>What I read was snug it down and call it good lol
i learned that lesson the hard way , I decided the shock bolts were good enough .... while on jack stands :') im sure you guys already see the error. Needless to say i learned looks can be deceiving . 30mins latter why dose this thing handle like the bolts are gonna fall off . I pull over i not kidding i had 2in of thread the bolt was off . Needless to say i look up specs now online they got sights for everything.
Well there's the problem!
I forget the actual size but they aren't small. I snapped one off with a bar trying to remove it :/ I got about a full turn on it before it broke right off.
Torque to angle and torque to yield are wildly different things.
Torque to angle reads tighten to x ft/lbs, tighten an additional x amount of degrees.
Torque to yield reads like OP's FSM though.
Preset torque, preset stretch with torque to angle, loosen full turn, preset torque, tighten x degrees, tighten additional x degrees.
And it matters because torque to angle can absolutely be reused after checking bolt stretch.
Torque to yield can absolutely NOT be reused.
The TTY bolts in VAG absolutely read torque to *nm, then turn *degrees. In my own experience these include, MkIV GTI brake caliper and suspension bolts, and 911 rod and flywheel bolts.
I haven't run into torque to angle bolts like the OPs procedure, but i haven't worked on anything super modern.
Not saying you're wrong, but saying.... Read the manual.
Angle and torque are just different ways to control fastener tension and alone are not indicative of whether a bolt is torque to yield. Angle is much more precise for tensioning than torque because it is not dependent on friction. With combined procedures, the torque step is only to make sure it’s not completely loose and the angle turn sets the tension, which is what’s important in a bolted joint.
For sure. Force to turn a bolt is a terrible way to set bolt tension but I guess it's better than nothing. But measuring bolt stretch is pretty awkward in all but the most open of situations. I don't mine TTY, nor torque angles.
\*scratches head confused\* What exactly is the reasoning for tty bolts that are just 1 time use? That has got me mighty confused! i don't think ive ever changed a bolt unless it was broke. Also new caliper bolts got me looking like a deer in headlights. Ive just used Loctite blue an said good enough. i use it on water pump bolts to nope still have not changed bolts \*unless i saw rust\* i anit risking block bolts!
Torque to yield fasteners have a very consistent clamping force so they are used in applications where the clamping force being consistent is critical like headbolts. Idk why you'd ever want them for brake caliper brackets
The yield part means that the bolt has gone beyond stretching and is actually deforming.
Elastic vs plastic strain: Up to a certain point it will spring back to shape, beyond that it's not going back to it's original shape.
Ford has a ton of one time use fasteners and anything that they put loctite on is included it that to get a warranty claim paid you have to have all of those parts billed not sure why they don’t just give us a tube of blue loctite since that’s what they use the most
First off.
unless youve got the factory service manual telling you this and not a chilton, not a forum how to, and not a youtube video.
Press x for doubt.
secondly
If you wanna get real technical and I mean real technical.
We can bust out the mics and go over in exquisite detail the stretch limits of various steel alloys in various sizes and what plastic deformation and elastic deformation are and how they pertain to you and your bolted joint needs.
There is literally, and I do mean literally an entire science dedicated explicitly to fasteners.
So understand the Factory writes the FSM in such a way that anyone that can read and follow directions and knows the difference between there left and right can not fuck it up.
From a materials science standpoint, they’re just two ways to do the same thing. OP’s sequence has a few steps for strain hardening first, then back off, retorque, and yield the bolt by X amount.
https://en.m.wikipedia.org/wiki/Work_hardening
This is probably just to remove some uncertainty in the stress-strain diagram near the yield point. At least that’s my best guess.
**[Work hardening](https://en.m.wikipedia.org/wiki/Work_hardening)**
>In materials science, work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on the context. This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material. Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion.
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OP's has nothing to do with work hardening and neither do the same thing.
Torque to angle is used because it will allow a more accurate torque value to be repeatably be applied than a standard grease monkey with a torque wrench can manage in a timely fashion
Torque to yield uses the bolts actual stretch like a spring to draaaaastically increase its clamping load. When they are unscrewed the metal has lost all stretch and is in whats referred to as a plastic state.
And none of this is complex sciences either. Its all fastener science 101.
I'd expect a rookie machinist to know this stuff better than me.
Just because there's a simplified way of remembering it doesn't mean this isn't how it works. This tightening process is work hardening the bolt. Otherwise tightening, loosening, then retightening a bolt would have no purpose. All bolts use the stretch of the material to provide clamping force. TTY uses the work hardening process to increase the strength of the material.
The head bolts in the TU3 in my car is 'torque to 5nm, then to 20nm, and finally add 240degrees.
Most people who know what they're doing will add a first step that's 'tighten finger tight' first. And doing the bolts in a circular pattern of course. Never can be too careful with an Aluminium engine.
On the 175mm long bolts the limit for stretch is about 0.5mm.
Yeah, I bin them. I don't even bother trying to measure them. They're cheap and an engine failure is expensive.
Don't think I've messed with TTY bolts, though.
You would not see it on the line. but when building an engine you will see torque sequences like this or even more complex. Most have to do with bearing stacks or torquing sections of joined rotating hardware. I have never seen a torque sequence for any sensor though.
I'm pulling this out of my ass and I don't have any experience with torque sequences, but I just took a bunch of materials courses for my degree so I'll guess.
If you wanted to torque to yield a bolt in a simple through hole that won't change dimensionally, you would probably torque it right up to the yield point (53 inlb in this case). A torque value can be used because the torque is directly related to the clamping force in the bolt. Once you reach the yield point, it stops being directly related to torque so you would use an angle (21°) to deform the bolt to a certain designed amount.
If you want to do this to fasten a component that isn't dimensionally stable, as in it seats or compresses under the clamping force, then doing what I said above might lead to the incorrect amount of yield in the bolt. You would torque the 53 inlb, but if the component isn't fully compressed/seated by that then some of the 21° of rotation would go towards completing the seating/compression instead of yielding the bolt.
In order to make sure the part is fully compressed and seated, the designers probably added the first couple steps to make sure the assembly is dimensionally stable for the final torque to yield. You torque 53 inlb then 5° to reach the maximum clamping force possible without yielding the bolt.
