For decades, automatic transmissions have been viewed as the antithesis of performance by most automotive enthusiasts. Power-sapping torque converters, glacially slow shifting, and driver feedback described as vague at best, are some of the key complaints about older 'traditional' automatics. With the DSG gearbox, a dual-clutch automatic, Volkswagen and Audi revolutionized the industry, providing an efficient option that offers reliability and race car-like performance for the masses.
DSG Transmission Guide Sections
What Is A DSG Transmission, And How Does It Work?
DSG is the Volkswagen marketing acronym for their family of dual-clutch transmissions or DCT. DSG stands for "Direkt-Schalt-Getriebe," or direct-shift gearbox. The VW DSG transmission is similar to all other common DCT designs in that it is effectively two separate electronically controlled manual transmissions built into one.
The DSG combines the best attributes and efficiency of a standard manual transmission and the ease of use of a more traditional automatic. DSG transmissions can be operated in a fully automatic mode, where the computer decides when and how to shift, or in a semi-automatic mode, where the driver uses either the gearshift shift lever or steering wheel-mounted paddles to select the desired gear. DSG and DCT transmissions have been a game-changer in the automotive world and in performance circles. Rarely has one component been able to increase both efficiency and performance with almost no downside.
All Volkswagen DSG transmissions are a transaxle design, which means that the same transmission case houses both the gears, the final drive, and differential in one unit, with shared oiling and lubrication. Much like a standard manual transmission, a DSG-equipped vehicle has a flywheel, which mates to the input shaft of the transmission, and is engaged by a clutch. This transfers power from the engine, through the transmission, and finally to the drive wheels.
As you would expect by the name "dual-clutch transmission," the DSG has two clutch packs, as well as two separate input shafts. Both are a concentric design, which means that one fits over the top of the other. The first clutch pack engages the odd gears of 1, 3, and 5, while the other engages the even gears of 2, 4, and 6. The two clutch packs are designated as K1 and K2.
The clutches in most DSG transmissions are a 'wet clutch' design, which means that the plates and friction rings are lubricated and cooled with transmission fluid, actuated via hydraulic pressure generated by a mechanical oil pump, and applied by the Transmission Control Unit (TCU). VW calls this the Mechatronic unit, and it is the brain behind the brilliance of the DSG transmission.
Since the Mechatronic unit effectively has two transmissions to work with, it is able to pre-select the next gear that you need before engaging the clutch and performing the shift. It simultaneously disengages one gear as it engages the next, resulting in that perfect power delivery. Where the DSG shines is in its ability to deliver both smooth and lightning-fast shifts, no matter the situation. From loafing along in commuter traffic to hitting back roads or race tracks on the weekend, it can do it all.
Connected via the vehicle's computer CAN bus system, the Mechatronic works in conjunction with other control units such as the ECU (Engine Control Unit) and the ABS braking system. It has a variety of inputs to decide how and when to shift, such as vehicle speed, engine speed, throttle position, brake pressure, and g-force measurements from the accelerometers in the car. The Mechatronic unit can guess with remarkable accuracy which gear you're going to want next, whether you are accelerating, braking, or cornering. It also knows how hard and fast to make the shift, and if it should upshift or downshift, using the same sensors and parameters.
For example, if you're just easing along in traffic and not accelerating or braking with a lot of force, the transmission will work its way up or down through the gears easily, ensuring smooth performance and shifting at low revs to maximize fuel efficiency. A DSG-equipped vehicle driven gently will use less fuel than the same car equipped with a manual.
However, if you press the accelerator pedal down like when you merge onto a busy highway, the Mechatronic unit sees the increased power produced by the engine and holds the gear longer, or performs a down-shift depending on the current gear and RPM, ensuring faster acceleration. It also will make the shift to the next gear more quickly, with a faster and more abrupt engagement of the clutch. A DSG transmission can perform a complete shift in around 200 milliseconds and can shift more quickly than the best drivers in a similar manual transmission vehicle.
