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Appealing to "sporty" drivers is not a mechanical advantage and VW press release page is not a neutral and unbiased POV
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*Very smooth gear-shift operations;<ref name=AutoZineTech/><ref name=DCTfactsHow/>
*Very smooth gear-shift operations;<ref name=AutoZineTech/><ref name=DCTfactsHow/>
*Consistent shift time of 600&nbsp;milliseconds, regardless of throttle or operational mode;<ref name=AutoZineTech/>
*Consistent shift time of 600&nbsp;milliseconds, regardless of throttle or operational mode;<ref name=AutoZineTech/>
*Appeals to 'sporty<ref name=VMS/> drivers' due to overall fast shifts and rapid responses,<ref name=VMS/><ref name=DCTfactsHow/> along with the 'latest technology'


;Disadvantages
;Disadvantages
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*Relatively expensive to manufacture,{{Citation needed|date=April 2008}} and therefore increases new vehicle purchase price;
*Relatively expensive to manufacture,{{Citation needed|date=April 2008}} and therefore increases new vehicle purchase price;
*Relatively lengthy shift time when shifting to a gear ratio which the transmission ECU did not anticipate (around 1100&nbsp;ms, depending on the situation);<ref name=AutoZineTech/><ref>{{cite web|url=http://www.autoevolution.com/news/how-dual-clutch-transmissions-work-5458.html|title=How Dual-Clutch Transmissions Work|work=SoftNews NET|publisher=AutoEvolution.com|date=31 March 2009|accessdate=30 October 2009}}</ref>
*Relatively lengthy shift time when shifting to a gear ratio which the transmission ECU did not anticipate (around 1100&nbsp;ms, depending on the situation);<ref name=AutoZineTech/><ref>{{cite web|url=http://www.autoevolution.com/news/how-dual-clutch-transmissions-work-5458.html|title=How Dual-Clutch Transmissions Work|work=SoftNews NET|publisher=AutoEvolution.com|date=31 March 2009|accessdate=30 October 2009}}</ref>
*Torque handling capability constraints perceive a limit on after-market engine tuning modifications (though many tuners and users have now greatly exceeded the official torque limits without any adverse effects);{{Citation needed|date=November 2009}}
*Torque handling capability constraints perceive a limit on after-market engine tuning modifications (though many tuners and users have now greatly exceeded the official torque limits without any adverse effects{{Citation needed|date=November 2009}});
*Heavier than a comparable [[Getrag]] conventional manual transmission ({{convert|75|kg|0|lk=on}} vs. {{convert|47.5|kg|0|abbr=on}});
*Heavier than a comparable [[Getrag]] conventional manual transmission ({{convert|75|kg|0|lk=on}} vs. {{convert|47.5|kg|0|abbr=on}});
*Greater potential for failure due to complexity.{{Citation needed|date=August 2009}}
*Greater potential for failure due to complexity.{{Citation needed|date=August 2009}}

Revision as of 10:08, 30 November 2009

Automotive transmissions
Manual
Automatic / Semi-automatic
Part-cutaway view of the Volkswagen Group 6-speed Direct-Shift Gearbox. The concentric multi-plate clutches have been sectioned, along with the mechatronics module. This also shows the additional power take-off for distributing torque to the rear axle for four-wheel drive applications. - View this image with annotations
Schematic diagram of a dual clutch transmission

The Direct-Shift Gearbox (‹See Tfd›German: Direkt-Schalt-Getriebe[1]), commonly abbreviated to DSG,[2][3] is a Volkswagen Group (Volkswagen AG) (VWAG) developed electronically controlled dual clutch[2] multiple-shaft manual gearbox, in a transaxle design - without a conventional clutch pedal,[4] and with full automatic,[2] or semi-manual control.

