TheSamba.com :: View topic - Lock this thread: Red, Blue, Green? What? Where? When?

Thu Feb 12, 2009 10:26 am

I'm getting some of the last of my supplies for my rebuild. It's bad enough that there are a zillion sealants out there, each with it's own serious advocates. I'm still trying to sort that out. Kuril vs Gascacinch, Yamabond vs Loctite - it goes on. I may start a thread for this topic as well, but I hate the sight of blood.

Anyway, one supply that has me flummoxed is thread locker. No manufacturer seems to follow any particular color code and even within specific companies and color hierarchies, the color code is not always the final word. And why are some products so damn expensive and others relatively cheap?

And it's not clear to me where, in the assembly of the Waterboxer, thread locker is essential, optional or detrimental. From my patchwork of info, the only hard rule I've found is that one should not use any kind of thread lock on rod bolts as it interferes with setting torque.

If anybody out there has some insights, that would be great.

Thu Feb 12, 2009 10:51 am

Good topic, bad title.
Let's see, thread lockers are used where a bolt could be loosened, like by vibration, or it's used to seal a bolt or nut from leaking.
They are typicaly graded by hardness, heat, and pressure.
That's my basic answer, I usually just follow directions and use it were it's called for.
My rule of thumb is I've a 50% chance of forgetting something and then having to loosen anything I've used loctite on.
I think they are used alot in the aircraft industy, Dogpilot?

Thu Feb 12, 2009 11:19 am

Torque ratings are always established with clean, lightly oiled threads, so for things where the right torque is critical, like rod bolts, case halves, head nuts, etc., that is how they should be done. You would do much better investing in even a rudimentary tap and die set so you can chase clean all the threads of reusable fasteners than buying a single tube of any type of thread locker. Properly prepared and carefully torqued, none of these fasteners will ever loosen inadvertently. The only location I use medium strength (blue) Loctite is the flywheel bolts; don't ask me why, I shouldn't but I just do. At some point I'll probably give up on even that use.

I use Loctite Thread Sealer in a few locations, but this isn't a thread adhesive. I o-ring my oil pumps so they have to be installed with the crankcase open, therefore I use bolts to secure the pump; thread sealer on those bolts assures there won't be seepage of oil out those threads.

The reason there are so many conflicting opinions on sealants is simple: they all work. People differ on matters of packaging, application methods, workability and working time, but in the end it's New York Super Fudge Chunk vs Cherry Garcia; you can be passionate about one over the other but you have to agree, they're both yummy good.

Thu Feb 12, 2009 12:04 pm

I agree with Chris that a properly tightened fastener will not come loose on it's own. Properly tightened means that all included threads are properly prepared and torqued to the manufacturer's specs. What causes the fastener to "lock" into place is the inherent "springiness" of the fastener.

When the fastener is properly torqued, it elongates to a specified length. The interference action between the male and female threads as the fastener is trying to return to it's original length creates the "lock" between the two. Ever wonder why lug nuts/bolts aren't thread locked?

Usually, thread lockers (liquid or mechanical) are used in applications where proper torque can't be achieved or in applications where extreme vibration is present. This could be for a variety of reason, but the most common would be when a male fastener is threaded into a softer material, such as aluminum. In this case, the torque necessary to elongate the fastener would/could strip out the threads in the softer material.

Common thread locker, like Loctite blue and Loctite red, has a temperature tolerance of 300ºF (remember this when trying to remove a liguid thread locked fastener). Using these on an exhaust would not be useful. For high temperature applications, an all metal self locking nut should be used. Nylon collared self locking nuts are good to 250ºF.

One other thing to remember about liquid thread lockers is that the male and female threads MUST be free of any oils or they won't do much good.

Thu Feb 12, 2009 2:01 pm

Nope, we almost never use loctite®. We use self locking nuts, with either the plastic inserts or ones that have a slight deformation in the end of the nut to hold for high heat applications. For flight critical items, we have a hole and put a cotter pin through the bolt and a special castellated nut. If fact on turbine engines we use silver plated nuts and bolts to allow them to be removed after the high temps without galling.

Most aviation applications are not bolt into, but bolt through. We like our bolts to hold items in shear, not tension. It sucks when the bolt fall out of your wing, like on a Beechcraft (the only aircraft certified with wing bolts in tension vice shear).

The place where I see loctite® used the most is on firearms.

Thu Feb 12, 2009 2:12 pm

What about silver?

Thu Feb 12, 2009 2:15 pm

While not a huge fan of the stuff, I have found that one of the unintended benefits of most threalock compounds is their anti-sieze characteristics. While they do "lock" threads, I have never had the same sort of difficulty disassembling thread-locked fastners than I have had with just plain old siezed hardware. Tight, to be sure, not siezed.

I would say that rust has been the best threadlocker I've used! :wink:

My guess is that the presence of the threadlock compound acts similarly to the sealant that tencent is using, by helping to keep moisture out of the threads.