How much faster? Depending on the exact trim level, the DSG equipped Mk7 GTI is about two-tenths of a second faster to 60 miles per hour at 5.8 seconds on average, compared to 6.0 seconds for the manual. Similarly, it is about two-tenths of a second faster in the quarter-mile, averaging 14.3 seconds over 14.5 for the manual transmission Mk7 GTI.
Most DSG-equipped models also feature a 'Sport' mode in addition to 'drive' or 'manual' modes. Sport mode changes the programming to be a bit more aggressive and not as focused on maximum efficiency and miles per gallon. The result is that it shifts faster, holds gears longer, downshifts to make use of engine-braking, and is generally more responsive for sporty driving. On many vehicles, Sport mode may also change the responsiveness or power of the engine, firmness of the suspension, or make other changes to enhance the driving experience.
There is one side-effect of the fast-shifting on DSG-equipped vehicles, which people tend to either love or hate. The "DSG Fart," as it's known in most enthusiast circles, is a loud 'crack' from the exhaust which occurs in between shifts on hard acceleration.
Although this is fairly muffled on factory vehicles, the more free-flowing the exhaust, the more likely you are to hear it. The sound itself is the result of the engine computer pulling timing from the ignition cycle when the shift occurs; This allows the engine RPMs to fall appropriately, the shift to occur, and for the next gear to be engaged smoothly. A small amount of unburned fuel passes into the exhaust on this process and ignites, creating this sound. This timing cut is the same reason you hear a loud pop on upshifts from race cars equipped with sequential or DCT transmissions.
For those of us who like to imagine we're driving a race car while we're running errands or commuting to work, it can add some fun to an otherwise dull drive. Some of the newer cars from Volkswagen and Audi tend not to do this as easily as early models thanks to changes in transmission design, engine specification, and programming. Regardless, if the idea of a flatulent car puts you off a bit, not to worry. If you don't modify the exhaust system from the factory specification, it will rarely, if ever, be audible.
History Of The DSG Transmission
The Volkswagen DSG, as we know it, debuted in the first-generation Type 8N PQ34 Audi TT, in the 2004 TT 3.2 Quattro. Volkswagen didn't provide the DSG as an option for their own vehicles until mid-2005, in the then-new Type 1K PQ35 Mk5 Jetta TDI. The DSG is a perfect match for a torquey turbo diesel engine and has been the go-to automatic option on most VW or Audi TDI cars since.
In 2006, the full Mk5 line up launched in the USA and added the DSG transmission as an option on the sporty GTI 2.0t and GLI 2.0t versions of the Rabbit/Golf and Jetta.
A vehicle equipped with a DSG transmission will have a traditional automatic-style gear selector with a 'PRND' indicator. Most but not all models will have "DSG" or "S Tronic" branding on the gear selector.
Volkswagen and Audi have typically used DSG and S Tronic DCT transmissions in their more sporty models, such as GTI, GLI, CC, and select R models from VW, most S and RS models from Audi, and nearly all TDI-powered vehicles from 2006 on. There are some models that gained or lost a DCT option depending on the year and model options, so be sure to double-check if you're looking to purchase a car and are unsure if it is equipped with a DSG or S Tronic transmission.
What Is The Difference Between VW DSG, Audi S Tronic, BMW DCT, And Porsche PDK?
Fundamentally, there are no major differences between the dual-clutch transmissions offered by the various German auto manufacturers.
Porsche wins the award for the hardest to pronounce name with "Porsche-Doppelkupplungsgetriebe" (Porsche double-clutch transmission), which is what PDK actually stands for. PDK operates in the same fashion as all other dual-clutch transmissions but is known to be one of the most refined and best-performing DCTs on the market. Similar to VW and Audi designs, PDK transmissions are all transaxle designs. Porsche is notable for having developed a PDK transmission for racing use back in the early-1980s as part of their 956 / 962 Group C program. The PDK didn't prove to be reliable enough at the time but has since been used in a variety of the entry-level Cayman GT4 machines from Porsche. Similarly, Volkswagen DSG and Audi S Tronic are both used on factory-built race cars, including our own Volkswagen GTI TCRs.