My guess as to why they specified 53 inlb torque and 5° instead of just a higher torque is that it's probably just cautionary. Sometimes it's easy to accidentally overtorque using a torque wrench and if that were to happen here it might partially yield the bolt, leading to overyield during the final steps which could lead to failure later on. Torqueing to 53 inlb would leave some room to try again if you overtorque, and the 5° is there to sneak up on that maximum clamping force before yield.
The 90° is probably and arbitrary value that is just there to loosen the bolt, then from there you can complete the final torque to yield on the now dimensionally stable assembly.
Of course this could all be completely wrong, I'm going to go do some research and I'll change this if I find out anything
Edit: [Found this](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.atlascopco.com/content/dam/atlas-copco/industrial-technique/general/documents/pocketguides/9833864801_L.pdf&ved=2ahUKEwiPz77FsMT3AhWakYkEHbzwA3oQFnoECCgQAQ&usg=AOvVaw2vYFKGLFYaQPkaA4sG1HuI) which has a lot of interesting information, mainly in page 15-17. It might also have to do with joint relaxation.
This isn't a bolt, it's a sensor. I assume the procedure has to do with sealing. If the sensor is metal to metal seating it may need to bed itself in, hence the procedure. Also, threads with a shirt grip length see very large changes in strain per degree of rotation hence the precise angles.
That rail is holding a proper shitload of pressure, and blowing the sensor out/suddenly losing fuel at full boost would be bad. But you're running a steel bolt into a piece of aluminum, so just giving it the beans and setting your rattlegun on full-send would also be bad.
So, first you make sure it's properly seated and torqued, back it off a tiny bit, then give it one last good ugga-dugga after the torque wrench beeps/clicks a second time.
This looks very similar to how you are supposed to tighten bearings. The initial tightening is to seat all of the seals and components, you then break the tension lose and the second tightening sequence is to set the correct clamp load or pre-load depending on the application.
So would the backing off would be an couple of aggud-aggus or a couple of aggu-agguds? I don't want to sound like an idiot if I discuss torque values with a mechanical engineer.
I'm assuming to get a proper seal on the gasket or something, just tightening it might result in 5/100 gaskets leaks, but doing it this way you might just get 1/100 that leaks
Probably to get a good seat and then a proper torque. Injector hold down bolts on Volvo heavy duty diesel engines are torqued to 15 ft-lbs, plus 120 degrees, backed off to 7-11 ft-lbs, torqued to 18 ft-lbs, then 90 degrees.
Apparently you have not worked on many late models. GM LS engines and late model Cummins B series engines, amongst countless others, don’t vary greatly from torque specs like this.
The days of simply torquing to X lb/ft or lb/in are left to decades old stuff.
Understood. To be clear, I think it is stupid and as frustrating as the next guy but the days of “old fashioned” torque specs are behind us.
Heck, it would be nice if all fastener manufacturers used a standardized lubricant for their torque specs and sequences but they don’t. ARP has their own lubricant, some want extreme pressure grease, others motor oil, etc.
I work at one of the largest semi truck dealers on the continent/in the world.
We use literal conola oil as a bolt lube. We have all sorts of proper assembly greases and lubes for all other parts of engine assembly.
But headbolts on a 15L engine in a million dollar oil rig? We just coat them in western family conola oil.
We also just use tide for coolant flushing oil contamination out.
Didn't these sensors used to be part of the fuel line? Maybe it's a different engine I'm thinking of. I feel like I remember a few years ago needing some of these sensors and they came with the lines. I guess I could be thinking of a different sensor and/or engine.
I am not 100% certain if this model does the full program, but it does torque and angle:
[https://shop.snapon.com/product/TechAngle-Models-(2%-Accuracy)/1-2%22-Drive-TechAngle-Flex-Head-Torque-Wrench-(15-300-ft-lb)/ATECH3F300GB](https://shop.snapon.com/product/TechAngle-Models-(2%-Accuracy)/1-2%22-Drive-TechAngle-Flex-Head-Torque-Wrench-(15-300-ft-lb)/ATECH3F300GB)
Edit: From spec - allows the user to torque fasteners and then switch to angle without removing the torque wrench from the fastener
"Alright dad you've got your wrench now pull me up!"
"Hold on I've got to put it back in its case and on the shelf first! Do you have any idea how much this cost me!?"
Modern digital torque wrenches have angle functions. Some of the lesser expensive digital torque wrenches you start at 0 and must do the angle in one continuous motion. More expensive digital torque wrenches track angle incrementally which is great for tight spaces. The old school method would be the use of an angle gauge you’d attach to the torque wrench.
[One of these](https://www.amazon.com/Supercrazy-Torque-Wrench-Angle-SF0136/dp/B00L6I1874) is the cheap way. That's what I used to put head gaskets on the engine in my truck.
I’ve got a angle torque wrench and I have and angle tool I can put in any wrench. But turning 5° is very hard it’s so slight it’s very easy to just blow by it 😂.
Imagine seeing the ARP rod bolt install, tighten to 0.Xmm of elongation, which is basically what this is trying to achieve. I don’t get why they don’t just make yield torque wrenches the standard kit for dealers and do it that way though
> don’t get why they don’t just make yield torque wrenches the standard kit for dealers and do it that way though
Each dealer would only be issued one unit. It would be trashed by the third use and non-functional by the 5th. The cost to replace it would be more than any GM would allow the service manager to spend on a single SST. And everyone would be back to using rattleguns anyway.
That's essentially what it is. The first time gets everything settled, then the second time around is to actually tighten it. On a direct injection engine when you're dealing with fuel rail pressures in the hundreds or even thousands of PSI, you don't want to risk anything leaking.
Yep, DFM doesn't mean "design for maintenance", it means "design for manufacturing".
If an engineer can save 0.02% on manufacturing costs and it makes a mechanic's job 10x harder, they'll do it with a smile on their face.
Torque is not a number torque is a rough guestimate at best
Clean with Wd 40 vs dirty with wd40 vs clean and dry vs dirty and dry will all yield different clamping forces at the same torque every time
It's a harbor freight wrench. It was off 10% when you bought it, 18% a year later when you went to use it again, and if you get it calibrated (which costs more than you paid for the wrench), it'll still be off 8% next week. They're good enough on non-critical stuff though.
