jonbearman said:
My brother and I use ARP fasteners in all our engine builds if possible.There cylinder head studs are second to none.Even a light machine oil like 3 in 1 machine oil is better than nothing.The arp is a bit much on a gun as is sticky too boot.LOL
+1 on ARP fasteners and the lube they supply.
Back before I retired my employer got interested in fastener friction coefficients unlubed and with various thread lubes and was kind enough to allow me to fund about a quarter of a million dollars worth of friction coefficient testing over a period of 7-8 years - sometimes just the fastener bill for one series of tests would run $18,000. Fastener surface finish plays a very important part in the friction coefficient, and while 3in1 is better than nothing, it's not better by much, unfortunately. Common oils (3in1 and similar, motor oil, etc) and automotive greases (chassis and bearing greases) make initial take up feel smoother, but once you get beyond about 20% of the specified preload, they don't have any positive effect. The reason is that the pressure additive packages in machine/automotive oils and bearing/chassis greases is not the type of pressure additive package needed for fastener assembly - a slight exception is automotive grease fortified with molybdenum disulfide, although the % of MoS2 in these greases is still lower than we would like for use as a thread lube. What works great as thread lubes are antiseize compounds, because their pressure additive package starts out with microfine pressure resistant ball bearings, usually in the form of graphite or MoS2, plus a ground up microfine metallic element usually in the form of aluminum, zinc, copper or, until the EPA cracked down on them, lead. The Holy Grail with any bolted joint is, within the limits of the joint design and material selection, high initial preload and minimizing fastener to fastener preload variation in the joint. Antiseize based thread lubes do this as well as it can be done - MoS2 based thread lubes have the lowest friction coefficients, but graphite based thread lubes generally have less fastener to fastener preload variation and their higher friction coefficient isn't a problem, it just means that the applied torque is higher than with MoS2 based lubes to get the same preload; both are way better than unlubed or machine/motor oil or lithium automotive greases used as thread lubes. Generally, the antiseizes have 12/15-20/25% graphite or MoS2, another 15-25% metallic additive, one or more other compounds like calcium hydroxide and zirconium oxide and as many as half a dozen other choices that can be slipped in in small %s (these will be listed as "proprietary substances" on the publically released MSDS sheets) and about 50% oil or light grease carrier. Incidently, these antiseize compounds make good lubes for the bearing faces of the lugs on our bolt actions for one of the several reasons thay make good thread lubes - they prevent galling. If you want a little less viscous lug lube, cut the antiseize with a little gun oil.
When you test for friction coefficient in bolted joints with normal household or automotive oils and greases, including teflon fortified greases, you will find that the friction coefficient is much higher than with antisieze compounds. Not only that, but the mean friction coefficient for any given material combination (and the extremes) and for unlubed fasteners is essentially the same! (remember, we're talking here what happens when you approach the target preload, not what it feels like when you are running it up for initial snug prior to tightening). When using household oils, automotive oils, or automotive greases, the surface finish of the particular lot of fasteners can have more influence on friction coefficient than the thread lube. We ran one series of tests using a specific lot of alloy steel fasteners unlubed and then duplicated the test series a few months later using alloy steel fasteners from a different manufacturer's lot and motor oil and got numbers that were slightly higher for the lubed fasteners than those for our previous test with unlubed fasteners!! That would never even come close to happening using a graphite based antiseize compound.
We commonly tested the following male/female material combinations: alloy steel/alloy steel, CRES/CRES (Corrosion Resistant Steel, Pentagonese for stainless steel), monel/monel and Kmonel/monel, and sometimes titanium/titanium. Alloy steel/alloy steel is the best behaved and shows by far the least propensity for galling, stainless/stainless gets into galling easily and needs an antisieze to keep you safe from galling, and the other combinations don't show up much in firearms, although we can see Ti/Ti occassionally - Always use antiseize with titanium on titanium as that combo is really, really prone to galling, to the extent that most quality Ti fasteners are supplied with a baked on lube to prevent galling unless the customer specifies otherwise.
A final thought; there are actually 2 major sources of friction in a bolted joint, the flank engagement of the threads, and the friction between the bearing surface of the bolt or nut and the clamped material, so when lubing action screws, to be procedurally correct, you need to lube the threads AND the bearing surface of the head of the screw.
And a last piece of fastener goon trivia: in round figures (it can very a few % either way) 90% of the energy put into tightening a fastener goes into overcoming friction and only 10% of that energy goes into stretching the fastener, which is what gives you the preload. Which is why torques given for unlubed or motor oil lubed fasteners need to be reduced significantly if a proper (antiseize type) thread lube is used. The percentages stay the same, but the required energy input is a bunch lower with a proper thread lube.
