Torque Vectoring Differential - Explained

[@glenb.9811]

On your diagram at 3:45, you state the clutch connects the output shaft to the differential housing, except you haven't drawn the housing-you have the clutch assembly connected to the diff carrier/crown gear. The clutch pack actually activates and slows the inside shaft down, allowing more torque to be transferred to the outside wheel. I'd say the planetary gearset is there to allow a smaller/lighter clutchpack to be used, as the planetary gearset appears to spin faster than the diff carrier, which would produce a torque multiplication effect to the splined axle hub through the planetary gearset when the clutchpack brakes it.

[@chadr1zw]

great description, the use of planetary gears to deliver torque at the proper ground speed or greater to the outside while still sharing traction with both wheels is amazing. The rcf is a heavy car by any standard. The tvd is able to make the car feel light and nimble to the point where there may even be voodoo involved. I own an rcf with tvd - it does feel a bit strange but it sure does the trick

[@Mbee16]

The principle of a differential can also be applied in reverse whereby individual braking can be applied to any wheel. If the right tyre requires more power than the left wheel will slightly be "braked". Lower end cars use these methods of torque vectoring as it is much cheaper.

[@trangtran6486]

Great explanation of the basics of how it works. I've watched your other videos especially on differentials so I can see the differences between this type and the other types

[@G55STEYR]

Sorry to say but you're wrong. You just explained a LSD or locking diff at min 3:45. If you lock one axle with the carrier you got a locked diff and then torque varies upon grip, and do opposite of what is desired in corner: understeer. The clutch packs actuates on that planetary reduction gearset which changes the ratio, thus multipliyng torque on that wheel. The clutch when locked stops the planetary gears from rotating, as you can see it's fixed on the case. Search image "torque vectoring activ diff research" it's the first schematic with 4 drawings. It's the c) variant.

[@BorisFrank242995]

Thanks man. I was completely confused by this video.

[@G55STEYR]

To understand is necessary to see the picture with the scheme

[@EngineeringExplained]

G55STEYR Great, thanks for sharing. I'll update the video description, add an annotation, and I may need to shoot an update video. Now, the torque does transfer from going through the spider gears to the axles, to the housing to the planetary gears, but its the gearing that causes the difference in torque, which is allowed by the planetary sets. Mind shooting me a quick e-mail - [e-mail] so I can discuss the link you're referring to? Thanks!

[@MrMichaelyokom]

I understand a vast amount about cars and yet Differentials when being explained still make me feel nauseous and head-spinny

[@binthe920]

I was thinking the same thing. All he had to do is read the promo info displayed with the unit to know it works by changing the drive ratio and thereby the torque going to the individual side. Seems to me it works similar to an automatic transmission's gear change except it's variable instead of only working in the fully on or off positions. If that's the case I would think clutch wear would be an issue!

[@Mbee16]

Hi very informative vidoe. If I'm not mistaken, the principle of a differential is that torque goes to the wheel with LEAST resistance, hence if the clutch is engaged on say the left side then more power will go to the left side due to it having lower resistance than the right...

[@ArjunSingh-qp9yy]

Clutch engagement and disengagement influence the friction within the clutch system, where friction acts as an internal force. In theory, an increase in friction (internal force) on the clutch on left side does not necessarily translate to a corresponding increase in resistance on that side. However, greater friction on one side enhances the torque transmission capability on that side, allowing more torque to be effectively transferred.

[@PoisionDragon]

Thank you for that explanation. Right after the diagram of how it worked through a turn, I then understood the mechanics of it, but then again my mind is a bit weird that way. Regardless; a very good explanation!

[@xXhunter47Xx]

It's actually amazingly simple how this works when you explain it! I'm also interested in how the computer reads and sends data, although that may be a lot more difficult to do so.

[@ebrainz101]

Wheel speed would be all it needs, right?

[@spiritsavage]

@@ebrainz101 Wheel speed, traction conditions, turn ratio and direction, driving dynamics (WOT or casual)

[@johnny0454]

The computer takes and considers inputs from the steering angle sensor, each wheel speed sensor (wheel speed variations), throttle position sensor (desired torque), vehicle speed, brake pedal pressure, as well as vehicle accelerometers to make decisions about axle clutch engagement using a pre-programmed table, or "map".

[@filipCARbova]

Making project at my university (FSB) about differentals, with help of your vids. Opened description and saw link from my university ... funny stuff

[@montlejohnbojangles8937]

Thanks man! That was a really great explainer, even for a luddite like me!

[@ajaeclacken2835]

amazingly plain explanation really helped

[@Pogaspm]

Since the clutch packs will be constantly engaging, disengaging and operating half engaged, will there not be a high rate of wear on them?

