Nyloc vs. All Metal Locking Nuts

[cv2065]

I was going through my IRS fastener goodie bag, matching up nuts to bolts and ensuring that there were no imperfections. Found one M14 bolt and metal locking nut that didn't like one another and is now permanently 'stuck'. Started looking on the internet and geeking out on fastener differences. Nyloc looks to be the champ when it comes to disassembly and reassembly, where all metal locking nuts are the champ when it comes to extreme high temps (+350F) and extreme low temps (-40F), UV and salt resistance, which is why I'm sure FFR uses the latter. Downside of all metal is deformity of the threads and potential galling.

Anyone in all year warm climates switch everything out to nyloc instead of the all metal fasteners provided?

[edwardb]

My experience with FFR's hardware selection and use of distorted-thread locknuts is that they're almost entirely used on major suspension points that are not taken apart and put together very frequently. If at all if nothing is wrong. I personally wouldn't replace them -- and I haven't. Stainless hardware is by far the most susceptible to galling. But I haven't seen any SS hardware they've provided with distorted-thread locknuts. Hardened steel can also gall, but not nearly as common. Pretty simple solution in both cases is to wipe some anti-seize on the threads before assembly. Yes, they sometimes take some effort to thread and torque. Especially the larger sizes. But the threads should remain intact. If you're getting damage -- especially heavy damage and locking up -- I'd check to make sure the sizes are correct.

Nylon lock nuts are "OK" IMO but not nearly as effective. Plus there's the discussion about how often you can really take them on and off before they lose their effectiveness. My personal build practice is I have a supply of regular non-locking nuts that I use for mocking up and initial assembly. I try to use the nylon locking nuts only one time during final assembly. Overkill, but can't hurt. For the airplane build I'm doing right now, the build manual comes right out and says they're one-time use.

[dbo_texas]

My experience with FFR's hardware selection and use of distorted-thread locknuts is that they're almost entirely used on major suspension points that are not taken apart and put together very frequently. If at all if nothing is wrong. I personally wouldn't replace them -- and I haven't. Stainless hardware is by far the most susceptible to galling. But I haven't seen any SS hardware they've provided with distorted-thread locknuts. Hardened steel can also gall, but not nearly as common. Pretty simple solution in both cases is to wipe some anti-seize on the threads before assembly. Yes, they sometimes take some effort to thread and torque. Especially the larger sizes. But the threads should remain intact. If you're getting damage -- especially heavy damage and locking up -- I'd check to make sure the sizes are correct.

Nylon lock nuts are "OK" IMO but not nearly as effective. Plus there's the discussion about how often you can really take them on and off before they lose their effectiveness. My personal build practice is I have a supply of regular non-locking nuts that I use for mocking up and initial assembly. I try to use the nylon locking nuts only one time during final assembly. Overkill, but can't hurt. For the airplane build I'm doing right now, the build manual comes right out and says they're one-time use.

Airplane build? Now I'm curious :)

[cv2065]

For the airplane build I'm doing right now, the build manual comes right out and says they're one-time use.

Agree on FFR's selection of hardware. I don't plan on changing anything but have read a few others that have. I forgot you were putting the plane together. Would love to see the progress!!

[edwardb]

Airplane build? Now I'm curious :)

Talked about several times in my truck build thread. Most recently: https://thefactoryfiveforum.com/showthread.php?37287-EdwardB%92s-35-Hot-Rod-Truck-Build&p=542952&viewfull=1#post542952.

Some months ago: https://thefactoryfiveforum.com/showthread.php?37287-EdwardB%92s-35-Hot-Rod-Truck-Build&p=524710&viewfull=1#post524710

And more info that you could possibly want to know: https://thefactoryfiveforum.com/showthread.php?45961-My-Journey-to-the-Next-Project-Sling-TSi-Build

[Mike.Bray]

My experience with FFR's hardware selection and use of distorted-thread locknuts is that they're almost entirely used on major suspension points that are not taken apart and put together very frequently. If at all if nothing is wrong. I personally wouldn't replace them -- and I haven't. Stainless hardware is by far the most susceptible to galling. But I haven't seen any SS hardware they've provided with distorted-thread locknuts. Hardened steel can also gall, but not nearly as common. Pretty simple solution in both cases is to wipe some anti-seize on the threads before assembly. Yes, they sometimes take some effort to thread and torque. Especially the larger sizes. But the threads should remain intact. If you're getting damage -- especially heavy damage and locking up -- I'd check to make sure the sizes are correct.

Nylon lock nuts are "OK" IMO but not nearly as effective. Plus there's the discussion about how often you can really take them on and off before they lose their effectiveness. My personal build practice is I have a supply of regular non-locking nuts that I use for mocking up and initial assembly. I try to use the nylon locking nuts only one time during final assembly. Overkill, but can't hurt. For the airplane build I'm doing right now, the build manual comes right out and says they're one-time use.

Edwardb is spot on here with everything he said. Definitely want to use anti-seize with any kind of locknut, especially stainless steel. And never use an impact wrench on a locknut.

IMO distorted-thread locknuts are superior to nylocks. Nylocks are definitely single use.

