7 SPEED DSG AUTOMATIC GEARBOXES

Everything You Need To Know About

Everything You Need To Know About

7 SPEED DSG AUTOMATIC GEARBOXES

WHAT IS DSG?

The dual-clutch transmission, also known as the Direct Shift Gearbox (DSG) or twin-clutch transmission, is an automated transmission that can change gears faster than any other geared transmission. Dual-clutch transmissions deliver more power and better control than a traditional automatic transmission and faster performance than a manual transmission. Originally marketed by Volkswagen as the DSG and Audi as the S-Tronic, dual-clutch transmissions are now offered by several automakers, including Ford, Mitsubishi, Smart, Hyundai and Porsche.

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THE MOST COMMON ISSUES WITH 7 SPEED DSG GEARBOX

Issue 1: Hydraulic unit fault.

Common know as Mechatronic. Combine from 2 parts. TCM (ECU) and valve body.  You will find out very soon that valve body can crack, leak oil, lose pressure and not working properly. That can occur even after 20k from brand new regardless of driving style. When running diagnostics, you will have faults with play protection and/or insufficient pressure build in. At this stage, you will need to replace the whole unit as separate parts are not available to buy. Also, you will need to check the clutch.

Issue 2: Gear selectors - forks damage.

There are millions of moving parts in the gearbox. One of them is gear selectors “forks” responsible for select gears via the mechatronic unit.  You will find out that VW Group has upgraded those parts in the second generation of the gearbox. They are made from metal now rather than plastic like in generation one.

Issue 3: Used or damaged clutch.

As we are all aware clutch will wear with time, there is no way around it. With 0AM DSG Gearbox we have a dry clutch. Fortunately, we are able to buy a complete repair kit from the main dealer and replace it.

ADVANTAGES OF THE DUAL-CLUTCH/DSG TRANSMISSION

The primary advantage of the twin-clutch is that it provides the same driving characteristics of a manual transmission and comes with the convenience of an automatic. However, the ability to perform near-instantaneous gearshifts gives the twin-clutch advantages over both manuals and SMTs. Volkswagen’s DSG takes about 8 milliseconds to upshift.

Compare that to the SMT in the Ferrari Enzo, which takes 150 milliseconds to upshift. Instant gear shifts mean faster acceleration; according to Audi, the A3 runs 0-60 in 6.9 seconds with a 6-speed manual and 6.7 seconds with the 6-speed DSG.

DISADVANTAGES OF THE DUAL-CLUTCH TRANSMISSION

The main limitation of the dual-clutch transmission is the same as all geared transmissions. Because there are a fixed number of gears, and the transmission cannot always keep the engine at its best speed for maximum power or maximum fuel economy, the dual-clutch transmissions generally cannot extract as much power or fuel economy from an engine as a continuously-variable automatic transmission (CVTs).

But because twin-clutch transmissions provide a more familiar driving experience than CVTs, most drivers prefer them. And while the twin-clutch provides superior performance compared to a manual, some drivers prefer the interaction that a manual clutch pedal and gearshift provide.

DSG Automatic Gearbox repair and replacement

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EXPERT TIP FOR DRIVING A CAR WITH A TWIN-CLUTCH, KNOWN AS DSG TRANSMISSION

Twin-clutch equipped cars do not have a clutch pedal; the clutch is engaged and disengaged automatically. Most twin-clutch transmissions use an automatic-style shift selector with a traditional P-R-N-D or P-R-N-D-S (Sport) shift pattern. In “Drive” or “Sport” mode, the dual-clutch transmission operates like a regular automatic.
In “Drive” mode, the transmission shifts to higher gears early in order to minimise engine noise and maximise fuel economy, while in “Sport” mode, it holds the lower gears longer in order to keep the engine in its powerband. Sport mode also provides more aggressive downshifts with less accelerator pedal pressure, and in some cars, engaging Sport mode causes the car to react more aggressively to the accelerator pedal.

Most dual-clutch transmissions have a manual mode which allows manual shifting via the shift lever or paddles mounted on the steering wheel. When driven in manual mode, the clutch is still operated automatically, but the driver controls which gears are selected and when. The transmission will follow the driver’s commands unless the selected gear would over-rev the engine, for example commanding first gear while driving 80 MPH.

Most, though not all, dual-clutch transmissions can skip gears when downshifting, such as shifting from 6th gear directly down to 3rd gear, and because of their ability to match revs, they can do so without the lurching or surging that is typical of traditional automatic and manual transmissions.

DOWNSHIFTING WITH DUAL-CLUTCH TRANSMISSION

One advantage to both SMTs and dual-clutch transmissions is the ability to perform matched-rev downshifts. When a driver selects a lower gear, both types of transmission disengage the clutch(es) and rev the engine to the exact speed required by the selected gear. Not only does this make for a smoother downshift, but in the case of the twin-clutch transmission, it allows plenty of time for the proper gear to be pre-selected. Most, though not all, dual-clutch transmissions can skip gears when downshifting, such as shifting from 6th gear directly down to 3rd gear, and because of their ability to match revs, they can do so without the lurching or surging that is typical of traditional automatic and manual transmissions.

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