[@kevbreezy5571]

thats where high maintenance costs come in

[@johnmoore1495]

At 4:44 what does the diagram mean by negative torque is applied. What is negative torque and how is it applied.

[@spiritsavage]

It will actually turn that side of the differential backwards sometimes in order to swing around more during a turn or something like that. Sounds weird, but for track laps it's actually pretty effective.

[@MaximusU76]

That is just braking.

[@punitm85]

The planetary gear set is overdriving the outside wheel in a corner. Can you provide info on how much? Like a gear ratio.

[@badhribalajiskcet]

You are simply amazing! loved that. Crisp and clear!

[@abepowers4379]

For regular legal driving speeds,how much better is this than a Torsen? Can the TVD benefits be realized in regular daily driving? Or only on track/autocross?

[@ItalianAvalanche]

Dynamics question: Cheap brake-based torque vectoring is inferior because it sacrifices engine power as heat into the brakes, among other things (also heats/wear brakes more quickly). These clutch packs generate heat also when they are not fully engaged. Where does that heat come from? Does this heat mean that engine power is being wasted?

[@2Phast4Rocket]

The main distinction of the brake-based torque vectoring versus clutch-pack on planetary gear is the clutch-pack only controls the rotational inertia of the planetary gear set. The brake-based system controls the rotational inertia of one of the four wheels thus it will rob more power.

[@MaximusU76]

The main idea of this devise is that the clutches are NEVER full locked while engaging. So yes, while vectoring the torque you dissipate engine power. Alas. But 1) that loss are smaller than using brakes; 2) you "direct the excess" of torque from one wheel to another through the diff, what doesn't happen when just braking one wheel.

[@jayfulf]

4:58 it actually says negative torque on the pamphlet which is a small but important difference.

[@EngineeringExplained]

Correct, important point that perhaps I could have been more clear on rather than just showing the backwards arrow.

[@parkkim5733]

+Engineering Explained just make additional video about Negative Torque. I don't get that concept with full fathom.

[@jayfulf]

park kim In this case it's just referring to torque in the opposite direction of travel.

[@MaximusU76]

It's just braking. No matter by what means, traditional friction brakes or recuperating E- motor. And yes, braking could also be vectoring, and are indeed. By individual brakes (traditional), individual motors (one per wheel while recuperating) or by such diffs.

[@alekivk]

I still don't understand how the planetary gears work in this. Is the output another sun gear? Is the ring gear fixed to the housing? If the clutch is engaged on one side, what is being locked together? Does it lock the planet carrier to the housing?

[@alekivk]

Eep, author mentioned this in the description

[@jackiefreeman8239]

Torque vectoring differentials is a win win win deal!

[@onkarmohite7560]

are torque vectoring differentials and LSDs same without the motor in the clutchpack?

[@EngineeringExplained]

Similar, but torque vectoring differentials are capable of proactively altering the amount of torque sent to each wheel, where as an LSD mechanically reacts to differing grip. You have significantly more control over how torque is applied with torque vectoring.

[@bocahdongo7769]

This torque vectoring doesn't involve any locking, but rather using planetary gearing system to vary the shaft speed (Like you know, automatic gearbox) So yeah, technically speaking, it is completely different

[@MaximusU76]

No, the motors for activating clutches are not the only difference. Cause it would be a regular active LSD. They are also planet gearsets on each axle.

[@roycezaro1998]

Can you cover Subaru's Active Torque Vectoring systems? I'm really confused on how ATV is any different than regular stability control, and why they call it torque vectoring when it really vectors the brakes and such- just like stability ctrl. I know the new WRX uses open diffs all around except for the proto-LSD in the center, so I can see how it and other Subaru vehicles may benefit from being able to brake individual wheels to control wheel spin. But the STI has like four LSDs, so why does it need Active Torque Vectoring? People like to talk about how the STI has ATV, but it already has a full suite of LSDs, soooo.... what's the deal? Thanks

[@WarzechaSoftWorks]

How does the Torque Vectoring Differencial compares to the Torsen LSD? Is the Torsen LSD solution more effective sending torque to the wheel with higher grip?

[@SumitBhowmick84ncr]

I just have one question, I saw the animation of the differential somewhere or probably on the ZF vector drive, construction is similar to this one, and essentially when you engage the clutch in that it locks the planet carrier to the differential housing as you also said, but when you demonstrated in the last part of the clip, you kept hold of the planet carrier to make it stationary, wasn't it supposed to mean the clutch is engaged in such condition rather than being disengaged? And more rotational power was sent to the left wheel instead? Another reason to ask this question is unlike a regular co-axial planetary set, where we have a sun, ring and planet carrier, this is a spur gear type set, where there are 2 coaxial gearsets, with their planet carriers married, and the ring gear here is actually the sun gear of the 2nd co-axial gearset which feeds power to the drive axles of the wheel. I tried clarifying by finding the detailed schematic of the gearing, but I couldn't hence I have such silly questions.

