The Myth of Marketing Hype: Separating Fact from Fiction with Torque Vectoring

As an engineer, we know that marketing buzzwords like "intoxicating form and compelling function" are nothing more than empty promises. But when it comes to torque vectoring, things get a little more complicated. In this article, we'll explore the world of torque vectoring and separate fact from fiction.

Big Thanks to Omaze

We want to start by thanking our sponsor, Omaze, for making today's video possible. Winning is great, and who doesn't love the idea of winning a car? But as our host so eloquently put it, "life is fleeting" and should be about more than just accomplishment. Unless you're Porsche, that is. The manufacturer of one of the most successful competition cars of all time has made a name for itself by pushing the limits of speed and performance.

The 2022 Porsche 911 GT3: A Dominant Force

The 911 GT3 is no exception to this rule. With its sleek aerodynamic body, shark-blue swan neck wing, comfy carbon-fiber bucket seats, and a four-liter flat-six engine unleashing 502 horsepower, it's clear that Porsche has outdone itself. And yet, as our host pointed out, "winning isn't everything." But let's be real, it feels pretty good.

Torque: The Rotational Force That Turns the Wheels

So what is torque vectoring? Simply put, it's a system that varies the amount of torque being sent to each driven wheel. This relies on multiple sensors, computer controls, and clever engineering to make it work. But not all torque vectoring systems are created equal.

The Diff: Understanding the Basics

To understand torque vectoring, we need to start with the diff, or differential. In a rear-wheel drive car, the input is the drive shaft, while the output is the left and right axles. The differential allows the outside wheel to rotate faster than the inside wheel, ensuring that both wheels cover the same distance as they turn around a corner.

A Pinion Gear, Ring Gear, and Spider Gears: The Anatomy of an Open Differential

At the end of the drive shaft is a pinion gear that drives a ring gear. The ring gear is attached to a case or carrier holding one or more spider gears. As the carrier rotates, the spider gears drive two side gears attached to the axles. When both axles turn at the same speed, the spider gears aren't rotating, but are mounted on bearings so they can rotate if there's a difference in speed between the axles.

The Problem with Open Differentials

However, open diffs have problems when there's a large difference in grip between the driven wheels. This is because the same rotational force doesn't always produce the same rotational speed. As our host noted, "the common unit of rotational force, or torque, is the pound foot." But did you know that saying "foot pounds" is technically incorrect? It's just a matter of who invented this system.

Torque Vectoring: Separating Fact from Fiction

So what does it take to create effective torque vectoring systems? According to our host, not all torque vectoring systems are created equal. Even the most sophisticated systems build upon equipment already in your car. To understand torque vectoring, we need to start with the basics and separate fact from fiction.

The Tools of the Trade: Torque Wrenches

Speaking of tools, our host mentioned that tool companies actually use foot pounds on their like, I don't know, torque wrenches. And if you ever find yourself at a tool show, be sure to check out Me and Job's show together – it's called [insert name here].

