DSG: Problems, Questions, Likes and Dislikes

[Brian]

Anyone notice that when you are in D mode (or M or S) and stopped at the lights with foot on the brake, there is a slight vibration noise/feel? When I change into N the vibration disappears.

I don't understand what could be causing this? I thought the clutch is disengaged when you are stopped, the same thing when in N?

I have a 118 TSI with 7sp DSG and have no vibrations/noises at idle in any gear (D,S or manual). You are correct when you state the clutch is disengaged at stop in gear. Suggest you see the dealer.

[logger]

Anyone notice that when you are in D mode (or M or S) and stopped at the lights with foot on the brake, there is a slight vibration noise/feel? When I change into N the vibration disappears.

I don't understand what could be causing this? I thought the clutch is disengaged when you are stopped, the same thing when in N?

It will be the K1 clutch creating the noise/vib you can sense. In D,S or M with foot on the brake you will have 1st gear selected on one shaft and Neutral on the other. K1 clutch will be partly engaged/disengaged (depending on your point of view) in anticipation of a start. When you move the selector to N your will have 1st and Rev selected and BOTH clutches will be fully disengaged

I have a 118 TSI with 7sp DSG and have no vibrations/noises at idle in any gear (D,S or manual). You are correct when you state the clutch is disengaged at stop in gear. Suggest you see the dealer.

Actually you will find the K1 clutch is at about 1/2 travel and not fully disengaged. It will be in a distinctly different position to when in Neutral or P. I expect it can be very lightly brushing the plates and causing the slight noise/vibration some people report. There will be variance between cars owing to different adaptations. I would not be concerned about it and it may well gain, lose or regain this characteristic over time as adaptation occurs. I think my car does it too, but have not checked lately.

[AdamD]

It will be the K1 clutch creating the noise/vib you can sense. In D,S or M with foot on the brake you will have 1st gear selected on one shaft and Neutral on the other. K1 clutch will be partly engaged/disengaged (depending on your point of view) in anticipation of a start. When you move the selector to N your will have 1st and Rev selected and BOTH clutches will be fully disengaged.

Great info logger! Do you happen to know if this is true for the 6-speed wet clutch gearbox also?

[prise]

The 6spd is different animal - I own a 7spd and have spent several weeks in a 6pd. (diesel not GTi). The 6spd has a noticeable torque transfer through the clutch in D when stopped and will start creeping at light brake pressures more like a traditional auto. The 7spd clutch is barely touching in readiness for the start and therefore there is the slightest delay from when you release the brake to when the clutch is further engaged and it starts rolling.

The advantage with a wet plate clutch is that it can transfer torque whilst slipping and without the clutch wearing as it is the thin film of oil between the plates that is transmitting the torque in this condition. That is until the oil gets too hot which is one reason why the 6spd DSG has an oil cooler. The disadvantage is that clutches spinning around in oil create drag and therefore the 6spd DSG loses a bit of fuel efficiency relative to a manual whereas the 7spd DSG does not.

[Karlosovic]

...plenty of people who believe the paddles are too small

It's not the size that counts...

after market extensions

oh geez, here we go
A whole new category of email spam

[logger]

Great info logger! Do you happen to know if this is true for the 6-speed wet clutch gearbox also?

AdamD, I do not know because I do not have access to a DSG6. But I expect it will be much the same. The underlying principle of the two Gearboxes are the same. It is pretty simple for someone to check. Jusst need access to VCDS and a DSG6. Then observe the clutch positions and gear selections.

[hazamatic]

The vibration in D when stopped is in a GTI (hence 6 speed wet clutch). The vibration when cold seems worse than when warmed up...

I have a theory about this. I believe that when you are in D and stopped, 1st gear is selected and the clutch is disengaged. The vibration you feel is because of the wet plate clutch, the oil is transferring some torque. More so when cold since the oil is thicker.

Now, when you are in N, no gear is selected but the clutch is actually engaged. Just like neutral in a normal manual. This means the torque cannot be transferred any where and so you get no vibration.

It would be nice if someone could confirm this

[logger]

I have a theory about this. I believe that when you are in D and stopped, 1st gear is selected and the clutch is disengaged. The vibration you feel is because of the wet plate clutch, the oil is transferring some torque.....

How does a disengaged clutch transfer torque?

Now, when you are in N, no gear is selected but the clutch is actually engaged. Just like neutral in a normal manual. This means the torque cannot be transferred any where and so you get no vibration.

Not that I can check - But if someone does I am pretty sure you will see this theory to be incorrect. I'll bet you R and 2 are selected and both clutches are disengaged when in N on the DSG6, like on the DSG7. Unlike DSG7 which has a separate shaft for R, DSG6 has 1&R on same shaft so they cannot concurrently be selected. So instead it will grab 2nd and R. Both clutches disengaged = no torque and no vibration. In fact I think I have a dsg6 service bulletin lying around that mentions this. Will see if I can dig it up.

[hazamatic]

How does a disengaged clutch transfer torque?

It's a wet clutch, so the fly wheel spinning spins up the oil which in turn puts some force on the clutch. Just like how a torque converter works in a normal automatic. This also means that a cold engine will have colder/thicker oil which will transfer more force.

Something defiantly happens when I go from D to N while stopped. I feel it! Maybe the clutch disengages "further"? I don't know...

Can the DSG gear shafts even select Neutral?

[logger]

Something defiantly happens when I go from D to N while stopped. I feel it! Maybe the clutch disengages "further"? I don't know...

What happens in N is the applicable clutch actuator moves to its resting position allowing the clutch to disengage. When you select D, a solenoid activates causing the clutch actuator piston to move, in turn activating the clutch engage lever and clutch. Position of the clutch is controlled by the clutch travel sender and at the point that it starts to engage you will be feeling something. When the clutch is not actuated which I equate to being disengaged there is no way it can transmit any torque.

Can the DSG gear shafts even select Neutral?

Selector forks shift the gears on the output shafts. 2 gears to each selector fork and the mid position of each selectors travel is Neutral.