[@mrhmd8308]

Very informative. So is the Audi Quattro the same as torque vectoring?

[@loukasantoniou8054]

For the rear diff yes

[@AnyaXPsyduck]

A newbie here. Don't rlly get stage 2 of the cornering. When turning, the outside wheel has higher velocity plus there's slightly more body roll(weight) to the left so shouldn't more torque be provided to the left wheels. Plus intuitively if u want to rotate clockwise u want more torque on the left than right, going forward

[@DennisKarlsson]

When you steer right you want more negative torque on the right wheels. You want it to brake more on the inside. It helps rotating the car towards the apex.

[@themi80]

What you described was a locking differential that uses clutch packs. This is not torque vectoring, that's just a LSD. Torque vectoring is achieved when the clutch is activated and power is sent through the planetary gears providing an overdrive to the outside wheel when cornering. Thanks

[@EngineeringExplained]

Themi Xinos Thanks - I've added some further details to the video description. May make an update but for now have provided a link.

[@albietbeck]

I don't quite understand how the torque is transferred thorough the planetary gear set. Or how the driveshaft bevel gear is connected to it.

[@abhikbhattacharjee3952]

Thank you for explaining it really well! Even though it's a bit complicated.

[@lindsay5985]

Torque is applied to the outside wheel because, due to cornering forces that cause body roll, the inside wheel has no weight on it and would slip, as is the case in a conventional differential where each wheel gets 50% of the torque and the inside wheel always breaks free.

[@50yearoldskier]

Would you recommend torque vectoring even if car will be just used around the city? More of a daily driver?

[@JohnSmith-lv8xk]

It seems like your whiteboard drawing is opposite of the display, it looks like the clutch packs hold the shaft to the housing so that the other side gets the torque rather than the clutch packs clamping to the diff and spinning everything together ??

[@youtbnyaindra]

Nice video, but I don't know if I'm getting it right. So the controller input is the driver steering angle and small part of the throttle gain? how wide is the torque ratio do you think this can transfer 20%-80%?

[@EngineeringExplained]

Some of these diffs are capable of sending 100% of torque to a single wheel.

[@oldfashionedwrx3574]

Sounds expensive, I'd rather just have the brake applied to the inside wheel like they do on most modern vehicles. Great video.

[@dominionian7193]

Thank you for the explanation. A technical question for anyone that can answer it, and I can't seem to find info on this anywhere. When the clutchpack is engaged one axle side, it is connecting that side to the differential housing, but is it also disconnecting from the spider gear? If not, wouldn't that immobilize the spider gears (inside the differential housing), and effectively locking the other side to the differential housing's rotation? I noticed there's a planetary gearset on each side that must somehow eliminate this, but I'm curious as to how? Thank in advance!

[@wdwickham]

I think his explanation is actually wrong, the axle is not directly clutched to the differential carrier. The axle is clutched to the carrier through a planetary gear system which then allows one axle to be driven faster than the carrier in turn driving the other axle slower due to the spider gears. It kind of forces one wheel to spin faster that the other thus creating a torque vector.

[@dominionian7193]

@@wdwickham Thank you. If that's what it does, then it seems like the torque vectoring is binary (on/off) rather than variable

[@MaximusU76]

Not binary. Because that clutches is not aimed to full lock. If so you get a fixed ratio between left and right wheels. And that's not the case. They are slipping all the time they are engaged. So you have some power loss, heating and more rapid clutch wearing during torque vectoring.

[@FlyingSnake110]

You forgot to mention role of planetary gearsets. If clutches would simply connect output shafts with diff-housing it would work like simple LSD with added control of how much it can slip. Planetary gear sets allow to direct power to one wheel instead of locking whole differential. Principle is similar like modern tanks steering systems with two power inputs.

[@EngineeringExplained]

+FlyingSnake110 Correct, it's incomplete. The gearsets allow the power to be redirected. I've included a link in the video description for more info.

[@exnihilo415]

+Engineering Explained Yeah, but seriously, no one without a master's degree in mechanical engineering from a top school is going to understand that linked document. Can you redo this video? I'd like to understand how torque vectoring actually works in 5 minutes, not 5 years worth of effort.

[@FlyingSnake110]

+exnihilo415 basically clutch with planetary gears try to spin output shaft faster than it spins, thus transferring power to it. That's why that gearset is needed, to multiply speed between clutch and shaft. Without it this differential would work as it would have electronically controlled slip.

