• Jul 10th 2007 at 7:11AM
  • 12
Two of the most anticipated features of the new Evolution X, not including the 4B11T engine, are the new all-wheel-drive system and the move to a dual-clutch gearbox. Mitsubishi has released some preliminary details on both systems, which aim to increase safety and driver involvement.
The S-AWC system, Mitsubishi-speak for their new electronic power-delivering masterpiece, includes the integration of ASC (Active Stability Control), ACD (Active Center Differential), AYC (Active Yaw Control) and Sport ABS (self explanatory). All four systems regulate brake force and torque distribution to individual wheels, along with a yaw rate feedback control that will make any ham-fisted Evo pilot feel like they're Sebastian Loeb.

As for the Twin Clutch SST, the automated manual gearbox, Mitsubishi employs two input shafts that control odd and even number gears (much like the VW/Audi setup), and drivers will be able to select between three different modes, as they've done in the past. "Normal" mode is for your daily slog, while "Sport" will include more engine braking and sharpened throttle responses, using higher shift points and quicker shifts. "S-Sport" mode takes Sport and cranks it to 11 by bringing the engine revs into the stratosphere and further quickening shifts.

All the details are posted in the press release after the jump.


Mitsubishi Motors develops S-AWC vehicle dynamics control system & Twin Clutch SST automated manual transmission

Tokyo, July 10, 2007 - Mitsubishi Motors Corporation has developed two new component systems that are expected to feature in the new Lancer Evolution*, due to be launched this autumn. S-AWC (Super All Wheel Control) is an advanced vehicle dynamics control system that regulates drive torque at each wheel. Twin Clutch SST (Sport Shift Transmission) is an automated manual transmission that delivers slicker shifting through the gears while freeing the driver from the need to operate the clutch.

In line with its corporate philosophy, Mitsubishi Motors strives to deliver a dynamic driving experience while making advances to keep drivers safe. Twin Clutch SST and S-AWC do so by making driving more intuitive. Both the systems work to efficiently distribute power appropriate to road conditions, and deliver outstanding control and stability maintained by an "intelligent" system that reads and reflects driver intent in real time.
The system now adds an ASC*1 (Active Stability Control) feature to the ACD*2 (Active Center Differential), AYC*3 (Active Yaw Control) and Sport ABS*4 (Sport Antilock Brake System) components that have proven themselves in the Lancer Evolution series. Integrated system management of these four components allows regulation of torque and braking force at each wheel. S-AWC also now employs yaw rate feedback control. This allows the system to control each wheel under a wide range of driving conditions, thus realizing vehicle behavior that faithfully reflects driver inputs and allows drivers of all abilities to enjoy sporty motoring with confidence.

Twin Clutch SST:
MMC's new automated manual transmission employs dual clutches to realize power transmission efficiencies on a par with a normal manual gearbox while also allowing slick and swift shifting. Allowing drivers of all abilities to shift rapidly up and down through the gears, Twin Clutch SST delivers satisfying acceleration while also returning superior fuel mileage thanks to its high-efficiency power transmission mechanism. The new transmission also features three operating modes tailored to different situations: from around-town drivability to instant-response and follow-the-line sporty motoring on the open road.

*1, *2, *3, *4: see following for details
1. S-AWC (Super All Wheel Control)

(1) System overview
The S-AWC vehicle dynamics control system integrates management of all its AYC, ACD, ASC and Sport ABS components (see below) while adding braking force control to Mitsubishi Motors' own AYC system. As a result S-AWC elevates drive power, cornering performance as well as vehicle stability under all driving situations, from everyday motoring to emergency evasion maneuvers.

(2) ACD (Active Center Differential)
The Active Center Differential incorporates an electronically-controlled hydraulic multi-plate clutch. The system optimizes clutch cover clamp load for different driving conditions, regulating the differential limiting action between free and locked states to optimize front/rear wheel torque split and thereby producing the best balance between traction and steering response.

