I understand it, but in reality the rear only has the power to match the fwd system. It only receives the 30/70 because of the gearing difference in the rear.
Really thanks for the explanation. I was struggling to understand how the 30:70 split was possible even though the driveshaft rotates at the same speed as the front 😅
Yes, Focus RS uses the same overspeeding trick but it is powering rear wheels separately. It has two clutch-packs on semi-axles instead of one on the driveshaft. System is called Twinster, supplied by GKN Driveline.
It reassures me, I had understood the same thing concerning the operation of this transmission. Including, the trick for the distribution of torque in favor of the rear. This is an interesting use of the ITCC, a multi-plat clutch pack found on many cars (JTECK belonging to Toyota)...
@@4x4.tests.on.rollers Me too. I heard so much criticism of ITCC in the mid-2000s when it was mounted on SUVs ... with stories of heating up and back to 2wd and that in conditions not particularly difficult... Improvements from generation to generation, I guess. It is, I believe, the 3rd.
@@Softroader Toyota Poland organised three days of track driving for automotive journalists. They were pushing the cars to the limits, there was not a single incident with overheat. I am really interested if the clutch is really engaged all the time or is it opening in every possible moment (like off throttle etc.) to cool down a little.
@@4x4.tests.on.rollers Toyota apparently managed to overcome the inherent overheating problem of such s system but big question comes to mine mind: how long it will last?
Great video! What would be the torque split between front and rear axle if the front wheels are on ice or in the air and the rear wheels are on tarmac? Is it possible to reach like 0/100 F/R in condition like that? I know it is not a realistic situation but I’m just curious
interesting to see that "jtekt itcc" has been around since 1998 and it's at least the third generation. the only novelty is the gearing differential and constantly adjusting the clutch slip to achieve precise RWD bias. they increased the number of discs probably to offset the fact it's gonna slip almost continuously on a track. I still hope they open the clutch when it's useless, stealing power/efficiency/reliability like highway cruising or even top speed run/long straights
So if i understand correctly the clutch pack for rear wheels is constantly slipping? Did they mention the life expectancy of the clutches? Great video btw!
Subaru actually uses slipping clutch packs in their automatic cars most of the time, so hopefully Toyota can make it as reliable as Subaru or even better. But I also don’t know, I can only hope
Could u pls help to address my general question below… in terms of better reliability or in order for the car to last much longer Which mode should i go for long distance drives that have long hours on the road
If I would be Mr. Toyoda, I would have put a lockable center torsen diff in stead of slipping and sliding disks. Constantly slipping disks really do not sound appealing at all. Basically the system is being worn out all the time when used, with each rotation of the crankshaft. Good job explaining the functionality, this solution would not be my choice as there many others not based on constant slipping.
It wouldn't be possible to overspeed rear axle with torsen differential. Another two-step rear differential would be needed then. So in general - a lot of weight and a lot of space.
Před 3 lety+2
Torsen center diff, as in most Audis, is very good for everyday driving and for spirited street driving too. It's torque split varies depending on the grip on each axle, but has it's limitations, and cannot be electronically controlled. But with this system, the torque split can be varied according to conditions and driver input using only software. I think the car would be very different with a center Torsen diff. And from what I've heard, it is very good as it is. I wouldn't have thought they made the AWD system like this, but I think the good people at Toyota knew what they were doing. :)
@@4x4.tests.on.rollers if I wasn't mistaken, audi have something like center diff with computer control variable locking, while by default it gave 60/40 split rear / front through gearing inside the differential itself.
@@4x4.tests.on.rollers Audi started using Torsen 40/60 nominal front/rear torque split from Audi S4/RS4 B7 I think, so there would be no need for overspeeding the rear axle as the torque split is acquired in the center differential gearing. But this solution is not electronically controlled for changing the torque split
Dobrze wyjaśnione. Chociaż jestem zaskoczony że nie zastosowali centralnego dyferencjału. Swoją drogą ciekawe skąd współcześnie u producentów taki strach przed tym prostym i niezawodnym rozwiązaniem. Nawet stary rodzinny RX300 posiadał centralny dyfer przy silniku umieszczonym poprzecznie. Tutaj , podobnie zresztą jak w Fordzie RS woleli zastosować skomplikowane rozwiązanie oparte na tarciu ( niezawodność ? ) które również nie wygląda na tanie.
Centralny dyfer to masa i miejsce. Ale przede wszystkim brak możliwości pełnej kontroli. Wbrew pozorom, ten układ awd jest banalnie prosty, skomplikowany jest software, który nim steruje. Natomiast niezawodność sprzęgła napędu to znak zapytania, czas pokaże.
Sweet. Can you drive the car on a daily basis using 50/50 and 30/70 without causing too much wear? Or are those two modes more geared towards occasional use?
These cars are built to drive. If a manufacturer puts a feature in a car it’s because it’s been designed to last the life of the vehicle. The majority of wear will happen if the system gets really hot so yeah don’t drive like you stole it and you’ll be fine driving it 30/70 daily
No, it is not haldex. It is ITCC, details are explained in the video. Usually there is no oil change in these type of clutch-packs but I don't know how is that in GR Yaris.
@@4x4.tests.on.rollers well i have changed on the rav4's dif oils, but i remember they had electro magnetic couplings with max 55/45split in lock. The gr yars is interesting..just would lile to know if it would need any service...cant last forever🤔
@@timoklap Oil in the diff is a different thing from oil in the clutch-pack. GR Yaris also has electromagnetic coupling. I'll check the service list soon to figure it out.
Mnie ciekawi niesamowicie jak działa i czy działa EDS czyl elektronische differentialsperre w FWD. Fajnie by było zobaczyć jak testujecie podkładając pod jedno koło z przodu w FW D taką rolkę z ESP i bez ESP. Akurat tak się składa, że mam takie auto z oficjalnie wbitym w wyposażenie taką opcją. Skąd jesteście?
Działa tak samo jak w awd, tylko bez napędu na tył, no i w większość aut po wyłączeniu ESP przestaje działać. Na przykładzie koejgo auta (Mazda 6 2005) esp off na śniegu kręci się jedno koło, ruszyć ciężko, po włączeniu esp komputer hamuje koło kręcące się szybciej uzyskując rotację obu kół, ruszyć z miejsca jest dużo łatwiej, oczywiście kiedy już auto jedzie, esp przeszkadza, także jadąc pod górkę lepiej wyłączyć jeśli opony nie dają rady.
I don't quite fully understand the idea of overspeeding the rear axle. Could you explain it a little bit more? If I understand the overspeeding axle is done by gearing which is changing the low speed high torque into high speed but lowering the torque (same as in motor gearbox). So if we are overspeeding the rear axle, we are also decreasing the torque its getting if I'm right. But from where does come the 30/70 torque split?