[@HellTriX]

+FlyingSnake110 I was confused until i read you're reply. I was thinking that this would just be an electronic slip control and that a center spool would be a better option. Then realized you are right, the planetary set is the key here.

[@MuchoBoosto7]

I agree with exnihilo - a short video describing how the planetary gearset causes the wheel to be overdriven would be great.

[@LukeMcGrew]

How about a video on the Electric Diff for the corvette or gti, or is it kinda the same as the torque vectoring?

[@scottstensland]

how does the rear axel know car is making a turn ? is it monitoring the steering or picking up differential wheel rotation speed ?

[@LaenPvP]

Why is more torque sent to the inner wheel to rotate as opposed to the outer wheel? Is it because while turning the weight of the vehicle compresses the outer wheels more giving them more grip, meaning the inside wheel essentially has less grip and needs more power? Thanks.

[@NeutralGenericUser]

Remember that under hard braking, the torque from the engine will work as "engine braking" which is why in the diagram, in the video, it is referred to as "negative torque". It is actually braking the inside wheel more by connecting it more to the engine using torque vectoring = more negative torque to the inside wheel. When coming out of a corner, you hit the accelerator, and when the car senses that positive torque is being applied, it shifts it to the outside wheel. I hope that makes sense.

[@MuchoBoosto7]

The link is dead that you posted in the description that explains how the planetary gears overdrive the outer wheel when the clutch pack partially engages - could you please do a short video elaborating?

[@cozyocelot]

Thanks for the video- short and detailed

[@sbond1963]

Recent purchase of a 2019 jeep Cherokee with Active Drive 1. It has this crazy wobble on acceleration, even after replacing the rear drive module. I’m wondering if torque vectoring problems in the programming are the actual cause of what seems to be a lateral wobble

[@cindycionerealtor]

Should this system ever make a kind of grinding sound? My new 2021 Forester does it rarely but on certain hwy 1 curves, mostly when going down hill.

[@rx8cosmo]

I also wanted to ask if there is a difference between LSDs and torque vectoring diffs! Also does ford's torque vectoring system use the same principle or is it just by applying the brakes to the wheels thus alternating torque distributtion?

[@EngineeringExplained]

Many use the method of braking individual wheels, as it's far cheaper to implement, though I think a dedicated system as shown in the video would ultimately be a better solution (and wouldn't cause brake wear).

[@d1sturb3d119]

LSD's are mechanical systems and do not react based on conditions, steering angle, yaw and throttle application. They are pretty much bullet proof but not smart. TVD like in a SHAWD Acura or the lexus are capable of sending 100% of the power to the outer wheel and can also help correct your angle. In bad weather conditions it can sense slip and send power to the wheel with the most grip. Ford's system is brake actuated and is very basic. It works but its older tech and isn't as good as an active system. blog.caranddriver.com/what-torque-vectoring-really-means-for-the-2012-ford-focus-and-why-you-shouldn%E2%80%99t-get-too-excited-about-it/

[@refrigeratoroven]

Engineering Explained Would be interesting to see comparison of available outside wheel energy (or system efficiency) of torque vectoring vs brake based vs clutch vs viscous LSD's at varying loads.

[@d1sturb3d119]

Chris Conroy Well it would be brand specific again. Acura's system can send 70% of the power to the rear and 100% of that to each side if necessary. Lexus may be different and Audi's split is 40:60.

[@FuturesPassed]

Seems like this would have to use some sort of ATF friction modifier with the viscosity of a gear oil or something close to that. I bet that flush and fill will be pretty expensive for the first few years, when only the dealers have the fluids on hand.

[@junoguten]

Will this allow you to have an even smaller turn radius in a RWD without the front wheels just sliding forward? How much smaller do you think? Alternatively, in a RWD, would having an open differential but having brakes that can apply to one rear wheel or the other when at very low speeds with the steering wheel is turned very far help you with that? Also, I have a general feel for when the front wheels will just slide instead of actually turn (from my sit-on lawn mower. It's RWD, open differential and can turn the front wheels really far. Measured about 65 degrees on the outer wheel on max turn). It seems to not want to turn anymore at different angles depending on the inclination of the ground, the direction I lean on it, and the surface it's on. Maybe there are other factors I don't know about too. What I have no idea how to do is calculate what angle it's gonna be. Anyway I had this idea because I discovered that short of spinning one wheel, leaning over the outer rear tire seemed to mean I could turn the steering wheel slightly more and still turn. Just figured if that could somehow be used to lessen the eternal pain of doing U-turns with your city car on tight roads, that'd be swell.

[@MrTimstaaa]

Hi Jason. Would the torque vectoring lsd diff be better than the torsen and viscous lsd diffs for regular and performance driving ? Whats your opinion ?

