The crew is discussing their experiment with bolts and torque. They're testing a bolt that's four times the size of a small bolt to see if it will break under different amounts of force.

Six guys are adding weight to the bolt, and this is 800 pounds. This one is about 900 foot-pounds. It's getting stressful.

One guy says, "I've got the hook." Another guy replies, "Alright." The crew starts to struggle with the bolt, and it's bending.

The tension increases, and they're all holding on tight. One guy laughs and says, "This is like Jenga."

They finally finish tightening the bolt, but it's getting harder and harder. One guy says, "I don't want to be anywhere near this." Another guy replies, "Nope. Hold on."

The crew is laughing and joking around, making light of the situation. They're all relieved that they've made it through the experiment without breaking any bolts.

One guy starts explaining how the math works. He says that when you buy bolts, they're measured in diameter, which is a one-dimensional measurement. To calculate tensile strength, you need to use a two-dimensional measure.

The area of the bolt's surface is partially determined by its thickness and partially by its thread pitch and depth. This means that even small changes in these factors can affect how much force a bolt can withstand.

One guy mentions that contaminants like grit, metal shavings, or rust on the threads can also lower the failure point of the bolt. He adds that some torque wrenches can give false readings due to dry torque (torque applied without lubricant).

Another technique for precise tightening is the "torque and angle" method. Instead of just measuring torque, you use a measurement and an angle. If your spec is 30 pounds feet at 90 degrees, you tighten it down to that amount and then give it a quarter turn.

The guy explains that every 360 degrees of rotation moves the nut by a fixed amount (thread pitch), which eliminates variations in friction. This makes it easier to achieve precise torque.

Finally, he invites viewers to check out their series "Money Pit" for more bolts and expertly torqued bolts. He also mentions behind-the-scenes footage on Donut.

You can follow Jeremiah Burton on Instagram (@jeremiahburton) or join the Donut community at @donutmedia