Just don't lose sight of locknuts and safety wire are meant as added insurance, not to maintain clamping force and torque on a fastener. Hook's Law is what keeps a threaded fastener tight. https://thefactoryfiveforum.com/showthread.php?42292-Why-the-Torque-Wrench-is-Your-Best-Friend

[ggunter]

Both the nylon and the prevailing torque lock nuts have their place. As said before the nylon works well up to about 350 degrees and then the nylon starts to run out of the nut. However, the nylon does a much better job sealing out water to keep the assembly from rusting and there for making disassembly easier. The prevailing torque nuts, (metal distorted) temperature really doesn't bother them, but the distortion of the nut allows water to penetrate the threads and rust or seize. Flip a coin.

[J R Jones]

No mention here of Loctite as an alternative? It lubes the threads during torque which is obfuscated by locking technology, and Loctite can seal the threads from corrosion.
BTW interference thread locking cuts through the fastener plating.
jim

[Jeff Kleiner]

No mention here of Loctite as an alternative? It lubes the threads during torque which is obfuscated by locking technology, and Loctite can seal the threads from corrosion.
BTW interference thread locking cuts through the fastener plating.
jim

With a caveat---Locktite melts the plastic on Nyloks...so don't try using it on them.

Jeff

[cv2065]

Another thought was around Grade 10.9 flanged bolts verses 10.9 bolts with 10.9 washers. Using the same 10.9 locking nut, is there a difference in clamping effectiveness between the two? FFR uses almost all flanged nuts and bolts for control arms, etc. Is this just a convenience to minimize parts inventory or is there more to it?

Interestingly enough, my local ACE Hardware carries 10.9 flanged nuts and bolts all the way up to M16-2.0 in a variety of lengths. These aren’t easy to find.

[CraigS]

I throw out all deformed metal nuts. Just refuse to use them. I don't consider anything to be permanent and have no interest in taking something apart and finding the bolt is damaged enough that I don't feel good about re-using it. If I have a situation where neither nylock nor loctite are good, I use double plain nuts. Torque the first one normally, run the second one on and use two wrenches to tighten it against the first one. CV I also like the flanged nuts and bolts but on my FFR the only metric fastners are the two rear IRS diff mount bolts. The others I replaced w/ fractional bolts. There is only a few thousandths of an inch difference between 16mm and 5/8. 16mm = .629 inches. 5/8" = .625".
I have spent 90% of my life working on metric cars so am definitely comfortable w/ the system. But I prefer the FFR to be all fractional except those two bolts.

[David Williamson]

I am with Craig on the deformed thread lock nuts, don't like them and avoid them. I have had to drill out too many broken bolts over the years on other cars because of them. On our cars the only place a nylock will not work is the header to side pipe (not including engine/trans parts) and I just use regular bolts and nuts. I use the supplied fasteners from FFR most of the time except for a few that were too short.
David W

[cv2065]

On the all metal locking nuts, adding anti seize to the threads really helps. Slowing down the wrenching speed also helps, as the nut has a higher chance of galling as it heats up.

[Mike.Bray]

Using the same 10.9 locking nut, is there a difference in clamping effectiveness between the two? FFR uses almost all flanged nuts and bolts for control arms, etc.

No difference. Clamping force is from stretch, Hook's Law.

[Hoooper]

I have never had a deformed nut cause issues on removal, sounds like an installation error. Maybe those lubricating the bolt with antiseize and then torquing to the dry bolt torque spec are having issues with deformed thread nut removal because they are overtorquing by 40% :eek:

[cv2065]

I have never had a deformed nut cause issues on removal, sounds like an installation error. Maybe those lubricating the bolt with antiseize and then torquing to the dry bolt torque spec are having issues with deformed thread nut removal because they are overtorquing by 40% :eek:

Good point. Ideal tightening torque for a lubricated 10.9 M16-2 bolt is 173 ft/lbs and for an M14-2 is 111 ft/lbs, so at FFR's recommended 100 ft/lbs, it's all good either way.

[mikeinatlanta]

Another thread overflowing with bad info.

Since aviation is the only place with actual rules, I'll use it as example. Most locking is done with deformed threads but not all. Both get used depending on circumstance. Regarding reusing them, both can be reused, however, the true determining factor is when you measure the running torque of the locking to verify that it is within spec, either new or used. Some maintenance outfits (and airlines) forbid reuse mostly because they don't trust the mechanics to measure running torque. A prime example of this would the lock nuts on jet engine mount bolts. Perfectly ok to inspect and reuse, but I'd guess less than 50% of maintainers do it and instead replace with either new or shop inspected. Even in the world of aviation there is more misinformation on this subject than fact.

A somewhat interesting automotive aside: Ford specifies replacing many (if not most) nuts and bolts after one use, even though the bolts are not torque to yield. They simply do not trust that the average mechanic is competent to inspect the bolt, clean, and reapply the factory thread locking compound, so specify bolt replacement in the service manuals.

[CraigS]

Mike I can definitely see that measuring running TQ would be a good procedure. OTOH, that procedure essentially proves that the deformed metal fasteners do in fact damage themselves when tightened.

[J R Jones]

I do not know about the (huge) aircraft industry but automotive and recreational vehicle industries use pre-applied (dry) thread locker that is not appropriatee for reuse. The pre-apply is a dependable engineered solution that is not as subject to installation error. The chemical is not harmful or an allergen as can be the case with liquid Loctite.
My experience with mechanical interference threads has been fastener damage and I never reuse them, as is the cases with lock washers.
Flange head fasteners are available with a locking type surface feature on the clamp face. I have not seen a comparison of breakaway torque.
jim