[@derxKai]

+Timur Hafouz Yes, it would be better, because with TV, the outside Wheel is more "accelerated", wich helps the car turning. The common LSD Types are only locking if one Wheel is losing traction. Also the Clutchtype LSD is often pretensioned, wich leeds to understeer. So in many cases, is the TV a better solution. Regards from Germany

[@mrvoyagerm]

Yes but what sensors etc activate the clutches and deactivates the rear driveline once up to speed? What tells it you are cornering? I have a 2021 Highlander with this system and it is both incredible and seamless. No more aggravating ABS noises trying to do this for you, just seamless traction like I have never experienced before and I have had a bunch of Toyota 4x4s in the past and they were good but not this good.

[@lostalx]

Highlander and other Torque Vectoring systems use Hydraulic pressure. Lexus TVD is Electronic and has a lot more to it. The TVD system has its own ECU that gets it from the main G Sensor, I think that data will be from the main ECU. This TVD is bespoke and not existing on any car right now. It's way too complex to engineer and heavy with high cost, so even Lexus killed it in the RC F 2023 MY onwards. Acura SH-AWD is Torque Vectoring as well, but they are Reactive systems, it does not work on Deceleration and all conditions, TVD is proactive, it's always On.

[@loukasantoniou8054]

So a torque vectoring diff is an lsd that is electronically actuated based on differend readings from sencors, instead of mechanically through the movement of the pinion. Thus making it a proactive diff instead of reactive. Which would you say its better and more reliable with less maintance required. Correct me if im wrong, im still an engineering student. Also big queation, might be dump. We know you can pretty much fit a torsen to any open differential housing. Could somebody theoretically put a torsen(or similar atb) in the place of the open diff in this diff assemply. Would that make any sence at all?

[@MaximusU76]

Not exact. This design has planet gearset reductors at each side. So wheel side of the clutch is rotating slower than diff housing side, even for faster wheel.

[@MrPl0xygen]

Does torque vectoring help in tight turns ?

[@BradsHacks]

Will you do a video on tank steering mechanism (double differential) and whether it can be used as torque vectoring in cars?

[@sachinraut5729]

what's the purpose of planetary gearset at each of the axles in the main gearbox?

[@OhYeaMista]

Seems like it works like a brake lock differential (bld) but at high speeds. Instead of using the brakes to move torque it uses clutch packs. Am I understanding it right? Seems like a lot of work for not such a great gain...

[@vahidpatel3426]

Suppose I am making a mid-engined sports car with an all-wheel drive system, which differential should I choose? Either a torque-vectoring one or an electronic differential?

[@Drunken_Hamster]

Seems like a high weight/complexity/point of failure-to-benefit ratio. Torsen seems like it could do 80%-90% of what this does for 1/2 the weight and 1/10 the complexity and points of failure. Not to mention clutches being worn items.

[@MaximusU76]

Torsen by itself doesn't make the same job. And it has its own inherent cons.

[@Drunken_Hamster]

@@MaximusU76 The only con of torsen that I know of is that it acts like an open diff of one side has zero grip. The solution to that is to press on the brakes. If there was anything else, I'd say the initial purchase price for the unit compared to a clutched 1-way, and that a torsen itself is also only 1-way IIRC, but I'm only 30% sure about that since I've seen several guys drift very well with them.

[@lostalx]

RC F TVD failures are very low and it has been 10 years since the model was introduced, saw a few GS F failures though. LSD on RC F will be natural but TVD feels psychic to the driver and it's built like a tank. Yes the failure point is introduced but as I said this car has been in production since 10 years, they killed the TVD silently though, 2023 model onwards no more TVD.

[@SavageBunny1]

Man... The good old days when you just had an LSD diff that's really good for fun and good old ABS to help you when your too distracted to help yourself out a sticky braking situation.... And that's is if your car was new enough with ABS if not you better be on point with your braking skills all the time, snow or raining... Or sand.... Or a muddy hill.

[@honsolo802]

How does the electric motor know when to engage the clutch? In other words, what is the actual trigger to engage torque vectoring? Since this is helpful on turns and slippery words, how does the motor know these conditions are met? Thanks for the awesome video!

[@RahulSharma-oc2qd]

It basically works on newton's third law... reaction to every action. There are sensors on wheels which tell you about the conditions which give motor the via some electronic unit that now motor should come into action which in turn would rotate the gear and the flow of power goes further.

[@lostalx]

TVD has its own ECU and Lexus RC F has a specific G Sensor with high calibration point which is probably where it will get the Yaw motion.

[@blackericdenice]

2:22 an electric G80 on both sides of the diff.

[@willesco5211]

So whats better torque vectoring or limited Slip Differential?