Audi S Tronic
S Tronic is simply Audi's marketing term for DCT-equipped vehicles. Audi's S Tronic and Volkswagen's DSG are identical in transverse powertrain vehicles, such as the Audi TT, TTS, TT RS, A3, S3, and RS3. Audi's more sporty longitudinal powertrain vehicles such as the S4 3.0t, S5 3.0t, RS5, and S6 4.0t are also offered with S Tronic transmissions.
BMW DCT differs only in that it is not a transaxle design like those from VW, Audi, and Porsche, but operates on the same principles and with the same primary components. BMW models have the final drive and differential divorced from the clutches, gear set, and fluids. The BMW DCT transmission is only offered on rear-wheel-drive models in the BMW lineup and is not an option on any of the xDrive variants. The BWM DCT transmission is primarily offered on performance models such as the M-badged cars and has received similar accolades to Porsche's PDK for being one of the most responsive DCT transmissions on the market.
DSG Transmission Specifications, Details, & Codes
The first production iteration of the DSG transmission, the DQ250, is a 6-speed transverse design utilized in a wide range of vehicles in the Volkswagen Audi Group. Exact specifications such as gear ratios and final drive will vary depending on the exact transmission code, but the design, function, and core components are all very similar. As technology has improved, the Mechatronic unit has been upgraded and improved, so the newest examples can shift faster, smoother, and are typically less likely to experience Mechatronic problems. The all-wheel-drive 4MOTION and Quattro DSG or S Tronic equipped DQ250 variants utilize an outboard transfer case design, and are otherwise the same as the FWD examples.
The DQ250 is the most commonly used DSG design. With factory Mechatronic programming, it's rated to handle up to 295 lb-feet of torque. The FCP Euro GTI TCRs were delivered with a motorsport variant of the DQ250, which shares almost all of its components with the street version.
The DQ500 is the first 7-speed transverse design sold in the USA by Audi, and also utilizes a wet clutch design like the DQ250. It was originally used in VW Transporters and other more industrial designs in Europe, which require high-torque handling, but has been adapted for use in the ultra-high performance Audi TT RS and Audi RS3 2.5T. With factory Mechatronic programming, the DQ500 is rated for up to 442 lb-ft of torque.
The newest transverse offering is the 7-speed DQ381, as introduced in the 2018 VW Golf R and 2019 VW GTI. It shares much of its design with the DQ500 and is rated for up to 317 lb-ft of torque with factory Mechatronic programming. Both the DQ500 and DQ381 transmissions offer even better fuel efficiency potential than the DQ250 with the addition of the seventh forward gear, along with their increased torque capacity.
Audi introduced the longitudinal DL501 7-speed S Tronic transmission in a variety of their more performance-minded sedans and CUVs such as the S4, S5, SQ5, and S6. The DL501 differs from all of the transverse type DQ transmissions in that it has divorced lubrication systems. The oil for the gearing and differentials is separate from the oil, which is utilized by the clutches, Mechatronic unit, and pump. This should, in theory, provide longer life and more reliability as there is no cross-contamination of fluids or particles between the two separated sections.
The R8, Audi's top-line sports car, received an S Tronic gearbox option in 2012 with the introduction of the 5.2 V10 engine. The DL800 is a 7-speed DCT transmission, utilized only in the Audi R8 and sister model from Lamborghini, the Huracan. This same street-derived S Tronic transmission is used without any internal changes in the R8 GT4 race car, lending further credibility to both the performance and reliability of the VW / Audi DCT transmission family.