WEBVTTKind: captionsLanguage: en- Car companies love to say things likeour car has intoxicatingform and compelling function.Yuck.But if you're an engineer,you know that's marketing bull poopy.You can smell it when you see it.It's not really sayinganything about the car.So what if they saidit's got, I don't know,more agile handling with improve behaviorbecause of torque vectoring.Is that more hype, orhigh tech engineering?Well, today we're gonna figure outwhich torque vectoringsystems are the real deal,and not just clever marketing.Let's go, dude.(upbeat urban music)- Big thanks to Omaze forsponsoring today's video.Winning is great.I do it a lot, but it'snot what really matters.Unless, it's aboutgetting the chance to winthis 2022 Porsche 911 GT3 withtaxes and shipping included.Now that kind of winning does matter.So head over to omaze.com/donutgt3to enter for your chance to win.Success and be fleeting,and you shouldn't live lifeonly for accomplishment.Unless you're Porsche, makerof one of the most successfulcompetition cars of all time,then yeah, you probably should.And this 911 GT3 right heredominated the Nurburgringin under seven minutes.Showing that you can improve on a winner.But again, life is isn'tabout winning, guys.Are you even listening to me?There's so much more more to it than that.Things like an aerodynamic body.This shark blue swan neck wing.Of course, comfy carbonfiber bucket seats,and a four liter flat sixunleashing 502 horsepowerto stampede the competition.Not that it's a competitionbecause as we know,winning isn't everything.But let's be real, it feels pretty good.You know what else makes you feel good?Knowing that every one of your donationsbenefits the Dempsey Center,which helps those managingthe impact of cancerby providing a varietyof diverse, personalized,and high quality services.All at no cost.And that's winning weshould all aspire to.So head over to omaze.com/donutgt3to enter for your chance to win,and help a support an incredible cause.Good luck.- Torque is the rotational forcethat turns the wheels on your car.Now torque vectoringvaries the amount of torquebeing sent to each of the driven wheels.That relies on multiplesensors, computer controls,and clever engineering.But not all torquevectoring is created equal,and even the most sophisticated systemsbuild upon equipment already in your car.So to understand torque vectoring,we need to start with thediff, AKA the differential.And we're not talking calculus here.Oh, calculus joke. (laughs sarcastically)When your car goes around a corner,the outside wheel coversa greater distancethan the inside wheel.If those wheels were locked togetherforced to rotate at the same speed,one would slip or skid losing tractionto compensate for the different distancesthat those wheels are traveling.So to prevent that, your carhas a differential in it.That is a mechanical devicewhich allows two input shaftsto rotate at different speedswhile driven by a single input shaft.So in a rear wheel drive car,the input is the drive shaftand the output is theleft and right axles.That differential allows the outside wheelto rotate faster than the inside wheelso it can cover a greater distance,and avoid slippingduring ordinary driving.And most cars use an open differentialcontaining a set ofgears that work togetherto send power to the axles,and also ensure that the wheelscan rotate at different speeds.At the end of the driveshaft is a pinion gearthat drives a ring gear.And that ring gear isattached to a case or carrierholding one or more spider gears.Ooh, spooky.As the carrier rotates,the spider gears drive two sidegears attached to the axles.When both axles turn at the same speed,that spider gears, they're not rotating,but they're mounted on bearingsso that they can rotateif there's a difference inspeed between the axles.By rotating, the spider gearscompensate for that difference.Even if you hold one axle in place,the other side can still turnbecause of those spider gears.That's great for making tightturns, but here's the thing.There's an issue with it.Open diffs have problems whenthere's a large differencein grip between the driven wheels.That's because the same rotational forcedoesn't always producethe same rotational speed.Oh.The common unit ofrotational force, or torque,is the pound foot.Now one pound foot isequal to one pound of forceapplied one foot fromthe axis of rotation.And we mess this up a lot.A lot of times we say foot pounds,they're technically different.Don't get mad at me.It's just the people whoinvented this system, okay?Yell at them, not at me.And to make matters worse,tool companies actually use foot poundson their like, I don'tknow, torque wrenches.Speaking of tool shows,click this right here.Me and Job did a show together.It's called "Tool Party."It's a lot of fun.An object isn'tnecessarily going to rotatejust because torque is applied to it.If you put one pound footof torque onto a boltthat's been tightenedto a hundred pound feet,bolt's not gonna go anywhere.Now how fast an object rotates dependson how much torque is being applied to it,and how much resistancethat torque has to overcome.So in the case of a car's wheel,some resistance comes from its mass,but most of it comes from the tires gripand the proportion of the weightof the car over that wheel.So the problem with an open differentialis that even though the rotational speedat each wheel can vary, thetorque is shared equally.And the maximum torque thateach wheel can receive,it's limited to the amountthat will break traction for the wheelwith the least resistance.That is the traction difference problem.And in extremely slippery circumstances,that can leave you stuck.Insert high low clip here.