I have a friend who swears that there is a flavor of loctite out there that CAN'T be broken free, ("double lockdown brownie"?)- but I have no actual experience with this one. I think there's a seven day waiting period, and a background check involved. Probably out of my price range, anyway.

Thu Feb 12, 2009 2:27 pm

Definitely, any threadlocking compound applied liberally will also seal off the threads, but of course if sealing is all one is after but not locking, then there are products that do that alone. That's why I use the sealer only, in locations where there is oil or water on the other end of the threaded hole. In real high-heat apps, as mentioned there is only one effective solution short of wiring things on, and that is a deforming fastener. The OEM copper exhaust nuts are an example. With a little antiseize on them, too, you might actually remove the nut ten years later without the stud coming out with it!

But I wouldn't count on it.

Best solution to exhaust removal is.... exhaust removal! If you don't want to find it frozen on there permanently after ten years, then climb under there and take it off every five.

I've found that Loctited fasteners loosen up when you apply mild heat to the item, just to a few hundred degrees, which softens the compound.

Thu Feb 12, 2009 3:17 pm

Its a borderline hijack, but here's some additional information on threadlocking, and what is actually happening when you torque a fastener (building on Loogy's response)

Thread friction, underhead friction, torsional losses and threadlockers all combine to reduce net torque on a fastener. See this case study for a good example:

http://www.boltscience.com/pages/casestdy.htm

Note in the piechart that the underhead torque loss due to friction is almost twice that of thread loss. This is because the center of pressure under the head is at a greater radius than the thread pitch diameter. While the frictional forces are for all intents and purposes equal in a uniformally lubricated fastener, the moments they create about the bolt axis are not equal. The moment created by forces acting at the underhead CoP will be greater than the moment created by the forces at the thread PD. Thus the frictional component under the head becomes more influential to net torque than thread friction. So while lightly lubricating threads is important, pay attention to underhead lubrication as well. And to really confuse the issue, heed the instructions in those rare cases when the threads should be lubricated but the underhead surface must be dry. The engineer who specifies that scenario must have actually went to the trouble to figure out net torque - he's controlling the final torque (and therefore fastener tension) primarily with underhead friction.

Since the original question is about threadlocking, it would be useful to know (or be in a postion to quantify) the effect a particular compound has on the applied torque. I'll do some digging and report what I find.

Thu Feb 12, 2009 4:31 pm

Didn't have to go too far to find out some useful info. Same site as above, different page.

http://www.boltscience.com/pages/vibloose.htm

Be sure and check out the video. Since the theory is that transverse motion of the clamped components is what causes joints to loosen, then this suggests thread locking of things like rod caps and case nuts is of little value (I hope there isn't any transverse motion between the case halves!).

So which engine components qualify? You could argue that the WBX waterpump could use threadlocking since the cases are rocking back and forth while the multitude of hoses attached to the pump housing are resisting that motion, all in a plane transverse to the 3 fasteners. I probably would not threadlock the pump fasteners. Alternator brackets would be a good candidate. Exhaust system fasteners - too hot for chemical locking; if you're really worried about losing clampload you could safety wire them. Engine to transmission bolts, that I'd have to think about. Might be less trouble to mark them with paint and watch for any loosening that way. CV bolts - tempting but probably a fatal move considering the propensity of the triple-square drives to cam when removing. Shock absorber bolts - if that's not random transverse motion at its finest I don't know what is.

Thu Feb 12, 2009 8:19 pm

jimbelmont wrote: Be sure and check out the video.
That video of the lock washers was disturbing. The nut undid almost immediately.

What the hell, man?

Thu Feb 12, 2009 10:20 pm

I have been removing split washer from most anything that I work on for the last 30-35 years. Those things are mostly worthless. I also like to use extra thick high strength flat washers under any heavily stressed fastener, they can be bought by the pound from an industrial supplier and are worth the extra money over junky hardware store washers or even the regular thickness hardened washers sold by FLAPS.

I get a lot of my bulk fasteners from wrecking yards, just offering the owner X amount per pound for his buckets of high tensile automotive bolts. It is hard to beat a washer headed bolt. I do use a lot of Loctite in any place where the fastener can't be kept properly loaded or where there is apt to be movement even with a tight fastener. Like 10c I Loctite my flywheel bolts and I do my clutch cover bolts as well.

Loctite often will make a fastener easier to remove in the long run as Loctite tends to prevent corrosion and if needed can be heated to get it to release.

Fri Feb 13, 2009 9:04 am

Like everything, it depends. In my opinion, I don't think a threadlocker will be able to keep a significantly under-torqued bolt from loosening. However, if that bolt does loosen the threadlocker will keep it from falling out.

For that reason, I apply threadlocker to things like the clutch pressure plate, shock mounting bolts, brake caliper, etc. If these things loosen I'd rather they stay in than fall out.