VAQ Active Differential
All transverse DSG variants sold in the USA are compatible with VW's VAQ Active Differential, which is an add-on, active, multi-plate limited-slip differential. It functions very similarly to the 4MOTION and Quattro Haldex systems used on the all-wheel-drive transverse cars. A computer controls the torque split between the left and right sides via a hydraulically controlled clutch pack.
VW/Audi Models & Years That Can Be Equipped With A DSG Transmission
|2005.5-2006 Mk5 Volkswagen Jetta TDI DSG||2004-2006 8N Audi TT 3.2 VR6 Quattro|
|2006-2009 Mk5 Volkswagen Golf GTI DSG||2008-2010 8J Audi TT 2.0t FWD S Tronic|
|2007 Volkswagen Mk5 Golf GTI Fahrenheit Edition||2009-2014 8J Audi TTS 2.0t Quattro|
|2006-2009 Mk5 Volkswagen Jetta GLI DSG||2010-2014 8J Audi TT 2.0t Quattro|
|2008 Mk5 Volkswagen Golf R32||2015-2018 8S Audi TTS 2.0t Quattro|
|2009-2010 Mk5 Volkswagen Jetta TDI DSG||2018-2020 8S Audi TT RS|
|2009-2010 Mk5 Volkswagen Jetta Wolfsurg DSG||2006-2013 8P Audi A3 2.0t FWD S Tronic|
|2009 Mk5 Volkswagen Jetta SportWagen TDI DSG||2008-2010 8P Audi A3 3.2 Quattro S Tronic|
|2010 Mk5 Volkswagen Jetta TDI Cup Edition DSG||2010-2013 8P Audi A3 TDI S Tronic|
|2010-2014 Mk6 Volkswagen Golf GTI DSG||2010-2013 8P Audi A3 2.0t Quattro S Tronic|
|2012-2018 Mk6 Volkswagen Jetta GLI||2015-2020 8V Audi S3 S Tronic|
|2011-2016 Mk6 Volkswagen Jetta TDI DSG||2017-2020 8V Audi RS3|
|2010-2014 Mk6 Volkswagen Jetta SportWagen TDI DSG||2010-2012 B8 Audi S4 S Tronic|
|2015-2017 Mk7 Volkswagen Golf GTI DSG||2013-2017 B8.5 Audi S4 S Tronic|
|2018-2020 Mk7.5 Volkswagen Golf GTI DSG||2018-2020 B9 Audi S4|
|2015-2017 Mk7 Volkswagen Golf R DSG||2013-2017 B8.5 Audi S5 S Tronic|
|2018-2020 Mk7 Volkswagen Golf R DSG||2018-2020 B9 Audi S5|
|2007-2010 Volkswagen Eos 3.2 VR6 DSG||2010-2015 B8 Audi RS5|
|2007-2010 Volkswagen Eos 2.0t DSG||2018-2020 B9 Audi RS5|
|2015-2016 Volkswagen Eos 3.2 VR6 DSG||2014-2017 B8.5 Audi SQ5|
|2015-2016 Volkswagen Eos 2.0t DSG||2014-2020 4S Audi R8 5.2 V10 S Tronic|
|2009-2010 B6 Volkswagen Passat 2.0t DSG||2013-2020 C7 Audi S6|
|2012-2015 B7 Volkswagen Passat TDI DSG|
|2018 B7 Passat GT 3.6 VR6|
Common Problems Of The DSG Transmission
For the vast majority of owners, Volkswagen DSG transmissions have proved to be remarkably reliable. Though, like any other type of transmission, they are not without flaws and occasional issues. With proper service and maintenance utilizing high-quality parts and fluids, however, a DSG transmission will provide years and many thousands of miles of reliable performance. As they have been developed and updated over the years, the DSG-family has only become more reliable.