Overspeeding of rear axle means oversteering or drifting or better cornering, depends how much, how long and when it is overspeeded. The point is that if rear axle is overspeeded - it is locked with front axle, no center diff, rear of the car wants to go faster the the front - but that's not continous, these are seconds or miliseconds which slide the car.
It's also down to the basic principle of a clutch, any kind of clutch. That is in order for a clutch to transfer motion - power it has input and output. The input has to be rotating faster than the output so then motion - power can be transferred. If the output where to suddenly rotate faster than the input then their roles change. So being that the rear axle is geared higher numerically that means the pinion of the differential for that axle spins slower than the pinion of the transfer box in the front and that slight speed difference promotes the constant torque transfer from the front axle to the rear, since there is a clutch that connects the two.
Let's consider for a moment that the multiplate clutch is fully locked. If the rear differential is only 1% "faster" , shouldn't it take only 1% more torque? Something like 49-51 split? It make more sense if the shaft to the rear rotates faster ( by using epicyclic layout front)
I have a question... If you put this car on a dyno in the different modes, will power figures be different? In other words, which mode is actually optimal in terms of power output?
@@4x4.tests.on.rollers thank you for the response sir and the great video, I really appreciate it ☺️ I was struggling to understand why the normal mode of 60/40 even exists but now I think I get it. I still haven't figured out which mode is best for daily driving though 😅
I'm currious about this as well. I love compex awd systems like the S-AWC on the evos but I'm always afraid of the maintenance and reliability. And I come from BMWs so that's saying something.
Hi perfect video thanks !! Finally, someone who doesn't just make videos about exhausts and intakes and says something useful for those who own GR or are interested in cars. It is clear from the video that the wear of the clutch occurs the least in the nomal mode. But I would like to ask you what happens when the clutch wears out and starts to slip. What will I feel or hear as a driver and what will actually happen ?
Thanks! Unfortunately I don't know what would the driver feel. I believe the computer would detect the wear and thus malfunction of the clutch-pack before the driver could feel it. But that's just my guess.
@@4x4.tests.on.rollers Thank you for the quick response ! Can i still ask one thing. Hypothetically, if the axles were hard-wired instead of the clutch. what would happen ? how would the torque be distributed between the axles? And the rear axle would still like to rotate against the rear axle, is that correct? And thanks again for the reply...
So GRC has no center diff like the subaru system. the clutch pack is constantly engaged and constantly slipping and there its fluid is not serviceable like the diff. I start to wonder how long that stuff will last for track duty.
@@4x4.tests.on.rollers Err, I'm talking about the TY75/85 manual trans, the fluid coupling has spider gears allowing it to slip, not sure about the auto trans, never dealt with one. I guess you're right, maual trans almost doesn't exist.
How do you get the data of 1%? I found the data on google that the final drive gear ratio of front and rear is 3.941 and 3.350, and the calculation shows that should be 17.64% faster.
Thank you for directing me to the video. I guess what I'm still confused about, partly, is when it completely locks and gets 30/70, how is that possible with only a .7% difference between the speeds the axles are trying to spin? I think I am getting more of the concept from this video, thank you...but I still can't grasp the .7% translating to 30/70 in a locked clutch pack. If you could point me to some math, I'd greatly appreciate it.
30/70 doesn't mean that the clutch-pack is locked. Rule is simple - torque goes towards the resistance. If rear wheels are are harder to spin than the front - they get more torque. According to JTEKT, maximum it can achieve is 20/80 but the most important thing - 60/40, 50/50 and 30/70 are not real constant torque splits but driving characteristics which system is providing. Try to find the discussion started by Mike Beale under Jason's video - maybe those guys can help in terms of math and .7 value
@@4x4.tests.on.rollers Thanks, I'll try that. I appreciate the further explanation. Yes, I will try to find the math, so I can better understand how that .7% turns into such splits.
@@tonypalmentera7752 it's quite complex but let's make things simpler, and just imagine an "ideal" world where the wheel wouldn't be able to slip (infinite traction, no wheel slip, like if your wheels were pinions rotating on a rack), the clutch is fully open, and the car has some speed, in a straight line. all wheels are rotating at the same speed. because of the different gearing, the shaft would be turning at slightly different speed, faster in the front, slower in the rear, all wheels have zero torque. when you'd try to engage the clutch, you start generating torque at the clutch because of the speed differential. it would send equal and opposite torque, positive to the rear, negative to the front, but because rear has longer gearing, the car would slow down and energy would be dissipated in the clutch with a net zero total torque on the 4 wheels, so no effect on the car speed. the stronger you engage the clutch, the stronger the torque, but the clutch keeps slipping. now if you add power from the motor you are adding positive torque to both wheel, that's how you end up with a rear wheel bias. in the rear world, wheels that are applying torque to the road are going to slip a certain amount depending on the torque, the tires and the road. because the difference in gearing is only 0.7%, the whole system wouldn't break even if you locked the clutch completely, because the tires would just give in and slip differently front/rear, but with a strong rear bias. constantly adjusting the clutch engagement allows to maintain exactly the desired torque split while allowing a small amount of slip. because the gearing difference is very low, the relative speed between the discs of the clutc is low, meaning you can apply strong torque through the clutch without burning/overheating, or wearing the clutch too quickly. think of it like using brakes at 1mph. you don't need lot of force to brake, and even if you go down a steep hill at 1mph using your brakes, they are not going to overheat. thanks to oil bath and 12 discs, wear should stay low too
@@geemy9675 thank you...that helped a lot...if you could point me to where that .7% in the math turns into rear bias, I would greatly appreciate it. I almost want to do a spreadsheet on it and play with the numbers to understand it better.
to put it more simply, because the front wheels wanna go slower than the car, they are not powering the car if the clutch is locked. the 0.7% must have been carefully tuned, so that even in a launch control if you are in first gear wide throttle, even if the rear wheel slip ratio is higher than the front wheels, the rear shaft is still rotating slower so the rear clutch can still be partially opened and maintain the torque split if you Google "optimal longitudinal tire slip ratio" you'll find: A general trend seen in tyres is a longitudinal force peak at a slip ratio of around 0.3 - 0.4. so I would say this is where the 0.7 is coming from. if you are driving on surface with less grip you might need more slip remember tire slip around .5% is not drifting (maybe like 100% or more) /burnout (infinite if front wheels are not moving) so even though you can force RWD bias, it is impossible to do RWD drifts or burnouts with this system, since rear wheels can only spin 0.7% faster than front. only AWD drifts/burnouts
@@lexuslfa4739 Every clutch wears out, especially if it works under constant slippage/friction. That's very different story from the one in automatic gearboxes.
@@odinisgod4577 Layout is the same (FWD based, rear wheels powered by clutch-pack). Clutch-packs are different. I also don't think that VW uses different gearing.
