GBOL & DSG Gearbox

Topics relating to Advanced Driving in cars
Pontoneer
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Re: GBOL & DSG Gearbox

Postby Pontoneer » Tue Aug 01, 2017 8:08 am

MichaelAC wrote:Hi,

with a sequential gearbox like VAG's DSG or S-tronic the ability to block gear change is removed. The problem here is that having removed your speed prior to a junction (roundabout or otherwise) having just left yourself time to change to the appropriate gear to advance my DSG box can sometimes be in the wrong gear. I may have been in sixth gear and when I've slowed it won't automatically change down quickly enough leaving me to try and click through several gears or if I had it in full auto mode (which I generally don't) it would simply leave me in the wrong gear to move me into the identified gap on a roundabout, for example.

The DSG rev matches and you don't need to remove hands from steering wheel so as long as I have completed my change downs before I make the manouvre, is BGOL actually relevant?

I'd love to hear your views and if you have a DSG and manage to avoid BGOL I'd be interested to know how you do it.

Thanks in advance.

Michael.


I've never driven a car with DSG or similar , but in the distant past I did drive motorbikes which similarly have a sequential gearbox , and on bikes , with proper timing , it was possible to declurch and click down two or three gears in rapid succession .

All my cars for years have been traditional four or five speed automatics and , for me , it is second nature to use the manual selector a lot of the time . Although BGOL is often thought of as a bad thing ( this stems from the old system of car control where the six features were to be separated out and applied in sequence somewhat inflexibly at times ) ; with the 'new' IPSGA system there is a lot more flexibility and potential to overlap the phases - so why not BGOL ? It has been taught at Tulliallan for some years now .

Because I've been driving automatics almost exclusively for the last 40 years , I take the view that I have two feet for two pedals and make the most efficient use of them : that can often mean preselecting the next gear whilst braking on the approach to a hazard , then bringing in a part throttle downshift towards the end of the braking phase by easing smoothly onto the throttle before easing off the brakes and then firming up on throttle - all very wordy , but it is very smooth and it works . Use of the selector isn't always required ; in many cases application of a little throttle before finishing with the brakes will bring in a desired downshift in a very smooth manner and is advantageous to making good progress . Other times the brakes don't come into it , such as selecting a gear for an overtake while following at a steady speed , but use of throttle in conjunction with the selector almost always brings in a smoother change .

To those who hold their hands up in horror and exclaim you shouldn't brake and accelerate in an automatic at the same time , I would reply that is an old fish wives tale : my two current cars are each on about 180K with no gearbox problems ; I have had several up around 300K and the record was my 300TE-24 which was on 430K on the original gearbox when written off by an uninsured driver who hit it whilst parked .

Sometimes conventional wisdom needs to be challenged , so if avoiding BGOL doesn't work with DSG boxes I wouldn't fret .

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GTR1400MAN
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Re: GBOL & DSG Gearbox

Postby GTR1400MAN » Tue Aug 01, 2017 8:50 am

Press both pedals together in a dual clutch and many will sound a warning and even go into limp home mode until you restart them. If you must use left foot braking you need to be very good at it and only use one pedal at a time (another form of separation).
Mike Roberts

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AndyP
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Re: GBOL & DSG Gearbox

Postby AndyP » Tue Aug 01, 2017 11:36 am

Beat me to it.

It is one of my checks. There are a lot of differences.
The VXR did that, The Megane does sometimes. The Corsa 1.4 trubo does not?

They are all manual though.
Cannot emulate the WRC guy's.

Loved the Chris Harris Vid. Thanks [Well I like Renno's and Chris Harris.
It is not WHAT you drive, BUT:-- the WAY that you drive it.
It is not HOW fast you drive, BUT:-- HOW you drive fast.

Cheers Andy

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MichaelAC
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Re: GBOL & DSG Gearbox

Postby MichaelAC » Tue Aug 01, 2017 10:41 pm

Thank you Pontoneer,

I think perhaps the key is to ensure it is smooth and unhurried and to tailor the method to the vehicle. I guess if that involves BGOL then it may be OK. I have developed a very particular way of driving the DSG and to be honest it took at least three months to understand it fully and get it smooth. The early ones are a little tempermental and need an understanding driver to drive in a manner that it will understand.

I can do quick consecutive changes like on a mororbike but it is not a smooth way to use the DSG on my car. If I leave the changes to the last minute after I've slowed on my approach it can 'wrong foor' the gearbox with it having pre selected a lower gear thinking I was still slowing down.

Your method with the traditional auto sounds good to me because to me it shows that you understand your car very well and know how to communicate with it to ensure that it behaves in the way you want it too.

I'm relatively new to advanced driving and have lots to learn and practice. This was one area that I have been struggling with because when practicing to avoid BGOL the control I had over the vehicle was reduced. I have now modified what I do though and this involves less BGOL and a slower approach so I have certainly changed my style.

Thanks to everyone on here that has helped me with this topic, its been really interesting to hear your views and experience.