[@GRANLALO25]

Question: what kind of center differential uses the 2017 Ford Focus RS ????

[@steviedellis]

So I've just watched all of this series in the past 24 hours. Would I be correct in saying modern formula one cars run torque vectoring diffs like these (a very loose, like)? After the viscous episode I thought they might use those with an ER fluid for the driver controls. Is it more possible that they do use viscous diffs with the only reasoning being that the mid corner control is usually labelled "viscous"? The only other thing I can think of is they use a "torque vector" setup like this with ER fluid instead of cams and step motors. Thoughts?

[@brodude2002]

Can you compare this system to the Ford eTVC that applies braking torque to the inside wheel during high speed cornering? Thanks!

[@loukasantoniou8054]

The fords system just brakes the wheel so it creates load to that wheel(load that would otherwise be the traction of that wheel but since it lost traction no torque is sent to that wheel via the trans, so "brake torque/resistance, replaces traction resistance), so more torque can be transferd to both wheels. Hope that makes sence

[@mangobanana7195]

Is it worth the weight? I'm guessing those gears and clutches aren't going to be light since they're part of the drive train.

[@mikef058]

In reference to the Evolution X and the 2015 WRX and STI, how do those torque vectoring systems differ. It seems like the Evo X uses a system like what was explained in the video. However, the WRX and STI uses a "brake assisted" system Subaru calls "active torque vectoring".

[@bailey12444]

Thinking about buying an rc f do I need tvd? Is it a safety feature? Thanks

[@carsonwong]

wont the clutch pack wear out very quickly ? and once the clutch pack wear out, the lsd no longer function?

[@MaximusU76]

That was said about vicious LSD. When the fluid lost its condition and there is no more much friction that device operates more like open diff.

[@conradhofer3494]

What is the AWD system consist of in 2004 Olsdmobile Silhuette mini van?

[@TheChris1610]

Sorry but I think you explained it wrong! You don´t get more torque to the right or left axle because of the clutch connection between diff housing and axle. What you are describing is a normal electronic lock differential. Key to sending more torque to one wheel are the planetary gearings. for example if the right clutch is engaged the planetary gears force the right output shaft to spin faster (i think it´s about 10%) than the left one. by doing this you can force the open diff into an imbalance which leads to more torque output on the left side. Because open diff means: nr+nl=2ni with nr= rpm right, nl= rpm left and ni= rpm input. So in case ni=1 nr=1,2 => nl= 2*1 -1,2 = 0,8. Also the gear ratio is i = ni/nr= -tr/ti => Right side ni/nr = 1/1,2 =0,83 => 0,83 = -tr/ti => tr=83,3Nm => left side ni/nl = 1/0,8 =1,25 => 1,25 = -tl/ti => tl=125Nm sorry for bad english

[@TheChris1610]

Engineering Explained

[@TheChris1610]

Realy? no answer? Thank you!

[@EngineeringExplained]

TheChris1610 Sometimes you miss a comment when there are thousands a month. I've added an annotation and a link to the video description clarifying some (misleading) points.

[@TheChris1610]

Engineering Explained Yes i understand that. But if you take your time to write a comment like this and explain things you may get a little mad if you see answers to short 10-word comments that were posted after you. Back to topic Differentials and especially torque vectoring differentials are a very complex and hard-to-explain topic. But if you try to explain it you should do it right or let it be. If you just say it’s a diff setup and it allows you to alter the torque distribution that´s ok. But if you start explaining operation and claim to do a “in-depht” review of the operation- principle do it right and if you made a mistake, correct it. And not only by writing “the operation of the planetary gears is not explicitly shown” into the description. 1. Most people don´t read the description 2. It´s still wrong! You explained the torque vectoring effect as additional torque being send to the individual axle via the clutch packs adding up with the 50% of the open diff and that’s simply not true! You didn´t mention the planetary gears or their role at all. No offense but I daresay you yourself don´t understand how the torque vectoring is working. That´s no shame! It took me long hours of research to understand the principle. There is almost no info about differentials on the internet and even less on the torque vectoring. I also was on a point where I thought that the principle you described was right but believe me it is not! I really like your other videos and It would be great to have a video describing the correct principle in an easy-to-understand way. This would make life much easier for many people. But please stop confusing people and correct your video

[@2Phast4Rocket]

So does the clutch pack lock or slow down the planet-carrier or does it slow down the planetary ring gear?

[@tacampbell]

Why use computer controlled clutch packs on the differential itself? It seems like a lot of extra mechanical (expensive) equipment that can fail. What is the benefit over just use the existing braking system with individual braking (via the computer controlled ABS system) on each corner?

