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[Closed] tell me about automatic gearbox please

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I had a traditional auto and there was no discernible lag at all on the kickdown.


 
Posted : 25/02/2016 7:42 pm
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molgrips/dezb - A quick question if you can answer it would be appreciated.

I'm thinking maybe DSG (or the similar Ford Powershift) on the next car. I'm trying to understand the points you were making about predicting the box's behaviour earlier in the thread and what it might mean in real terms.

Say you're approaching the last few metres before a roundabout or reasonably wide junction at 10-15mph looking for a space to slip into. My reference point is this would be comfy 2nd gear rolling/trailing throttle speed in the current manual Mondeo so you're down to a speed where you can have extra decision making time but still carrying some momentum.

Would a DSG be hanging on to 3rd and if I spy my smallish gap and want to go fairly quickly would you manually shift down or would you need to squeeze or thump the throttle?

HOw does that compare to having to stop but then just a second or so later your gap appearing and wanting to make a quick getaway?

OP - really sorry for the quick hijack. I've started enough car threads lately, didn't want to add yet another...


 
Posted : 25/02/2016 10:41 pm
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It doesn't. I said the dsg was smooth instant changes, and you said it was shit for an auto. Smooth instant changes are shit? Or are you saying a traditional auto is better?

I have never driven a traditional auto (apart from a godawful hire car in the USA). Yes, smooth gear changes are nice but I hate the pause (two seconds is probably not accurate - did I say that or someone else) on pulling away from junctions but it continues to feel unnatural to push on the accelerator and either crawl away or shoot off. Maybe my 3.0tdi with S-Tronic is different to yours so maybe we are arguing a pointless argument.


 
Posted : 25/02/2016 11:04 pm
 DezB
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[i]Would a DSG be hanging on to 3rd and if I spy my smallish gap and want to go fairly quickly would you manually shift down or would you need to squeeze or thump the throttle?

HOw does that compare to having to stop but then just a second or so later your gap appearing and wanting to make a quick getaway?[/i]

To be honest, its exactly the same as in a manual car, but you don't have to faff about with shifts and clutches. (ie. easier)


 
Posted : 26/02/2016 12:48 am
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I like the 8 speed ZF in my bimmer. Having said that, I'd buy the manual if I were choosing again. Occasionally I really miss swapping cogs. Manuals are potentially a more involved drive, you have to think more about what the car is doing so for 'spirited' driving

However, from a logical point of view I can see no real benefit in getting the manual. Auto is easier around town, there's no clutch to tire you out, it's faster (0-60mph, if you're bothered about that), the manual mode still retains all the control you would want. They're pretty commonplace now too, and proven reliability so I'm not even sure the repair bill would be any worse than a manual.


 
Posted : 26/02/2016 1:17 am
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As I'm having a similar dilemma to the OP and I've been out test driving two otherwise practically identical Mondeos, one auto, one manual I thought I'd resurrect this and put down my experiences.

The power shift auto was really really good. It's similar to the dsg system it seemed to give engine braking and good power delivery. If you just mash the throttle it stirs a bit of porridge then takes off but I started to get the hang of avoiding that after a couple of goes. Tried the manual shift mode then couldn't be bothered as it just worked as was without it. The sport mode seemed to make a noticeable difference. The other thing I noticed was how easy it was driving through a relatively unfamiliar town centre with more attention focussed out on the road. That actually surprised me as I never really think of the motor skills bit of changing gear as taking any real brain power.

An hour or two later manual version of same car. A little bit more fine control over timing of shifts but frankly noticed not much performance difference in normal driving.

After a few hours touring the countryside on my car hunt I was starting to get cheesed off with the manual box in the current car.

I think I am just talking myself into my first auto/semi auto.


 
Posted : 27/02/2016 5:59 pm
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The reality is that if you're approaching a junction or roundabout looking for a gap and the box goes up a gear, if you spot a gap you want to go for then just hit the accelerator a bit more than you would with a manual. This will coax the auto gearbox's ECU into dropping a gear and you're off with very little delay (a fraction of a second). It might be the case that to coax the kick down you would hoof the accelerator initially but then pull it back to influence the box, but the kick down change of the box should be pretty much intent in a modern DSG or other type. This is the case in my wifes BMW box. The kick down is intent with a very very tiny delay in hoofing the throttle and getting the performance - again its all in the mind, that small delay turns into an age, but once you're used to it its not a problem at all.

This is infinitely better than the similar case with a manual hanging in 2nd gear, seeing the gap, hoofing the throttle to make the gap but almost instantaneously having to change gear as you run out of revs in second, cutting off power for half a second or so just as you get the car in the thick of the traffic.


 
Posted : 27/02/2016 6:31 pm
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Would a DSG be hanging on to 3rd

So inside a DSG (and a Powershift) are two input gear shafts, and two clutches. One has 1st, 3rd and 5th on it, the other has 2nd, 4th and 6th. When you start off, the one shaft is in 1st, but the other is in 2nd. So when the time comes to change to 2nd it simply switches between the two shafts, using the clutches. This is the almost instant part - there's no interruption in power delivery, because the engine is never disconnected from the wheels.

Now - if you are rolling towards a junction, slowing down slightly, it'll hold onto 3rd until low revs, about 1100rpm or so - which is a trundle. But - the other shaft will be in 2nd already, it probbaly shifted into second as soon as it shifted out of 4th. So if you see your gap and decided to go, you push the pedal a bit more, it switches into 2nd instantly and off you go.

Now - here's the thing. If you mash the pedal, it's programmed to give you the lowest gear it can so you can go as fast as you want. In our situation that might be first. But you're already in third, so to select 1st it has to actually disengage drive, select 1st, and re-engage. This takes probably less than a second, maybe 3/4s. The same is true if you are in say 5th and stamp on the pedals, it'll give you 3rd, which will give you the pause.

It can also happen if you are in 6th and wish to overtake. IF you are at say 50, behind me in my caravan, it'll be in 6th, and the other shaft will be in 5th. But if you push the pedal to the floor it'll pause whilst it selects 3rd on the one shaft, but at the same time 4th on the other. So it'll pause, give you 3rd at high revs, but then it can move quickly on to 4th for maximum zip.

It's this kind of thing that you learn to get used to. You get a feel for how much throttle will result in changing down two gears instead of one.

Of course, if you are going to overtake a caravan say, you'll pick 3rd in manual mode ready - and it'll automatically pick 4th ready on the other shaft.

It can get confused though, if you mash the pedal to go for a gap, then change your mind, then press lightly again - it'll get mixed messages.


 
Posted : 27/02/2016 8:26 pm
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Thanks molgrips

That puts some science against my experience. I'm on track to buy one now. Just trying to decide whether the one I saw today is "the one" although there's an r-line dsg Passat I've got an eye on too...


 
Posted : 27/02/2016 10:13 pm
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