Rainmaker
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Re: GBOL & DSG Gearbox

Postby Rainmaker » Sat Jan 20, 2018 2:54 pm

Sorry to bump this, but it caught my eye over Christmas and I then promptly forgot about it for a while. :hit:

OP, have you made the same mistake I did when I got my first DSG? You talk about losing speed before a hazard, but then talk about the box not being in the correct gear in time. That leads me to strongly suspect you've fallen into the same trap I did when I got my first DSG - forgetting the gear phase. Bear with me...

Without me really noticing at first, no longer having the necessity of a planned manual gear change I had basically started braking later on approach, or at least finishing braking later on approach, to a hazard. In absence of knowing any other auto drivers who could have taught me its quirks, it was logically thus: The car changes gear for you, right? I just need to stop and go, right? Well I don't want to stop before the line, so I'll brake up to it 'obviously'. Now, why is the car hunting for gears when I want to go again?!

Let's take a give way as an example (roundabouts are probably a better example of one), and assume it has good visibility on approach. In a manual you'd have shaved off the speed as required on approach, had a look (planning to stop but looking to go, etc), and then chosen 2nd or a rolling 1st before confirming it was clear and being able to cross the line in your new gear and accelerating smartly away to blend into your gap.

The DSG sees things very simply, and it isn't psychic. It can guess, based on various tables and your current inputs, but it can't always be correct. When you hit the brake, are you planning to come to a complete stop or just momentarily hesitating while getting ready to floor it? Or maybe you're just momentarily shaving off a couple of MPH for the pedestrian to finish crossing and want to then continue bimbling along at much the same speed as before. The box can't possibly know.

So, in that moment of braking you could possibly want neutral with 1st ready to re-engage later, 2nd or 3rd (depending on your previous speed) for maximum acceleration, or to be in the gear you were in before you started braking at all (top?), so that you can continue along the empty straight road at much the same speed as before.

Given the car only has two shafts and two clutches, there are less clutches than there are possibilities available. As such, you need to give it time to react. Try driving it more like a manual, and keep hold of that G in IPSGA rather than discarding it for all intents and purposes because 'gears are the auto's job'. For example:

dsg.jpg
dsg.jpg (271.99 KiB) Viewed 706 times


Taking the blue line, as I did at first (and as you seem to describe in your OP, given the results) you can see that you finish braking late - almost at the give way line where the first T bar is. Then you go back onto the throttle, wondering why the car is so dim-witted and why you only get the gear you actually need well into the new road, when it's often too late (see the second T bar on the blue line). Quite possibly with established traffic wondering what moron just 'rolled out' in front of them into the bargain!

If you practice driving it 'like a manual', maintaining mental space for the Gear phase, you finish braking earlier to the point where you would change down in a manual car (see the first T bar on the teal/green line). You'll find that because you're back on the throttle early and have set your position, speed and gear already, the car will now know what's coming next and will have pre-selected the appropriate (usually 2nd) gear. You'll be able to power positively through the hazard, whether it's a give way, a roundabout, a right hand turn, or whatever.

I've made a mince of the words, but in reality it's a very simple tweak that may feel a little unnatural at first if you've really ingrained the habit of stopping later. Just remember, 'everyone else' in their manual car is driving as you are about to; so although it can feel alien finishing braking short it's actually only what almost everyone else does anyway. Give it a go and see how you find it. It really did transform my understanding of - and enjoyment of - my 2.0 TSI. Sorry this went on so long but it's the best way I could think to explain it in writing.

Edited to add: Sorry, in my haste to stop this getting any longer I forgot to add a quick comment about RoSPA and tests etc. I had no issues using the box sequentially a couple of times when I wanted to override the box for whatever reason, even with some BGOL (mainly on NSL roads). In my case the examiner was none the wiser and - as someone said above - overall just impressed I understood how to get the best out of that particular vehicle without affecting the safety, system or smoothness. With a modern DSG type box the changes are microsecond fast and very smooth. You can't really upset the balance of the vehicle even with overlap or whatever, so that argument is moot and it's all about tailoring the drive to the car in question imho. That's what I tell my associates, and I've never had an examiner object (yet)...

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jont-
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Re: GBOL & DSG Gearbox

Postby jont- » Sat Jan 20, 2018 3:38 pm

Rainmaker wrote:The DSG sees things very simply, and it isn't psychic. It can guess, based on various tables and your current inputs, but it can't always be correct. When you hit the brake, are you planning to come to a complete stop or just momentarily hesitating while getting ready to floor it? Or maybe you're just momentarily shaving off a couple of MPH for the pedestrian to finish crossing and want to then continue bimbling along at much the same speed as before. The box can't possibly know.