- So you can see passengerside tire, all sorts of grip.But because the driver sidetire doesn't have any grip,all the powers going thereand they're not going anywhere.- But a more common symptomof the traction difference problemis when a slipping wheelis getting too much torque.That's the one wheel tire firethat open diffs are known for.Insert high low clip againBoom.- Yep, That's one tire fire.- And in performance driving situations,traction differencesoccur almost constantly.I got traction difference problems.This girl likes me and this one doesn't.Maybe I should just stopdating girls. (laughs)During cornering, the carexperiences body roll or leanas its weight transfersto the outside wheels.That weight shiftunloads the inside wheelsreducing their resistance to rotation.If a car is turning andthe unloaded inside tirecan only take 50 pound feetbefore it breaks traction,the grippy tire on the other sidewill only get a maximumof 50 pound feet too.So if you match the throttleand send more torque than that,the inside tire it is just goingto break traction and spin.And once your traction isbroken and the tire is slipping,that reduces its resistance further.So 50 pound feet is now farmore torque than it can use,and it just keeps spinninguntil it slows down enoughto regain that lost grip.Now, throughout all ofthis, the outside tire,which has plenty of grip,doesn't get all that torquethat it deserves, and it needs it.It's like torque me, baby.Torque me.And the outside tire that'sjust ripping and smoking,it's like, it's my torque.♪ It's my torque ♪♪ And I'm just gonna do it forever. ♪♪ It's my torque ♪(Jeremiah imitates song riff)So one way to solve that problemis to simply back off the accelerator,but what (beep) fun is that? (laughs)Not fun at all.So here is where torquevectoring can help.Unlike an open differential,torque vectoring canvary the amount of torquebeing sent to each wheel.Slowing one that's slipping,and making sure there's enoughfor one that's gripping.Now some of you are saying,hold on, hold on, wait a minute.Limited slip differentialssolve the traction difference problem.And that is true.LSDs provide a mechanicalsolution to the problemof open differentials, butthey're not a perfect solution.There are several types of LSDs,and we can't cover how all of them work.We probably need an entire B2B for that.If you want it, put a comment down below.But knowing how a clutch pack LSD worksis gonna be helpful in understandinghow a torque vectoring system worksthat we're gonna see later.Now clutch pack LSDs usealternating friction discin steel plates, like theclutch in a motorcycle.The friction discs rotatewith the side gears and axles,while the steel platesrotate with the ring gearand differential case.And under normal conditions,that clutch pack is disengaged.All those plates justspin past each other,and the LSD operates like a normal diff.Transferring power from thering gear, to the spider gears,to the side gears, to the axles.But if the driver presses the acceleratorwhile the wheels are slipping,drag causes the pinholding the spider gearsto shift backwards relative tothe rest of the differential.And that movement pushestwo spring plates outward,engaging the clutch packs.When the clutch platesare pressed together,the rotation of the differential caseis sent directly to the wheelsbypassing the spider gears.So this locks the wheels togetherforcing them to rotate at the same speed.And this limits how much a wheelthat's lost traction can slip.It can only rotate asfast as the other wheel,the one that has grip.But clutch pack LSDs andevery other type of LSDs,they have a few drawbacks.Mainly just having a great time.But for one thing, theyrequire maintenance.They're also complex and can be expensive.And because they're solelymechanical, they're a bit dumb.They can only react towhat's already happening.Torque vectoring on the other hand,it's like an LSD thatcan see into the future.Like me on LSD.And even though torque vectoringrequires a differential to function,it can work with any typeof diff, open or LSD.Doing that requires a sophisticatedbut very small piece of equipmentthat's probably already on your car.A yaw rate sensor.Heck yeah y'all, let's get going.This is my kind of sensor.If you don't know what yaw is,yaw is the rotation of the cararound its center access while turning.Yaw rate is how quicklythat rotation happens.Now you might hear someone saya car feels slow to turn in,or quick to rotate.And what they're feelingis changes in yaw rate.Yaw rate.I wanna do so many y'alljokes, but I can't.Automotive journalists freakinglove to talk like this.They salivate at the thoughtof having to use that word,but they never seem to measure yaw.Engineers do though, using a microscopicelectrically conductive gyroscope.Or euroscope depending onwhere you live in the world.That's nothing like thegyroscope you've seenwith spinning concentric discs or circles,but the principle is still the same.Gyroscopes can be used to measurethe inertia produced by rotation.From that, a computer cancalculate the rate of yaw,which makes electronicstability control possible.And the same process lies atthe heart of torque factory.Electronic stability control, or ESC,uses sensors in the car's ECUto prevent loss of tractionthat can lead to accidents.So for example, if the ECU detectsa large steering angle but a low yaw rate,that means that the vehicle isn't turningas much as the driveris telling it to turn.It's under steering,and the car can be headedtowards an obstacleinstead of turning to avoid it.So the ECU will apply breakingforce to the inside