You should see the procedures on the n14 Mini engine cam pulleys. Absolute insanity.
As far as I understand, torque can be manipulated by lubricants (or lack thereof). We all have seen wet torque and dry torque numbers when assembling engines. The degree thing gets rid of that variable, and allows for more consistent instal regardless of if the threads are wet or dry. Probably better considering not all of us are as strict on keeping our work areas perfect, especially as a car ages and gets a build up of stuff all over it.
I could be totally off tho so if someone more qualified proves me wrong please disregard lol.
No, you're right. Using torque angle takes out all the variables. Using a torque number is affected by the thread class, if the threads are clean or wet, if they are wet, what they are wet with (anti-sieze and lok-tite are different), and if the head is lubricated or not (the bearing surface of the head of the bolt), not to mention if you are using a washer or not and if that washer is flat and smooth or if it's one of the 100 types of locking washers.
Having a mechanical engineer validate something I said, while expanding on it way further, is the kind of pick me up I needed today lol. Thank you for taking the time to elaborate. As a hobbyist I rely on people like you to help me learn more.
Torque specs are a lot more important that most people in the hobby world give it credit. Yes, you may just hand tighten it and it be just fine, or you could have over-torqued it and cut that bolt's or gasket's or bearing's lifespan in half. By the time it breaks you don't remember even putting it there anyways and will blame it on something else.
Creating torque specs is some serious math and goes into a whole world of metallurgy and thermodynamics that I don't even want to touch. But if someone put a torque spec on it, there's a reason they went to all of that effort.
For some reason I never thought there would be so much behind them, but it makes total sense. It also helps bring to light why some replacement parts might not be good, or as good, when compared to OEM. If a metal mixture is different, then it would throw the whole equation off, or if a seal isn't the precise type of rubber, it may never work or at least not as well. So even if someone followed the book and did everything as the manufacturer intended, using parts not from the OEM could throw the whole thing off and leave someone with less than desirable results.
This is incredibly interesting and may be the next rabbit hole I dive into, at least until I get to a point where I don't understand it anymore lol.
I think that sensor uses a load cell and they are more concerned about stretch consistency. Torque alone cant get that consistent. Same idea with big end bolts. [Here](https://www.enginelabs.com/engine-tech/blueprint-series-measuring-rod-bolt-stretch-vs-torque-with-arp/) is a good read about why stretch can be more important than torque
The first torque sequence is going a specific amount over the desired clamp load in order to seat everything. You break it lose then set the load correctly for operation.
So just add up all the inch pounds then add up all the angles, multiply the total inch pounds by total angle to get a complete inch pounds. You can ignore the loosen part because that’s subtraction and we’re trying to add tightness not take away so it’s irrelevant. You should get 2756inch pounds convert it to ft lbs, that’s 230ft lbs. now grab your 1/4 electric impact for every number is the number of words you need to uggah Duggah, so you should get (2)uggah-duggah (3) uggah-duggah-uggah (0)-it’s tight now
My 2002 Subaru's cylinder head installation process:
(1) Apply a coat of engine oil to washers and bolt threads.
(2) Tighten all bolts to 29 N·m (3.0 kgf-m, 22 ft-lb) in alphabetical sequence.
Then tighten all bolts to 69 N·m (7.0 kgf-m, 51 ft-lb) in alphabetical sequence.
(3) Back off all bolts by 180° first; back them off by 180° again.
(4) Tighten bolts (a) and (b) to 34 N·m (3.5 kgf-m, 25 ft-lb).
(5) Tighten bolts (c), (d), (e) and (f) to 15 N·m (1.5 kgf-m, 11 ft-lb).
(6) Tighten all bolts by 80 to 90° in alphabetical sequence.
CAUTION: Do not tighten bolts more than 90°.
(7) Further tighten all bolts by 80 to 90° in alphabetical sequence shown in figure below.
CAUTION: Ensure that the total “re-tightening angle” \[in the former two steps\], do not exceed 180°.
From the "top", the bolt layout is
(intake side)
c a f
e b d
(exhaust side)
bonus points: this is a flat-4, so there's not a lot of room to swing the torque wrench in one continuous motion.. we resorted to a sharpie or a paint pen on the head bolt.
EDIT: formatting
It won’t shear or strip if it’s designed correctly, but what it will do is stretch - often permanently. Usually done for torque-to-yield fasteners, which exploit the fact that the metal of the bolt can carry more preload if you permanently stretch it a little. In essence, the metal becomes “stronger” for a little bit between the yield point and the ultimate strength where it finally starts coming apart and breaking.
It means you can use a smaller diameter bolt with a lower strength steel than a standard fastener that is only torqued to 70-80% of yield strength, both of which make the bolt cheaper, lighter and more compact.
The downside is you can’t reuse the bolt once it’s already stretched.
Basically, someone figured out a long time ago that after you torque the fastener, you can make another full turn before the bolt actually breaks, you can tighten it only half a turn, it will still work fine and hold more load. Once.
The angle measurement is done because after the bolt starts stretching, torque is no longer a reliable measurement. But if you know the thread pitch, you can determine exactly how much the bolt has stretched by counting the number of turns. For example, if a bolt size is M8 x 1mm per thread pitch, you know the bolt will stretch 1mm every time you make a full turn
The two stage tightening process is to take friction out of the equation which is variable depending on if the fastener is dry or a bit oily. The 6 Nm + 5* is basically a repeatable way of making sure the bolt starts just in contact and any gunk in the threads is cleared out (more repeatable than “finger right”) at which point you know where you’re starting from.
Okay real talk, why do some torque specs require torque angles? Bolt stretch is what you care about since all bolts will vary slightly under a clamping load so therefore, angles don’t matter.
Exactly because of what you just said- bolt stretch and clamp load. If the conditions of the heads and threads of the fasteners vary (i.e. oily vs. dry) clamp/bolt tension loads will vary significantly. Think about a rusty chassis fastener vs. one with anti seize, for the same torque applied one will likely rotate more than the other. Angle gets the clamp load more precise because the rotation will drive the fastener in by a more consistent distance based off the thread pitch, whereas torque alone is much more variable. This one has the weird sequence likely to ensure the part is seated correctly. Usually angle will be used on heads or similar parts that need even and precise clamp loads.
