Block gear changing.
Discussion
I've been on a course today and one of the things we were told to do was to use block gear changing. To be honest it felt incredibly wrong and I felt I had less control of the car. Coming from the motorcycling world I am used to a sequential gear box and would never attempt a double down shift without steadying the vehicle between changes.
So why has block shifting become popular? I can see the benefit in that it requires more forward planning and focuses you on which gear you should be in but surely the consequences of a potential mismatch of engine and road speed are more serious? I currently can't envisage it ever feeling right to be travelling on a back road and slotting down two gears on the entry to a corner.
As my current car is also sequential I won't be putting it into practise for a while but I thought I would understand the reasons why it's now recommended before electing to continue with the old method.
So why has block shifting become popular? I can see the benefit in that it requires more forward planning and focuses you on which gear you should be in but surely the consequences of a potential mismatch of engine and road speed are more serious? I currently can't envisage it ever feeling right to be travelling on a back road and slotting down two gears on the entry to a corner.
As my current car is also sequential I won't be putting it into practise for a while but I thought I would understand the reasons why it's now recommended before electing to continue with the old method.
I find that which method is "natural" depends on circumstances, in my (unqualified) experience...
In "relaxed" mode I barely use the brakes. I slow gently for the hazard using engine braking and a touch of friction brake, there's no rush about including a couple of relaxed gearchanges with a couple of seconds between them. In this situation I feel just as BliarOut does about block changing. The "coasting" period - not a technically accurate description for slowing down purely on the friction brakes with the drive disengaged, but that's what it feels like - gives me a disquieting sensation of lack of control. Consequently I only do it that way in a car with crap synchro combined with a bad pedal layout for heel-and-toeing or an unblippably "mañana" style of throttle response.
In "press-on" mode block changing becomes much more natural. There isn't really time to fit in all the sequential gearchanges during the braking period and I'm not looking to use engine braking, so there's little point in trying. Also the higher rate of deceleration makes the procedure feel much more controlled. Funny how the mind works.
The interesting thing is I find it much the same on the bike. (Though it has to be said that the vehicle the MZ reminds me of in car terms is my Morris Minor
) Gentle approaches I use sequential changing, press-on style approaches I block change (defined in terms of clutch engagement since it's a sequential box). The MZ gearbox does not respond well to rapid downchanges at significant revs, but if you declutch and let the revs fall to idle while braking it's no problem to click it down two or three gears all in one hit with suitable throttle blipping during the last second of braking and then take up drive smoothly in the lower gear.
The major difference on the bike is that for the early stages of a gentle approach from high speed I'll essentially use a block method and switch to sequential once I get to third-gear speeds. The reason for this is that there's bugger all engine braking in fifth and not a lot more in fourth, so there would be a very long period of slowing down while still at fairly high revs on a closed throttle, which is not good for a premix-lubricated two-stroke.
In "relaxed" mode I barely use the brakes. I slow gently for the hazard using engine braking and a touch of friction brake, there's no rush about including a couple of relaxed gearchanges with a couple of seconds between them. In this situation I feel just as BliarOut does about block changing. The "coasting" period - not a technically accurate description for slowing down purely on the friction brakes with the drive disengaged, but that's what it feels like - gives me a disquieting sensation of lack of control. Consequently I only do it that way in a car with crap synchro combined with a bad pedal layout for heel-and-toeing or an unblippably "mañana" style of throttle response.
In "press-on" mode block changing becomes much more natural. There isn't really time to fit in all the sequential gearchanges during the braking period and I'm not looking to use engine braking, so there's little point in trying. Also the higher rate of deceleration makes the procedure feel much more controlled. Funny how the mind works.
The interesting thing is I find it much the same on the bike. (Though it has to be said that the vehicle the MZ reminds me of in car terms is my Morris Minor
) Gentle approaches I use sequential changing, press-on style approaches I block change (defined in terms of clutch engagement since it's a sequential box). The MZ gearbox does not respond well to rapid downchanges at significant revs, but if you declutch and let the revs fall to idle while braking it's no problem to click it down two or three gears all in one hit with suitable throttle blipping during the last second of braking and then take up drive smoothly in the lower gear. The major difference on the bike is that for the early stages of a gentle approach from high speed I'll essentially use a block method and switch to sequential once I get to third-gear speeds. The reason for this is that there's bugger all engine braking in fifth and not a lot more in fourth, so there would be a very long period of slowing down while still at fairly high revs on a closed throttle, which is not good for a premix-lubricated two-stroke.