@@octaviangeorge5455 How do you know it is not reliable? You can only guess but you don't know that. It is not complicated to. Software is complicated but mechanical structure is simplified to the maximum. Wear off - another thing to guess, not to know.
@@4x4.tests.on.rollers jak miło to słyszeć, mam nadzieję że poświęcisz im czas i również wyjaśnisz ich fenomen, podziwiam i zarazem dziękuję za wkład w kanał, jest bardzo interesujący
Is this permanent all wheel drive. Anyone know the difference between the GR Yaris and Lancia Delta Integrale all wheel drive. I believe Lancia is permanent
thx for that cool video :) I am not a big fan of this AWD - in my opinion its not possible to compare it to a real AWD like the Quattro with 3 differentials. In bad words: its just a FWD with support - or a Haldex with a different clutch - little bit boring :/
@@kxSPORTING76 _you need to blip the engine on downshifts. If you press the small button down in the centre console marked IMT, which stands for Intelligent Manual Transmission, the system will do it for you once engaged and will also encourage you to rev the three-cylinder engine right out to its red line before upshifting_
Byłoby super, jakbyś podłożył polski głos, ale i tak dobrze, że to wrzuciłeś. Ludziom trudno to skumać. Zresztą - ludzie nie rozumieją nawet działania zwykłego dyfra, a tu mózg im pewnie wybucha ;)
Z inżynierskiego punktu widzenia, różnicówka za wałem to śmierć dla wału, ogromne naprężenia i siły wpływające na scentralizowany ruch obrotowy wału, zły design stosowany w nowych śmietnikach. Zwykle były to zachowania rwące/udarowe w układ napędowy w haldexie przez co te auta zawsze źle jeździły dla dobrego kierowcy, zawsze irytowały tym zachowaniem, tym skokiem i rwaniem układu napędowego. Ciekawe jak będzie tutaj, gdy mamy stały napęd. Mechanizm różnicowy w osobówkach zawsze powinien być centralny z przodu, by układ generujący moment na gotowo przekazywał wałowi ten moment, a nie na odwrót, że zestaw silnika+skrzyni+wału napędzony przez układ dopiero jest moderowany przy tylnej osi.
Ten układ (jak i te z haldexem) nie ma centralnego mechanizmu różnicowego. Jest sprzęgło, zatem to, czy układ jest stały czy nie zależy tylko od software. Kiedyś sterowanie tymi układami było zero-jedynkowe, ale od wielu lat sprzęgła te są sterowane płynnie, w pełnym zakresie od otwartego do zamkniętego (często z jakimś stałym, inicjalnym momentem, w tych przypadkach sprzęgło nigdy nie jest w pełni otwarte), nie ma zatem żadnego rwania. Co więcej - wał jest nadpędzany (3-4 krotnie) na przekładni kątowej.
Czyli moje poronione głupie pomysły o założeniu na tył kół o większej średnicy, wcale nie były takie głupie. Ciekawe co na to sterownik haldexu w volvo i kontrola trakcji?
@@4x4.tests.on.rollers miałem nadzieje że uzna różnice prędkości obrotowych jako minimalny uślizg przedniej osi, napędzając tył. To była tylko luźna myśl, ale kusząca w obecności tyłu zaśnieżonych parkingów :)
@@MateuszCieslakWorkshop Uślizg przedniej osi to odwrotna sytuacja, przód kręci się szybciej. Większe koła z tyłu raczej od razu zostaną zdiagnozowane i przyporządkowane do kategorii "Different tires counter" i po zabawie :)
@@4x4.tests.on.rollers a gdyby wyłączyć zasilanie sterownika? Haldex 2gen bazowo jest załączony (oczywiście pompa wytworzy ciśnienie dopiero przy różnicy prędkości obrotowej), czy rozłączony i ciśnienie generowane przez pompę ma obejście?
@@MateuszCieslakWorkshop Myślałem, że mówimy o haldexie 4 lub 5. Nie wiem, czy starszy haldex będzie na tyle sprytny, że wykryje większe koła z tyłu, więc nie jest powiedziane, że trick nie zadziała :) Nie mam wiedzy, jak i co się stanie bez zasilania sterownika, chyba Chris robił sekcję drugiej generacji, można się przyjrzeć :)
Nope. It has the engine in front of the front axle, in addition it's a longitudinal one. It is the worst layout for handling of all possible ones. Even the engine hanging behind the rear axle is a bit better for handling. Everything within the wheelbase is good for handling. The best is when the engine rests behind the driver and in front of the rear axle. For handling. The car you've mentioned is a really great machine!
I know all the armchair engineers are concerned about the clutch slipping like grazy and wearing out fast. I mean it has to be since the wheels are turning like 40% different speeds. :-D LOL
Planned obsolescence at it's finest, a drivetrain deliberately designed to wear down with each rotation. A lockable torsen center differential would be a much more robust solution, but it's apparent that cars are increasingly designed more like consumer electronics with each passing year, with the expectation expiring soon after warranty instead of the 20 years design life that was typical just a decade ago.
It wouldn't be possible to overspeed rear axle with torsen differential. Another two-step rear differential would be needed then. So in general - a lot of weight and a lot of space.
They designed it to not wear out. It's not normal clutch at all. Both cars and electronics are going to last well over any warranty definitely over 20 years.
@@bobbybooshay5854 Cause multi plates wet clutches have been used for many applications without any problems. You can imagine how much engineering toyota did with this one.
The thing is the front wheel drive system is connected 100% of the time, it can't be disconnected. Whereas the rear uses the clutch packs to lock. In that theory the rear can never see more torque than the front. The whole 30/70 thing is artificial, only because the 1% gearing difference in the rear.
It is not artificial, whole trick is explained in the video. That simply comes from physics and that's how you can achieve rwd characteristic from fwd based awd system.
If that is really such a serious problem then just mute the sound and turn the subtitles on. No metal music, no robot voice, just quiet, perfect conditions for concentration.
@@4x4.tests.on.rollers "driftmode for beginners" :-) 5 minutes entertaining, then it's boring. The 50:50 mode in the Ford RS MK3 is pretty cool on ice, snow and wet track, mayby is this also th best in the GR Yaris. I have to drive one first...
@@PKraemer81 I meant that Ford was first in relation to Toyota. As far as I am concerned - Saab wasn't overspeeding rear axle, it just had eLSD integrated with haldex. First overspeeding which I remember was one of SH-AWD versions and Lancer Evo.
Wrong! FWD based car can NOT send more than 50% torque to the rear axle. 1% overdriven rear axle cannot be explanation. Here is why: Whenever you overdrive axle or gear in gearbox you always increase speed but DECREASE torque, basic physics. As we all should know, torque to the rear comes from front differential ring gear, makes 90° turn and goes to the rear through clutch pack to the rear diff. Basically rear diff is stealing tourqe from front axle and not other way around to have 30/70. I dont know why everybody believes in this 30/70% torque split BS from Toyota.