In simple terms, it is two separate manual gearboxes (and clutches), contained within one housing, and working as one unit.[2][3][5] It was designed by BorgWarner,[4] and was initially licensed to the German automotive industry conglomerate Volkswagen Group (which owns the Volkswagen Passenger Cars, Audi, SEAT, Škoda, Lamborghini, Bentley, Bugatti, and Volkswagen Commercial Vehicles automotive marques), with support by IAV GmbH.[citation needed] By using two independent clutches,[2][5] faster shift times can be achieved,[2][5] and the traditional torque converter of a conventional epicyclic automatic transmission is eliminated.[2]

The seven-speed DSG transmission fitted in the 406 kilometres per hour (252 mph) Bugatti Veyron is a notable exception, its dual clutch transmission (DCT), capable of handling 1,250 newton-metres (922 lbf⋅ft) was developed and produced by the English specialist consulting engineering company Ricardo plc.[6]

Overview

Transverse DSG

At the time of launch in 2003[2][7] - it became the worlds first dual clutch transmission in a series production car,[2][7] in the German-market Volkswagen Golf Mk4 R32[2][7] and shortly afterwards, worldwide in the original Audi TT 3.2;[8] and for the first few years of production, this original DSG transmission was only available in transversely-orientated[2] front engine, front-wheel drive - or Haldex Traction-based four-wheel drive vehicle layouts.

The first DSG transaxle that went into production for the VWAG mainstream marques had six forward speeds (and one reverse),[7][8] and used wet/submerged multi-plate clutch packs[2][4] (internal VWAG code: DQ250, parts code prefix: 02E).[8][9] It has a maximum torque handling capacity of 350 newton-metres (258 lbf⋅ft),[7][8] and the two-wheel drive version weighed 93 kilograms (205 lb). It is manufactured at Volkswagen Groups Kassel plant,[2] with a daily production output of 1,500 units.[7]

At the start of 2008, another world first,[7] an additional 70 kilograms (154 lb) seven-speed DSG transaxle[7] (internal VWAG code: DQ200, parts code prefix: 0AM)[9][10][11] became available. It differs from the six-speed DSG, in that uses two single-plate dry clutches (of similar diameter).[11] This clutch pack was designed by LuK Clutch Systems, LLC.[12] This 7-speed DSG is used in smaller front-wheel drive cars with smaller displacement engines with lower torque outputs,[7][8][11] such as the latest Volkswagen Golf,[7][11] Volkswagen Polo Mk5,[11] and the new SEAT Ibiza,[8] due to it having a maximum torque handling capacity of 250 newton-metres (184 lbf⋅ft).[7] It uses considerably less oil than the six-speed DQ250; this new DQ200 uses just 1.7 litres (0.37 imp gal; 0.45 US gal) of transmission fluid.[7]

Audi longitudinal DSG

In late 2008, an all-new seven speed longitudinal[8][13] S tronic[13] version of the DSG transaxle went into series production (internal VWAG code: DL501, parts code prefix: 0B5),[9] lead by Audi transmission design engineer Mario Schenker.[13] Initially, from early 2009, it is only used in certain front engined Audi cars, and only with longitudinally-mounted engines. Like the original six-speed DSG, it features a concentric dual wet multi-plate clutch.[13] However, this particular variant uses notably more plates - the larger outer clutch (for the odd-numbered gears) uses ten plates, whereas the smaller inner clutch (driving even-numbered gears and reverse) uses 12 plates.[13] Another notable change over the original transverse DSGs is the lubrication system[14] - Audi now utilise two totally separate oil circuits.[13] One oil circuit, consisting of 7.5 litres (1.65 imp gal; 1.98 US gal), lubricates the hydraulic clutches and mechatronics with fully synthetic specialist automatic transmission fluid (ATF),[13] whilst the other oil circuit lubricates the gear trains and front and centre differentials with 4.3 litres (0.95 imp gal; 1.14 US gal) of conventional hypoid gear oil.[13] This dual circuit lubrication is aimed at increasing overall reliability, due to eliminating cross-contamination of debris and wear particles.[13] It has a torque handling limit of up to 600 newton-metres (443 lbf⋅ft),[8] and engine power outputs of up to 330 kilowatts (449 PS; 443 bhp).[8] It has a total mass, including all lubricants and the dual-mass flywheel of 141.5 kilograms (312 lb).[8]

This was initially available in their quattro four-wheel drive variants,[9] and is very similar to the new ZF Friedrichshafen-supplied[15] Porsche Doppel-Kupplung (PDK).[16][17]