(3) AYC (Active Yaw Control)
AYC uses a torque transfer mechanism in the rear differential to control rear wheel torque differential for different driving conditions and so limit the yaw moment that acts on the vehicle body and enhance cornering performance. AYC also acts like a limited slip differential by suppressing rear wheel slip to improve traction. The first component of its type, AYC was first used in the Lancer Evolution IV launched in April 1996. It then took an evolutionary step forward in the Lancer Evolution VIII launched in January 2003 as the Super AYC when it switched from the use of a bevel gear to a planetary gear differential, thereby doubling the amount of torque it was able to transfer. In comparison to the system used in the Lancer Evolution IX, AYC now features yaw rate feedback control using a yaw rate sensor and also gains braking force control. Accurately determining the cornering dynamics on a real-time basis, the system operates to control vehicle behavior through corners and realize vehicle behavior that more closely mirrors driver intent.

(4) ASC (Active Stability Control)
The ASC system stabilizes vehicle attitude while maintaining optimum traction by regulating engine power and the braking force at each wheel. Taking a step beyond the previous generation Lancer Evolution, the fitting of a brake pressure sensor at each wheel allows more precise and positive control of braking force. ASC improves traction under acceleration by preventing the driving wheels from spinning on slippery surfaces. It also elevates vehicle stability by suppressing skidding in an emergency evasive maneuver or the result of other sudden steering inputs.

(5) Sport ABS (Sport Anti-lock Braking System)
ABS allows the driver to maintain steering control and keeps the vehicle stable by preventing the wheels from locking under heavy braking or when braking on slippery surfaces. The addition of yaw rate sensors and brake pressure sensors to the Sport ABS system has improved braking performance through corners compared to the Lancer Evolution IX.

(6) S-AWC control system
The use of engine torque and brake pressure information in the regulation of the ACD and AYC components allows the S-AWC system to determine more quickly whether the vehicle is accelerating or decelerating. S-AWC also employs yaw rate feedback for the first time. The system helps the driver follow his chosen line more closely by comparing how the car is running, as determined from data from the yaw rate sensors, and how the driver wants it to behave, as determined from steering inputs, and operates accordingly to correct any divergence. The addition of braking force regulation to AYC's main role of transferring torque between the right and left wheels allows S-AWC to exert more control over vehicle behavior in on-the-limit driving situations. Increasing braking force on the inside wheel during understeer and on the outer wheel during oversteer situations, AYC's new braking force control feature works in concert with torque transfer regulation to realize higher levels of cornering performance and vehicle stability.
Using integrated management of the ASC and ABS systems allows S-AWC to effectively and seamlessly control vehicle dynamics when accelerating, decelerating or cornering under all driving conditions. S-AWC offers three operating modes: TARMAC for dry, paved surfaces; GRAVEL for wet or unmade surfaces, and SNOW for snow covered surfaces. When the driver selects the mode best suited to current road surface conditions S-AWC operates to control vehicle behavior accordingly and allow the driver to extract the maximum dynamic performance from his vehicle.

2. Twin Clutch SST (Sport Shift Transmission)

(1) The mechanism
Twin Clutch SST puts odd (1st, 3rd, 5th) and even (2nd, 4th and 6th) gears on separate input shafts, each connected to an individual clutch. With both clutches under precise system control, this arrangement allows lightening-fast, smooth and lag-free gear changes with no interruption in power delivery. Using clutches instead of a torque converter to transmit power makes the Twin Clutch SST simpler in structure and reduces power transmission losses for higher transmission efficiency that leads to improved fuel mileage.

(2) Drive modes
Twin Clutch SST allows the driver to switch between three shifting programs - Normal, Sport and S-Sport - to cover the full range of driving situations, from town use to sporty motoring on open roads.
a. Normal mode
For use around town and other normal driving situations, Normal mode scheduling uses relatively low-speed shift points to deliver unobtrusive shifting for maximum comfort together with optimum fuel economy.
b. Sport mode
For use when driving in the mountains or when engine braking is required, Sport mode scheduling uses higher shift points and quicker shifting to deliver instant throttle response that instills in the driver a closer man/machine relationship.
c. S-Sport mode
Compared with Sport mode, S-Sport mode scheduling keeps the engine turning at higher revs while allowing lightening-fast shifting.

