A lot of people on forums have questions about the DSG gearbox and in particular do notice, or complain of, a "hesitation" when getting going with it. Or they may find that it takes an inordinately long period of time for it to change up or down a gear. This guide is aimed at providing more understanding of this unique gearbox.
I'm not a mechanic, but info for this thread has been gained through personal experience and trawling forums such as this.
The 6-speed DSG (Direct Shift Gearbox) is a twin multi-plate clutch gearbox with gears 1, 3, 5 ,R on one transmission unit and 2, 4, 6 on the other. The gearbox can predictively decide which gear you are likely to go to next and get it ready, so that when you decide to shift it can (almost) seamlessly switch from one gear to the next with minimal delay (8ms is quoted by VW IIRC).
In this way it is a lot more akin to a manual gearbox than a traditional automatic with a torque converter.
How it works
To see more details about the workings look here:
If you aren't convinced about the speed of DSG vs manual check this Youtube vid.
For the rest of us, I'll assume you know what the basic workings are and I'll explore what/how the DSG mechatronic brain does/thinks.
Statistics for 6-speed DSG 02E
The DSG "brain" - the mechatronic unit
Hill holder function - if the vehicle begins to move when stationary, light brake pressure increases clutch pressure to halt movement.
Creep regulation - allows movement of the vehicle without pedal input (e.g. for parking)
Peculiar points about DSG
Warm-up phase
As the 6-speed DSG is a wet box it does take time for it (especially oil i guess) to warm up. This means that shifts can feel a bit cluncky or take longer depending on how warm it is. Once it's warmed up there really should be no problems with the speed of its shifts.
Over-rev protection
The DSG gearbox will not allow you to over-rev the engine thereby preventing damage. Unlike a manual gearbox where you could shift into an excessive RPM range by mistake the DSG will not change until the RPM drops sufficiently to allow a gearchange which will put the engine speed into a safe zone. For example hitting the gearstick or paddles in 2nd at 6000rpm to change into 1st will result in nothing happening until the engine speed drops sufficiently.
As part of this protection system there is a limit to how long you can hold the engine speed at or above redline as the DSG will upshift to put you into the next gear.
I suspect this may only happen IF the pedal position dictates that more accelerative effort is required.
I suspect that if the pedal position is low (e.g. low throttle thru corner to do shift at corner exit) then the DSG will allow holding of the engine speed a little longer.
I have not confirmed this as yet.
Rev matching
The DSG can request the ECU to increase engine speed to allow smoother downshifts. This is akin to a manual driver "blipping" the throttle or what would happen when you "heel-toe" increasing engine speed to reduce the time required for synchronisation. If you are altering the rate at which the engine speed drops (e.g. by staying on throttle) you can find that downshifts either take a long time or do not occur at all.
1st into Reverse gear
As 1st and Reverse gears share the same gear wheel and an additional reverse shaft is required quick changes from 1st into Reverse or vice versa are not really possible. Situations where this might be required e.g. motorkhana or stunt driving would be better suited by a manual gearbox.
Fuel saving methods
One of the ways in which the DSG allows better fuel consumption over a manual gearbox is the ability to disconnect it's clutches when no engine effort is required. This occurs when the brake pedal is depressed (e.g. at stop light) and also when driving on a straight road when no pedal input is detected. When braking the clutches do not disengage unless the car is at a complete standstill.
The fuel injectors are also cut when no pedal input is detected also saving fuel. It is easy to see when you have the "instantaneous" fuel consumption figure in your MFD showing - it will be 0.0 when you take your foot off the pedal whilst moving.
An unfortunate side effect of this is a common complaint of "hesitation" when taking off from a standstill. This is because there is a delay between the DSG being told the brake pedal is no longer being depressed and it re-engaging the clutches.
Ways around this include:
This also means that one must take car when on an incline. Hillstarts are different with the DSG compared to a traditional automatic. You cannot simply lift your foot from the brake and quickly transfer it to the throttle. All that will happen is you will roll back (no clutch engaged right at beginning) with the 1st gear clutch spinning up and causing wheelspin when it suddenly engages if you have hit the throttle to hard.
A better way is to use the e-brake for your traditional "proper" hill start, or a dual foot method of light throttle combined with easing off the brake - for a seamless takeoff without ANY rollback.
I'm not a mechanic, but info for this thread has been gained through personal experience and trawling forums such as this.
The 6-speed DSG (Direct Shift Gearbox) is a twin multi-plate clutch gearbox with gears 1, 3, 5 ,R on one transmission unit and 2, 4, 6 on the other. The gearbox can predictively decide which gear you are likely to go to next and get it ready, so that when you decide to shift it can (almost) seamlessly switch from one gear to the next with minimal delay (8ms is quoted by VW IIRC).