Operational introduction

The internal combustion engine drives two clutch packs.[2][4][5] The outer clutch pack drives gears 1, 3, 5[2][4] (and 7 when fitted), and reverse[2] - the outer clutch pack has a larger diameter compared to the inner clutch, and can therefore handle greater torque loadings. The inner clutch pack drives gears 2, 4, and 6.[2][4] Instead of a standard large dry single-plate clutch, each clutch pack for the six-speed DSG is a collection of four small wet interleaved clutch plates (similar to a motorcycle wet multi-plate clutch). Due to space constraints, the two clutch assemblies are concentric, and the shafts within the gearbox are hollow and also concentric.[5] Because the alternate clutch pack's gear-sets can be pre-selected[2][4][5] (predictive shifts enabled via the 'unused' section of the gearbox), un-powered time while shifting is avoided[2][5] because the transmission of torque is simply switched from one clutch-pack to the other.[2] This means that the DSG takes only about 8 milliseconds to upshift.[3][4] In comparison, the sequential manual transmission (SMT) in the Ferrari F430 Scuderia takes 60 milliseconds to shift,[18] or 150 milliseconds in the Ferrari Enzo.[3] The quoted time for upshifts is the time the wheels are completely non-powered.

DSG controls

The Direct-Shift Gearbox utilises a floor-mounted transmission shift lever, very similar to that of a conventional automatic transmission.[11] The lever is operated in a straight 'fore and aft' plane (without any 'dog-leg' offset movements), and utilises an additional button to help prevent an inadvertent selection of an inappropriate shift lever position.

"P"

P position of the floor-mounted gear shift lever means that the transmission is set in "Park". Both clutch packs are fully disengaged, all gear-sets are disengaged, and a solid mechanical transmission 'lock' is applied to the crown wheel of the DSG's internal differential. This position must only be used when the motor vehicle is stationary. Furthermore, this is the position which must be set on the shift lever before the vehicle ignition key can be removed.

"N"

N position of the floor-mounted shift lever means that the transmission is in "neutral". Similar to P above, both clutch packs and all gear-sets are fully disengaged, however the parking lock is disengaged. This position should be used when the motor vehicle is stationary for a period of time, such as at red traffic lights, or waiting in a queue of stationary traffic.[19] The DSG should not be held in any of the active gear modes while stationary using the footbrake for other than brief periods - due to the clutches being held on the bite point, as this can overheat the clutches and transmission fluid.[19]

"D" mode

Whilst the motor vehicle is stationary and in neutral (N), the driver can select D for "drive" (after first pressing the foot brake pedal). The transmission's first gear is selected on the first shaft,[3] and the outer clutch engages at the start of the 'bite point'. At the same time, on the alternate gear shaft, the second gear is also selected[2][3] (pre-selected), but the clutch pack for second gear remains fully disengaged. When the driver releases the foot brake pedal, the outer clutch pack increases the clamping force, allowing the first gear to take up the drive through an increase of the 'bite point', and therefore transferring the torque from the engine through the transmission to the driveshafts and roadwheels - and the vehicle moves forward. Pressing the throttle / accelerator pedal will fully engage the clutch, and causes an increase of forward vehicle speed. As the vehicle accelerates, the transmission's computer determines when the second gear (which is connected to the second clutch) should be fully utilised. Depending on the vehicle speed, and amount of engine power being requested by the driver (full throttle, or part-throttle normal driving),[4] the DSG then upshifts. During this sequence, the DSG disengages the first outer clutch whilst simultaneously engaging the second inner clutch[2][3][4] (all power from the engine is now going through the second shaft), thus completing the shift sequence. This sequence happens in 8 milliseconds (aided by pre-selection),[3][4] and can happen even with full throttle opening, and as a result, there is virtually no power loss.[2][4]

Once the vehicle has completed the shift to second gear, the first gear is immediately de-selected, and third gear (being on the same shaft as 1st and 5th) is pre-selected,[2][3][4] and is pending. Once the time comes to shift into 3rd, the second clutch disengages and the first clutch re-engages.[2] This method of operation continues in the same manner up to 6th (or top) gear.

Downshifting is similar to upshifting but in reverse order, and is slower, at 600 milliseconds, due to the engine ECU needing to 'blip' the throttle, so that the engine crankshaft speed can match the appropriate gear shaft speed.[2][4] The car's computer senses the car slowing down, or more power required (during acceleration), and thus engages a lower gear on the shaft not in use, and then completes the downshift.