Interestingly, I had a very good experience with a Nissan CVT box a month or so back, particularly when in sport mode. While it's a CVT box, it fakes up gears and jumps rpms, rather than being truly continuous. However it had a neat trick under braking, which I suspect almost nobody driving the cars actually notices :lol: If you were gentle on the brakes, it would let the revs drop slowly with speed, then pick up again when you moved to the gas, with the usual pickup lag. However if you braked firmly, while you were braking it would "downshift", and keep the engine sitting at about 4000rpm, so as soon as you jumped on the gas again, it was already at peak torque. It worked really well on some lovely californian twisties, and in fact was one of the better experiences I've had with an auto box.

vanman
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Re: GBOL & DSG Gearbox

Postby vanman » Sat Jan 20, 2018 3:45 pm

jont- wrote:
Rainmaker wrote:The DSG sees things very simply, and it isn't psychic. It can guess, based on various tables and your current inputs, but it can't always be correct. When you hit the brake, are you planning to come to a complete stop or just momentarily hesitating while getting ready to floor it? Or maybe you're just momentarily shaving off a couple of MPH for the pedestrian to finish crossing and want to then continue bimbling along at much the same speed as before. The box can't possibly know.

Interestingly, I had a very good experience with a Nissan CVT box a month or so back, particularly when in sport mode. While it's a CVT box, it fakes up gears and jumps rpms, rather than being truly continuous. However it had a neat trick under braking, which I suspect almost nobody driving the cars actually notices :lol: If you were gentle on the brakes, it would let the revs drop slowly with speed, then pick up again when you moved to the gas, with the usual pickup lag. However if you braked firmly, while you were braking it would "downshift", and keep the engine sitting at about 4000rpm, so as soon as you jumped on the gas again, it was already at peak torque. It worked really well on some lovely californian twisties, and in fact was one of the better experiences I've had with an auto box.


Used to be able to do the same with me old Daf 66 and the 340 volvo, brilliant when you got it right, as you say though if not there was quite a bit of lag, no lots of lag. Even the 1100 Daf could be made to move, the trick was firm braking to keep it in the lower ratio. :racing:

Rainmaker
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Re: GBOL & DSG Gearbox

Postby Rainmaker » Sat Jan 20, 2018 4:56 pm

jont- wrote:
Rainmaker wrote:The DSG sees things very simply, and it isn't psychic. It can guess, based on various tables and your current inputs, but it can't always be correct. When you hit the brake, are you planning to come to a complete stop or just momentarily hesitating while getting ready to floor it? Or maybe you're just momentarily shaving off a couple of MPH for the pedestrian to finish crossing and want to then continue bimbling along at much the same speed as before. The box can't possibly know.

Interestingly, I had a very good experience with a Nissan CVT box a month or so back, particularly when in sport mode. While it's a CVT box, it fakes up gears and jumps rpms, rather than being truly continuous. However it had a neat trick under braking, which I suspect almost nobody driving the cars actually notices :lol: If you were gentle on the brakes, it would let the revs drop slowly with speed, then pick up again when you moved to the gas, with the usual pickup lag. However if you braked firmly, while you were braking it would "downshift", and keep the engine sitting at about 4000rpm, so as soon as you jumped on the gas again, it was already at peak torque. It worked really well on some lovely californian twisties, and in fact was one of the better experiences I've had with an auto box.


That sounds like a big improvement on the older style CVTs. I've never driven one yet, but I believe a few manufacturer's are starting to take a similar tack. There's nothing wrong with keeping the revs up well into peak torque and ready to leap to peak power, as I'm sure you know. Someone earlier in the thread commented they thought their IAM observer wouldn't be keen on them using sport mode or keeping the revs up around 4k. I can't speak for IAM but at RoSPA that'd be positively encouraged so long as it wasn't needless (eg 5,000rpm in 1st around town). I always tell my associates I've paid for 220 horses, so get the buggers whipped! :gear: :mrgreen:

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Horse
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Re: GBOL & DSG Gearbox

Postby Horse » Sat Jan 20, 2018 8:52 pm

GTR1400MAN wrote:Press both pedals together in a dual clutch and many will sound a warning and even go into limp home mode until you restart them. If you must use left foot braking you need to be very good at it and only use one pedal at a time (another form of separation).


Can't remember whether I posted this: a colleague had a faulty brake light switch which operated whenever it wanted - cutting the throttle when it did.
My own views. For better or worse :)

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jont-
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Re: GBOL & DSG Gearbox

Postby jont- » Sun Jan 21, 2018 2:24 am

Rainmaker wrote:Someone earlier in the thread commented they thought their IAM observer wouldn't be keen on them using sport mode or keeping the revs up around 4k. I can't speak for IAM but at RoSPA that'd be positively encouraged so long as it wasn't needless (eg 5,000rpm in 1st around town). I always tell my associates I've paid for 220 horses, so get the buggers whipped! :gear: :mrgreen:

Oh, I dunno about 5000rpm in 1st being useless around town. If you've got a section with lots of speed humps you can do all of it with acceleration sense in 1st gear in the Caterham (it's geared for about 40 in 1st). I assume the locals must like the noise and want to hear it, otherwise they'd get rid of the bastard things and I could trickle through at 30mph in 6th instead :twisted:


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