Why would you end up mismatching engine and road speed through block changing? Missing out the intermediate gear surely doesn't mean that you'd be selecting a different engine/road speed than if you went down through the box. I advocate block changing as it's less work for the driver, and more mechanically sympathetic.
vonhosen said:
It's not new as far as roadcraft is concerned. Get the speed right & then get the gear for that speed. No point in taking a gear you aren't going to actively use.
Precisely, exactly. Why piss about stirring the pot when you can just get the gear you need?
If you actually look at what most drivers do "going down the box" they have their foot on the clutch the whole time they're moving the gear stick from 4th to 3rd to 2nd to 1st anyway...so they never "use" any of the gears the stick gets moved to...
I even block downchange 4th to 2nd on track (with a ruddy great throttle blip of course).
If the car had a high-speed sequential racing box things would be different, of course - but most cars don't.
As I usually spout a load of old cods here, I'm at it again. Why not view incremental down changes as an iterative approach to hazard approach management. It allows for changing circs and is potentially more flexible.
After all, how valid are the arguments for block changing per se? Mechanical sympathy - nope, chances of getting it wrong are much higher, cleverer than iterating, yes but clever is just well...clever. Of course there is the whole thing of more time with both hands on the steering under braking, yep agree with that.
As for me, I block change down and almost always blip (often using heel and toe in the TVR), sometimes just rev matching.
Graham
editted to correct speelling
After all, how valid are the arguments for block changing per se? Mechanical sympathy - nope, chances of getting it wrong are much higher, cleverer than iterating, yes but clever is just well...clever. Of course there is the whole thing of more time with both hands on the steering under braking, yep agree with that.
As for me, I block change down and almost always blip (often using heel and toe in the TVR), sometimes just rev matching.
Graham
editted to correct speelling
Edited by gridgway on Thursday 28th September 22:31
Don said:
vonhosen said:
It's not new as far as roadcraft is concerned. Get the speed right & then get the gear for that speed. No point in taking a gear you aren't going to actively use.
Precisely, exactly. Why piss about stirring the pot when you can just get the gear you need?
If you actually look at what most drivers do "going down the box" they have their foot on the clutch the whole time they're moving the gear stick from 4th to 3rd to 2nd to 1st anyway...so they never "use" any of the gears the stick gets moved to...
I even block downchange 4th to 2nd on track (with a ruddy great throttle blip of course).
If the car had a high-speed sequential racing box things would be different, of course - but most cars don't.
Changing down isn't simply a motion as far as I'm concerned, it's a part of setting up the balance of the car as you enter a corner.
I can see the point about keeping your hands on the wheel, as on a bike you are always in constant contact with the controls, whereas in a car your hand has to leave the wheel to change gear. Changing more than one gear at a time on a bike is an accident waiting to happen.
I think my main questions are:
Is block changing now essential if you're considering advanced driving?
What are the advantages of block changing over sequential changing?
What are the disadvantages of sequential changing?
Unfortunately I don't have time to write too much, but a good discussion so wanted to join in
Rather than looking at it as block changing vs sequential changing, may I suggest you look at it as "being in the right gear for the hazard". What I mean by this is that you will change your speed coming up to a hazard (be that a red light, a roundabout etc. etc)...you will slow down. At the point you are able to drive away you then change into the appropriate gear. If that gear happens to be 2nd from 4th, so be it. This way you will always be in the correct gear for that roundabout, and you won't have gone 4th - 3rd - oh no I really needed 2nd - and introduced a whole other point of action that was ultimately not needed.
Of course with sequential boxes it is completely different, but I assume here we are talking of straight manual cars.
Rather than looking at it as block changing vs sequential changing, may I suggest you look at it as "being in the right gear for the hazard". What I mean by this is that you will change your speed coming up to a hazard (be that a red light, a roundabout etc. etc)...you will slow down. At the point you are able to drive away you then change into the appropriate gear. If that gear happens to be 2nd from 4th, so be it. This way you will always be in the correct gear for that roundabout, and you won't have gone 4th - 3rd - oh no I really needed 2nd - and introduced a whole other point of action that was ultimately not needed.
Of course with sequential boxes it is completely different, but I assume here we are talking of straight manual cars.
