The Art and Science of Dragster Clutches: A Look Inside the High-Speed World of Top Fuel Cars

When it comes to the world of top fuel dragsters, there's one component that's often overlooked but is absolutely crucial to success: the clutch. Located at the front of the engine, the clutch is responsible for transmitting power from the engine to the wheels, and its failure can mean disaster on the drag strip. But what makes a clutch so important in this high-speed world? And how do teams go about optimizing their clutches to achieve the fastest possible times?

One of the key factors that determines clutch performance is the design of the clutch fingers themselves. Each finger can be adjusted individually, allowing teams to fine-tune the locking of the plates to ensure smooth engagement and maximum power transmission. The six primary fingers are all made of the same tool steel material, but the secondary fingers can vary in length, which affects the timing of engagement with the clutch. By adjusting these lengths, teams can achieve optimal clutched performance.

But it's not just the fingers that need to be adjusted – the weight of the lever also plays a crucial role in determining clutch performance. The addition or removal of weights, usually in the form of nuts, allows teams to fine-tune the rate of clutch engagement. Adding weights means the clutch will engage at a lower RPM on the initial hit of the throttle, while removing weight allows the motor to reach higher RPMs before fully engaging. This subtle adjustment can make all the difference between a fast run and a disappointing one.

So why does this matter? The answer lies in the principle of centrifugal force, which is present in the clutch system. As the lever swings out, it's essentially creating a centripetal force that acts outwardly away from the center of rotation. This force can be harnessed to improve clutch performance by adding or removing weight from the lever. By doing so, teams can optimize the rate of engagement and achieve better power transmission.

But how does this translate to real-world racing? When a track has plenty of grip, the crew chief will often add weight to the clutch to provide a quicker hit from the system. This means the power will be deployed faster, resulting in a faster run. However, if the track is slippery or wet, they'll remove weight to provide a softer hit from the clutch. It's all about finding that perfect balance between speed and control.

And what about the driver? Do they have any say over the clutch engagement? The answer is no – it's entirely up to the crew chief and engineer to make these decisions based on data and calculations. The level of locking is controlled by a pneumatic release bearing, which limits movement of the clutch fingers and locks in the clutch as the timer counts down. This system allows for precision control over the clutch engagement, but also means that adjustments can't be made once the time is punched into the computer.

Technology has come a long way since its early days, with most teams now using advanced materials and multiple plates to improve performance. However, a clutch failure is still catastrophic – it means no power goes to the wheels and the run is over. The cost of replacing parts can be upwards of $10,000 per run, making it a serious concern for any team.

So why is the clutch so important? It's not just about raw horsepower – it's about precision timing and control. When you see a top fuel dragster cross the finish line at 300 miles per hour, there's a lot more going on than just nitro fuel and turbocharged engine power. There's science, math, and engineering that has gone into optimizing every component of the car, including the clutch. And for those who love the intricacies of this high-speed world, it's a fascinating topic to explore.

As we wrap up this episode of B2B, we'd love to hear from you – hit that like button, subscribe button, and leave a comment below if you have any questions or topics you'd like us to cover next time. Follow us here on Donut at Donut Media, follow me at Jeremiah Burton, and until next week, bye for now.