wheels.Slowing them in increasing rotation.The simplest forms of torque vectoringuse that same system toovercome the disadvantageof an open differential.Now the most basic formof torque vectoringis brake based systems,and they work because thelimitation of open differentialsisn't based on the traction at the tire.It's based on the resistance,or lack thereof, at the axle.Basic torque vectoring applies the brakesto add resistance to the axleof a wheel that's slipping.This slows the wheel so it can make useof that torque it's given.An increasing resistanceat a slipping inside wheelalso increases the total torquethat can go to the other wheel.So it's win-win.And this type of torque vectoringcan often figure out what to dosimply by comparing differencesin wheel speed sensors.So that's got the same problem as an LSD.It's purely reactive.So by incorporating other sensorslike a steering angle for example,torque vectoring systemslike the one used at Porschecan apply braking to the inside wheelas soon as a turn begins.That encourages rotation at corner entry,and prevents the insidewheel from slipping at all.Porsche's system also includesa mechanical limited slip differentialso it doesn't have to relyon the brakes too much.Fucking Porsche, dude.German engineering at it's finest.Systems which don't have an LSDcan sometimes rely on the brakes too much,causing brake fade whendriven at the limit.We know you like doing that.But for drivers who don'ttake their cars to the track,a solely brake basedtorque vectoring systemcan make a huge differencein how the car drives.It's less prone to under steerand with a sharper turning response.And another cool thing?They're like stupid cheap to manufacture,because there's no new equipmentneeded to make them work.You just need the right programin your already established ECU.Car and Driver evenreferred to these systemsas dollar store torque vectoring.I would've said 99 centstore torque vectoring,but I'm not a journalist.But that really wasn't a compliment.Car and Driver and many enthusiaststhink that brake based systemsaren't real torque vectoring.And some of them do soundlike marketing hype.Ford described one of their systemsas applying brake torque to the wheels.Now braking force canbe described as torque,but it's the torquethat's driving the wheelsthat most of us are interested in.And since brakingdoesn't directly increasethe torque being sent toa wheel, like an LSD can,these systems can come offas just performance versionsof stability control.Tricky, tricky, little Ricky.Unlike Ford, manufacturerslike Porsche have shied awayfrom the term torque vectoringfor solely brake based systems.Instead referring to afunctionally identical systemas an automatic braking differential.So if you want real torque vectoring,you may wanna talk to Lexus'cause in 2014, they debuted the RCFwith a new torque vectoring differentialthat uses clutch packs like an LSD,but the clutches areelectronically controlled.As we saw earlier, withan ordinary clutch pack...As we saw earlier.(Jeremiah sips water)Oh, that beautiful H2O.Okay.Now, as we saw earlier withan ordinary clutch pack LSD,high torque at the input shaftduring a loss of tractioncauses a reaction in the diff.Clutch is engaged lockingthe wheels together.Lexus's torque vectoring differentialis engaged predictivelybased on vehicle sensorsand settings chosen by the driver.So far, that's a bit like thecheaper brake based systemsbut because it's gota set of clutch packs,like a proper mechanicallimited slip diff,it can vary the torque side to side.Something an open diff cannot do.One electric motor ateach axle rotates a camthat locks the clutch plates together.That motor can vary the cam positionto adjust the amount ofslip in the clutch plates,and that means the system can applydifferent amounts of lockingto each wheel independently.It also works with the brakesto apply negative torque,that's what Ford called brake torque,to the wheels independentlyto encourage rotation.So what does this all looklike going around a curve?As the driver turns into a corner entry,the system applies thebrakes to both drive wheelsadding resistance to prevent slip.As the steering angle increasesheading towards the apex,the braking force is transferredto just the inside wheelwhile the clutch packengages to send more torqueto the outside wheel encouraging rotation.When the driver unwinds thewheel and steps on the throttleto power through the corner exit,the system sends even moretorque to the outside wheels,and monitors the insidewheels applying breakingif a slip is detected.And all that's doing it'spreventing under steerthat could push the car wide,or reduce your exit speed.Nothing dollar store about that system.And it's only a $1,250 option.That torque vectoringdifferential decreases lap time,increases lateral grip, and even reducesthe steering angle necessaryto get the car to rotate.We only had time to scratch thesurface of torque vectoring.We didn't even get time to talk aboutthe most sophisticated systems yet,which are all found inall-wheel drive vehiclesbecause those rely on upto three differentialsto maintain grip.They also have to vary torquebetween the front and rear,as well as side to side.But look for that in a future episodeabout the Audi Quattro.And maybe we'll do another episodeabout how electric carsdeal with torque vectoring.Hmm. You're into that?Leave a comment down below.- Are you tired ofseeing so many junk cars?Then buy this shirt and wear it every dayso junk car owners know we buy junk cars.Hi, I'm Junk Car Jimmy.I want you to gimme a call.Look at this car. 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