Anti-seize / thread-locker

[Lyle O]

MY apologies if this is a dumb question, but is there any "rule" as to when to use anti-seize or thread-locker compounds on fasteners? Is it strictly case-by-case? What criteria should I use? Engine/tranny? Steering/suspension? I am not a trained mechanic, so maybe this is handled in "basic training", but I want to do it right and am afraid there are a few bolts on my car where I should have used one instead of the other, or used nothing when I should have used something (found that out today)...TIA everyone...

[Robey5]

Lyle:

I do not think that is a "dumb" question.

Thread locker is a material that would typically be used on a bolt that is under constant load that has a possibility of backing out over time because of cycling.

Anti-seize is a material that is typically used on a bolt that is in an area that over time is going to see a fair amount of corrosion.

My examples are:

Thread locker is used on a CV bolt, where a bolt is relied on to transfer a torsional load from the CV shafts to (ultimately) the wheels.

Anti-seize is used on an external bolt connecting the exhaust system (heat cycling, and road debris, etc) so that you can remove the bolt after a lot of the "elements" get to it.

These compounds are not used on every bolt, pay attention to the fasteners that are used when you pull apart something and you will see the applicable material to use.

I am sure that there are other applications and other people who are much smarter than I who will comment, but these are the typical applications that I could come up with off the top of my head.

Where in "motown" are you???

[Flieger]

Wheel studs and lug nut ball seats get anti-seize.

[Racekar]

Never use anti-seize on the seat of any lug bolt or nut!
The friction of the seat is what keeps the bolt/nut tight and using a lubricant which is what anti-seize becomes will cause the nut to loosen over time.

If you want to use anti-size only put a minimal amount on the first few threads, and it will spread to the rest, never on the seat.

[RWebb]

Porsche's engineers disagree with that and a Tech. Bull. specifically tells mechanics where to put anti-seize on the alloy lug nuts used with Fuchs wheels, as per Flieger's post.

Thread locker can be used on any fastener, and I used to put it on every fastener on a vehicle I beat over every jeep trail and gravel road in Orygun.

Recent studies show that chemical locking compounds work BETTER than general-purpose lock nuts

You can torque any fasteners that need that and then use the wick-in Green Loctite.

I often use Loctite Purple on small fasteners.

[Concestor0]

"Thread locker is used on a CV bolt, where a bolt is relied on to transfer a torsional load from the CV shafts to (ultimately) the wheels."

This may not be a good example of when to use thread locker as CV bolts must be re-torqued after 100 miles or so which will damage the thread locker. Grady Clay and others have some very important info regarding CV bolts in this thread.

[Ronnie's.930]

Originally Posted by Racekar

Never use anti-seize on the seat of any lug bolt or nut!
The friction of the seat is what keeps the bolt/nut tight and using a lubricant which is what anti-seize becomes will cause the nut to loosen over time.

If you want to use anti-size only put a minimal amount on the first few threads, and it will spread to the rest, never on the seat.

Uhhh, no - the torque induced stretch is what keeps things tight (not seat friction) and a lubricant such as anti-seize actually helps this process.

[combatic]

There are lots of rules to keep things from falling off of our cars.

Here is what I have learned over a lifetime and recently while restoring/driving my car.

Advice from a friend who is a motorsports Porsche mechanic-
"If a catastrophic failure will occur if it comes apart then go look up the torque setting" (ie- drive train, suspension, steering, motor), "all else, hand-tight will do"


Torque settings are available in your Porsche mechanics manual or you can google torque settings by size and thread pitch, bolt material and lubed/unlubed-example for steel bolts
*aluminum and magnesium get LIGHTER torque settings! Ask me how I know

Loctite I use it on things I don't want to come apart due to vibration or loading, especially if I don't touch it very often. Rule of thumb- Blue Loctite on small bolts + non-permanent connections. Red- bigger bolts and stuff you don't want to come apart.
Loctite User Guide (pages 4-7)
*as mentioned in an earlier post, parts that must be re-torqued after a seating period (CV-Joints) don't get loctite.
**anti-seize or oil and grease (dirty fastners) void the powers of Loctite (see guide)

Anti-seize Use anti-seize on parts that may corrode and you want to easily get apart. I use it on spark plug threads and lug nuts because those parts are steel and aluminum and galvanic corrosion can occur over time...but I am always fidgeting with the car and checking the plugs and pulling the wheels off. Anti-Seize site & guides

[RichardNew]

Ronnie's 930 is absolutely correct. A bolt is really a spring. Here's a whole article I did on bolts last year for Vintage Motorsport magazine.