It is explained in the video - it is not the point to overdrive the rear axle but to be on the level just before overdriving. The point where clutch-pack is almost locked but still slipping.
@@FutureProofNothing Different gearing means higher resistance of rear axle just beyond the level of overspeed. That's a peak. The same trickery is used in Focus RS, A45S or new RS3. Mazda (and others) are using it to eliminate the backlash and get faster response but these systems do not apply maximum possible clumping force to the clutch-pack (max 2.8A from 3.0A possible). That's why they do not claim to achieve more torque to the rear. In case of static torque split, 50/50 is achieved when the clutch-pack is fully locked (the same gearing). In case of different gearing, 50/50 is achieved when clutch-pack is partly open.
@@4x4.tests.on.rollers This is the guy from GKN, Ray Kuczera who created Focus RS' AWD system. czcams.com/video/RaAKxzJidUw/video.html Listen what he says when journalists asks specifically and very subtly about magic drift mode where car supposedly becomes, with some clutches, rear wheel biased. I've seen ford brochure, focus rs sending 55% torque to the rear. Toyota improved that - 70%. What's next? 100%, while doing wheelies? I know companies over claim and it backfired. Explained it here. czcams.com/video/kFbZ8ZT2hE0/video.html This is why I don't believe in Magic, a BS most of the time. Eather make shit look good to sell(AMD) or overhype and make the feature as major selling point(Toyota and other who claim cheap hach made RWD Disney world). If Toyota is not doing some trickery in the front to allow such big torque split I stand my ground to call it BS. One thing to clarify here: I'm not talking messy situation where some tires loose traction and god know what's going on. I'm talking about very simple scenario when all 4 tires have all the grip in the world and goes straight line.
@@FutureProofNothing Mr Kuczera didn't personally create the system and I don't find anything in this interview about torque split, just a sentence about "majority of power". Interviews with JTEKT engineers are much more technical and they do explain the torque issue. You seem to be continously omitting the most important thing which I mentioned - clutch-pack compression just before the overspeed. You simply skip to overspeed when traction is already lost. Consider your own example when all four wheels have full grip. If the gearing is the same then you may lock the clutch-pack easily, there's no additional resistance, nothing happens. But when the gearing is different then rear axle resists a lot just before clutch-pack lock-up, it actually mimics the situation of different grip between front and rear, like there was more grip at the back. This way there's kind of switch from static to dynamic torque split, where every locked system has variable split from ~100/0 to ~0/100. I am aware of the fact that many people interpret 30/70 as rwd based mode but as a few polls on my channel shows - about 80% of people do not understand the difference between the torque and wheelspin. To sum up - we can agree that we disagree. Regards!
Test on rollers: Toyota GR Yaris vs Ford Focus RS: czcams.com/video/9kUMNtcrxXA/video.html
Finally somebody explained me how 30:70 split is possible at GR Yaris. Many thanks!
My pleasure 🙂
I understand it, but in reality the rear only has the power to match the fwd system. It only receives the 30/70 because of the gearing difference in the rear.
@@SupramanTRD it's kinda like the rs drift mode.
But the Toyota seems like a much smarter system tho overall.
@@fukkinkana Don't know about smarter, as it lacks torque vectoring in relation to steering input. It's an entirely passive system.
@@Vermonstered It's active system, steering input is one of the most important factors for clutch pack operation.
Really thanks for the explanation. I was struggling to understand how the 30:70 split was possible even though the driveshaft rotates at the same speed as the front 😅
Can't wait to see this on the rollers
Interesting video.
Now get one for a test 😀
I will try to get it 🙂
@@strangelove9608 Poland.
Thank you for the great video! Do you know if Focus RS uses similar technology?
Yes, Focus RS uses the same overspeeding trick but it is powering rear wheels separately. It has two clutch-packs on semi-axles instead of one on the driveshaft. System is called Twinster, supplied by GKN Driveline.
Interesting and well explained.
Thank you.
It reassures me, I had understood the same thing concerning the operation of this transmission. Including, the trick for the distribution of torque in favor of the rear. This is an interesting use of the ITCC, a multi-plat clutch pack found on many cars (JTECK belonging to Toyota)...
To be honest, I was really surprised that they took ITCC for GR Yaris. It must be really strong clutch-pack.
@@4x4.tests.on.rollers Me too. I heard so much criticism of ITCC in the mid-2000s when it was mounted on SUVs ... with stories of heating up and back to 2wd and that in conditions not particularly difficult... Improvements from generation to generation, I guess. It is, I believe, the 3rd.
@@Softroader Toyota Poland organised three days of track driving for automotive journalists. They were pushing the cars to the limits, there was not a single incident with overheat. I am really interested if the clutch is really engaged all the time or is it opening in every possible moment (like off throttle etc.) to cool down a little.
@@4x4.tests.on.rollers Toyota apparently managed to overcome the inherent overheating problem of such s system but big question comes to mine mind: how long it will last?
@@4x4.tests.on.rollers At 4:00 in this swiss video, the guy stops cause the ITCC overheated: czcams.com/video/Ry2kQsjb0C4/video.html
Спасибо, неплохой разбор
Спасибо!
Great video! What would be the torque split between front and rear axle if the front wheels are on ice or in the air and the rear wheels are on tarmac? Is it possible to reach like 0/100 F/R in condition like that? I know it is not a realistic situation but I’m just curious
Thanks! Yes, in such situation torque split would be almost 0/100 FR, it is simulated here czcams.com/video/9kUMNtcrxXA/video.html
@@4x4.tests.on.rollers thanks! Keep up the good work guys I love your videos 👍🏻
What impact would front and rear clutch pack LSD's that can have 100% true lock, have on the GR Four system?
That's an experimental question...
interesting to see that "jtekt itcc" has been around since 1998 and it's at least the third generation. the only novelty is the gearing differential and constantly adjusting the clutch slip to achieve precise RWD bias.
they increased the number of discs probably to offset the fact it's gonna slip almost continuously on a track. I still hope they open the clutch when it's useless, stealing power/efficiency/reliability like highway cruising or even top speed run/long straights
On straights they do open the clutch-pack, mainly for cooling purposes.
So if i understand correctly the clutch pack for rear wheels is constantly slipping? Did they mention the life expectancy of the clutches?
Great video btw!
Yes, it is slipping but each one is, there's never equal speed of front and rear. I don't know life expectancy 🙂
Subaru actually uses slipping clutch packs in their automatic cars most of the time, so hopefully Toyota can make it as reliable as Subaru or even better. But I also don’t know, I can only hope
Could u pls help to address my general question below… in terms of better reliability or in order for the car to last much longer
Which mode should i go for long distance drives that have long hours on the road
Normal (front) as there is the lowest clutch-pack compression.