Rough Or Hard Shifting
The most frequent complaint from most DSG owners is clunky or hard shifting in certain conditions or at certain throttle positions. While this can be indicative of a transmission problem, accessory components such as engine and transmission mounts should be checked and ruled out before looking for more significant problems. Likewise, the driveline components such as CV axles and wheel bearings should be checked and confirmed as good, as they can also result in other noises and vibrations if they are worn and need replacement. This complaint is more often levelled at the transverse DQ250 models rather than the newest DQ500 or DQ381, or longitudinal DL501.
If you are used to driving a manual transmission vehicle, you will find that a more direct, decisive driving style will help to avoid clunks and provide the smoothest driving experience. Despite the speed with which the DSG can go from gear to gear, inconsistent throttle application or too many inputs in quick succession can 'confuse' the Mechatronic unit and result in some of the common driveability complaints. Essentially, the Mechatronic unit is always trying to guess which gear you will need next, whether that is one up or one down from where you currently are. Because it can only do that so quickly, that shift may seem less smooth or more sudden, or slower, than what you normally experience—this is not a problem, merely a quirk of the system and how it works. Performance tuning, which we will dive into later, can help to rectify this issue even when it comes to normal driving situations and result in smoother and better DSG drivability.
In terms of real problems, failure of the dual-mass flywheel is probably the most common wear-related issue on DSG vehicles. Signs of a flywheel issue include failure to engage gears from a stop, slow or hard shifting, and in the most extreme cases, RPM-dependent vibration and audible noise. Due to the vibration of the diesel engine, TDI models are most commonly affected by flywheel failure, with replacement often needed around 100,000 to 135,000 miles.
Gasoline engines typically can go much longer on mileage before requiring flywheel replacement, but results can vary depending on use. Worst-case scenario, failure to replace a bad flywheel can result in damage to the bellhousing and parts of the transmission, so it is best to stop driving if you suspect a flywheel issue until you can diagnose and repair it. After replacement, proper adaptation and recalibration of the clutches are required for the best performance and return of smooth shifting.
Mechatronic Unit Failure
Although it's not a widespread issue, the most serious and typically most expensive problem that can arise on a DSG transmission is a failure of the Mechatronic unit itself. Failures can result in a number of issues, ranging from hard or jerky shifting, failure to shift or engage from a stop, or complete and total transmission malfunction. In this instance, the transmission goes into a 'limp mode' with a limited number of gears available for use, or it may completely disengage the clutches to avoid damage, even while driving. Proper diagnosis with an electronic scan tool is the best and most accurate way to begin the process of determining if there is a Mechatronic fault. Even in the instance of total Mechatronic failure, the physical transmission itself, such as the gears, clutches, and differential, is typically not damaged in any way.
There have been recalls on a few DSG and S Tronic transmissions. Select examples of DSG-equipped VW models built between September of 2008 and August of 2009 were manufactured with a bad batch of Mechatronic units. The fault is specifically with the transmission temperature sensor, which was prone to failure. The result ranged from a fault on the dashboard, to the transmission automatically going into neutral even when 'drive' or 'reverse' is selected. Any vehicles in the affected range should have been repaired by now, but if not, an open recall repair should be able to be performed by a Volkswagen dealer. Although they were not included in the recall, the 2008 VW Mk5 R32 also featured a higher number of similar Mechatronic failures at that time.
Reconditioning of your original Mechatronic unit is a possibility, as is replacing it with a used example from a salvage yard. Still, your results and the quality of repair may vary. These units are not typically able to be changed out unless the replacement is an exact match for both the box code and version type. Calibration and coding of the Mechatronic unit should always be performed after replacement to ensure proper performance.
Unfortunately, both the flywheel failure and Mechatronic failure can result in a DSG transmission which does not shift gears or shift properly, so it can be difficult to determine which issue you're dealing with if it is an intermittent problem. Neither a flywheel replacement or a Mechatronic unit replacement is an inexpensive fix, so be sure to diagnose properly before replacing either part.