WEBVTTKind: captionsLanguage: en- Engine bolts, lugnuts, even your oil caphas a specific torquespec from the factory.Sometimes, you just got no timeor you got no patience oryou got no torque wrench.And you just want totake your own air gun,it down to snug as you can get it.But why is putting a nut onas tight as you can go a bad thing?Why do we even have torquespecs in the first place?And what would happen if we triedto tighten a bolt witha 13 foot breaker bar?(beep)This is crazy, man.Well today's video, we are goingto show you exactly whatis happening inside a bolt,as it gets over torqued.We are also going to set up an experimentto see if we can replicate our research.So sit back and enjoy as we get downto the nuts and bolts of torques spec.Thanks to bowl for sponsoringthis week's episodeof bumper to bumper.Now, if you guys don't know, we do a lotwith Omaze because they offeryou guys, the fans, chancesto win dream cars in oncein a lifetime experiences,all while supporting amazing causeslike the Ronald ReaganMedical Center at UCLA,the same place that savedour dear friend, James Pumphrey's life.The cars that Omaze offers you,the chance to win are sick.How would you like to wina custom Tesla Model X,or maybe even a Dodge Challenger Demon,or maybe even something like this?I know I would, and you could too,just like my buddy Sebastianwho won the Corvette Stingray,we helped Omaze giveaway earlier this year.How's that stingray, Sebastian?I hope you having fun with it.So don't miss out on thechance to win your dream carand support a greatcause at the same time.Head on over to omaze.com/carsand enter now for your chance to win.What are you guys waiting for?Now let's get back to some B2B.Don't worry, the car's not on fire,this is practical effects.Welcome to Donut, baby.(laughs)(beep)Torque spec is the measurement of a forcea given nut or bolt isdesigned to be used at.It's tight enough tohold the bolt in place,but not too tight so thatit damages anything, including itself.And if we keep on turningthat nut, however,a combination of thingsare going to happen.The bolt will break, like we've seen.The metal clamped in between your nutand your bolt, it's going tobuckle, it's going to squishor the bolt will permanently deform.Now the strength of a boltis known as tensile strength.And this is the amount of tensionthe bolt can withstandwithout being fractured.Now, if you multiplythis by the surface areathat tension is being applied to,you can get the tensile loadthat you're going to apply to the bolt.So as bolts get more andmore tension put on it,there comes a point called yield point.And this is the amount of tensionthat it takes topermanently deform a bolt.Everything below this point,is called the elastic rangeand everything above this point,is called the plastic range.Now, when you apply a load toa bolt in the elastic range,and then take away that load,the material goes back to normal.The molecules that make upwhatever material stretching,they snap back, like elastic pants.Just think of that, that'llmake you remember that.But when you apply a force thatgets into the plastic rangeand then take off the load once again,the material, it doesn't snap back.Those molecules are permanently brokenand the material has undergone,what's called plastic deformation.Now torque spec is often 70to 95% of this yield point,depending on the application,so it's in that elastic range.After the yield point,the bolt hasn't necessarily failed though.In fact, you may have heard of TTYor torque to yield bolts.Beyond the yield point, the bolt can stillbe stretched a bit and holdup to higher tensile load.But eventually, that tensilestrength will plateauand then start to drop off.And that's the pointwhere you break a bolt.Now imagine a spring,now you can compress it,just a little bit, or youcan pull it a little bit,but if you pull too far,it's going to permanently deform,and it won't go back toits nice springy self,even though you didn't actually snap it.That's plastic defamation.Shout out to every 90's kid,who broke a slinky that way.So to show you this, we've setup a few experiments outside.We're going to use my F150 as a test rig.How I got suckered intothis, I don't know,but let's go to outside Jerryand see what he's doing.Thanks to inside Jerry.So we're going to put someof this stuff to the test.We got a rig that we built upon the back of my F-150, here.We have an extendercoming out of the hitchand through that extender, we have a bolt.And what we're going to do,is we're going to start off by torquingthat bolt to 40 foot poundsand work our way up, allthe way to 150 foot pounds.And my buddy here, Joe,he's going to be measuringbolt length changesas we go up, and over torque this bolt.And then, we're going touse this big old honker,to see if we can actually getenough torque to snap an...- One inch thick- Bolt. We also boughta 13 foot stainless poleto give us a little bit more leverageto see if we can usemath, to make it happen.And if not, we'll just use these guns.- We're gonna use the math.So what I'm doing now,is I'm measuring our boltto see how long it is beforewe put it under tension.So that when it stretches,when we do torque it to spec,we can see how much it's stretched by.- Now we tested severaldifferent types of boltsat varying degrees of torque.And what we found was that ourthree and a half inch boltswould stretch about half a millimeterat 120 pound feet of torque.Now, when we undid those bolts,they sprung back to their original length.Now this is a bolt thatis torqued down properly.It's got enough stretch,that the elastic tensionclamps the assembly together,but it still remains trueto its original shape,when the bolt tension is loosened.Now we tried this experimentagain with thinner boltsto see if we could reallyshow the bolts stretching,but you know, these freakingguns of mine showed upto do some damage and well,we rig him, we broke it.