If I would be Mr. Toyoda, I would have put a lockable center torsen diff in stead of slipping and sliding disks. Constantly slipping disks really do not sound appealing at all. Basically the system is being worn out all the time when used, with each rotation of the crankshaft. Good job explaining the functionality, this solution would not be my choice as there many others not based on constant slipping.
It wouldn't be possible to overspeed rear axle with torsen differential. Another two-step rear differential would be needed then. So in general - a lot of weight and a lot of space.
Torsen center diff, as in most Audis, is very good for everyday driving and for spirited street driving too. It's torque split varies depending on the grip on each axle, but has it's limitations, and cannot be electronically controlled. But with this system, the torque split can be varied according to conditions and driver input using only software.
I think the car would be very different with a center Torsen diff. And from what I've heard, it is very good as it is. I wouldn't have thought they made the AWD system like this, but I think the good people at Toyota knew what they were doing. :)
@@4x4.tests.on.rollers if I wasn't mistaken, audi have something like center diff with computer control variable locking, while by default it gave 60/40 split rear / front through gearing inside the differential itself.
@@krisnadiimam4556 No, they don't have computer controlled center diff. Here are all diffs used by Audi: czcams.com/video/ItTkEb_pf1A/video.html
@@4x4.tests.on.rollers Audi started using Torsen 40/60 nominal front/rear torque split from Audi S4/RS4 B7 I think, so there would be no need for overspeeding the rear axle as the torque split is acquired in the center differential gearing. But this solution is not electronically controlled for changing the torque split
Thank you! So it turns out that you gotta be driving in sport all the time if you want to avoid greater power and torque losses.
Dobrze wyjaśnione. Chociaż jestem zaskoczony że nie zastosowali centralnego dyferencjału. Swoją drogą ciekawe skąd współcześnie u producentów taki strach przed tym prostym i niezawodnym rozwiązaniem. Nawet stary rodzinny RX300 posiadał centralny dyfer przy silniku umieszczonym poprzecznie. Tutaj , podobnie zresztą jak w Fordzie RS woleli zastosować skomplikowane rozwiązanie oparte na tarciu ( niezawodność ? ) które również nie wygląda na tanie.
Centralny dyfer to masa i miejsce. Ale przede wszystkim brak możliwości pełnej kontroli. Wbrew pozorom, ten układ awd jest banalnie prosty, skomplikowany jest software, który nim steruje. Natomiast niezawodność sprzęgła napędu to znak zapytania, czas pokaże.
Sweet. Can you drive the car on a daily basis using 50/50 and 30/70 without causing too much wear? Or are those two modes more geared towards occasional use?
Both modes will cause more wear. However - if you drive the car normally, not too sporty, everything should be OK.
These cars are built to drive. If a manufacturer puts a feature in a car it’s because it’s been designed to last the life of the vehicle. The majority of wear will happen if the system gets really hot so yeah don’t drive like you stole it and you’ll be fine driving it 30/70 daily
so, its a haltex? how long will the clutches last, do they need to be changed, or just change the packs oil time to time? or are they dry clutches?
No, it is not haldex. It is ITCC, details are explained in the video. Usually there is no oil change in these type of clutch-packs but I don't know how is that in GR Yaris.
@@4x4.tests.on.rollers well i have changed on the rav4's dif oils, but i remember they had electro magnetic couplings with max 55/45split in lock. The gr yars is interesting..just would lile to know if it would need any service...cant last forever🤔
@@timoklap Oil in the diff is a different thing from oil in the clutch-pack. GR Yaris also has electromagnetic coupling. I'll check the service list soon to figure it out.
Mnie ciekawi niesamowicie jak działa i czy działa EDS czyl elektronische differentialsperre w FWD. Fajnie by było zobaczyć jak testujecie podkładając pod jedno koło z przodu w FW D taką rolkę z ESP i bez ESP. Akurat tak się składa, że mam takie auto z oficjalnie wbitym w wyposażenie taką opcją. Skąd jesteście?
Działa tak samo jak w awd, tylko bez napędu na tył, no i w większość aut po wyłączeniu ESP przestaje działać. Na przykładzie koejgo auta (Mazda 6 2005) esp off na śniegu kręci się jedno koło, ruszyć ciężko, po włączeniu esp komputer hamuje koło kręcące się szybciej uzyskując rotację obu kół, ruszyć z miejsca jest dużo łatwiej, oczywiście kiedy już auto jedzie, esp przeszkadza, także jadąc pod górkę lepiej wyłączyć jeśli opony nie dają rady.
would it be possible to get a video to compare it to the GT-Four system such as in the Caldina or Celica?
Unfortunately for now I don't have plans to do such a video.
I don't quite fully understand the idea of overspeeding the rear axle. Could you explain it a little bit more?
If I understand the overspeeding axle is done by gearing which is changing the low speed high torque into high speed but lowering the torque (same as in motor gearbox). So if we are overspeeding the rear axle, we are also decreasing the torque its getting if I'm right. But from where does come the 30/70 torque split?
Overspeeding of rear axle means oversteering or drifting or better cornering, depends how much, how long and when it is overspeeded. The point is that if rear axle is overspeeded - it is locked with front axle, no center diff, rear of the car wants to go faster the the front - but that's not continous, these are seconds or miliseconds which slide the car.
It's also down to the basic principle of a clutch, any kind of clutch. That is in order for a clutch to transfer motion - power it has input and output.
The input has to be rotating faster than the output so then motion - power can be transferred. If the output where to suddenly rotate faster than the input then their roles change.
So being that the rear axle is geared higher numerically that means the pinion of the differential for that axle spins slower than the pinion of the transfer box in the front and that slight speed difference promotes the constant torque transfer from the front axle to the rear, since there is a clutch that connects the two.
So what is the service interval of those clutches if you drive like crazy in 50:50 or 70:30 ?
I have no information.
Let's consider for a moment that the multiplate clutch is fully locked. If the rear differential is only 1% "faster" , shouldn't it take only 1% more torque? Something like 49-51 split?
It make more sense if the shaft to the rear rotates faster ( by using epicyclic layout front)
That's not that direct correlation. Actual difference is 0.7%.
I have a question... If you put this car on a dyno in the different modes, will power figures be different? In other words, which mode is actually optimal in terms of power output?
I think it would be the same in each mode, there's no cornering factor on a dyno.
@@4x4.tests.on.rollers thank you for the response sir and the great video, I really appreciate it ☺️ I was struggling to understand why the normal mode of 60/40 even exists but now I think I get it. I still haven't figured out which mode is best for daily driving though 😅
Is there a way to mod an awd car like this like a kit or parts or something?
I don't think so...
Interesting. Thanks for explain us. How often will need to change rear diff/clutch oil and will be expansive ?
I'm currious about this as well. I love compex awd systems like the S-AWC on the evos but I'm always afraid of the maintenance and reliability. And I come from BMWs so that's saying something.