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    • 1 Second Ago
      • 8 Years Ago
      i'm still very much opposed to the twin clutch system...
      i was surprised when i heard it would find its way into the X.
      i do not feel it fits the spirit of the Evo and it's rally roots.
      but i am aware that some cars on the rally circuit employ the automated manual gearbox.

      maybe i'm just becoming one of those old farts
      who thinks whatever was from their generation is best.

      i'm sure it'll still be an amazing machine.
        • 8 Years Ago
        The first use of dual clutch system in WRC was 1985 with the Audi Sport quattro S1 with 530hp Group B Rally car useing the PDK tranny (Porsche dual clutch tranny) the different between dual clutch and stick shift in this car was 2.6s vs 3.1s 0-62mph acceleration ... 2.6s for the PDK equipped dual clutch Audi Sport quattro S1.
        Sticking dual clutch into a Rally car is going back to were it comes from... 24h LeMans and WRC racing..
        • 8 Years Ago
        ...If by *some* you mean *all.*

        I like rowing my own gears too, but aside from the issue of launching and the automatic upshift at redline (two issues that seemingly can be corrected by software), and perhaps the issue of gear strength (which should be a non issue as more mature DSG systems on cars with higher HP emerge) there are no performance downsides to the DSG/AutoManual.
        • 8 Years Ago
        You should go for a test drive in one. I think you'll be suprised by them. They are very performance oriented, and although they aren't the same as rowing your own gears, they shift more quickly, and provide good feedback (I've only driven the DSG in an Audi A3) even blipping the throttle on downshifts.

        I still drive a 6 speed, but would consider an automated manual trans as they become more popular. And I suspect that it's only a matter of time before most ofter it as an option, perhaps even dropping a traditional slush box altogether.
        • 8 Years Ago
        DSG does have performance disadvantages. It has the same disadvantage that lockup-type automatics currently have. That is, the engine has to run a hydraulic pump all the time because the output of this pump is used to move the gears in the gearbox. This reduces your fuel economy and of course hurts acceleration.

        It seems that auto-shifted manual gearboxes have enough advantages that this loss of energy into pumping is considered a worthwhile tradeoff. I don't think even F1 teams lose much sleep over the few HP they have to give up to gain all the other advantages of hydraulic shifting.

        However, in theory, a truly manual gearbox will always be more efficient and thus get more power to the wheels than a traditional planetary-geared automatic or hydraulically-shifted cog-style manumatic.
      • 8 Years Ago
      I do have a concern about clutch wear and replacement. I'm sure the computerized dual-clutch system minimizes wear by nearly perfectly rev-matching, but what if something goes wrong, or I want to replace the clutches with lighter ones? It seems like a far more arduous process to get into the dual-clutch set-up, and a lighter clutch would require a reprogramming of the transmission computer.
      • 8 Years Ago
      Also, Mitsubishi's goal is to make the highest performing car possible, which means a twin clutch transmission. For those people who enjoy rowing their own gears, a standard manual will continue to be available- this isn't BMW after all.
      • 8 Years Ago
      Sorry, I don't care how awesome the computers can do it for you, if there is no clutch pedal then it ain't what I want. There is such a huge world of difference between having absolute physical command of your vehicle and essentially playing a video game behind the wheel.

      • 8 Years Ago
      We've got an A3 with DSG (and I've spent many hours in a GTI with DSG). We've also got several 6 speed manuals. The DSG is intoxicating and outright fun. I imagine on a track it would be great as you could get perfect, near instant shifts right before entering a corner and never have to fiddle with heel-toeing.

      Of course, the A3 and GTI are not track cars, so I can't say how this would really work in a tracking situation. But my track experience tells me it'd be a good thing in the Evo.
      • 8 Years Ago
      Another big advantage of twin clutch systems over standard manual transmission is the seamless power to the wheels, with a standard box there's always a slight interruption of power to the wheels when shifting, I'd think this probably mitigates the losses of keeping the hydraulic system pressurized.
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