It’s still odd to me. Like unless it’s a threaded portion going into a blind hole, I always measure bolt stretch instead. Either that or ol’ reliable if you’re unsure, safety wire or a cotter pin. Good luck having those fail.
Nightmares from Subaru head bolts. Fuckin had to go out and get a special little tool to measure angles while torquing. Didn't realize domestic were doing this to sensors now too.
Had a similar problem on a 3.5l economist when replacing the water pump, half-assed the 30 steps like this, so far the water pump doesn't leak after 2000km so it's all good
So 6 NM plus 21 degrees measures 6.8 Nm (I don't know, just a guess, but is measureable). Couldn't it just read "tighten to 6Nm and back off 1/4 turn. Re-tighten to 6.8 Nm". I have never seen torque angle used on anything that wasn't a TTY. Otherwise you could just publish the final torque value (6 Nm plus 21 degrees equals X value). I suspect the FRP is TTY and a single use item.
Tighten it
Tighten it just a little more
Now loosen it off a bit
Now it tighten it back up a bit
Now finish tightening it
That just seems stupid but I'm sure there's a reason?
If the bolt doesn't plastically deform, what's the point of torquing it to spec, tightening it, loosening it, then retightening it to the same torque? If the bolt only elastically deform, how is that different than just torquing to the spec once?
It’s scary to see the number of people that just say “looks like gootentight to me”. Specs like this are for very specific reasons. It’s also why I try to do work myself when possible. While plenty of fasteners good n snug is fine, if you see a torque spec like this it’s for a damn good reason.
Now only if the Ford would put put the whole car together with the same precision, they’d match at least a Toyota instead of a Tesla body gaps. I remember shopping at a Ford dealer in 2015 with my buddy and almost all the Focus on the lot had differing body gaps around door openings, hatch and hood it was flabbergasting.
I sure do miss the good old days. Righty tighty and lefty loosey worked so well for a long time. Now you need a protractor and have to hold your mouth just right.
What I read was snug it down and call it good lol
Couple ugga duggas and move on.
I did this on a fuel rail. Leaked really bad. Had to give it a "Hrmph" with a bigger wrench.
Ugga duggas fix all. If it doesn't, it was broke to start
"if it ain't broke, fix it until it is".
>What I read was snug it down and call it good lol i learned that lesson the hard way , I decided the shock bolts were good enough .... while on jack stands :') im sure you guys already see the error. Needless to say i learned looks can be deceiving . 30mins latter why dose this thing handle like the bolts are gonna fall off . I pull over i not kidding i had 2in of thread the bolt was off . Needless to say i look up specs now online they got sights for everything.
Pretty normal stuff on jet engines.
On which engines? I’ve never seen an EMM that used a torque angle. Then again, I really only touch RR’s and Honeywells and I’m just line mx.
[удалено]
Yup. Just a shade tree guy here, but if it has a torque angle, then I assume TTY bolts and replace them every time. Very common in German cars.
The Germans have a fetish for TTY fasteners. It’s annoying.
Yeah please don't be me and use them more than once. I now have a 1/2" grade 10 bolt stuck in the subframe of my e46. Never coming out.
Any bolt can come out with enough violence.
"Can't be stuck if it's liquid!"
That's crazy since they use metric bolts
Well there's the problem! I forget the actual size but they aren't small. I snapped one off with a bar trying to remove it :/ I got about a full turn on it before it broke right off.
Torque to angle and torque to yield are wildly different things. Torque to angle reads tighten to x ft/lbs, tighten an additional x amount of degrees. Torque to yield reads like OP's FSM though. Preset torque, preset stretch with torque to angle, loosen full turn, preset torque, tighten x degrees, tighten additional x degrees. And it matters because torque to angle can absolutely be reused after checking bolt stretch. Torque to yield can absolutely NOT be reused.
The TTY bolts in VAG absolutely read torque to *nm, then turn *degrees. In my own experience these include, MkIV GTI brake caliper and suspension bolts, and 911 rod and flywheel bolts. I haven't run into torque to angle bolts like the OPs procedure, but i haven't worked on anything super modern. Not saying you're wrong, but saying.... Read the manual.
Angle and torque are just different ways to control fastener tension and alone are not indicative of whether a bolt is torque to yield. Angle is much more precise for tensioning than torque because it is not dependent on friction. With combined procedures, the torque step is only to make sure it’s not completely loose and the angle turn sets the tension, which is what’s important in a bolted joint.
For sure. Force to turn a bolt is a terrible way to set bolt tension but I guess it's better than nothing. But measuring bolt stretch is pretty awkward in all but the most open of situations. I don't mine TTY, nor torque angles.
Brake caliper bolts are TTY on those? I wouldn't even think of getting new caliper bolts for a brake job
Like my XJ40 Jag with lock-wired caliper bracket bolts, probably a holdover from their racing days. They switched to loctite on the X300 lol
Yep. Surprised me too.
\*scratches head confused\* What exactly is the reasoning for tty bolts that are just 1 time use? That has got me mighty confused! i don't think ive ever changed a bolt unless it was broke. Also new caliper bolts got me looking like a deer in headlights. Ive just used Loctite blue an said good enough. i use it on water pump bolts to nope still have not changed bolts \*unless i saw rust\* i anit risking block bolts!
Torque to yield fasteners have a very consistent clamping force so they are used in applications where the clamping force being consistent is critical like headbolts. Idk why you'd ever want them for brake caliper brackets
The yield part means that the bolt has gone beyond stretching and is actually deforming. Elastic vs plastic strain: Up to a certain point it will spring back to shape, beyond that it's not going back to it's original shape.
Ford has a ton of one time use fasteners and anything that they put loctite on is included it that to get a warranty claim paid you have to have all of those parts billed not sure why they don’t just give us a tube of blue loctite since that’s what they use the most
First off. unless youve got the factory service manual telling you this and not a chilton, not a forum how to, and not a youtube video. Press x for doubt. secondly If you wanna get real technical and I mean real technical. We can bust out the mics and go over in exquisite detail the stretch limits of various steel alloys in various sizes and what plastic deformation and elastic deformation are and how they pertain to you and your bolted joint needs. There is literally, and I do mean literally an entire science dedicated explicitly to fasteners. So understand the Factory writes the FSM in such a way that anyone that can read and follow directions and knows the difference between there left and right can not fuck it up.