The actual shift points are determined by the DSG's transmission Electronic Control Unit, or ECU, which commands a hydro-mechanical unit.[2] The transmission ECU, combined with the hydro-mechanical unit, are collectively called a "mechatronics"[2] unit or module. Because the DSGs ECU uses "fuzzy logic", the operation of the DSG is said to be "adaptive"; that is, the DSG will "learn" how the user drives the car, and will progressively tailor the shift points accordingly to suit the habits of the driver.

In the vehicle instrument display, between the speedometer and tachometer, the available shift-lever positions are shown, the current position of the shift-lever is highlighted (emboldend), and the current gear ratio in used is also displayed as a number.

Under "normal", progressive and linear acceleration and deceleration, the DSG shifts in a "sequential" manner, i.e. under acceleration: 1st > 2nd > 3rd > 4th > 5th > 6th; and the same sequence reversed for deceleration. However, the DSG can also skip the normal sequential method, by 'missing out' adjacent gears, and shift two or more gears.[3] This is most apparent if the car is being driven at sedate speeds in one of the higher gears with a light throttle opening, and the accelerator pedal is then pressed fully to the floor against a further additional 'resistance'; this activates the "kick-down" function. During kick-down, the DSG can skip gears,[11] going from 6th gear straight down to 2nd gear (conditions permitting).

When the floor-mounted gear selector lever is in position D, the DSG works in fully automatic mode,[3][5] with emphasis placed on gear shifts programmed to deliver maximum fuel economy.[3][11] That means that shifts will change up and down very early in the rev-range. As an example, on the Volkswagen Golf Mk5 GTI, sixth gear will be engaged around 52 kilometres per hour (32 mph), when initially using the DSG transmission with the 'default' ECU adaptation - although with an "aggressive" or "sporty" driving style, the adaptive shift pattern will increase the vehicle speed at which 6th gear engages.

"S" mode

The floor selector lever also has an S position.[2] When S is selected, "sport" mode[2] is activated in the DSG. Sport mode still functions as a fully automatic mode,[3] identical in operation to "D" mode, but upshifts and downshifts are made much higher up the engine rev-range.[2][3][11] This aids a more sporty driving manner,[2] by utilising considerably more of the available engine power, and also maximising engine braking. However, this mode does have a detrimental effect on the vehicle fuel consumption, when compared to D mode. This mode may not be ideal to use when wanting to drive in a 'sedate' manner; nor when road conditions are very slippery, due to ice, snow or torrential rain - because loss of tyre traction may be experienced (wheel spin during acceleration, and may also result in roadwheel locking during downshifts at high engine rpms under closed throttle).

S is highlighted in the instrument display, and like D mode, the currently used gear ratio is also displayed as a number.

"R"

R position of the floor-mounted shift lever means that the transmission is in "reverse". This functions in a similar way to D, but there is just one 'reverse gear'. When selected, R is highlighted in the instrument display.

Manual mode

Additionally, the floor shift lever also has another plane of operation, for manual[3][5] mode, with spring-loaded "+" and "−" positions. This plane is selected by moving the stick away from the driver (in vehicles with the driver's seat on the right, the lever is pushed to the left, and in left-hand drive cars, the stick is pushed to the right) when in "D" mode only. When this plane is selected, the DSG can now be controlled like a manual gearbox, albeit only under a sequential shift pattern.

The readout in the instrument display changes to 6 5 4 3 2 1, and just like the automatic modes, the currently used gear ratio is highlighted or emboldened. To change up a gear, the lever is pushed forwards (against a spring pressure) towards the "+", and to change down, the lever is pulled rearwards towards the "−". The DSG transmission can now be operated with the gear changes being (primarily) determined by the driver. This method of operation is commonly called "tiptronic".[2] In the interests of engine preservation, when accelerating in Manual/tiptronic mode, the DSG will still automatically change up just before the redline, and when decelerating, it will change down automatically at very low revs, just before the engine idle speed (tickover). Furthermore, if the driver calls for a gear when it is not appropriate (i.e., engine speed near the redline, and a down change is requested) the DSG will not change to the driver's requested gear.[3]

Current variants of the DSG will still downshift to the lowest possible gear ratio when the kick-down button is activated during full throttle whilst in manual mode. However, on vehicles equipped with steering wheel mounted paddle shifters, if the "+" paddle on the right side of the steering wheel is acitvated and held before the kick-down button is activated (and continued to be held), the DSG will not downshift, and will simply perform a full-throttle acceleration in whatever gear was previously being utilised.