@@memememine1 Electromagnetic clutch-packs are usually hermetic, no oil change. I don't know if it is the same in GR Yaris.
@@4x4.tests.on.rollers love this tech videos 😉. Did you find out already if it is hermetic? Or does it share the oil with the LSD?
@@jpdw7543 I wasn't checking it. I will during the roller test of GR 🙂
Hi perfect video thanks !! Finally, someone who doesn't just make videos about exhausts and intakes and says something useful for those who own GR or are interested in cars. It is clear from the video that the wear of the clutch occurs the least in the nomal mode. But I would like to ask you what happens when the clutch wears out and starts to slip. What will I feel or hear as a driver and what will actually happen ?
Thanks! Unfortunately I don't know what would the driver feel. I believe the computer would detect the wear and thus malfunction of the clutch-pack before the driver could feel it. But that's just my guess.
@@4x4.tests.on.rollers Thank you for the quick response ! Can i still ask one thing. Hypothetically, if the axles were hard-wired instead of the clutch. what would happen ? how would the torque be distributed between the axles? And the rear axle would still like to rotate against the rear axle, is that correct? And thanks again for the reply...
@@michalpovolny8461 I'm not sure what do you mean by hard-wired - stiff connection instead of clutch-pack?
@@4x4.tests.on.rollers Yes exactly . Its only hypotetical qvestion .
@@michalpovolny8461 It would be impossible to drive it cause rear axle would be continously overtaking the front 😉
So GRC has no center diff like the subaru system. the clutch pack is constantly engaged and constantly slipping and there its fluid is not serviceable like the diff. I start to wonder how long that stuff will last for track duty.
Majority of Subaru cars do not have center diff to.
@@4x4.tests.on.rollers Err, I'm talking about the TY75/85 manual trans, the fluid coupling has spider gears allowing it to slip, not sure about the auto trans, never dealt with one. I guess you're right, maual trans almost doesn't exist.
so if I put 235/50 on the audi s3 instead of 235/45 on the rear axle should i get the same result ??
If you update the awd control software then yes. To the point when haldex will explode 😉
Guess the wheel speed sensors would make the car go crazy and think that the rears are always slipping a bit and apply brakes on rear?
@@timoklapSystem wouldn't be braking the wheels, it would be locking the haldex.
@@4x4.tests.on.rollers it would be braking wheels, its the traction control system
@@lexuslfa4739 Not in this case.
How do you get the data of 1%? I found the data on google that the final drive gear ratio of front and rear is 3.941 and 3.350, and the calculation shows that should be 17.64% faster.
Interviews with JTEKT guys. The difference comes from angular gear ratio at front and its reduction at the back.
In details - the difference is 0.7% (in the PTU teeth ratio is 17 : 39, in the rear differential - 41 : 18).
replacement for the clutch pack wont be cheap...
Normal 1% won't do squat actually but might help wear vs inetia forced initial slippage
okay that is pretty clever!
Does that mean 30/70 split would be in theory more wear then 60/40?
Yes, much more.
Is a 10 / 90 % torqe split possible when the ecu is flashed?
I don't it can reach that level (static).
@@4x4.tests.on.rollers i have seen toyota say ut can be completely rear wheel drive and that is what people are trying to do by using modded ECMs
@@lexuslfa4739 It can't be rear wheel drive, that's mechanically impossible, video shows the structure of the system.
here from carwow!
What do you mean?
Edit: got it, thanks!
Thank you for directing me to the video. I guess what I'm still confused about, partly, is when it completely locks and gets 30/70, how is that possible with only a .7% difference between the speeds the axles are trying to spin? I think I am getting more of the concept from this video, thank you...but I still can't grasp the .7% translating to 30/70 in a locked clutch pack. If you could point me to some math, I'd greatly appreciate it.
30/70 doesn't mean that the clutch-pack is locked. Rule is simple - torque goes towards the resistance. If rear wheels are are harder to spin than the front - they get more torque. According to JTEKT, maximum it can achieve is 20/80 but the most important thing - 60/40, 50/50 and 30/70 are not real constant torque splits but driving characteristics which system is providing. Try to find the discussion started by Mike Beale under Jason's video - maybe those guys can help in terms of math and .7 value
@@4x4.tests.on.rollers Thanks, I'll try that. I appreciate the further explanation. Yes, I will try to find the math, so I can better understand how that .7% turns into such splits.
@@tonypalmentera7752 it's quite complex but let's make things simpler, and just imagine an "ideal" world where the wheel wouldn't be able to slip (infinite traction, no wheel slip, like if your wheels were pinions rotating on a rack), the clutch is fully open, and the car has some speed, in a straight line. all wheels are rotating at the same speed. because of the different gearing, the shaft would be turning at slightly different speed, faster in the front, slower in the rear, all wheels have zero torque. when you'd try to engage the clutch, you start generating torque at the clutch because of the speed differential. it would send equal and opposite torque, positive to the rear, negative to the front, but because rear has longer gearing, the car would slow down and energy would be dissipated in the clutch with a net zero total torque on the 4 wheels, so no effect on the car speed. the stronger you engage the clutch, the stronger the torque, but the clutch keeps slipping. now if you add power from the motor you are adding positive torque to both wheel, that's how you end up with a rear wheel bias. in the rear world, wheels that are applying torque to the road are going to slip a certain amount depending on the torque, the tires and the road. because the difference in gearing is only 0.7%, the whole system wouldn't break even if you locked the clutch completely, because the tires would just give in and slip differently front/rear, but with a strong rear bias. constantly adjusting the clutch engagement allows to maintain exactly the desired torque split while allowing a small amount of slip. because the gearing difference is very low, the relative speed between the discs of the clutc is low, meaning you can apply strong torque through the clutch without burning/overheating, or wearing the clutch too quickly. think of it like using brakes at 1mph. you don't need lot of force to brake, and even if you go down a steep hill at 1mph using your brakes, they are not going to overheat. thanks to oil bath and 12 discs, wear should stay low too
@@geemy9675 thank you...that helped a lot...if you could point me to where that .7% in the math turns into rear bias, I would greatly appreciate it. I almost want to do a spreadsheet on it and play with the numbers to understand it better.
to put it more simply, because the front wheels wanna go slower than the car, they are not powering the car if the clutch is locked. the 0.7% must have been carefully tuned, so that even in a launch control if you are in first gear wide throttle, even if the rear wheel slip ratio is higher than the front wheels, the rear shaft is still rotating slower so the rear clutch can still be partially opened and maintain the torque split
if you Google "optimal longitudinal tire slip ratio" you'll find:
A general trend seen in tyres is a longitudinal force peak at a slip ratio of around 0.3 - 0.4.
so I would say this is where the 0.7 is coming from. if you are driving on surface with less grip you might need more slip
remember tire slip around .5% is not drifting (maybe like 100% or more) /burnout (infinite if front wheels are not moving)
so even though you can force RWD bias, it is impossible to do RWD drifts or burnouts with this system, since rear wheels can only spin 0.7% faster than front. only AWD drifts/burnouts
Does that mean 60/40 split would cause more wear than 50/50
Nope, there would be less wear.