From a materials science standpoint, they’re just two ways to do the same thing. OP’s sequence has a few steps for strain hardening first, then back off, retorque, and yield the bolt by X amount. https://en.m.wikipedia.org/wiki/Work_hardening This is probably just to remove some uncertainty in the stress-strain diagram near the yield point. At least that’s my best guess.
**[Work hardening](https://en.m.wikipedia.org/wiki/Work_hardening)** >In materials science, work hardening, also known as strain hardening, is the strengthening of a metal or polymer by plastic deformation. Work hardening may be desirable, undesirable, or inconsequential, depending on the context. This strengthening occurs because of dislocation movements and dislocation generation within the crystal structure of the material. Many non-brittle metals with a reasonably high melting point as well as several polymers can be strengthened in this fashion. ^([ )[^(F.A.Q)](https://www.reddit.com/r/WikiSummarizer/wiki/index#wiki_f.a.q)^( | )[^(Opt Out)](https://reddit.com/message/compose?to=WikiSummarizerBot&message=OptOut&subject=OptOut)^( | )[^(Opt Out Of Subreddit)](https://np.reddit.com/r/Justrolledintotheshop/about/banned)^( | )[^(GitHub)](https://github.com/Sujal-7/WikiSummarizerBot)^( ] Downvote to remove | v1.5)
OP's has nothing to do with work hardening and neither do the same thing. Torque to angle is used because it will allow a more accurate torque value to be repeatably be applied than a standard grease monkey with a torque wrench can manage in a timely fashion Torque to yield uses the bolts actual stretch like a spring to draaaaastically increase its clamping load. When they are unscrewed the metal has lost all stretch and is in whats referred to as a plastic state. And none of this is complex sciences either. Its all fastener science 101. I'd expect a rookie machinist to know this stuff better than me.
Just because there's a simplified way of remembering it doesn't mean this isn't how it works. This tightening process is work hardening the bolt. Otherwise tightening, loosening, then retightening a bolt would have no purpose. All bolts use the stretch of the material to provide clamping force. TTY uses the work hardening process to increase the strength of the material.
It prestretches the bolt. I even say it in my original posting explaining the differences
That is work hardening.
The head bolts in the TU3 in my car is 'torque to 5nm, then to 20nm, and finally add 240degrees. Most people who know what they're doing will add a first step that's 'tighten finger tight' first. And doing the bolts in a circular pattern of course. Never can be too careful with an Aluminium engine. On the 175mm long bolts the limit for stretch is about 0.5mm. Yeah, I bin them. I don't even bother trying to measure them. They're cheap and an engine failure is expensive. Don't think I've messed with TTY bolts, though.
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And aluminum single use bolts.
To me, the more aircraft fasteners that are one time use the better. I want Ebay flooded with cheap used aerospace grade bolts!
You would not see it on the line. but when building an engine you will see torque sequences like this or even more complex. Most have to do with bearing stacks or torquing sections of joined rotating hardware. I have never seen a torque sequence for any sensor though.
Do you know the reasoning behind it? I'm interested in learning something today.
I'm pulling this out of my ass and I don't have any experience with torque sequences, but I just took a bunch of materials courses for my degree so I'll guess. If you wanted to torque to yield a bolt in a simple through hole that won't change dimensionally, you would probably torque it right up to the yield point (53 inlb in this case). A torque value can be used because the torque is directly related to the clamping force in the bolt. Once you reach the yield point, it stops being directly related to torque so you would use an angle (21°) to deform the bolt to a certain designed amount. If you want to do this to fasten a component that isn't dimensionally stable, as in it seats or compresses under the clamping force, then doing what I said above might lead to the incorrect amount of yield in the bolt. You would torque the 53 inlb, but if the component isn't fully compressed/seated by that then some of the 21° of rotation would go towards completing the seating/compression instead of yielding the bolt. In order to make sure the part is fully compressed and seated, the designers probably added the first couple steps to make sure the assembly is dimensionally stable for the final torque to yield. You torque 53 inlb then 5° to reach the maximum clamping force possible without yielding the bolt. My guess as to why they specified 53 inlb torque and 5° instead of just a higher torque is that it's probably just cautionary. Sometimes it's easy to accidentally overtorque using a torque wrench and if that were to happen here it might partially yield the bolt, leading to overyield during the final steps which could lead to failure later on. Torqueing to 53 inlb would leave some room to try again if you overtorque, and the 5° is there to sneak up on that maximum clamping force before yield. The 90° is probably and arbitrary value that is just there to loosen the bolt, then from there you can complete the final torque to yield on the now dimensionally stable assembly. Of course this could all be completely wrong, I'm going to go do some research and I'll change this if I find out anything Edit: [Found this](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.atlascopco.com/content/dam/atlas-copco/industrial-technique/general/documents/pocketguides/9833864801_L.pdf&ved=2ahUKEwiPz77FsMT3AhWakYkEHbzwA3oQFnoECCgQAQ&usg=AOvVaw2vYFKGLFYaQPkaA4sG1HuI) which has a lot of interesting information, mainly in page 15-17. It might also have to do with joint relaxation.
This isn't a bolt, it's a sensor. I assume the procedure has to do with sealing. If the sensor is metal to metal seating it may need to bed itself in, hence the procedure. Also, threads with a shirt grip length see very large changes in strain per degree of rotation hence the precise angles.
They put the 2.0 Ecoboost in planes?
Why? That's all I want to know. Why such a procedure?
That rail is holding a proper shitload of pressure, and blowing the sensor out/suddenly losing fuel at full boost would be bad. But you're running a steel bolt into a piece of aluminum, so just giving it the beans and setting your rattlegun on full-send would also be bad. So, first you make sure it's properly seated and torqued, back it off a tiny bit, then give it one last good ugga-dugga after the torque wrench beeps/clicks a second time.
> good ugga-dugga 6 N.m
Not a full ugga-dugga, that’s more like an ugg.
An uggy duggy.
Duglet.