WEBVTTKind: captionsLanguage: en- What is super hot,needs a specialist for optimal function,and has 18 fingers?This guy.Actually, it's a Top Fuel Dragster clutch.And today we're gettingdeep into its mini layersand what can cause it to get so hot.And it welds itself together.Freaking laying down dimeson the old clutch, let's go.(chill music)Top field Dragsters producean absolutely insane11,000 horsepower.Enough to trash their entire enginein just under four seconds.Pistons, rings, connectingrods and spark plugs,all have to be tossed after a single run,but we're not talkingabout all those components.Oh no.We're talking about their clutches.Those clutches can reach4,000 degrees Fahrenheit,twice as hot as lava,and just a little bithotter than your boy.Because of all that horsepower,these clutches get so hotthat they can weld themselves together.So to figure it out,we first gotta see howa Top Fuel clutch works.Not to oversimplify things,but you probably know what a clutch does.It regulates power from theengine to the drive shaft,and ultimately to the wheels.Now the purpose of a TopFuel clutch is the sameas in any other car.You can think of a Dragsterclutch setup like a sandwich.Within the bell housing,you'll find the highly tunedTop Fuel centrifugal clutch.I call it centrifugal sometimes,sometimes people say thesame words differently.I'm gonna call it centrifugal.'Cause some kid yelled atme on Instagram about it.At the engine in is the flywheel,which forms that all important connectionto the Dragster's 11,000 plus horsepower.And in this case, theflywheel will be a lot likethe bottom bread of our sandwich.Then we have the filling,the nice meat that's inside,and that is the five orsix discs clutch pack.The clutch pack is an alternating stackof six clutch disks andfive steel floater plates.It really is the meat of thecentrifugal clutch systemand the source of a lotof the friction and heatthat can cause the platesto weld themselves together.The base metal melting anda Top Fuel clutch is iron,and iron is super dense, itmelts around 2,800 degrees.Now typically more mass,especially dense mass like iron,means more heat energy dissipation,otherwise known as cooling.So heat energy dissipationacross a dense surfacemeans the heat energy is diminishedas it spreads across that surface.And this is why the clutchdoesn't weld itself togetheron every single run, but it does happen.And when it does it's because of friction.That friction causes theclutch temperature to riseabove the melting point ofthe clutch pack materials.The manufacturer andmaterial type are tippy topTop Fuel secrets when it comesto the plates and the disc.Steel floater plates areactually a blended steelunique to each team's tuningand performance calculation.A steel is just an alloyof iron and carbon.And the choice of ratiosof metals in that steelwill obviously have an effecton the clutch performancebased on the friction orslippage that they provide.That blend can also be more or less proneto heat damage or welding.So, that's the steel plates, right?But you also have clutch discsand those are made of iron.Specifically made of sintered iron.Well, what is sintered iron?Well, so freaking glad you asked.Here's some hot footage.(romantic music)Oops, sorry about that.That was just me with my shirt off.Here's some sintering footage, sorry.I don't know why just keephitting a wrong button.For real, here's some sintered footage.Sintering is the processof putting parts made ofcompressed iron powderthrough a very toasty furnaceand adding high pressure.The goal is to control the temperatureso it reaches just belowthe melting point of ironwithout actually liquefying.The heat and pressureworks at a molecular levelcausing the metalparticles to bond togetherso you get a stronger discwith enhanced propertiesfrom the original metal.It diffuses other elements like carbonthat may be in the mixand reduces pore size,increasing the strength of thebonds between the particles,and because the discs areso dense from being heatedand compacted duringthe sintering process,they can absorb and dissipatea lot of heat energybefore their temperature goes up.Not only that, but sintered iron discsalso have a super strong grip.It has a high coefficient of frictioncompared to standard iron disc.They grip even better when they get hot.That's why you'll see a reallyquick burnout before a run.That not only gets thetires ready for the run,but it also warms upthe clutch disc enoughto start engaging better.That gives the discthe heat that they needto withstand slippage without sacrificingthe all important coefficient of frictionthat makes a clutch work.There are many different types of frictionthat we could get into here.There's static friction, slidingfriction, rolling friction.The obvious friction between me and Jameson the subject of wheel.- You're making me regrethaving you on the show!- The obvious frictionbetween me and my girlfriendwhen deciding where we'regonna go eat on Tuesday nights.It's B2B day, baby, okay?I get to pick, Tuesday's my day.You get all the other days.You get Wednesday, Thursday,Friday, Saturday, Sunday, Monday.I get Tuesday, B2B day, my day.But let's talk about thecoefficient of friction,or how well or how poorlyfriction exhibits itselfbetween two objects.In even simpler terms,just remember it like this,a higher coefficient of frictionmeans the better a discwill be able to do its job.It also means a super harsh engagement.So more parts aresacrificed, but it's worth itso you can go faster down the track.That being said, thesame sintering processthat strengthens thematerial for more gripmakes it ideal for welding.The lower the carbon content present,the easier it is to weld,and generally low carbonmetals have good weldability,and do not requirespecial process measuresin order to weld with another metal.So when you combine thelow carbon sintered ironwith the steel blend plates,you're only a few factors awayfrom a welded panini pressof a clutch sandwich.Mm, mm, mm, mm, yum.On the other end of the clutch sandwichis a pressure plate hat or cap,and it has many names and rolesincluding providing thepressure onto the clutch packand the flywheel.There's a titanium donut.Yes, a donut, underneaththe clutch hat as well.Speaking of donut, if youwant some cool, (beep)I'm not wearing a donut shirt.Speaking of donut, why don'tyou go to donutmedia.com?Get some cool merch like this donut pen.I don't have a donut shirt,'cause I'm going to ninja practice today.So I had to wear myNinja shirt, no big deal.