This means that the clutch is permanently slipping because the tires have the same speed. So the clutch will wear out very quickly.
Yes, it is. But we don't know if it will wear out quickly, we have to wait 🙂
It's a wet plate clutch pack with a DLC coating so it will probably be fine.
I am more interested in the energy loss by the slipping clutch though.
@@4x4.tests.on.rollers wet clutch, does not wear, its the same as the mercedes automatic gearbox that uses a wet clutch instead of a torque converter
@@lexuslfa4739 Every clutch wears out, especially if it works under constant slippage/friction. That's very different story from the one in automatic gearboxes.
@@4x4.tests.on.rollers sure bud ;
so is this more like vw haldex or subarus awd????????
Yes but different front/rear diffs gearing.
@@4x4.tests.on.rollers that didn't answer the question is it like vw haldex?
@@odinisgod4577 Layout is the same (FWD based, rear wheels powered by clutch-pack). Clutch-packs are different. I also don't think that VW uses different gearing.
finally...
doesn't mitsubishi and acura use the same higher-rear-wheel-speed trick on their evolution and SH-AWD systems?
They do but in very different mechanical way 🙂
So the concept is close to Acura ah-awd.
So sad there is no longer exist a center diff on a transverse engine like lancer evo 😢
I always thought yaris got similar drivetrain as the evo/ralliart. Too bad is more similar to the haldex one.
@@octaviangeorge5455 Why too bad? It is doing great job :)
@@4x4.tests.on.rollers not reliable. Complicated. And wear off fast. Not sure how will handle abuse and miles.
@@octaviangeorge5455 How do you know it is not reliable? You can only guess but you don't know that. It is not complicated to. Software is complicated but mechanical structure is simplified to the maximum. Wear off - another thing to guess, not to know.
It's still miles better than audi's haldex
Moze teraz jak działają napędy w evo i sti
Narazie powstaje szkic materiału o S-AWC w modelach Outlander i Eclipse Cross, może Evo i STI będą następne 🙂
@@4x4.tests.on.rollers jak miło to słyszeć, mam nadzieję że poświęcisz im czas i również wyjaśnisz ich fenomen, podziwiam i zarazem dziękuję za wkład w kanał, jest bardzo interesujący
@@Merom3k Dziękuję i zapraszam 🙂
Is this permanent all wheel drive. Anyone know the difference between the GR Yaris and Lancia Delta Integrale all wheel drive. I believe Lancia is permanent
Both are permanent but Lancia was using center differential, GR Yaris doesn't have it.
@@4x4.tests.on.rollers I the GR Yaris FWD biased?
@@radiogreenblue It's fwd based. But handling can be fwd biased, neutral or rwd biased.
thx for that cool video :)
I am not a big fan of this AWD - in my opinion its not possible to compare it to a real AWD like the Quattro with 3 differentials. In bad words: its just a FWD with support - or a Haldex with a different clutch - little bit boring :/
Thanks 🙂 Try to drive it to be sure if it's boring 😉
@@4x4.tests.on.rollers good point tho 😄
Do a Audi a7 3.0 quattro vs bmw 6 series diesel
If I only find these...
No wszystko fajnie, ale jak przyjdzie do wymiany sprzęgła to może zabolec finansowo, ciekawe jak z żywotnością :)
Tanio nie będzie... A żywotność zależy od tego, jak auto będzie używane 😉
and IMT bottom?
You mean button? What about it?
@@4x4.tests.on.rollers what is it for?
@@kxSPORTING76 _you need to blip the engine on downshifts. If you press the small button down in the centre console marked IMT, which stands for Intelligent Manual Transmission, the system will do it for you once engaged and will also encourage you to rev the three-cylinder engine right out to its red line before upshifting_
Same technology as the Porsche 959, just flipped around back to front.
Nope, 959 was very different.
Byłoby super, jakbyś podłożył polski głos, ale i tak dobrze, że to wrzuciłeś. Ludziom trudno to skumać. Zresztą - ludzie nie rozumieją nawet działania zwykłego dyfra, a tu mózg im pewnie wybucha ;)
Dzięki, są polskie napisy 🙂 Widzów z Polski jest garstka, więc idzie w języku międzynarodowym 🙂
Z inżynierskiego punktu widzenia, różnicówka za wałem to śmierć dla wału, ogromne naprężenia i siły wpływające na scentralizowany ruch obrotowy wału, zły design stosowany w nowych śmietnikach. Zwykle były to zachowania rwące/udarowe w układ napędowy w haldexie przez co te auta zawsze źle jeździły dla dobrego kierowcy, zawsze irytowały tym zachowaniem, tym skokiem i rwaniem układu napędowego. Ciekawe jak będzie tutaj, gdy mamy stały napęd. Mechanizm różnicowy w osobówkach zawsze powinien być centralny z przodu, by układ generujący moment na gotowo przekazywał wałowi ten moment, a nie na odwrót, że zestaw silnika+skrzyni+wału napędzony przez układ dopiero jest moderowany przy tylnej osi.
Ten układ (jak i te z haldexem) nie ma centralnego mechanizmu różnicowego. Jest sprzęgło, zatem to, czy układ jest stały czy nie zależy tylko od software. Kiedyś sterowanie tymi układami było zero-jedynkowe, ale od wielu lat sprzęgła te są sterowane płynnie, w pełnym zakresie od otwartego do zamkniętego (często z jakimś stałym, inicjalnym momentem, w tych przypadkach sprzęgło nigdy nie jest w pełni otwarte), nie ma zatem żadnego rwania. Co więcej - wał jest nadpędzany (3-4 krotnie) na przekładni kątowej.
so baisically in order to maximise the lifetime of the clutch pack you're better of drifting the blody thing everywhere xd
Czyli moje poronione głupie pomysły o założeniu na tył kół o większej średnicy, wcale nie były takie głupie. Ciekawe co na to sterownik haldexu w volvo i kontrola trakcji?
Sterownik od razu rozłączy tylną oś 🙂
@@4x4.tests.on.rollers miałem nadzieje że uzna różnice prędkości obrotowych jako minimalny uślizg przedniej osi, napędzając tył. To była tylko luźna myśl, ale kusząca w obecności tyłu zaśnieżonych parkingów :)
@@MateuszCieslakWorkshop Uślizg przedniej osi to odwrotna sytuacja, przód kręci się szybciej. Większe koła z tyłu raczej od razu zostaną zdiagnozowane i przyporządkowane do kategorii "Different tires counter" i po zabawie :)
@@4x4.tests.on.rollers a gdyby wyłączyć zasilanie sterownika? Haldex 2gen bazowo jest załączony (oczywiście pompa wytworzy ciśnienie dopiero przy różnicy prędkości obrotowej), czy rozłączony i ciśnienie generowane przez pompę ma obejście?