DSG Transmission Clutch Pack Wear
The clutch packs themselves can eventually wear and require replacement; This is fairly atypical and is usually the result of an underfilled transmission, failure to service the transmission fluid regularly, or extremely modified engines and heavy use such as drag racing. With factory power levels and programming, it is unlikely that the clutches will ever need to be replaced if the car is serviced properly. One significant benefit of a wet clutch is that it is tough to overheat them, and they are generally very long-wearing thanks to the lubrication of the hydraulic fluid.
One of the challenges of the DSG transmission is that Volkswagen considers the unit to be non-serviceable outside of the clutches, flywheel, Mechatronic unit, and lubrication & filtering systems. Internal repairs, although technically possible, are not easy to perform. Part numbers, parts availability, and crucial information such as bearing shim tolerances and gear lash are not published. Even the case half bolt specs used to hold the transmission together aren't specified. Replacing the complete transmission is sometimes the only solution if there are more significant internal faults or problems.
Common Maintenance On DSG Transmissions
Fluid & Filter Service
The most important service to perform on any dual-clutch transmission is to keep the fluid and filters replaced on schedule, with the best quality parts. Exact service intervals will vary depending on the exact vehicle year, model, and transmission code. Performance models such as the 8J TTS have a slightly shorter service interval from the factory than other models that use the same basic transmission. If you have a heavy foot, have a highly modified car, or drive your car on the track, you may want to consider shortening the service interval as preventative maintenance.
If you are driving your DSG-equipped vehicle on track days or in situations with extreme temperatures, it is possible for oil to be pushed out of the overflow vent located on the top front of the transmission case. This is rare and may be a side-effect of a slightly overfilled transmission. Although this is typically a very small amount of fluid, if it occurs with a decent amount of regularity or you're attending a lot of track days, it is worth checking the fluid level in between events to ensure you are not running the system low on oil. There are a handful of aftermarket DSG cooling solutions to help eliminate or mitigate this.
Outside of the fluid service, DSG transmissions don't have any other regular maintenance requirements. Clutches and flywheels are service-free as long as they are functioning correctly and will benefit from regular fluid changes. Related components such as engine and transmission mounts, should be checked and replaced as needed, as well as the CV drive axles.
DSG Transmission Oil Service Information
Performing a transmission oil service on a DSG transmission is the most important thing to ensure maximum life and maximum performance. If your vehicle is new to you, is within the DSG service mileage window, and has unknown service history, you should always perform a DSG transmission oil service to ensure it is up to date. It's a fairly straightforward process and easy to perform in your driveway with the right tools.
DSG Transmission Oil Service Interval
Every vehicle from Volkswagen or Audi will include a recommended service interval in the owner's manual. On the vast majority of models, a DSG transmission oil service is required every 40,000 miles. Audi specifies a slightly shorter interval of 35,000 miles on older transverse models such as the 8J TTS and Audi A3. Conversely, Some of the newest models from Volkswagen equipped with the front-wheel-drive DQ381 are now specifying an 80,000-mile service.
Although it isn't specifically mentioned by Volkswagen or Audi, a vehicle experiencing extremely heavy use such as on-track performance driving, competitive racing, or towing, may benefit from a slightly shorter change interval. Based on past experiences, continuing to abide by a 40,000-mile service interval even on the DQ381 transmission will likely provide the longest life from the gears, clutches, and Mechatronic unit. It's inexpensive insurance on such an expensive driveline component.
If your DSG transmission is experiencing slipping, hard shifting, or other drivability issues, a transmission service could help to rectify these problems. A DSG transmission that is low on fluid will not function properly, and continuing to drive a transmission that is low on oil may result in damage to the clutches, gear sets, or other internal components.
What Fluid And How Much Does The DSG Transmission Require?