[@NeutralGenericUser]

Brake vectoring systems don't actually alter the torque sent to the wheel, just the wheel's tendency to slow down. If you'll notice in the diagram, torque vectoring not only helps with the entry into the turn, but also the exit. If you tried to do that with brake vectoring (brake the inside wheel during entry and exit from a turn), you would cause the car to be braking while you're applying the accelerator trying to speed up. Not to mention, brake wear would be a big issue if you use the system frequently enough.

[@tacampbell]

NeutralGenericUser Isn't the clutch pack effectively acting as a brake on the axle, as it locks up against the differential? Whether as a clutch pack applying pressure against the side of the differential or a brake pad applying pressure against a rotor, it is effectively creating resistance on that one axle and slowing it so that the torque is forced to the other axle. The only thing I can think of that could make the argument for the clutch pack vs brake rotor approach would be if the clutch pack applied resistance to one side of the spider gears, but allows the actual axle to free-wheel at its own speed and therefore doesn't slow it - but simply redirects the torque. That doesn't appear to be the way this is designed, unless that is some of the functionality that is hidden within the planetary gear set? Brake pads are cheaper and easier to replace than differential clutch packs, so the cost of brake pads isn't a strong argument for the manufacturers either.

[@NeutralGenericUser]

Thomas Campbell The clutch pack locks up against the differential not to cause drag, but to lock the two in unison. It might cause a second of drag between 0 torque and full lock, but that's not the point, that's just a tiny inconvenience. The brake vectoring is entirely there to cause drag.

[@tacampbell]

NeutralGenericUser Got it. I was confusing the term differential housing with differential case. My mis-understanding had me thinking that the clutch pack was engaging the axle against some sort of machined surface on the outer case, thereby producing drag on one axle forcing torque to the other axle. Like a brake based system would do (and why I was somewhat aghast at the idea of it "locking." I see now that it is like a clutch-driven LSD, but the clutches are on the outside of the case passing through the case and against the differential housing. Unlike a brake driven redirection which slows the axle, this forces a tighter synchronization with the driveshaft which guarantees more power to the axle. Thanks for the video - hopefully I'm in the minority with my misconception about what the clutch pack is pushing against (it's the being on the outside that mislead me.)

[@NeutralGenericUser]

Thomas Campbell You might be in the minority just because your vast knowledge in this area caused you to overthink it. It is clear from that comment that you have a deep understanding of the topic :)

[@vineethkumargs1]

So what is the need of planetary gear set at both the sides when there is clutch pack?

[@Nontas1993]

The planetary gearsets on both sides speed up their corresponding wheel by a marginal amount of about 1.5%, the clutch packs lock up the planetary carrier of the planetary gearsets and when they lock it up they do their job and start to speed up their axle. All of that speeding up of each axle is needed to draw torque from the opposite wheel. It's an open diff in the middle, and we all know an open diff will transfer torque to the slipping wheel. The planetary gearsets simulate a ''slipping'' wheel when they activate through the clutch packs.

[@AeroPR]

Amazing explanation and video! Awesome

[@powl_cz3736]

This explanation sucks...you completely skipped overdrive units on both sides of diff...these are actually doing the work!

[@HTBLuVA]

so, is it possible to LOCK such a diff(both clutchpacks fully engaged)?

[@aNiederbayer]

i really don't get it... in your description link it's figure (c) thats most common to this kind of torque vectoring differentials i guess? In the draft i get it, there are two different size sun gears and two different size planet gears, the planet gears are directly connected. When the clutch pack is open, it does not influence the torque distribution. When one is closed, the planet gear carrier is braked down and the torque comes from the differential housing, to the inner sun gear, to the planet gears, to the faster spinning outer sun gear and finally to the wheel. But in your video the planet gears look totally the same size? how does this work? there's a video animation on youtube of the "ZF vector differential" and there it looks the same, the planet gears are not only the same size, they are one gear! This thing is really complicated...

[@VINAYAKVARMABME]

How is this different from an LSD ? What if I could use a Torsen differential/LSD which could be activated during cornering as well (and not just during the case of unequal grip) ? Won't that essentially act as an equivalent Torque Vectoring Differential?

[@Mamac2006]

is this the same thing as electronic limited slip differential (ELSD)?

[@nowornever2504]

Good until the part about how the Lexus system works, which is poorly explained. “Negative torque vectoring” on 1 and 2 sounds like automatic brake application. “Positive torque vectoring” on 3 and 4 is when the clutch pack is engaged to send more torque that specific drive wheel.

[@IDSKoT]

I was wondering if you know about the lifespan of the clutch packs. It seems with systems like these that the clutches would get used often and heavily and would cause wear quickly.