Paddle shifters

Initially available on certain high-powered cars, and those with a "sporty" trim level - such as those using the 2.0 TFSI and 3.2/3.6 VR6 engines[2] - steering wheel-mounted paddle shifters[3][5] were available. However, these are now being offered (either as a standard inclusive fitment, or as a factory optional extra) on virtually all DSG-equipped cars, throughout all model ranges, including lesser power output applications, such as the 105 PS Volkswagen Golf Plus.[11]

These operate in an identical manner as the floor mounted shift lever when it is placed across the gate in manual mode. The paddle shifters have two distinct advantages: the driver can safely keep both hands on the steering wheel when using the Manual/tiptronic mode; and the driver can immediately manually override either of the automatic programmes (D or S) on a temporary basis,[11] and gain instant manual control of the DSG transmission[11] (within the above described constraints).

If the paddle-shift activated manual override of one of the automatic modes (D or S) is utilised intermittently, the DSG transmission will "default" back to the previously selected automatic mode after a predetermined duration of inactivity of the paddles, or when the vehicle becomes stationary. Alternatively, should the driver wish to immediately revert to fully automatic control, this can be done by activating and holding the "+" paddle[11] for at least two seconds.

Advantages and disadvantages

Advantages
  • Better fuel economy[2][7] (up to 15% improvement) than conventional planetary geared automatic transmission (due to lower parasitic losses from oil churning)[5] and for some models with manual transmissions;[2]
  • No loss of torque transmission from the engine to the driving wheels during gear shifts;[2][4][5]
  • Extremely fast up-shift time of 8 milliseconds when shifting to a gear the alternate gear shaft has preselected;[3][4]
  • Very smooth gear-shift operations;[4][5]
  • Consistent shift time of 600 milliseconds, regardless of throttle or operational mode;[4]
Disadvantages
  • Marginally worse overall mechanical efficiency compared to a conventional manual transmission, especially on wet-clutch variants (due to electronics and hydraulic systems);[5]
  • Expensive specialist transmission fluids/lubricants with dedicated additives are required, which need changing on a regular basis;[14]
  • Relatively expensive to manufacture,[citation needed] and therefore increases new vehicle purchase price;
  • Relatively lengthy shift time when shifting to a gear ratio which the transmission ECU did not anticipate (around 1100 ms, depending on the situation);[4][20]
  • Torque handling capability constraints perceive a limit on after-market engine tuning modifications (though many tuners and users have now greatly exceeded the official torque limits without any adverse effects[citation needed]);
  • Heavier than a comparable Getrag conventional manual transmission (75 kilograms (165 lb) vs. 47.5 kg (105 lb));
  • Greater potential for failure due to complexity.[citation needed]

Applications

For applications of similar transmissions in other vehicles beyond Volkswagen Groups DSG and S tronic, see dual clutch transmission.

Volkswagen Group vehicles with the DSG gearbox include:[9]

Audi

After originally using the 'DSG' moniker, Audi subsequently renamed the Direct-Shift Gearbox to "S tronic".

Bugatti

SEAT

Škoda

Volkswagen Passenger Cars

Volkswagen Commercial Vehicles

Recall of DSG-equipped vehicles

In August 2009, Volkswagen of America issued two recalls of DSG-equipped vehicles. The first involved 13,500 vehicles,[22] and was to address rare unplanned shifts to the neutral gear,[22] while the second involved similar problems (by then attributed to faulty temperature sensors) and applied to 53,300 vehicles.[22][23][24] These recalls arose as a result of investigations carried out by the US National Highway Traffic Safety Administration (NHTSA),[25] where owners reported to the NHTSA a loss of power whilst driving.[22] This investigation preliminary found only 2008 and 2009 model year vehicles as being affected.[22][25]