(Japanese battle music)The two parts of the cap are held togetherwith six stall springs.The springs can be adjustedto be free or looseso that the crew can pushthe vehicle to the burnout.Then because the clutch has heated,the springs expand enoughto make the clutch stickier.Now mounted on the top of the hat,are up to 18 clutch fingers,which sound creepy, littlefrigging salad fingers,but they are essential to the operation.A traditional clutchuses springe steel armsto create the plate loadneeded to hold the clutch disc.A Top Fuel clutch uses centrifugal forceand pistons to compress the clutch packusing a set of weightedlevers on the pressure plate.Sound confusing?Well, it sort of is andit's also why the clutchis really where tuningmakes such a differencebetween wins and losses.Yeah, that's right.This clutch needs to be tuned.And the art of clutchtuning lies in the handsof a clutch specialist and crew chief,or more accurately their fingers.They calculate the weightsneeded on the fingersas well as the timing mapthat will release the throwout bearing.The clutch fingers act as leversbeing forced out againstthe pressure plate,compressing the clutch andlocking the friction discand floaters together.So you have one holeassembly from the engine,to the flywheel, to theclutch, to the wheels.Now that allows more powerto be transmitted graduallyto the wheels, as opposed to all at once.You don't want that.You want a smooth operation,so you can get that power to the wheelsand not break tractionso you can get a nice rundown the drag strip.Later sucker, oh, you burned out?Get a new clutch man, dude,you need to tune your fingers more.Each of the clutch fingerscan be adjusted individuallyto control locking of the plates.The six primary fingers,they'll all be the same length,all made of tool steel,but the secondary fingers,they can vary in length.That vary in length willmean different timingfor reaching engagement with the clutch.The addition of weights,usually in the form of nutscan fine tune the rateof clutch engagement too.So adding weights meansthe clutch will engageat a lower RPM on theinitial hit of the throttle.Whereas taking weight off,will allow the motor to reach higher RPMsbefore fully engaging.Thinking about this interms of centrifugal forcepresent in the clutch, the more weight,the faster a lever will swing out.You can try it at home, holdyour arms in front of youand bend your elbows so that your handsare now in front of your face, okay?Now spin around as fast as you can, okay?Do you feel forced tryingto pull your arms outaway from your body like this?If you do the same thingwhile you're holdingsay five or 10 pound weights,it'll be even tougherto keep your hands upand your arms in.That's cental force at play.It's the apparent force felt by an objectmoving in a curved paththat acts outwardlyaway from the center of rotation.It's that pullout when you're rotating,and it's what forces the leversout to engage the clutch.Now, if a track has plenty of grip,the crew chief will addweight to the clutch.Meaning the power willbe deployed quicker,resulting in a faster run.But if a track is slippery or it's wet,they will remove weightto provide a softer hitfrom the clutch.There truly is a fine linebetween pulling a fast runand just smoking the tires.And the interesting thingis the driver has no controlover the clutches engagement.I guess it doesn't matter ifyou're a good or bad driver.It's all up to the old engineerswho are working on the car.The level of locking is really controlledby pneumatic release bearing.As the driver hits the throttle,a micro switch initiates a pneumatic timerthat controls the release bearing,sometimes called the cannon.This bearing limits movementof the clutch fingersand locks in the clutch.As the clutch timer countsdown, pressure is releasedfrom the system, movingthe release bearingand allowing the fingersto lock the clutch up.Since only a very basicmechanical system is allowed,the timer sequence cannot be adjustedonce the Dragster is setto the starting line.So all these elementsare set ahead of time.No adjustments can be madeonce the time is punched inand everything has to goright, unless it doesn't.And then that can leadto, you got it, welding.Technology has changedover the years though.And most teams have uppedthe number of plates they useand improved the materials as well.But a clutch failureis still catastrophic.It means no power goes to thewheels and the run is over.You're also looking at costs,which add about 10,000 bucksper run to replace all those parts.It's not a cheap fix.There's so many things thatcan go wrong in a Dragster run,that it's sort of amazingwhen things don't go wrong.And out of all the componentsinvolved in a successful runask any team's crew, and theclutch will be at the topof their list for prioritized parts.The secrecy aroundmaterials used in the clutchand the calculations foreach team is well founded.A factor of mere gramson the clutch leverscan make or break a run.So when you do see a win,know that there wasn't just nitro fueland turbocharge engine power behind it.There's a little revengethere for us nerds,determining all the weatherand track conditions,inputting data into complex equationsto determine weight ratios onlevers, et cetera, et cetera.All that science and math thatmight not seem super cool,actually wins or loses a runfor the turbocharge Dragster.Thank you guys so much forwatching this episode of B2B.If you could hit that like button,hit that subscribe button,that really helps us out.If you guys wanna seemore Dragster content,leave comment down below, let us know.Follow us here on Donut at Donut Media.Follow me at Jeremiah Burton,and until next week, bye for now.