I was thinking that the thread was about torquing fasteners.
That should include head and the lug nuts also.

 

Yeah I started it about head bolts and studs, kind of went off about all bolting, then someone had to mention lug nuts and things went sideways ...... OH! That was ME!

Seriously, do you think I can refrain subconsciously bringing in something about my past life.

A brief "my life in lug nuts". In 25 years we only had two cases where wheel studs sheared off. Like two is an acceptable amount. First time all torque wrenches and impact guns went out for calibration and then put on a routine. Second time we started the time-in-service schedule. Occasionally they broke while doing work. And it in all cases it was on Jeep or Chrysler vehicles. The quality of the material chosen for the bolt, and nut, really matters. At the same time of these failures we had other test vehicles (Ford) that were never an issue.

So yes Scott, you can have a long life with studs and nuts if they are a proper quality part. You save pennies at manufacturer and you give test managers ulcers. Especially when its higher grade people driving the vehicle at the time.

Installed rotor runout was a real important aspect of our test builds. Every rotor was measured before and after a test, and some tests that I talked about in the "What" thread were only about rotor runout. And we had very special equipment to measure the rotors.

Within 4 months of the P131 launch warranty complaints were over the trigger point for engineering intervention for brake pulsation. A massive effort for all concerned and the result along with a tightening of rotor and hub spec's was the change in design of the 4x4 front hub flange with more width for better stability. And with the change in the hubs flange and tightening of the bearing clearance spec, the rotor hat depth had to change to accommodate. And that's why the early model hub and rotor differences. Rotor runout in service.

Go back 6-10 years and everyone was dealing with stress distortion of rotors due to lug nut torquing. Steel wheels are really prone to causing this, but aluminum wheels can be designed to have a more even distribution of load. Notice that now just about everything has aluminum wheels - it's not that aluminum is cheap. And that's how we all got torque sticks. And by the way, impact wrench design and supplied air pressure can alter those torque stick outputs.

So as you can imagine lug nut tensioning was also in the mix when poop hit the SD fan on pulsation. It was a real interesting time 'cause with the high scrub radius of the SD's, brake torque steer was also a complaint. To the point that batch control in manufacturing also got a fire, so brake pads were also segregated by batch. (There was a TSB for that). There was also a brake squeal issue, steel wheels only, that rose it's head only with in-service vehicles. It took me a month to figure out the procedure to find that. Friction was not the place to be.

So lug nut torque (stud clamping force) and the pattern was highly investigated due to the rotor thickness variation. Steel wheels sucked, aluminum not so bad. With the equipment that cost two SD's we could see how the SD rotors could get stress distorted. The common service manual method was fine, even with these torques that reach up to 100% higher then many vehicles (80-100lbft).

But there was a better way and it's how I had the guys tighten all SD wheels. All lugs tightened to one level, then the next, then the final. All to 60, then to 130, then to 165 left. The exact value other then the last is not critical, but it evenly compresses the mounting flange of an 8 lug wheel and rotor package.

It's a modification of a cross, my nickname a "triple play". One of my guys called it walking the dog because of the repeated circling. Three steps of torque, every 3rd lug, and three revolutions of the wheel. You don't get lost in your crossing.




So yes the clamping force has some variation in keeping the wheels on. But for those of us who live with brake hardware we are real concerned with rotor stress distortion which will lead to rotor thickness variation and the dreaded complaint of pulsation. And then someone is going to say my rotors warped, as in heat warped, and I'm going to go all "Niagara Falls, slowly I turn..." on ya.

On to other things.......

 

Thanks for the explanation Jack! I always did lugs in two passes to make sure to get an even force. However with the SDs needing a lot higher torque then other vechicles I was used too I went to three. The problem was remembering where I was at so I went back to two. This looks like a neat trick in not forgetting your spot.

Anyway I thought this thread was to discuss bolt/stud, torque, etc in general. I apologize for taking it off topic.

 

I really don’t think anything about fastening should be not included. Thread drift is always a good adventure. Hey, this started in a coolant thread. We can continue with lug nuts. I just started it, I don’t own it.


This is a basic starting point video for some who may follow.



And the second part.


Sean, yes the type of added finish is another one of the factors in the lubrication, or the rabbit hole of friction.

Pete, I agree the results of ARPS lube is remarkable. On ARPS site the only chart I found is the torque requirements of bolts with the lube, but the lowest grade bolt is SAE 9!

 

Jack I think we are past Rabbit Hole theory and into Worm Hole theory.

You never know where or when your going to pop out.

 

Actually I like threads like that, although I know those who are looking for specifity don’t see it the same.

I would love to see these type of bolts as engine head bolts. I think we would have a much more reliable clamping of the heads. It was a vid done by the company to show the variability of using torque as the methodology for clamping loads. Every time I wander into the ASTM area I think those guys are ahead of the curve compared to auto. Bridges, piping, whatever.

But here’s the curve ball (sorry Pete), pretend it’s not a pipe flange but one of our wheels being installed and the stresses of the rotor clamping. They are using a standard cross, 8 fastener pattern for the initial stepped torque, then around the world for the last sequence.



However, it’s the same with 6.0 heads. As we go through the process, bolts that are being tightened are lessening the clamping force of other bolts when using the torque value method.

The rabbit keeps digging.

 

Ford, Nav, et al have the resources to use ultra sonics and other means to measure bolt clamping loads and come up with the tensioning procedure and pattern for even clamping force, but with studs we alter force measurement by using torque rather then preset torque and rotation. Rotation is their means of eliminating the widest variable, friction. The ASTM guys commonly note that torque as the control causes a 25 to 30% variation in clamping force. And this is why ARP demands the use of their lubricant and keeps coming up with improved lubricants. But as Pete noted, there’s no great resources for us to determine how to use that product with non-ARPs fasteners.

