Zen and the art of changing gear.

[vonhosen]

TripleS said:

vonhosen said:

TripleS said:

vonhosen said:

If you've got the timing optimum there won't be much spare time, you'll have used it all productively, none wasted. I do more catching up on others under braking to roundabouts than accelerating away from them.

So sayeth the last of the late brakers?

Actually, unless a fairly high rate of progress is sought, what is wrong with braking fairly early and gently, which is what I normally tend to do, so long as the low rate of speed loss, and the extended period during which it is done, is not taken to the point of causing inconvenience to a following driver?

Best wishes all,
Dave.

I don't think you prescribe to brake gear separation or waiting to take the gear until you know if you can go though Dave (which is what ST2 appears to want to do). The firmer later braking will help in achieving those aims.

You can use whatever method you like or works for you, but my advice is geared towards someone wanting to do it incorporating those methods or goals.

Hiya, Von - I was merely commenting in relation to the intensity of braking - in your case typically fairly late and quite firmly - as opposed to my normal style of early and gently, thus taking more time and a longer distance over it, which means I sacrifice some progress of course. I wasn't thinking about the timing of gear changes and their relationship to the braking.

Best wishes all,
Dave.

I try to employ some degree of firmer stage braking, even where I'm not starting from higher speeds. It helps in applying the system.

[TripleS]

R_U_LOCAL said:

GreenV8S said:

Playing devil's advocate for a moment, what's your position on coasting either with the clutch down and/or out of gear, while approaching a hazard? There's a follow-on question that you can probably guess, but I won't ask it yet because I don't want to presuppose your answer.

ETA: this was really a response to instructormike's post, not Vonhosen's.

Edited by GreenV8S on Friday 10th August 18:05

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

The braking should be dome in the higher gear right down until the engine revs approach tick-over speed in that gear. Once you've reached that speed, then you should dip the clutch to prevent judder. This is different from coasting in the accepted sense, which is more a case of dipping the clutch as soon as you start to brake, or even putting the car in neutral whilst braking.

Even in top gear, you'll be down to 10-15mph before you have to dip the clutch, so the distance travelled with the clutch down is generally only a few yards.

Sorry, Reg, but that doesn't work in a six speed Mondeo TDCi, for example. They seem to do about 36 mph/1000 rpm in 6th gear, and I found I was having to change down or declutch before the speed dropped to 30 mph with that model. This may not seem too bad if you're a fairly late and firm braker, but with my early and gently braking it meant that I had to either change down to a lower gear during the slowing process, or declutch and slip into neutral - which is a style that will offend some people - 'not under full control' they'll say. On the other hand, if you can't have a suitable gear selected and the clutch engaged, you might as well be in neutral for all practical purposes.

Best wishes all,
Dave.

[vonhosen]

TripleS said:

R_U_LOCAL said:

GreenV8S said:

Playing devil's advocate for a moment, what's your position on coasting either with the clutch down and/or out of gear, while approaching a hazard? There's a follow-on question that you can probably guess, but I won't ask it yet because I don't want to presuppose your answer.

ETA: this was really a response to instructormike's post, not Vonhosen's.

Edited by GreenV8S on Friday 10th August 18:05

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

The braking should be dome in the higher gear right down until the engine revs approach tick-over speed in that gear. Once you've reached that speed, then you should dip the clutch to prevent judder. This is different from coasting in the accepted sense, which is more a case of dipping the clutch as soon as you start to brake, or even putting the car in neutral whilst braking.

Even in top gear, you'll be down to 10-15mph before you have to dip the clutch, so the distance travelled with the clutch down is generally only a few yards.

Sorry, Reg, but that doesn't work in a six speed Mondeo TDCi, for example. They seem to do about 36 mph/1000 rpm in 6th gear, and I found I was having to change down or declutch before the speed dropped to 30 mph with that model. This may not seem too bad if you're a fairly late and firm braker, but with my early and gently braking it meant that I had to either change down to a lower gear during the slowing process, or declutch and slip into neutral - which is a style that will offend some people - 'not under full control' they'll say. On the other hand, if you can't have a suitable gear selected and the clutch engaged, you might as well be in neutral for all practical purposes.