[@ruanjiayang]

If there is slipping on one wheel during cornering (say, the inside wheel, which needs to lower torque), disengagement of the clutch pads will unexpectedly send more torque to this slipping wheel since the torque goes to the minimum-friction path, wont' it?

[@normt5463]

Except for Lexus FWD Awith AWD based SUVs that only send 50% power to the rear maximum and only have brake based vectoring. Can you cover which brakes are used in brake-based vectoring?

[@EngineeringExplained]

Some companies apply brake vectoring to just a single axle, others will do both front and rear.

[@orangecabbage7867]

Could you do a video on transmissions in heavy machinery equipment (Like tractors, skidders, ADT etc..) and how it is different from car transmissions?

[@BrianLee-w4k]

what purpose is that planetary gear set?

[@timmy22withan38]

Had is options available for long while fully custom diff with adjust controller box they just gave it a name evo 7 had. Had option of ayc or yaw and vtc or controller box

[@89Trashmaster]

How does the electric motor know that it has to engage now? By the steering angle sensor?

[@nataldiego]

Really cool explanation.. really enjoy your vids...

[@Mikhaspearo]

Can you cover suspension setup for track purposes.

[@tvsorgatz]

excellent description!

[@abc-ov4oh]

Does the tvd make the rcf faster than the normal differential?

[@gravisan]

I've heard it being said that LSD are essential for drifting, how does a standard torque vectoring program compare?

[@Etande]

Can u do this in a ford 9" or do u need the Lexus rearend

[@murraymadness4674]

Seems like this adds a lot of weight. For a lightweight car, is it going to be worth it, or does the extra weight causing the car to want to fly out of the corner more offset the torque? I suppose you will spin the inner wheel at the limit and lose traction, but isn't this just fine for a racecar, at least with a good driver.

[@RahulSharma-oc2qd]

I think, it would be beneficial to use to for some XUVs

[@murraymadness4674]

@@RahulSharma-oc2qd One with a high COG will lift the inner wheels rather easily in a corner so yeah this would help maybe a lot and of course adding 200lbs to a 5000lb suv is not a big deal.

[@adamwyt917]

What's the difference between torque vectoring differential and Acura SH-AWD?

[@misdeismo]

Acura's SHAWD is actually very similar in concept but operates the clutch pack using an electromagnet rather than a DC motor. I think Acura has the best implementation as the torque can be varied with better resolution and accuracy. The only downfall of Acuras system is that it weighs more because it also has a hydraulic pump that is uses to accelerate the driveshaft going into the diff, this accelerates the wheel an additional +5% (on RLs only).

[@joshbalman969]

You carry on going on about this being a really "simplified version" (basically a dumbed down version for people who don't have much knowledge about cars and mechanical engineering) but I do not want a simplified version, I want the complicated every little detail version. Can you start making more technical videos? For those of us who more in depth details about for example torque vectoring differential's? people

[@EngineeringExplained]

josh balman Apologies for dumbing this one down - I wasn't certain how it worked but I felt there was a good amount to be learned regardless. In the meantime, I've included a link in the video description which contains more details that should satisfy your desire for complicated and detailed.

[@wiryantirta]

So if I tldr summarize this: It has a clutch on either side of the diff housing for each wheel. The clutches can essentially cut off power to one side thus essentially bypassing the diff housing altogether when needed? Someone correct me if I'm wrong.

[@NoelAWinslow]

With a cam actuating the clutches and can change the amount of pressure on the clutch.

[@riwajpoudel1415]

It seems like it will send more torque to one side only but not by the requirement. Am I confused ?

[@rafaellopez2536]

Fantastic video!

[@dabok2]

i confused... based on 5.00 minutes you mention that "it transfer more torque to the inside Tyre to help rotate the vehicle" but if i read description in SAE page it mention "Entering a turn, torque is reduced evenly to both rear (drive) wheels for deceleration stability. As the car approaches the apex of the turn, torque is further reduced to the inside wheel to help the car rotate slightly. Closer to and at the apex, the system transitions to positive torque, with somewhat more going to the outside wheel to promote stability. As the car starts to accelerate out of the turn, the torque to the outside wheel is increased further." it means it reduce the torque transfer to the inside wheel.. which one is true? ref: articles.sae.org/13845/

[@kylesanders6844]

Great video. Thanks for sharing.

[@Autodevot]

Thanks for this video. Can you please tell me what devices you use to record your voice?

[@preschau]

He's using Lavelier microphone clipped to his shirt.

[@djowsvideos]

Transfer more torque to the inside tire? (on stage 2, the end of the video) Looks like it's breaking... the is going backwards... Than stage 4 is going forward.. and to more torque to the outside tire..

[@JahjaMan]

If you read the blurb on the right, it mentions negative torque during stages 1 and 2, then positive torque when power is applied.