Loctite... Yes or No? + Torque Specs!

Seems like most of the videos on youtube of folks installing their Westcott (or other) lifts show them adding red loctite and then giving a full send to the nuts/bolts when reassembling the suspension...

If you are actually taking the time to torque the nuts/bolts properly, is any form of loctite even necessary?

Outside of my Harley (where loctite is your friend), I've always gone by the "if the bolt you pulled had loctite on it, put it back that way" thought process, until I realized that not all residue on factory bolts is actually loctite, it could be some other sort of anti-corrosion, anti-seize product.

UPDATE:

adding the torque specs for the suspension parts fiddled with during Westcott install… Thanks to @Brums & @TakiEvo for the help compiling the list.

 

I like it, but not red, blue - medium strength. There are no contraindications I can think of. I don't put it everywhere on the truck, but places of consequence.

 

well none of the repair articles that are in TIS say to use thread locker...

 

I don't know why I didn't think to as you for that info first haha... But this is great to know...

I think I'll just torque dry and hit anything I've touched with a paint marker to check after 100, 500, and periodically after...

 

I won't claim to be an expert, but in my experience, I've always been told that for bolts which need to be torqued, both the female and male threads should be clean and dry. Anything added to the bolts will interfere with the threads working as designed and you will not achieve the proper torque value (even though the torque wrench may indicate that you have). In other words, the torque values are arrived at by calculations based on clean, dry threads.

 

there are exceptions to that, such as ARP bolts, alot(if not all) of their cylinder head bolts and the like all require a lubricant before torquing

https://arp-bolts.com/p/arpultratorque.php

 

Hi Brums - Yes, you are right! - I should have included the caveat "unless otherwise specified".

 

I've always added thread locker on suspension components. I usually use blue for things like the top hat bolts, etc. If it's a high stress application then I use red for things like spindle bolts, etc.

My school of thought is this: The TIS/Service Manual rarely calls for it, but they write out the TIS specs it's based on the original engineering design. If I'm adding suspension components for a lift, then I'm beefing up my suspension for a reason. That reason being because I want to take my truck beyond the stock capabilities. I'll be putting the suspension components under a lot more stress, lateral torque, and vibration than the engineers originally intended.

Thread locker is cheap insurance and your friend...when you use it right. Don't be a dunce and coat the entire bolt.

 

Speaking of torque values, I try to do final torque on suspension components with the tires on the ground (mainly those with rubber bushings). But I see youtube pros torque them while up on a lift. Waste of time and effort to try it on the ground?

Tires on the ground It's not easy to get a torque wrench on many components like UCA's.

 

For control arms, if you have chemically bonded rubber bushings like most OEM, on the ground is going to be important. If you are aftermarket with polyurethane, probably not as critical, the two work differently.

 

Bolted Joint Expert here: Senior Design Engineer and Lead Sustaining Engineer for an automotive aftermarket company that works directly with Ford, Ram, Aisin, Peterbilt, etc.

If you are actually taking the time to torque the nuts/bolts properly, is any form of Loctite even necessary? NO

Also, if the bolt kit includes spring "lock" washers it is best to throw them in the trash. Literally.

Best bolted joint will have a hardened flat washer under both the bolt and nut. If the nut has a built-in wide flange (usually also serrations) it is best to hold that nut stationary and rotate the bolt head side with the flat washer.
Loctite requires Iron Oxide molecules to fully cure, and many times that is not actually available (think about an aluminum transmission with a coated bolt). In those cases you need to use the green spray primer in order for Loctite to cure.
However, the goal is to get the bolt tension to 60-90% of the bolts Proof Strength. I aim for 75% Proof tension in my designs. You won't know what that value is without performing torque-tension testing which helps determine the joint's "K-Factor" which is a unitless representation of the friction coefficients. The Proof Strength is determined by the cross sectional area of the threaded bolt and its' Ultimate Tensile Strength (think Grade 5, Grade 8, 12.9). If the bolted joint is above 60% Proof Strength you are safe against loosening. After the Engineer analyzes the Torque-Tension of the joint with regards to the bolt strength they will provide you with a recommended Torque to achieve that tension value (with some scatter involved in reality). If the bolt is "boggered up" and hard to thread together by hand, much of your applied torque will be lost to that friction and not get converted to proper tension. If there is a prevailing torque of say 5 ft-lbs just to run the nut down, I would add that 5 ft-lbs to the final torque applied.

Loctite use on Harley's? If it makes you feel good, go for it. Racing vehicles also use lock wire to ensure brake rotor bolts don't back out, so there are exceptions to everything.