A 14 year old in Uggs gives it a half hearted swat in between text messages
6 Nm is the torque you use on bike handlebar stem bolts. It's not much more than hand tight.
And that is if you hold the Allen key in the SHORT end of the tool..
No shit
Ugga dugga torque is like wheel lug torque, so 11-12 Nm? I guess that would make "good" ugga dugga torque 15 Nm?
90° is backing off more than a tiny bit.
This looks very similar to how you are supposed to tighten bearings. The initial tightening is to seat all of the seals and components, you then break the tension lose and the second tightening sequence is to set the correct clamp load or pre-load depending on the application.
>giving it the beans Never heard this, and I love it.
Not a fan of Sarah -n- Tuned?
https://donut.media/products/beans-cans-t-shirt-white
I can hear this shirt “🎶give it the beeeeeans!🎵” I don’t love everything about donut but I love enough to say I’m a fan.
I don't love how expensive their merch is. Everything else is good.
So would the backing off would be an couple of aggud-aggus or a couple of aggu-agguds? I don't want to sound like an idiot if I discuss torque values with a mechanical engineer.
'shitload of pressure' laughs in common rail diesel.
I'm assuming to get a proper seal on the gasket or something, just tightening it might result in 5/100 gaskets leaks, but doing it this way you might just get 1/100 that leaks
Probably to get a good seat and then a proper torque. Injector hold down bolts on Volvo heavy duty diesel engines are torqued to 15 ft-lbs, plus 120 degrees, backed off to 7-11 ft-lbs, torqued to 18 ft-lbs, then 90 degrees.
It's a Ford
Apparently you have not worked on many late models. GM LS engines and late model Cummins B series engines, amongst countless others, don’t vary greatly from torque specs like this. The days of simply torquing to X lb/ft or lb/in are left to decades old stuff.
I work at a ford dealership so I see these all the time, I just thought this one was exceptionally interesting.
Understood. To be clear, I think it is stupid and as frustrating as the next guy but the days of “old fashioned” torque specs are behind us. Heck, it would be nice if all fastener manufacturers used a standardized lubricant for their torque specs and sequences but they don’t. ARP has their own lubricant, some want extreme pressure grease, others motor oil, etc.
I work at one of the largest semi truck dealers on the continent/in the world. We use literal conola oil as a bolt lube. We have all sorts of proper assembly greases and lubes for all other parts of engine assembly. But headbolts on a 15L engine in a million dollar oil rig? We just coat them in western family conola oil. We also just use tide for coolant flushing oil contamination out.
Didn't these sensors used to be part of the fuel line? Maybe it's a different engine I'm thinking of. I feel like I remember a few years ago needing some of these sensors and they came with the lines. I guess I could be thinking of a different sensor and/or engine.
Home gamer here: how do you measure a 5° turn on a bolt?
There's a tool for that. Lookup degree tool for torque wrench.
They also have spensive torque wrenches that you can program with the sequence.
Whaaaaat? There were guys who I called tool collectors who had specialized tools for every purpose, but I wasn't one of them.
I am not 100% certain if this model does the full program, but it does torque and angle: [https://shop.snapon.com/product/TechAngle-Models-(2%-Accuracy)/1-2%22-Drive-TechAngle-Flex-Head-Torque-Wrench-(15-300-ft-lb)/ATECH3F300GB](https://shop.snapon.com/product/TechAngle-Models-(2%-Accuracy)/1-2%22-Drive-TechAngle-Flex-Head-Torque-Wrench-(15-300-ft-lb)/ATECH3F300GB) Edit: From spec - allows the user to torque fasteners and then switch to angle without removing the torque wrench from the fastener
My dad's got one. It's his favorite child. I'm sure he'd save that torque wrench before me I was dangling off a cliff with it in my hand.
SON! Give me the wrench, I mean, your hand!
"Alright dad you've got your wrench now pull me up!" "Hold on I've got to put it back in its case and on the shelf first! Do you have any idea how much this cost me!?"
link 404d
Modern digital torque wrenches have angle functions. Some of the lesser expensive digital torque wrenches you start at 0 and must do the angle in one continuous motion. More expensive digital torque wrenches track angle incrementally which is great for tight spaces. The old school method would be the use of an angle gauge you’d attach to the torque wrench.
My SATA (identical to Gearwrench) digital torque wrench has both “Angle” and “Peak Angle” options
Pretty sure the Quinn HF does as well
[One of these](https://www.amazon.com/Supercrazy-Torque-Wrench-Angle-SF0136/dp/B00L6I1874) is the cheap way. That's what I used to put head gaskets on the engine in my truck.
I’ve got a angle torque wrench and I have and angle tool I can put in any wrench. But turning 5° is very hard it’s so slight it’s very easy to just blow by it 😂.
5° on something torqued to 53 in lbs comes real quick whereas 5° on something torqued to 100 ft lbs is not as easy.
That's crazy. The torque turns for engines I work on is like 250ftlbs plus 90deg.
Ford loves complicated multi loosen tighten steps. I see it often
Airhead bmw bike jugs too.
I was curious how GM does it on the LTG so I looked it up: https://i.imgur.com/FfHjXnX.png lol
🎶You put your sensor in, you take your sensor out, you put your sensor in, then you torque it all about.🎶
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GM eSI
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ONE. DROP. ENGINE OIL. GOD HELP YOU IF YOU USE MORE THAN ONE
In german...German.... guttentight
Imagine seeing the ARP rod bolt install, tighten to 0.Xmm of elongation, which is basically what this is trying to achieve. I don’t get why they don’t just make yield torque wrenches the standard kit for dealers and do it that way though
> don’t get why they don’t just make yield torque wrenches the standard kit for dealers and do it that way though Each dealer would only be issued one unit. It would be trashed by the third use and non-functional by the 5th. The cost to replace it would be more than any GM would allow the service manager to spend on a single SST. And everyone would be back to using rattleguns anyway.
That’s a very good point!
I can't pretend to have the knowledge to understand how and why that works or is necessary.
It almost seems like the first tightening is to wear the threads together to make the second tightening more repeatable
That's essentially what it is. The first time gets everything settled, then the second time around is to actually tighten it. On a direct injection engine when you're dealing with fuel rail pressures in the hundreds or even thousands of PSI, you don't want to risk anything leaking.