Any lubricant you use on the threads will have an impact on the torque setting. Keep in mind that the torque specification is really an approximation of bolt stretch. If you get really precise you tighten connecting rod bolts to a specific length.

Richard Newton
Race Car Images

[Lyle O]

Thanks a lot for all of the input...quite an education. One of the things that got me wondering about this was my spring plate covers; I am installing new bushings there and the cover bolts had anti-seize on them (from the factory I believe). I would have thought they get thread locker (suspension parts, vibration, etc.). Also glad there is the Loctite "Green", so I can go back and add to where I missed . Robey5, glad there there are a few of us around Motown; I'm in northern suburbs (Bloomfield Hills)...

[Flieger]

The clamping force itself is not what keeps bolts tight. It is because the clamping force causes more frictional force in the threads (because of the helix angle multiplying the effect like a ramp) and that frictional force then prevents the bolt from turning. When you have vibrations then the clamping force is momentarily reduced and can allow the bolt to loosen bit by bit.

You torque to the setting that the manufacturer provides, under the conditions the manufacturer demands. Porsche says somewhere around 96 ft-lb with anti-seize so that is what you do. If you don't use anti-seize then you need to adjust the torque up because there is more friction on the threads when tightening, meaning that it takes more torque to reach the same stretch (directly related to clamping pressure).

[cgarr]

I always thought is was tensile stress when tightened properly that kept bolts tight? That's why they discontinued the use of pal nuts on engines, not needed.

[Bob Kontak]

Originally Posted by cgarr

I always thought is was tensile stress when tightened properly that kept bolts tight?

Interesting thread. Here's an excerpt from the below link:

The act of tightening a bolt engages several different types of mechanical force that help the resultant joint remain secure. The main forces generated by bolt installation include:

Clamping Force: This is a type of compression that the bolt applies to the joint, holding the two components together.
Preloading Force: Turning the bolt causes the threads to engage and stretch, which produces the preload force that keeps the threads in place.
Shear Force: The shear force is the transverse pressure working against the bolt in a perpendicular direction. It can be present alone or in combination with tension force.
Tension Force: Tension force applies to the length of the bolt, providing pressure along its vertical dimension, rather than its width.


How a Bolt Works

[Quicksilver]

To learn a bunch about fasteners start by getting a copy of Carroll Smith's "Prepare To Win" and if you want more pick up his "Nuts, Bolts, Fasteners, and Plumbing Handbook".
Pretty much everything that Carroll Smith wrote should be on any car junky's bookshelf...

One thing not mentioned here is the type of antiseize. The aluminum based stuff that is found at pretty much any auto parts store is close to junk and is useless on exhaust systems. Spend the time and find some copper based antiseize. It is WAY better and will actually help keep exhaust components from rusting together. Put some thought into its use as copper based antiseize can damage an OČ sensor more then the aluminum stuff.
Pelican has tubes of copper based anti seize but I prefer the Loctite copper Quickstix. I doubt there is a performance difference other then the packaging/delivery method.

You can also get nickle based antiseize that is good to higher temperatures then the copper. I've never actually seen the stuff but if I was running a turbo I would definitely give it a try.
If you look on the internet you can find it pretty easily.

[Lyle O]

Good point on the type of anti-seize, thanks for the recommendation. Copper is not too easy to find; I went to 3 different auto parts stores and no luck. Finally found at a NAPA store (though Amazon has it).

[porterdog]

FWIW in a recent thread in the Rebuilding forum chris_seven posted this, which I had never known before:

"In active surfaces such as stainless steel (Dilavar for example) generally need longer cure times before they develop full strength but if temperature is low - less than 5 degC then they may fail to set.

Henckel generally recommend the use of a primer or activator with this type of material.

Activators also have another important feature that when they are used to coat the stud they also provide reasonably good electrical isolation which prevents galvanic corrosion.

The more passive the stud - stainless steels, Inconels etc the more likely there is for corrosion to occur in the reactive metal of the case.

The thread locker does provide some protection in this respect but using a primer will eliminate risk almost entirely.

We always use a primer for this reason. The cost is low and it can be brushed onto the thread and allowed to dry before using the thread locker. We also use a low strength locker which also generally has a lower viscosity." (emphasis added)

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