 

I stumbled across the installation instructions from Toyota for the gen 2.5 TRD Pro suspension install, and the only front parts it specifically mentioned to torque once on the ground was the sway bar bolts and lower strut bolts (if I recall correctly). The lower spindle bolts and the top hat bolts were torqued still in the air... As for the rear, only the lower strut bolts there too. There might have been something mentioned about the track bar too, I'll have to try to find it again.

 

So... I've was taught (early in life) that suspension items needed to be re-torqued after driving a certain distance on newly replaced items. Is there truth to this, or was it just a thought/technique that was passed down through the years, and it's not necessary?

 

IF those parts were installed using a Loctite, you should not touch them again because you will "break the seal" of the Loctite. It is never a bad thing to be safer than sorry, BUT if you applied the proper torque the first time there will not be any reason for the bolts to have stretched and cause anything to loosen. You SHOULD re-torque items that are held together with gaskets in between because the gaskets do compression set to a smaller thickness with time. That would also apply to the top hat of the shock if it has a rubber base.

 

Recommended text, journal articles, white papers, etc? I've accumulated a variety of sources but, like greases and oils, find this topic to be difficult to get a good 'go-to(s).' Have had enough to get by for all designs and past FEA work but would like more definitive sources.

Separate question - can you rank, or quantify, importance of various contact interfaces? Clean threads are a given, but what about bolt head-to-part vs nut-to-part vs part-to-part? I just powder coated my calipers and did not mask off bolt and nut interfaces but did did mask off part mating interfaces. Major mistake and I should clean them up before rebuild?

 

I appreciate the detailed response. I'm going to go ahead and leave the loctite out of the equation and just torque everything to spec... I'll mark everything I've touched with a paint pen and keep an eye on them at the 100 and 500 miles marks, and periodically beyond that...

As for the Harley, I should clarify that I only use it on the parts in which it was provided by Harley in the parts packaging... The first time I didn't, the rear exhaust bracket bolts worked themselves out at some point during a trip and that sucked ass to deal with...

 

This is pretty extensive, a bit of overkill in some areas in my experience. But it is for a nuclear submarine.

 

The SAE J174 is the tension-torque testing procedure we use, but there are other more detailed and specific than that, such as the ASTM F606. I took a Seminars for Engineers course a few years back that was excellent, and I would highly recommend it: https://seminarsforengineers.com/seminars/fastening-technology-boltedscrewed-joint-design/

Under head friction is slightly more important than the cleanest threads. Paint under the head of bolt should be "slippery" enough to not cause a concern. If the paint breaks off as you torque the bolt down, just pull the bolt back out, clean the hole of paint cracks and do over.

I guess there is another reason Harley bolts like to walk out.... our Toyota metric threads have a larger root radius

 

This is all just a bunch of jibberish to my brain hahaha... I'll take your word for it!

 

Guys, perfect. Thank you. The PDF looks to be a good read. And here I was thinking of underhead friction in the inverted sense. I actually made this scenario better as have lowered the stiction coeff giving to a more effective torqueing. Goes back to your statement about loading the bolt with flat washer instead of the serrated nut.

 

Where thread locker is useful is with small bolts where I cannot rely on torque alone and usually they are torqued in inch lbs of less than 20.
Even wheel nuts which are subject to a good deal of vibration are not done with a locker and if anything it is best to use an anti-seize compound.

 

I know this thread has been sitting for a while so sorry to revive it, but I have a question about the op, the info given is partly the reason I found this site and joined but I have a question about it. I've been looking for torque specs for the front sway bar, both the 4 bolts to the frame and the end links. The listed torque in this post is 111ft/lb, is that for the 4 bolts to the frame? Or to the end link? It was my understanding that the end link torque should be snug but not super tight, but on another site I found specs for 2nd gen (which may or may not be correct) that listed 111ft/lbs for the top end link torque, which seemed pretty tight to me. There's a story behind my quest for these specs, I don't want to go into it here and hijack this thread so maybe I'll create another thread and post the link here.

 

Working on heavy trucks and hydraulics for years loctite has its place but I didn't use it on my wescott lift proper torque is everything. I think wescott is cya because most guys at home won't have a nice snap on digital tourqe wrench , or torque adapters for the hard to reach nuts.

In my industry really the only thing that's torqued and re tourqed after running is wheels because of the huge saftey concern involved in a wheel off situation, u bolts because they stretch also they settle, lastly kingpins on certain trucks again they settle.

Loctite is used in my shops for permanent stud securment in , hydraulic motors because of extreme vibrations cycles and size of the bolts , and when we have to convert a stripped allison transmission filter housing to studs.