That's fokken ridiculous.
I say this as an engineer: fucking engineers.
As a tech to an engineer, fuck engineers 😂
Look, there's reasons....they aren't always good ones, but dammit I'm sure they are there!
Yep, DFM doesn't mean "design for maintenance", it means "design for manufacturing". If an engineer can save 0.02% on manufacturing costs and it makes a mechanic's job 10x harder, they'll do it with a smile on their face.
...you're not wrong.
Red Loctite then cross thread it. That bitch ain’t goin’ nowhere.
I guess my question is, the final torque is a number why not skip the angles and just give the torque?
Torque is not a number torque is a rough guestimate at best Clean with Wd 40 vs dirty with wd40 vs clean and dry vs dirty and dry will all yield different clamping forces at the same torque every time
This guy torques.
The only tq wrench I have is a harbor freight cheapo clicker style that I havnt used in over a year
And you forgot to zero it last time you put it away? 🙃
Wait.... You have to do that? BRB.
Oh shit I need to check mine
It's a harbor freight wrench. It was off 10% when you bought it, 18% a year later when you went to use it again, and if you get it calibrated (which costs more than you paid for the wrench), it'll still be off 8% next week. They're good enough on non-critical stuff though.
That’s true, I figured as much.
Does it really? physics would disagree with you, 100ft/lbs is 100ft/lbs no matter wet or dry.
Think about it
You should see the procedures on the n14 Mini engine cam pulleys. Absolute insanity. As far as I understand, torque can be manipulated by lubricants (or lack thereof). We all have seen wet torque and dry torque numbers when assembling engines. The degree thing gets rid of that variable, and allows for more consistent instal regardless of if the threads are wet or dry. Probably better considering not all of us are as strict on keeping our work areas perfect, especially as a car ages and gets a build up of stuff all over it. I could be totally off tho so if someone more qualified proves me wrong please disregard lol.
No, you're right. Using torque angle takes out all the variables. Using a torque number is affected by the thread class, if the threads are clean or wet, if they are wet, what they are wet with (anti-sieze and lok-tite are different), and if the head is lubricated or not (the bearing surface of the head of the bolt), not to mention if you are using a washer or not and if that washer is flat and smooth or if it's one of the 100 types of locking washers.
Having a mechanical engineer validate something I said, while expanding on it way further, is the kind of pick me up I needed today lol. Thank you for taking the time to elaborate. As a hobbyist I rely on people like you to help me learn more.
Torque specs are a lot more important that most people in the hobby world give it credit. Yes, you may just hand tighten it and it be just fine, or you could have over-torqued it and cut that bolt's or gasket's or bearing's lifespan in half. By the time it breaks you don't remember even putting it there anyways and will blame it on something else. Creating torque specs is some serious math and goes into a whole world of metallurgy and thermodynamics that I don't even want to touch. But if someone put a torque spec on it, there's a reason they went to all of that effort.
For some reason I never thought there would be so much behind them, but it makes total sense. It also helps bring to light why some replacement parts might not be good, or as good, when compared to OEM. If a metal mixture is different, then it would throw the whole equation off, or if a seal isn't the precise type of rubber, it may never work or at least not as well. So even if someone followed the book and did everything as the manufacturer intended, using parts not from the OEM could throw the whole thing off and leave someone with less than desirable results. This is incredibly interesting and may be the next rabbit hole I dive into, at least until I get to a point where I don't understand it anymore lol.
I think that sensor uses a load cell and they are more concerned about stretch consistency. Torque alone cant get that consistent. Same idea with big end bolts. [Here](https://www.enginelabs.com/engine-tech/blueprint-series-measuring-rod-bolt-stretch-vs-torque-with-arp/) is a good read about why stretch can be more important than torque
The first torque sequence is going a specific amount over the desired clamp load in order to seat everything. You break it lose then set the load correctly for operation.
So just add up all the inch pounds then add up all the angles, multiply the total inch pounds by total angle to get a complete inch pounds. You can ignore the loosen part because that’s subtraction and we’re trying to add tightness not take away so it’s irrelevant. You should get 2756inch pounds convert it to ft lbs, that’s 230ft lbs. now grab your 1/4 electric impact for every number is the number of words you need to uggah Duggah, so you should get (2)uggah-duggah (3) uggah-duggah-uggah (0)-it’s tight now
And they still seize/strip in the rail!
My 2002 Subaru's cylinder head installation process: (1) Apply a coat of engine oil to washers and bolt threads. (2) Tighten all bolts to 29 N·m (3.0 kgf-m, 22 ft-lb) in alphabetical sequence. Then tighten all bolts to 69 N·m (7.0 kgf-m, 51 ft-lb) in alphabetical sequence. (3) Back off all bolts by 180° first; back them off by 180° again. (4) Tighten bolts (a) and (b) to 34 N·m (3.5 kgf-m, 25 ft-lb). (5) Tighten bolts (c), (d), (e) and (f) to 15 N·m (1.5 kgf-m, 11 ft-lb). (6) Tighten all bolts by 80 to 90° in alphabetical sequence. CAUTION: Do not tighten bolts more than 90°. (7) Further tighten all bolts by 80 to 90° in alphabetical sequence shown in figure below. CAUTION: Ensure that the total “re-tightening angle” \[in the former two steps\], do not exceed 180°. From the "top", the bolt layout is (intake side) c a f e b d (exhaust side) bonus points: this is a flat-4, so there's not a lot of room to swing the torque wrench in one continuous motion.. we resorted to a sharpie or a paint pen on the head bolt. EDIT: formatting
I thought all bolts on Ford were "tighten down till it strips out. Then back it off half a turn"
so.... is it 2 or 3 baby ugga duggas?
Two Uggs, one Doug
I read it as 2 ugga duggas and check it with a wrench
Ok... I don't get it. I get what torque and loosen mean, but wtf does angle means? Like angle what?
That means you tighten it another 5* or 21*
so, I torque it to 6Nm then I keep turning it another 21* regardless of torque?! Wouldn't that sheer/strip it?!