Best wishes all,
Dave.

With some modern 6 speed diesels, it may be necessary to take an intermediary gear on approach.

[rsv gone!]

vonhosen said:

The Stressed one posted a video a while back showing a bit of straightlining in roundabouts, although you can't see the lateral vision that's clear to go, you can get a feel for the firmer later braking & you can hear the rev for the gearchange to establish when it's done in some (although you'll notice he is going down through the box on some, but the purpose for you is the illustration of carrying some speed to the roundabout.)
Here's the link he posted.
http://www.hpc.org.uk/mkrb.wmv

Thought that looked familiar - Milton Keynes.

I have a query/comment. At 2:58 (looks like A5/A421) he is straightlining a roundabout and moving to the nearside for the easiest path. That is understandable but I ride a bike and tend to ride not only for my view but also for my visibility to others. If I were to approach following Dave's line then I'd be worried that cars at 9 o'clock might not see me and pull out in front. Even in a car I think this might be the case. I know we don't get the same peripheral view as him but I know that roundabout and the shrubbery on the left can prevent much of a view. I would tend to stay more central in the road, giving up a little speed through the roundabout but gaining a view into the first exit of the roundabout.

[vonhosen]

rsv gone! said:

vonhosen said:

The Stressed one posted a video a while back showing a bit of straightlining in roundabouts, although you can't see the lateral vision that's clear to go, you can get a feel for the firmer later braking & you can hear the rev for the gearchange to establish when it's done in some (although you'll notice he is going down through the box on some, but the purpose for you is the illustration of carrying some speed to the roundabout.)
Here's the link he posted.
http://www.hpc.org.uk/mkrb.wmv

Thought that looked familiar - Milton Keynes.

I have a query/comment. At 2:58 (looks like A5/A421) he is straightlining a roundabout and moving to the nearside for the easiest path. That is understandable but I ride a bike and tend to ride not only for my view but also for my visibility to others. If I were to approach following Dave's line then I'd be worried that cars at 9 o'clock might not see me and pull out in front. Even in a car I think this might be the case. I know we don't get the same peripheral view as him but I know that roundabout and the shrubbery on the left can prevent much of a view. I would tend to stay more central in the road, giving up a little speed through the roundabout but gaining a view into the first exit of the roundabout.

You should consider whether your positioning will leave you not only short of vision, but leave unsighted to others or mislead them.

Personally if it goes two lanes into three on approach (left most lane designed for those turning left) I wouldn't use lane one to striaghtline unless I have the vision to be sure that a) there is nothing from the right to make me have to stop & b) nothing from the left to be misled by my using that lane. I'd use the nearside of lane two as a (virtual) apex.

[ST2]

Thank you both Mr.Local and Mr. Vonhosen for your replies. A problem I have one particular RA is the lack of view, because of shrubbery on the island, of vehicles approaching from the 12o'clock position.
This RA is on a dual-carriageway and I need to turn right to exit at 3o'clock so am approaching in lane 2. View to vehicles coming from 12o'clock is restricted to about 30 feet. Often moving away fromm being stopped at the give way a car comes into view quickly. To stop and give way
to it leaves me in lane 1 of the RA, from where it is even harder to move off again wth vehicles now coming from 3o'clock driving around you. Would it be better, once started to continue although it may cause the vehicle to slow?

[rsv gone!]

vonhosen said:

You should consider whether your positioning will leave you not only short of vision, but leave unsighted to others or mislead them.

Personally if it goes two lanes into three on approach (left most lane designed for those turning left) I wouldn't use lane one to striaghtline unless I have the vision to be sure that a) there is nothing from the right to make me have to stop & b) nothing from the left to be misled by my using that lane. I'd use the nearside of lane two as a (virtual) apex.

I agree entirely. That was the point I was trying to make. The view left just looked compromised. Everywhere else, Dave takes the path you describe.

I daresay he could stop if someone did emerge from the first exit but being a biker, and valuing my health, nerves and bike, I prefer to be seen - to avoid the need for heavy braking.