Most DSG transmission services will require an approved DCT transmission fluid, transmission oil filter, sealing o-rings for the filter and housing, and a drain plug gasket. The longitudinal DL501 is equipped with a second, non-serviceable internal oil filter or screen which does not need to be changed during a normal service. The only time to replace or clean the internal filter would be if there is known internal damage or a large amount of metal is present in the DCT transmission oil. The transmission pan has to be dropped to perform the service and will require additional gaskets and seals.
The transverse DQ250 requires somewhere between four and five liters of DCT oil to perform a transmission service. The larger longitudinal DL501 typically requires between seven and eight liters of DCT fluid. These two fluids are not necessarily interchangeable, so be sure that whatever fluid you are using is specified and approved for use in your exact model.
Tools Required to Perform a DSG Transmission Oil Service
Performing a DSG transmission oil service requires a few standard hand tools and a few specialty tools to complete properly. Refilling occurs through the drain hole, which features a 2-stage drain plug. The fluid is transferred using a fill adaptor matched to either a fluid transfer pump or a gravity fill kit. After filling, the vehicle must be started, and the transmission fluid temperature needs to be brought up to 35C, as measured via a scan tool, and excess oil should be allowed to drain before re-installing the final drain plug.
- Fluid transfer pump with fill adapter or gravity fill kit with fill adapter
- 14 mm hex drive socket or drain plug wrench
- 8 mm hex drive socket (long)
- 24 mm socket
- 10mm socket or wrench (battery terminals and battery tray)
- 13mm socket (battery hold down)
- Rachet (⅜" and ½" drive)
- ⅜" Drive Extension
- Torque wrench
- Scan tool
DSG Transmission Performance Upgrades
The DSG transmission has absolutely changed the landscape of performance tuning options for VW and Audi vehicles. Out of the box, they are strong, reliable, and offer nearly uninterrupted power delivery. With performance tuning of the Mechatronic unit, a whole new world of possibilities is opened up.
A performance tune on a DSG transmission typically offers a few standard improvements of the factory programming.
First, the shift points and logic behind how and when, and how hard the transmission goes through the gears, is optimized more for performance, response, and acceleration rather than pure fuel economy. This usually results in better overall drivability and a more rewarding driving experience, as the car no longer seems eager to simply get to top gear as quickly as it can and loaf around at 1,200rpm. This translates into more fun behind the wheel with daily driving or with a spirited run on a back road. Smaller changes, such as reduced pull-away delay, gear selection displayed in the gauge cluster, and faster response from paddle-shift input, further improve the driving experience.
Driveability is especially improved for vehicles that have had some kind of ECU upgrade or performance tune installed. When an engine is making more power and the TCU is not remapped for managing the increased power and torque, all of the decisions made by the TCU are thrown off, and it may result in less desirable performance. For example, for a mild increase in engine power, this means that there may be an occasional hard shift, oddly chosen gear, or unexpected downshift depending upon the situation at hand.
Added to this, because the Mechatronic unit is constantly monitoring and managing engine power output, it has the ability to interfere with the amount of power that makes it to the ground. A performance DSG tune, even on stock programming, will usually result in noticeably improved power output and delivery characteristics.
Since virtually every aspect of a DSG transmission is computer-controlled, a performance tune can also increase the effective power handling of the transmission tremendously. A stock TCU matched to a highly modified engine may result in slipping clutches or even clutch damage. By fine-tuning not only the clutch pressures but also the timing and overlap of the gear changes, a performance tune can ensure near-standard clutch life even with much higher torque outputs. Although most software companies don't rate their DSG tunes with a specific number, it is generally accepted that a standard DQ250 with a performance tune can handle between 400-500 lb-fit of torque on stock clutch packs depending on the tune. This is an increase of over 100-200 lb-fit over the factory rating with no other changes.
Most performance tunes will also offer some kind of 'full manual mode' where the TCU doesn't downshift automatically in the same situations where it normally would. Anyone who has driven an automatic transmission equipped car can probably relate to the car downshifting aggressively when all you wanted was a tiny bit more passing power. A performance DSG tune improves or sometimes eliminates that depending on your drive mode and exact tune.