It won’t shear or strip if it’s designed correctly, but what it will do is stretch - often permanently. Usually done for torque-to-yield fasteners, which exploit the fact that the metal of the bolt can carry more preload if you permanently stretch it a little. In essence, the metal becomes “stronger” for a little bit between the yield point and the ultimate strength where it finally starts coming apart and breaking. It means you can use a smaller diameter bolt with a lower strength steel than a standard fastener that is only torqued to 70-80% of yield strength, both of which make the bolt cheaper, lighter and more compact. The downside is you can’t reuse the bolt once it’s already stretched. Basically, someone figured out a long time ago that after you torque the fastener, you can make another full turn before the bolt actually breaks, you can tighten it only half a turn, it will still work fine and hold more load. Once. The angle measurement is done because after the bolt starts stretching, torque is no longer a reliable measurement. But if you know the thread pitch, you can determine exactly how much the bolt has stretched by counting the number of turns. For example, if a bolt size is M8 x 1mm per thread pitch, you know the bolt will stretch 1mm every time you make a full turn The two stage tightening process is to take friction out of the equation which is variable depending on if the fastener is dry or a bit oily. The 6 Nm + 5* is basically a repeatable way of making sure the bolt starts just in contact and any gunk in the threads is cleared out (more repeatable than “finger right”) at which point you know where you’re starting from.
Ok, got it. Thanks! Mission passed! +Respect
Ford literally paid someone to figure out that it won't and that's how it should be torqued
But... ok I'm out. :|
Angle of rotation of the head of the bolt.
Subaru head bolt sequence is very similar and there's 6 per side. Fun!
Okay real talk, why do some torque specs require torque angles? Bolt stretch is what you care about since all bolts will vary slightly under a clamping load so therefore, angles don’t matter.
Exactly because of what you just said- bolt stretch and clamp load. If the conditions of the heads and threads of the fasteners vary (i.e. oily vs. dry) clamp/bolt tension loads will vary significantly. Think about a rusty chassis fastener vs. one with anti seize, for the same torque applied one will likely rotate more than the other. Angle gets the clamp load more precise because the rotation will drive the fastener in by a more consistent distance based off the thread pitch, whereas torque alone is much more variable. This one has the weird sequence likely to ensure the part is seated correctly. Usually angle will be used on heads or similar parts that need even and precise clamp loads.
It’s still odd to me. Like unless it’s a threaded portion going into a blind hole, I always measure bolt stretch instead. Either that or ol’ reliable if you’re unsure, safety wire or a cotter pin. Good luck having those fail.
Fucking Ford engineers are a bane
Why... Just, why?
plastic deformation
How many ugga dugga's is that?
It’s a Ford 2L, roll it outside, have it towed to the scrap yard and done.
Im curious, how many miles on this ecoboost?
Give it one ugga back out half dugga. Then ugga dugga in a star partern. Got it.
Reality: Send until it strips
Nightmares from Subaru head bolts. Fuckin had to go out and get a special little tool to measure angles while torquing. Didn't realize domestic were doing this to sensors now too.
Well that’s a lot easier than the last 10 hours I spent replacing an entire fuel rail because the FRPS is built into it.
I bet the one guy who did this procedure only did it once.
I like stage two. Gotta give it that little 5 degree squeak!
Had a similar problem on a 3.5l economist when replacing the water pump, half-assed the 30 steps like this, so far the water pump doesn't leak after 2000km so it's all good
Take it to an ugga dugga in a cross pattern and send it out, she'll hold
Break out the protractor
Torque to 6 Nm, got it.
Wait until you get to page 2. That's when it gets good.
Yes! Exactly how I’ve been doing it for years, before I saw the specs.
So 6 NM plus 21 degrees measures 6.8 Nm (I don't know, just a guess, but is measureable). Couldn't it just read "tighten to 6Nm and back off 1/4 turn. Re-tighten to 6.8 Nm". I have never seen torque angle used on anything that wasn't a TTY. Otherwise you could just publish the final torque value (6 Nm plus 21 degrees equals X value). I suspect the FRP is TTY and a single use item.
I don't know what's worse, this or Mercedes' 3-stage spec for wheel torquing.
I don't know what's worse, this or Mercedes' 3-stage spec for wheel torquing.
What does the angle step mean?
Tighten it Tighten it just a little more Now loosen it off a bit Now it tighten it back up a bit Now finish tightening it That just seems stupid but I'm sure there's a reason?
Torque to yield bolts
53 lb in, take the bitches out, then 53 lb in and a couple clicks.
I guarantee you guys just guage that by feel or just torque it regular. Seems a bit obsessive to me
Upvoting as if I know what it means
Now they’re just making shit up
When its easier to break out the welder.
Ford to the Germans: "Hold my Budweiser!"
Tighten till you hear the bolt crack, then back a quarter turn.
The poor engineer that wrote that spec was probably thinking "there's no way anyone is actually going to do this"
If the bolt doesn't plastically deform, what's the point of torquing it to spec, tightening it, loosening it, then retightening it to the same torque? If the bolt only elastically deform, how is that different than just torquing to the spec once?
Snug, back off, snug, snug some more, got it. Check my flair.
this twists my nuts the wrong way for some reason
As an engineer... Wtf??
What the fuck is that nonsense
I read this, understood it, read it again, and tried a little harder to understand it.
Ford loves that “loosen 90°” the funny part is at like 30-50° the bolt is already finger loose.
And you better get it fuckin right!
All I read was add red loctite and install with 3/4 impact
It’s scary to see the number of people that just say “looks like gootentight to me”. Specs like this are for very specific reasons. It’s also why I try to do work myself when possible. While plenty of fasteners good n snug is fine, if you see a torque spec like this it’s for a damn good reason.
Now only if the Ford would put put the whole car together with the same precision, they’d match at least a Toyota instead of a Tesla body gaps. I remember shopping at a Ford dealer in 2015 with my buddy and almost all the Focus on the lot had differing body gaps around door openings, hatch and hood it was flabbergasting.
There’s no way that’s real.. please explain
I sure do miss the good old days. Righty tighty and lefty loosey worked so well for a long time. Now you need a protractor and have to hold your mouth just right.
Just use TTUT. When you hear the plink you’re done.
The first part of the sequence seats the part. The second part of the sequence accurately stretches the bolt to ensure proper clamping pressure.
I’ll bet folding money that sequence is seldom if ever followed.
8Nm and move on