I advise my Associates to select the correct gear for the hazard, just as Tony explained and for those very reasons. That's how it was explained to me when I was an Associate. It really is the most efficient method and one that ensures optimum control of the vehicle.
Edited by EmmaP on Thursday 28th September 10:46
BliarsGoing said:
I think my main questions are:
Is block changing now essential if you're considering advanced driving?
What are the advantages of block changing over sequential changing?
What are the disadvantages of sequential changing?
Is block changing now essential if you're considering advanced driving?
What are the advantages of block changing over sequential changing?
What are the disadvantages of sequential changing?
I'm fairly new to this Advanced driving lark, but these are my thoughts:
Block changing may be regarded as being more efficient. You will spend more time with hands on wheel and are therefore in a better position to steer, to be in control. You will spend less time with clutch dipped, so less coasting and again, more control. Why go up or down the box when a block change will get you to the same place in half the time without detriment to the engine? I think that you need to stop thinking like a motorcyclist and like a car driver. You may miss a gear whilst block changing, but there exists the potential to do so when you are changing sequentially too. It shouldn't happen, but sometimes it does. That shouldn't prevent you from adopting a more efficient driving style. I'm sure that once you adopt this method it will feel entirely natural and logical.
Tony, I completely see that point, but is the gear change actually unneeded if it forms part of settling the car for a bend?
We're probably discussing at cross purposes slightly as there are many different scenarios. A series of s bends following a long straight on a country road requires a different style of driving to approaching a junction of whatever description in an urban setting.
I know someone will introduce the point about loading up the rear tyres on the entry to a bend is an undesirable thing, particularly in a 911! but I feel the consequences of an error are potentially greater the more you alter gearbox speed at any one time.
I suppose I'm having a bit of a debate in my head about driving using a planning system versus a constant adaptation system if that makes sense.
We're probably discussing at cross purposes slightly as there are many different scenarios. A series of s bends following a long straight on a country road requires a different style of driving to approaching a junction of whatever description in an urban setting.
I know someone will introduce the point about loading up the rear tyres on the entry to a bend is an undesirable thing, particularly in a 911! but I feel the consequences of an error are potentially greater the more you alter gearbox speed at any one time.
I suppose I'm having a bit of a debate in my head about driving using a planning system versus a constant adaptation system if that makes sense.
BliarsGoing said:
I suppose I'm having a bit of a debate in my head about driving using a planning system versus a constant adaptation system if that makes sense.
Sounds like it.
For the "Advanced Driver" for any hazard the ideal is one smooth brake, one smooth gearchange. The ideal doesn't always happen - mainly due to a failure in either observation (misjudged the hazard completely) or timing (misjudged the point at which it is known what gear is needed).
BliarsGoing said:
I suppose I'm having a bit of a debate in my head about driving using a planning system versus a constant adaptation system if that makes sense.
Ideally the plan will incorporate a strategy that will enable you to adapt in the most appropriate manner depending on the hazard. You will adapt accordingly, having weighed up the advantages and disadvantages of your potential plan of action. One must constantly adapt to the changing environment and be sufficiently flexible to manage potential and real hazards.
One factor that I think is significant, is how 'far away' (in terms of desired gearing versus actual gearing) from the right gear, for how long. If the speed is falling off rapidly then the benefits of going through the intermediate gears will be quite small, if the speed is coming off very gradually then it will be greater.
Changing gear is obviously expensive in terms of driver workload, so the fewer times you need to do it, the better.
On the other hand, in circumstances where matching revs is important (powerful rwd car close to the limit of grip for example) going through the gears enables you to make lots of little mistakes instead of one big one.
Changing gear is obviously expensive in terms of driver workload, so the fewer times you need to do it, the better.
On the other hand, in circumstances where matching revs is important (powerful rwd car close to the limit of grip for example) going through the gears enables you to make lots of little mistakes instead of one big one.
EmmaP said:
BliarsGoing said:
I suppose I'm having a bit of a debate in my head about driving using a planning system versus a constant adaptation system if that makes sense.
Ideally the plan will incorporate a strategy that will enable you to adapt in the most appropriate manner depending on the hazard. You will adapt accordingly, having weighed up the advantages and disadvantages of your potential plan of action. One must constantly adapt to the changing environment and be sufficiently flexible to manage potential and real hazards.
