (well under yield), and return to their original length when the torque load is removed. This type of fastener is loaded through elastic tension, past yield, into plastic tension, and do not return to their original length when the torque load is removed.
Contestant: What is Torque-to-Yield?
(Billavista drives up in the Wolf, bowling Trebek over and putting an Interco atop his podium...)
Billa: Not so fast, there....
Randy continues: TTY fasteners see most common use in attaching cylinder heads and U-bolts. IIRC, using TTY fasteners allows better clamping with fewer fasteners (a boon to designers and a bane to shadetree mechanics, who may not want to replace fasteners every time, and may want to just hit a torque spec and not sweat the snug, then staged-angles tightening).

Randii (bottom tap, light oil, and spot-face just to be sure)
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Old 08-22-2003, 05:23 PM   #22 (permalink)
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Billa (from the podium).

Just a minute - that don;t make sense to me. By the very definition, what possible advantage could there be to taking a fastener into plastic deformation. The very definition of plastic deformation is thatit is a permanent deformation - will not "spring back" therefore does not impart any greater clampnig force. Matter of fact - once you cross that critical line of where stress is proportional strain, and get into plastic deform....do you not lose sig. clamping force?

From an article I'm working on:

________________________________________

Plastic deformation. This is the ability of the metal to undergo a permanent change in shape without rupture. Exactly how steel is able to do this is a bit too complicated to go into here, suffice it to say it has to do with the dislocation or slip of atomic bonds in the crystal lattice. The crucial thing about steel though, is not that you can bend it and have it stay in that shape – but more importantly that you can do so, and have it retain the new shape as well as its original strength. There are limits, of course. As we discussed in the introduction, there is a trade-off between a metal’s malleability and its strength (which makes perfect logical sense – since malleability is the ease with which we can form it, by applying force, and strength is its ability to resist force). There are a whole group of people employed in a field called “physical metallurgy” whose job it is to figure out how to use things like alloying, heat treatment, and cold-working to skew this relationship (malleability/strength) in our favour. More on these processes later – for now – remember plastic deformation is the permanent change in shape of a metal, which, if done properly retains its original strength.

Elastic deformation. Elastic deformation is almost the opposite of plastic. As its name implies, it is the ability of a material to deform under a force (load) and then return to its original shape when the load is removed. Obviously, an elastic band is very elastic…duh! We can stretch it, then let go and it returns to its original shape and size. Of course, stretch it too far, and it distorts (undergoes Plastic Deformation). Steel is no different, no matter how big or thick. It may seem improbable that steel deforms in this manner, but it surely does. When you walk across a big steel bridge, the steel beneath your footfalls deforms a little, and then returns. A more obvious example might be a small spring – stretch it (or compress it) and it changes shape – let it go and it returns to it’s original shape. How many times it can do this is a concept called “fatigue” which we will discuss later. You can imagine though, that if something were entirely (or almost entirely) elastic in nature – like an elastic band, it would be of little use for making things out of – it would not be stiff enough to resist any loads imposed on it, it would just bend all over the place.
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Old 08-22-2003, 05:35 PM   #23 (permalink)
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Billa (from the podium).


You can get much of the same benefit of TTY (more consistent clamping) in a series of conventional fasteners by getting them snug and then angle-torquing, right?

...once you cross that critical line of where stress is proportional strain, and get into plastic deform....do you not lose sig. clamping force?
Dunno. I'm not sure that bringing a fastener to yield decreases the compressive force (depends on the fastener, perhaps?). Interesting discussion.

More specifically -- is post-yield clamping necessarily smaller than pre-yield clamping? Remember, we're just talking a small bit of plastic deformation, not a full wrench-it-til-it-snaps yield exercise.

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Old 08-22-2003, 06:10 PM   #24 (permalink)
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I done sum checking.

It doesn't make any sense.

Stress = the load
Strain = the change in shape because of the stress.

If you plot a stress / strain chart (stress on vertical axis, strain on horizontal) - it's a near vertical line till the yield point, but then a critical thing hapens, once you pass the yield point, the line flatens to near horizontal, and strain increases, despite constant stress. Exactly what you wouldn;t want in a fastener.

Therafter, you;re in the "plastic range", and very small increases in stress (as might be encountered as the bolt does its job under load) produce large increases in strain...again, just exactly what you would nOT want in a bearng cap or head bolt.

I therefore maintain, thet no fastener is designed to be tightened to the point that it stretches beyond it's yield point and enters plastic deformation....even just a little bit
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Old 08-22-2003, 06:19 PM   #25 (permalink)
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Daymn Billa, you love this shit don't you?

Keep it coming guys, this is some good stuff.
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