(metal clanking)That's called snapping off the bolt, baby.(upbeat music)So we were able to snapthis 1/4 inch bolt,with around 140 foot pounds of torque.So that means to snapthis one inch shank ball,we need around fourtimes as much, right Joe.- Yeah, maybe. Let's see.- Now this is a one inch shank ball,it's course thread, SAE grade five.So we're going to put about600 foot pounds of torque usingthis nice little rig that Joe rigged up,is a breaker bar with a 13foot stainless steel pole.We're gonna hang sandbags on the end of itand see if it can snap this.So right now we have 182foot pounds of torqueon this bolt right here.That's factoring in,the weight of this 13foot stainless steel pole.And the first sand bag Joeis going to put on, is 35 pounds.And we're going to keepadding bags from thereto see what happens.- Alright, let's do it.- Let's go.Do you need a ladder?- A ratcheting wrench won't work for this,so we got to bust out a ladderto get this bar on the breaker bar.- So that's about 600foot pounds of torqueon that bolt right there.So now we're going to addanother 25 pound sandbag.See if it bends it even more.- Six that we're adding,comes down, so this is 800.And this is about 900 foot pounds.- This stressful.Do you guys really want to keep going.- I've got the hook, Yeah.Alright. This is now gettinglike hard for me to move.- Damn, look at that pole bend.I don't want to be anywhere near.- Nope. Hold on.That's good.(laughs)(laughs)This is like the worst game of Jenga.- This is the worst, Isay, we're done, dude.- (laughs).- This is crazy, man.So we put over a thousandfoot pounds of torqueand it didn't shear. So what gives?Did our math fail us?Joe, is it your fault?- You know what?I can't put any more torque on this.- So why did a bolt, four times the sizeof the little bittyexperiment bolts not breakwith four times or heckeven seven times the force.Well, let me explain.And when you're buying bolts,they're measured in diameter.And diameter, that's a onedimensional measurementand to calculate tensile strength,we got to use a two-dimensional measure.A one inch diameter circleis 16 times the area of aquarter inch diameter circle.So we would have needed over2200 pound feet of torqueto break that bolt.But the math, it doesn't end there,because the area we needto use for the calculation,isn't the flat end of the bolt.It's the area of thesurface area of the threads.And that area is partially determinedby the thickness of the bolt,but it's also determined bythe thread pitch and depth.So with the larger bolt,you also have a larger nutand the amount ofthreads contacting withinthat nut increases the surface areaof threads touching andspreading out that force.So even a minor increase inbolt diameter, thread length,or thread pitch can really changethe amount of torque a bolt can take.Because of this, one of the big thingsthat can really become a problemwith torquing downbolts, are contaminants.Now threads, if they're dirty,if they got grit in them,they got metal shavingsor even surface rust,that can change the amount ofsurface area making contactand lower the failure point of the bolt.Also the amount of force neededto break up some of thosecontaminants can leadto a false reading on a torque wrench.I'm sure some of you guysmay have heard the term,dry torque and that refersto the torque appliedwithout lubricant, becauselowering the frictionthat comes with lubricationcan also throw off torque.So if you're a whiz boy,or you're whiz girl watching this show,you can see by just using a torque wrench,you can get an unreliable measurement.And that's because,torque is the measurementof turning force applied to a bolt,not the amount of tensionin the bolt itself,but unfortunately there'sno cheap or easy wayto measure the actual tension in a bolt.So torque is the onlynumber we've got to rely on,but because of this, there'sanother technique out therethat makes torquing down fastenersto perfect spec, super duper easy.It's called the torqueand angle technique,and here is how it works.Instead of just themeasurement in pound feet.You have a measurement and an angle.So if your torque spec is30 pound feet at 90 degrees,you torque your boltdown to 30 pound feet,and then you'd give it a quarter turn.Why are quarter term?Well, every 360 degreesof rotation of the bolt,the nut moves down thethread by fixed amount.This is called the thread pitch.So when you start off witha lower torque value, snugtorque, every degree of rotationafter this will be usedto stretch that bolt.Because no matter what, thatquarter turn is going to movethat bolt down the same amountof thread every single time.So this pretty much eliminates the factthat variations in friction haveon the torquing process comparedto when you're just usinga torque value on its own.And if you want to seebolts, get expertly torquedby Mr. Zack Joe, go checkout our series, Money Pit.If you want to see somebehind the scenes footageof all the stuff we can'tinclude in this episode,because we're very serious in B2B,but sometimes we do a lot of goofy thingsthat you don't get to see.Go hit that join button down thereand be a part of the Donut underground.Follow me on Instagram, @jeremiahburton.Follow us on Donut, @donutmedia.Until next week, bye for now.