In this way it is a lot more akin to a manual gearbox than a traditional automatic with a torque converter.
How it works
To see more details about the workings look here:
- Wikipedia site with good detailed info
- http://www.arinahnell.com/other/vw/tech/Direct_Shift_Gearbox_02E.pdf
- VW/Audi DSG : How It Works (Youtube vid)
If you aren't convinced about the speed of DSG vs manual check this Youtube vid.
For the rest of us, I'll assume you know what the basic workings are and I'll explore what/how the DSG mechatronic brain does/thinks.
Statistics for 6-speed DSG 02E
- 350Nm max torque handling as officially quoted by VW
- 7.2L of gearbox oil
- Wet-type multi-plate clutch
- 1st and Reverse gear use the same gear wheel
- Max temperature for DSG oil 135degC, torque reduced when temp over 138degC and clutches opened as failsafe above 145degC
The DSG "brain" - the mechatronic unit
VW said:
VW said:
Hill holder function - if the vehicle begins to move when stationary, light brake pressure increases clutch pressure to halt movement.
Creep regulation - allows movement of the vehicle without pedal input (e.g. for parking)
Peculiar points about DSG
Warm-up phase
As the 6-speed DSG is a wet box it does take time for it (especially oil i guess) to warm up. This means that shifts can feel a bit cluncky or take longer depending on how warm it is. Once it's warmed up there really should be no problems with the speed of its shifts.
Over-rev protection
The DSG gearbox will not allow you to over-rev the engine thereby preventing damage. Unlike a manual gearbox where you could shift into an excessive RPM range by mistake the DSG will not change until the RPM drops sufficiently to allow a gearchange which will put the engine speed into a safe zone. For example hitting the gearstick or paddles in 2nd at 6000rpm to change into 1st will result in nothing happening until the engine speed drops sufficiently.
As part of this protection system there is a limit to how long you can hold the engine speed at or above redline as the DSG will upshift to put you into the next gear.
I suspect this may only happen IF the pedal position dictates that more accelerative effort is required.
I suspect that if the pedal position is low (e.g. low throttle thru corner to do shift at corner exit) then the DSG will allow holding of the engine speed a little longer.
I have not confirmed this as yet.
Rev matching
The DSG can request the ECU to increase engine speed to allow smoother downshifts. This is akin to a manual driver "blipping" the throttle or what would happen when you "heel-toe" increasing engine speed to reduce the time required for synchronisation. If you are altering the rate at which the engine speed drops (e.g. by staying on throttle) you can find that downshifts either take a long time or do not occur at all.
1st into Reverse gear
As 1st and Reverse gears share the same gear wheel and an additional reverse shaft is required quick changes from 1st into Reverse or vice versa are not really possible. Situations where this might be required e.g. motorkhana or stunt driving would be better suited by a manual gearbox.
Fuel saving methods
One of the ways in which the DSG allows better fuel consumption over a manual gearbox is the ability to disconnect it's clutches when no engine effort is required. This occurs when the brake pedal is depressed (e.g. at stop light) and also when driving on a straight road when no pedal input is detected. When braking the clutches do not disengage unless the car is at a complete standstill.
The fuel injectors are also cut when no pedal input is detected also saving fuel. It is easy to see when you have the "instantaneous" fuel consumption figure in your MFD showing - it will be 0.0 when you take your foot off the pedal whilst moving.
An unfortunate side effect of this is a common complaint of "hesitation" when taking off from a standstill. This is because there is a delay between the DSG being told the brake pedal is no longer being depressed and it re-engaging the clutches.
Ways around this include:
- Easing off the brake rather than quick release. The "Hillhold" function means that under partial brake application at standstill clucthes are engaged. This means that at partial brake, the clutches will be connected allowing instant power transfer.
- Tapping the throttle to "wake up" the DSG and cause it to connect the clutches. The DSG will stay awake for 1-2 seconds before it disconnects clutches again if you still have your foot on the brake.
This also means that one must take car when on an incline. Hillstarts are different with the DSG compared to a traditional automatic. You cannot simply lift your foot from the brake and quickly transfer it to the throttle. All that will happen is you will roll back (no clutch engaged right at beginning) with the 1st gear clutch spinning up and causing wheelspin when it suddenly engages if you have hit the throttle to hard.
A better way is to use the e-brake for your traditional "proper" hill start, or a dual foot method of light throttle combined with easing off the brake - for a seamless takeoff without ANY rollback.
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