Thread locker also has the previously mentioned ability to seal the threads to keep corrosion out. It works better than any grease as once the anaerobic threadlocker hardens, it can't be washed out. It's a bit expensive for this purpose so for most things I use marine anti-seize.

The "green" style Loctite, the bearing retainer compound, is an extremely useful thing to have around. It is capable of making worn, loose fitting items like new again. It also works as a fine thread sealant.

In summary there aren't any disadvantages to using a threadlocker that I can see. On things like lug bolts that are specifically meant to be torqued dry, or connecting rods that are meant to be lubed with oil, the threadlocker will change the resulting tension of the bolt, if torqued to spec, and shouldn't be used. The most useful thing of all is proper torque, no washers or threadlocker needed; for example, when I did the big brake conversion I didn't use any washers on the pad carrier, nor did I use threadlocker, just a little dab of anti-seize and 150 ft-lbs.

Split washers are pretty marginal in their usefulness, I think. Mostly they just bend out the side and don't allow the bolt to reach proper torque. Flat washers can be useful if the material being bolted is aluminum or thin.

Fri Feb 13, 2009 10:44 am

One important point you all seem to be missing is one taught to me by an FAA-Certified Airline Mechanic.

"The properly crossed thread will never come loose."

:twisted:

Fri Feb 13, 2009 11:06 am

You know, I had previously thought that thread locker was essential for most fasteners. On all of the SPIKE-TV car shows, they always mention threadlocker for everything. Of course, they mention it because Loctite is a sponsor and most of those shows are just infomercials for JEGS and Royal Purple and whoever the hell else is writing checks that week.

Anyway, I think that's where I got it in my head that threadlock was a do-or-die. It's really more of an "I-guess-so".

This has been very informative and put my mind to rest on some issues. On the other hand, the video of that machine jiggling fasteners loose really has me up a tree.

Fri Feb 13, 2009 12:18 pm

Thread locking is more important in an environment like offroad racing where vibration is extreme.

The guy who used to prep Malcolm Smith's race buggy which dominated offroad racing in the late 70s and early 80s used a triple method. Split lock washers, Nylock nuts, and blue locktight on most everything possible outside of the engine and gearbox.

Inside the engine and gearbox is a different world than outside due to the oil on everything and torque specs based on the presence of oil.

Loc-Tite brand started the color coding of the various solutions when they introduced the Blue stuff in the 70s. Before that there was only red bottle/beer-colored fluid. Then they added color to the Red and later added the Green. Their Green is a penetrating solution which one applies after the fastener is tightened. This can't work in all situations, only where the interface between male and female thread is exposed.

Other brands may use different color coding, so beware of its intended use. Loc-Tite Red is high strength for installing studs and elsewhere the thread is not expected to be removed. Their Blue is medium strength for where a component is expected to be removed/unbolted., like shock bolts, bumper cage flanges, oil cooler mounts, seat mount bolts, etc....
The Green is comparable to the Blue in strength. There used to be another low strength version, but I've never used it and haven't seen it for a very long time. I don't even remember what color it was.

Fri Feb 13, 2009 12:57 pm

scobax wrote:

I would say that rust has been the best threadlocker I've used! :wink:

And on that note..... combine rust with a metal self locking thread, and the uneducated shade-tree wrench (like me) may snap off a bolt/stud. (pic of strut bar below)

My question:

Should one assume that when removing an "always replace" metal self locking nut, one MUST anticipate that even if the threads are clean, the nut may bind to the point of snapping the bolt? i.e. take your time. Loosen each one little by little.

I felt so strongly about the perils of snapping one of these bolts, I brewed/am brewing up a web page with musings/images. Just want to know if the above theory is correct.

Sat Feb 14, 2009 12:26 pm

[quote="Vanagon Nut"] scobax wrote: i.e. take your time. Loosen each one little by little.... Just want to know if the above theory is correct.
Well, always take your time. I've never done any wrenching that went better because I rushed it.

Sat Feb 14, 2009 4:26 pm

deprivation wrote: Vanagon Nut wrote: i.e. take your time. Loosen each one little by little.... Just want to know if the above theory is correct.
Well, always take your time. I've never done any wrenching that went better because I rushed it.

I hear ya. :) But I swear. I wasn't in a hurry and the nut turned fairly easily for two 1/4 turns then "snap". :roll: Live and learn. Next time, I'd be sorely tempted to drop the strut bar/lower control arm as a "unit". (this is possible)

I guess my question should have been a warning. Something like:

"Metal self locking nuts may bind during removal possibly causing snappage!" ;)

Sat Feb 14, 2009 4:29 pm

Looks like fouled threads coupled with corrosion are what got you. If the the fastener was overtorqued at assembly it would neck down right around that point where it failed. Its possible you may have been doomed no matter what you did. Turning it little by little would just mean you're shearing it little by little.