Q about DSG

[jamieall]

In both Audi and VWs I have driven both feel like they have a small switch on the left paddle (change down). It feels like a 0.5-1mm of travel before the normal motion of the paddle depression. I assume this is so the unengaged clutch can pre select a lower rather than higher gear - is this right?   

[RedRobin]

....I don't know, but as I understand the DSG, it selects the next saddle of gear cogs the instant you manually select your cog so it's all instantly in readiness.

[JonnyG]

Yes, but I think the point that jamieall is making is ...

suppose you're in manual mode, and cruising in 4th gear, the DSG may well have preselected 5th gear as the next change up.  But say there's a corner comimg up and you want 3rd on the approach ?  ... 3rd won't be preselected and you won't get that intantaneous change down. 

If what jamieall says is correct, then this would get round that problem ... but I certainly was'nt aware of it ! 
   

[jamieall]

Exactly Jonny 
Have a feel next time you drive a DSG and it would get around the problem of preselection! 

[MarkS]

The first clutch is for gears 1, 3 and 5
The second is for 2, 4 and 6
If you are in 4th for example, the first clutch will have both 3rd and 5th ready to engage depending on which paddle you press.

If you are in 2nd, 1st and 3rd will be ready to engage.

The clutch does not have to pre-select a lower gear, as both high and low gears are already pre-selected by the first clutch in concordance with your current gear

I hope that kinda makes sense?
I think that's right
Kinda confused myself there 

[JonnyG]

If you are in 4th for example, the first clutch will have both 3rd and 5th ready to engage depending on which paddle you press.

mmmm.. I'm not sure that's right at all ...surely it can only have 3rd OR 5th preselected, and not both at the same time.  Afterall, it is a twin clutch system with 1 gear engaged and 1 gear preselected for instant engagement

Have a look at the step by step demo towards the bottom of this link :

http://auto.howstuffworks.com/dual-clutch-transmission.htm

Notice how the blue gear selector moves across to preselect 3rd gear, just before the change up from 2nd.  Now if for any reason you wanted to go back to 1st gear this would not be selected straight away as the gear selector would have to move back to 1st.  What jamieall is saying, is that by using that 1mm of travel in the paddle, you could instruct the gear selector to go to 1st rather than 3rd before actually making the manual change on your left paddle ?

Well I think that's the gist of it anyway    

My DSG used to occasionally hesitate in changing down to in such circumstances and I learnt to accelerate slightly before the manual downchange.  This would make the DSG controller think I wanted more acceleration, so it would preselect a lower gear rather than the higher gear.   

[MarkS]

Yeah I think I stand corrected.

"Once the vehicle has shifted up 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, and is pending. Once the time comes to shift, the second clutch disengages and the first clutch re-engages. This method of operation continues in the same manner up to 6th gear.

Downshifting is similar to upshifting but in reverse order. The car's computer senses the car slowing down or more power required, and thus lines up a lower gear on one of the shafts not in use, and then completes the downshift. The actual shift timings are determined by the DSGs Electronic Control Unit, or ECU, which commands a hydro-mechanical unit, and the two units combined are called a "mechatronics" unit. Because the DSG 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 tailor the shift points accordingly."

http://en.wikipedia.org/wiki/Direct-Shift_Gearbox

 

[R32UK]

Could this be another flaw in the world changing DSG??

[RedRobin]

....This is getting silly - All anyone has to do is stick the DSG in M-mode (Manual) and use the paddles to select whichever gear you want whenever you want. Drive it as a Manual and only use D-mode for slow urban or traffic crawls. Even when in D or S modes, you can override the gear anyway! WTF is the problem?

[john_o]

I think R32 is winding you up Red 
Interesting the gear preselection thing though
but even then its states 400 ms for a non expected change.
Which is hardly slow

Can someone in a DSG try and fool the box and see if the delay is noticeable?