In my head I have this scenario. You're arriving at a second gear corner from a long straight. For whatever reason you have made a mistake and you now need to accelerate. Your speed is almost scrubbed off for second gear but the change hasn't been made. Now you're in a situation where you find yourself two gears away from the ideal and having to react AND go for the correct gear.
I'm playing devils advocate here, ideally you don't get in such a situation, but I was always taught that you should be in the correct gear at all times for exactly this reason.
If I appear anti block change it's because I want to test all the arguments before altering my driving style.
What is the IAM viewpoint on sequential changing?
BliarsGoing said:
In my head I have this scenario. You're arriving at a second gear corner from a long straight. For whatever reason you have made a mistake and you now need to accelerate. Your speed is almost scrubbed off for second gear but the change hasn't been made. Now you're in a situation where you find yourself two gears away from the ideal and having to react AND go for the correct gear.
Well I have learnt that nobody is perfect (still doesn't stop me from beating myself most of the time). Everyone makes mistakes. it is part of being human. The important thing is that we learn from them and seek to avoid repeating those errors or indeed be more prepared to deal with the situation should it arise again.
If I found myself in the situation that you describe, I would take immediate and quick action to rectify it, ie. a quick block change down to second, increasing throttle until at the desired speed, then block change back up to fourth. While it isn't an ideal situation to be in, a snatched gear change is better than being in the wrong gear and unable to get yourself out of a situation in sufficient time.
BliarsGoing said:
In my head I have this scenario. You're arriving at a second gear corner from a long straight. For whatever reason you have made a mistake and you now need to accelerate. Your speed is almost scrubbed off for second gear but the change hasn't been made. Now you're in a situation where you find yourself two gears away from the ideal and having to react AND go for the correct gear.
I'm playing devils advocate here, ideally you don't get in such a situation, but I was always taught that you should be in the correct gear at all times for exactly this reason.
If I appear anti block change it's because I want to test all the arguments before altering my driving style.
What is the IAM viewpoint on sequential changing?
OK, where would you see such a situation arising on the public highway? In other words, where would you need to accelerate into a potential hazard (the "2nd gear" corner)?
If it was that as you approach the corner you realise it has a potentially higher transit speed and as such 3rd gear would be more appropriate, then just select 3rd and accelerate.
If it is a case where you were unable to make enough observtions on approach, trying to fit in another one or two sequential grearchanges on the approach will have taken up more of your attention and time thus reducing your observations further.
Another consideration is that in some modern diesel engines with 6-speed 'boxes, the gear ratios are very closely spaced and when slowing for a hazard it is much easier and quicker to block change to the correct gear for the speed. In my current car, this means I often block change from 6th to 3rd for example when approaching a junction at the top of a slip road or at a roundabout.
I also often block change when accelerating, for example after completing an overtake going from 3rd to 5th or 6th, or pulling away from a junction onto a downhill, where i will often change 1st to 3rd or 2nd to 4th.
If you ever want to experience an extreme of where block changing is essential, try to drive or imagine a modern truck with 12 or 16 ratios to choose from. It is veery intensive trying to select each of those in sequence up or down.
EmmaP said:
BliarsGoing said:
In my head I have this scenario. You're arriving at a second gear corner from a long straight. For whatever reason you have made a mistake and you now need to accelerate. Your speed is almost scrubbed off for second gear but the change hasn't been made. Now you're in a situation where you find yourself two gears away from the ideal and having to react AND go for the correct gear.
Well I have learnt that nobody is perfect (still doesn't stop me from beating myself most of the time). Everyone makes mistakes. it is part of being human. The important thing is that we learn from them and seek to avoid repeating those errors or indeed be more prepared to deal with the situation should it arise again.
If I found myself in the situation that you describe, I would take immediate and quick action to rectify it, ie. a quick block change down to second, increasing throttle until at the desired speed, then block change back up to fourth. While it isn't an ideal situation to be in, a snatched gear change is better than being in the wrong gear and unable to get yourself out of a situation in sufficient time.
BTW. I lost one mark on block changing on yesterdays assesment and considering I have been driving a tiptronic box for the last year I didn't think that was too bad. It's twenty years since I did any advanced motorcycle training the observer marked me 86 out of a possible 90 and commented that it was the best drive he had observed in six years of taking the course
[/ShamelessBrag]
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