Here goes the wheel end experience again. You guys probably wish I was an engine or gasket guy. Back in the 90’s when we were hip deep in rotor investigation our noise engineer used a film to look at the contact forces in the clamped region. I remember it was also used in engine investigation. Just thought I’d through this in the info mix. I would love to see this with our heads.

 

Digging still... So the Fuji Film would be great for say: verifying calibration of the Head Torquing Robots at the engine assembly plant, along with sample checks for deck and head trueness of the parts coming in.

But you have to pull the thing apart to see the result! So while it makes sense in a mass assembly process, can you imagine doing this on your own heads, and then saying: yup, that Would've been, a perfect seal -- now let's see if we can do it again without the film...

-Scott: aka: one of your rabbit friends...

 

Yeah it’s not an in process checking tool. We used to understand the contact stress pattern using the bolt up sequences until we found what we needed.

So with heads, lay on some film, follow the cross pattern and steps, pull down see how it worked out, and if good put it in the service manual. I’d not, change your pattern. The video of the flange to me was interesting as when it was done there wasn’t even tension on all the bolts, based on the readings from the bolts.

God I go with lug nuts again .... after doing my triple play as just a normal action just about all of us would do a round the world to make sure all were to torque. It was instinctive but really was useless. All of the nuts final step was a dynamic friction to 165lbft. Either by education or pushing a boxed refrigerator across the floor we know static friction is higher then dynamic friction. Like a mule it takes extra work to get it to move. So we just dynamically set the bolt/nut to 165lbft and say 20,000lbs clamping force for that one nut. The recheck to 165 again is meaningless as static friction may be taking up 20-30lbft of the reapply and the nut clamping force is really 16,000lbs.

I’m just grabbing this chart quickly to illustrate.




I’ll have to go back and read what this chart is really about later. But I think A is first snap, B might be crackle, and C pop. Then we go dynamic.

Now in a head situation with long bolts you also have a twisting component. Actually you would even have that with a stud, too.

Later ....

 

Here are four good on-line references in looking at fastening with an engineering swing.



Fastenal had provided a really good source and for me it's not that hard of a reference.

https://www.fastenal.com/content/fed...t%20Design.pdf



Another good resource with an index so yo can search for topics.

Bolt Science Web Site



For me this is a good paper and goes through several issues with finishes and lubricants without overly burying you.

http://projekter.aau.dk/projekter/fi...s_of_bolts.pdf



And last I feel like I'm talking to my friend and past director.

https://mechanicalc.com/reference/bolted-joint-analysis

 

So with all the videos Jack posted how practical from a cost and strength stand point would it be to work in a go/no go indicator for clamping force in a head stud?

Maybe ARP and the rest think the lube and torque are repeatable and reliable enough but seems we are still talking about such things.

 

We as a group have talked about how successful ARPs lube is in consistency, and it has a lower coefficient of friction which is why the torque value had to be lowered to prevent yielding the studs. But there is another aspect to that. Jacob Mortensen talked about this in his bachelor degree project under the friction area, 2.2.4. There are cases where low friction lubricants that remain and are low friction (his paper is one of the few that indicates friction in the threads and under the head) can in time with vibration (and thermal cycling - my input) loosen. So since we have situations of gasket failure after studs, could some of the ARP fasteners have loosened in time due to the lubrication? Anyone check? . Although any discrepancy could also be improper install, inconsistency after the last step (Maxbolt vid reference), or head gasket compression due to thermal cycling. Rabbit hole.

The Maxbolt isn’t the only fastener or method of directly or indirectly measuring clamping force. The washers are used as indicators for install by either popping a colorant (onetime only) or by checking with a feeler gauge (no idea one time or multiple). But Valley Forge also has another modified fastener, which it seems would be acceptable under high heat discussions, and has a means of in process checking. But I would imagine these would be very expensive, where ARP studs are easily incorporated into the market with a slight sting.

https://www.vfbolts.com/casestudy/16...eat-exchanger/


Edit - wheel end again. Notice in the heavy truck and transit fields that indicators are more and more used to indicate any backing off. I could link, I won’t. Head bolts or studs and their corresponding mounting surface should be marked with a high temp marker so with any visual inspection you can tell if they have moved. Markings don’t have to just be used to indicate it’s been tightened stretched.

 

I use to use Dykem Cross Check. It comes in pretty colors! I don't have the access to it anymore so my last tube dried up.


For stud jobs going bad I believe it comes down to improper prep (surface & threads), improper install (seating the threads and installing studs hand tight only), and/or inaccurate torque.

 

Temporary teleportation from the Rabbit Hole.

We use a lot of witness markers in the aviation field.
You can find a lot of mechanics that like and use the
paint type stuff in work that they do. But that tends
to be cold locations if safety wire is not used. Hot locations
the only real reliable option is wire. What a PITA that
would be to wire a head bolt set. They would also need
to be drilled before hand, I did see a lock set that uses an
Eclip to hold the locking tab on the fastener. But that
brings to the other issue special fastener. Back to the Rabbit Hole.

 

I’ve got several types, but here one that just bought if I ever get internal on my driveway anchor. It’s rated for 800°F so it might be fine. Yeah, I wouldn’t want to wire up heat bolts. It’s also what we used to mark rotor and brake pads. Yeah, there’s that brake thing again.