A performance DSG tune will also typically provide the option for a user-controlled launch control RPM. Some early DSG models had launch control defeated in USA models, so this essentially taps into that factory Euro-spec option and adds some adjustability for better functionality. It is worth noting that for most front-wheel-drive cars, the launch control option just results in a futile attempt to control wheel spin without sticky tires. On the all-wheel-drive models such as the Golf R, S3, TT RS, and RS3, launch control can turn them into absolute beasts off of the line.
DSG Transmission Software Tuning Companies
Most performance tuning companies that also offer ECU tuning will also offer TCU tuning. Some of the most popular companies, such as Unitronic, APR, REVO, and United Motorsport, have established dealer networks to support their customers. Unitronic also offers a DIY flash at home option via their Uniconnect cable, which makes it easy to change options or upgrade from the comfort of your garage or driveway. COBB is a newer player in the VW tuning world, which offers a similar flash-at-home option with their Accessport cable.
DSG Transmission Hardware Companies
Despite the out of the box durability of the DSG transmission, there are upgraded hardware parts available for most models. For extreme power applications, performance clutch friction material is a popular upgrade. Kits are available from Dodson Motorsport, TVS Engineering, and SSP, and when combined with appropriate software, installing one of these kits can raise power handling to well over 700 lb-ft of torque. RS3 and TT RS drag racers have been quoted as putting more than 1,300 wheel horsepower (over 1,500 horsepower to the crank) through DQ500 gearboxes with upgraded components. Proper calibration and adaptation of the TCU is imperative after changing or upgrading the DSG clutch packs.
DSG Transmission Limited-Slip Differential Upgrade Companies
A limited-slip differential is another popular upgrade, especially for road racers and drag racers. The factory differential struggles to put down power evenly, especially at extreme power levels or while accelerating out of a corner, even with the VAQ active differential option. Most aftermarket differentials are a planetary gear torque-biasing type, which diverts power to the wheel with the most traction. This is the opposite of how the stock differential works. Popular brands include Wavetrac, Peloquin, and Quaife Engineering. There is a difference between early and late parking ring gear designs, so if you are planning on upgrading the differential inside your DSG transmission, be sure to purchase the correct design.
As mentioned before, there are no published specs for bearing tolerances, fastener torque, or the assembly process of the DSG transmission. Be sure to have all of the necessary information before tackling this job, or ensure that the shop performing the job for you is capable and knows what they're getting into.
Important Torque Specifications For The DSG Transmission
- Drain plug: 33 lb-ft (45 N m) (replace crush washer)
- Spillover tube: 2 lb-ft (24 inch-pounds / 3 N m)
- DSG oil filter cap: 15 lb-ft (20 N m)
- CV Axle to output flange: 52 lb-ft (70 N m) (replace)
The DSG transmission has been a game-changer for fans of Volkswagens and Audi vehicles. With proper care they offer versatile performance, efficiency, and have raised the bar for automatic transmissions worldwide.
As we continue to learn more about the DSG transmission through DIYs and project builds, this guide will continue to evolve. For updates, be sure to check back here or the blog home page. If you'd like to learn more about Volkswagen/Audi systems, specific DIYs, news, and car features, you can find all of that on our Volkswagen and Audi hubs.
FCP Euro's Event Director by day, writer and contributor by night, and wanna-be race car driver on the weekends. Nathan has been working in the VW and Audi performance aftermarket for nearly two decades, and dabbled with Porsche and BMW. He also used to write under the pen-name of Alex Rogan for magazines like Eurotuner, Performance VW, Total 911, and European Car. He has a Cornflower Blue Rabbit Edition GTI daily driver which is surprisingly still mostly stock, and a Mk5 GTI track car which is mostly not. ••• Instagram: @njbrown55