See also

References

  1. ^ Volkswagen Service Training Manual 308 - 02E 6-speed DSG
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al "Volkswagen DSG - World's first dual-clutch gearbox in a production car" (Press release). Volkswagen Group / Volkswagen AG - Volkswagen-Media-Services.com. 22 November 2002. Retrieved 30 October 2009.
  3. ^ a b c d e f g h i j k l m n o p q r "Twin Clutch / Direct Shift Gearbox (DSG) - What it is, how it works". Cars.About.com. Retrieved 27 October 2009.
  4. ^ a b c d e f g h i j k l m n o p q r s Mark Wan. Gearbox "Transmission - Twin-Clutch Gearbox". AutoZine Technical School. AutoZine.org. Retrieved 27 October 2009. {{cite web}}: Check |url= value (help)
  5. ^ a b c d e f g h i j k l m n "How the Dual Clutch Transmission Works". The Lubrizol Corporation. DCTfacts.com. ©2009. Retrieved 27 October 2009. {{cite web}}: Check date values in: |date= (help)
  6. ^ a b "Ricardo Extends DCT Production for Open-top Bugatti". The Lubrizol Corporation. DCTfacts.com. 16 January 2009. Retrieved 28 October 2009.
  7. ^ a b c d e f g h i j k l m n o p "The 7-speed DSG - the intelligent automatic gearbox from Volkswagen". Volkswagen Group / Volkswagen AG. VolkswagenAG.com. 21 January 2008. Retrieved 3 November 2009.
  8. ^ a b c d e f g h i j k l m "Volkswagen Group extends reach of dual clutch transmissions". The Lubrizol Corporation. DCTfacts.com. 8 May 2009. Retrieved 27 October 2009.
  9. ^ a b c d e ETKA
  10. ^ Volkswagen Service Training Manual 390 - 0AM 7-speed DSG
  11. ^ a b c d e f g h i j k l m "Golf Plus on the Road". The Lubrizol Corporation. DCTfacts.com. ©2009. Retrieved 28 October 2009. {{cite web}}: Check date values in: |date= (help)
  12. ^ "LuK Dual Dry Clutch 7-Speed DSG Gearbox in volume production at Volkswagen". Schaeffler Group USA Inc., BÜHL, GERMANY. LuKclutch.com. 13 February 2008. Retrieved 27 October 2009.
  13. ^ a b c d e f g h i j k l "Inside Audi's premium DCT". The Lubrizol Corporation. DCTfacts.com. 8 May 2009. Retrieved 27 October 2009.
  14. ^ a b "Special Transmissions Need Special Lubricants". The Lubrizol Corporation. DCTfacts.com. ©2009. Retrieved 28 October 2009. {{cite web}}: Check date values in: |date= (help)
  15. ^ "ZF 7-speed dual clutch transmission". ZF Friedrichshafen AG. ZF.com. Retrieved 28 October 2009.
  16. ^ "Top 911 moves to industry-standard shift controls". The Lubrizol Corporation. DCTfacts.com. 24 September 2009. Retrieved 27 October 2009.
  17. ^ "Porsche Joins the DCT Set". The Lubrizol Corporation. DCTfacts.com. Retrieved 28 October 2009.
  18. ^ Mark Wan (17 October 2007). "Ferrari F430 Scuderia". AutoZine.org. Retrieved 27 October 2009.
  19. ^ a b "Mitsubishi Evo X - Precautions". The Lubrizol Corporation. DCTfacts.com. 9 March 2009. Retrieved 28 October 2009. engage neutral while waiting at lights or in a traffic queue, rather than holding the car on the footbrake – a practice which could lead to overheating
  20. ^ "How Dual-Clutch Transmissions Work". SoftNews NET. AutoEvolution.com. 31 March 2009. Retrieved 30 October 2009.
  21. ^ "Volkswagen (Commercial Vehicles) medium van is first with DCT". The Lubrizol Corporation. DCTfacts.com. 24 September 2009. Retrieved 27 October 2009.
  22. ^ a b c d e "VW DSG Transmission Problem Leads to Recall". New York Times. wheels.blogs.nytimes.com. 21 August 2009. Retrieved 30 November 2009.
  23. ^ "VW Has More Problems With Its DSG Transmission". New York Times. wheels.blogs.nytimes.com. 28 August 2009. Retrieved 30 November 2009.
  24. ^ "Volkswagen will repair DSG transmissions on 53,300 vehicles". Hachette Filipacchi Media U.S., Inc.,. Blog.CarAndDriver.com. 28 August 2009. Retrieved 27 October 2009.{{cite web}}: CS1 maint: extra punctuation (link)
  25. ^ a b Template:PDFlink, NHTSA, Retrieved 30 November 2009. The direct shift gearbox can malfunction at any speed and cause the vehicle to loose motive power suddenly and without warning
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