@@MateuszCieslakWorkshop Myślałem, że mówimy o haldexie 4 lub 5. Nie wiem, czy starszy haldex będzie na tyle sprytny, że wykryje większe koła z tyłu, więc nie jest powiedziane, że trick nie zadziała :) Nie mam wiedzy, jak i co się stanie bez zasilania sterownika, chyba Chris robił sekcję drugiej generacji, można się przyjrzeć :)
GC8 STi RA 1998 is the best mechanical layout for handling.
Nope. It has the engine in front of the front axle, in addition it's a longitudinal one. It is the worst layout for handling of all possible ones. Even the engine hanging behind the rear axle is a bit better for handling.
Everything within the wheelbase is good for handling. The best is when the engine rests behind the driver and in front of the rear axle. For handling. The car you've mentioned is a really great machine!
I know all the armchair engineers are concerned about the clutch slipping like grazy and wearing out fast. I mean it has to be since the wheels are turning like 40% different speeds. :-D LOL
So this is very similar to haldex it seems with the open diffs...
Planned obsolescence at it's finest, a drivetrain deliberately designed to wear down with each rotation. A lockable torsen center differential would be a much more robust solution, but it's apparent that cars are increasingly designed more like consumer electronics with each passing year, with the expectation expiring soon after warranty instead of the 20 years design life that was typical just a decade ago.
It wouldn't be possible to overspeed rear axle with torsen differential. Another two-step rear differential would be needed then. So in general - a lot of weight and a lot of space.
They designed it to not wear out. It's not normal clutch at all. Both cars and electronics are going to last well over any warranty definitely over 20 years.
@@dkdanis1340 how do you know?
@@bobbybooshay5854 Cause multi plates wet clutches have been used for many applications without any problems. You can imagine how much engineering toyota did with this one.
The thing is the front wheel drive system is connected 100% of the time, it can't be disconnected. Whereas the rear uses the clutch packs to lock. In that theory the rear can never see more torque than the front. The whole 30/70 thing is artificial, only because the 1% gearing difference in the rear.
It is not artificial, whole trick is explained in the video. That simply comes from physics and that's how you can achieve rwd characteristic from fwd based awd system.
Want so bad!
For fuck sake, remove the unnecessary metal music. It ruins the whole video when trying to focus on that robot voice.
If that is really such a serious problem then just mute the sound and turn the subtitles on. No metal music, no robot voice, just quiet, perfect conditions for concentration.
The idea (overdrive rear axle speed) ist copied by Ford. But, it't a nice car!
Actually Ford was first... And to be more precise - not Ford itself but GKN Driveline.
@@4x4.tests.on.rollers "driftmode for beginners" :-) 5 minutes entertaining, then it's boring. The 50:50 mode in the Ford RS MK3 is pretty cool on ice, snow and wet track, mayby is this also th best in the GR Yaris. I have to drive one first...
@@4x4.tests.on.rollers was not the Saab 9-3 turbo X the first with overdriving overspeeding rear axel 2008??
@@PKraemer81 I meant that Ford was first in relation to Toyota. As far as I am concerned - Saab wasn't overspeeding rear axle, it just had eLSD integrated with haldex. First overspeeding which I remember was one of SH-AWD versions and Lancer Evo.
@@4x4.tests.on.rollers heard something about the Saab 9-3 X a long time ago and never let that go. Just curious
Wrong! FWD based car can NOT send more than 50% torque to the rear axle. 1% overdriven rear axle cannot be explanation.
Here is why:
Whenever you overdrive axle or gear in gearbox you always increase speed but DECREASE torque, basic physics.
As we all should know, torque to the rear comes from front differential ring gear, makes 90° turn and goes to the rear through clutch pack to the rear diff.
Basically rear diff is stealing tourqe from front axle and not other way around to have 30/70.
I dont know why everybody believes in this 30/70% torque split BS from Toyota.
It is explained in the video - it is not the point to overdrive the rear axle but to be on the level just before overdriving. The point where clutch-pack is almost locked but still slipping.
Let's go one by one:
1. Function of clutch pack:
A. Fully locked: take 50% torque
from front axle.
B. Slipping: take
@@FutureProofNothing Different gearing means higher resistance of rear axle just beyond the level of overspeed. That's a peak. The same trickery is used in Focus RS, A45S or new RS3. Mazda (and others) are using it to eliminate the backlash and get faster response but these systems do not apply maximum possible clumping force to the clutch-pack (max 2.8A from 3.0A possible). That's why they do not claim to achieve more torque to the rear. In case of static torque split, 50/50 is achieved when the clutch-pack is fully locked (the same gearing). In case of different gearing, 50/50 is achieved when clutch-pack is partly open.
@@4x4.tests.on.rollers
This is the guy from GKN, Ray Kuczera who created Focus RS' AWD system.
czcams.com/video/RaAKxzJidUw/video.html
Listen what he says when journalists asks specifically and very subtly about magic drift mode where car supposedly becomes, with some clutches, rear wheel biased.
I've seen ford brochure, focus rs sending 55% torque to the rear.
Toyota improved that - 70%.
What's next? 100%, while doing wheelies?
I know companies over claim and it backfired.
Explained it here.
czcams.com/video/kFbZ8ZT2hE0/video.html
This is why I don't believe in Magic, a BS most of the time. Eather make shit look good to sell(AMD) or overhype and make the feature as major selling point(Toyota and other who claim cheap hach made RWD Disney world).
If Toyota is not doing some trickery in the front to allow such big torque split
I stand my ground to call it BS.
One thing to clarify here:
I'm not talking messy situation where some tires loose traction and god know what's going on.
I'm talking about very simple scenario when all 4 tires have all the grip in the world and goes straight line.
@@FutureProofNothing Mr Kuczera didn't personally create the system and I don't find anything in this interview about torque split, just a sentence about "majority of power". Interviews with JTEKT engineers are much more technical and they do explain the torque issue.
You seem to be continously omitting the most important thing which I mentioned - clutch-pack compression just before the overspeed. You simply skip to overspeed when traction is already lost. Consider your own example when all four wheels have full grip. If the gearing is the same then you may lock the clutch-pack easily, there's no additional resistance, nothing happens. But when the gearing is different then rear axle resists a lot just before clutch-pack lock-up, it actually mimics the situation of different grip between front and rear, like there was more grip at the back. This way there's kind of switch from static to dynamic torque split, where every locked system has variable split from ~100/0 to ~0/100.
I am aware of the fact that many people interpret 30/70 as rwd based mode but as a few polls on my channel shows - about 80% of people do not understand the difference between the torque and wheelspin.
To sum up - we can agree that we disagree. Regards!