(Of course, there is still no guarantee that the vehicles which might be looking to emerge won't take the most cursory of glances and still pull out in front of you. Oh, the joys of biking!)

[R_U_LOCAL]

I have to agree with VH. The main problem in that video is when the driver approaches roundabouts which have three lanes on the approach, and uses the lane marked left turn only in order to go straight on. There are advantages with regards to vehicle balance in taking the roundabout this way, but I feel this is outweighed by the possibility that another road user will be confused by your positioning. If I were approaching those roundabouts from the left, I would be quite within my rights to expect someone in the left lane to turn left, although I think the approach speed would be a giveaway.

Other than that, from a system and gearchange timing point of view, that was a reasonably good example. I'll try to film some similar footage in a couple of weeks.

[Major Bloodnok]

TripleS said:

R_U_LOCAL said:

GreenV8S said:

Playing devil's advocate for a moment, what's your position on coasting either with the clutch down and/or out of gear, while approaching a hazard? There's a follow-on question that you can probably guess, but I won't ask it yet because I don't want to presuppose your answer.

ETA: this was really a response to instructormike's post, not Vonhosen's.

Edited by GreenV8S on Friday 10th August 18:05

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

The braking should be dome in the higher gear right down until the engine revs approach tick-over speed in that gear. Once you've reached that speed, then you should dip the clutch to prevent judder. This is different from coasting in the accepted sense, which is more a case of dipping the clutch as soon as you start to brake, or even putting the car in neutral whilst braking.

Even in top gear, you'll be down to 10-15mph before you have to dip the clutch, so the distance travelled with the clutch down is generally only a few yards.

Sorry, Reg, but that doesn't work in a six speed Mondeo TDCi, for example. They seem to do about 36 mph/1000 rpm in 6th gear, and I found I was having to change down or declutch before the speed dropped to 30 mph with that model. This may not seem too bad if you're a fairly late and firm braker, but with my early and gently braking it meant that I had to either change down to a lower gear during the slowing process, or declutch and slip into neutral - which is a style that will offend some people - 'not under full control' they'll say. On the other hand, if you can't have a suitable gear selected and the clutch engaged, you might as well be in neutral for all practical purposes.

Best wishes all,
Dave.

I don't know how this accords with accepted practice, but my usual approach in this circumstance (MR2, so petrol and slightly different) is to drop down to fifth early - well before I start braking. This gives a slightly lower speed before the need to dip the clutch.

[GreenV8S]

R_U_LOCAL said:

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

Not what I was leading up to. Back to the question: coasting with the clutch dipped and/or out of gear, views for / against and why?

[R_U_LOCAL]

GreenV8S said:

R_U_LOCAL said:

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

Not what I was leading up to. Back to the question: coasting with the clutch dipped and/or out of gear, views for / against and why?

It takes away the engine's assistance in slowing the car down. This assistance is obviously less in higher gears and more in lower gears, but it's always there when the clutch is out.

Acceleration sense is a very important aspect of advanced driving. Used correctly, the ability to vary vehicle speed through accurate use of the accelerator(1) can smooth a drive considerably and helps to improve observation skills.

(1)Yes, I know - straight lift from roadcraft. Shoot me.

[PeteG]

R_U_LOCAL said:

Acceleration sense is a very important aspect of advanced driving. Used correctly, the ability to vary vehicle speed through accurate use of the accelerator(1) can smooth a drive considerably and helps to improve observation skills.

And one of the most satisfying to get right. I'm better at it on urban roads than rural lanes at the moment, partly through experience, partly because I'm in 3rd or even 2nd, depending on conditions, up to 30mph. Rural roads, I think I tend to back off a fraction too late, which then means braking so as not to enter a bend too quickly...

[GreenV8S]

R_U_LOCAL said:

It takes away the engine's assistance in slowing the car down. This assistance is obviously less in higher gears and more in lower gears, but it's always there when the clutch is out.

In situations where you intend to slow the car down, and where the gear you're in affords enough engine braking to make a useful contribution to doing that, it's clearly a benefit. In other situations?

Actually I was fishing for a more general answer, along the lines that it gives you the flexibility to accelerate or decelerate if it is (or becomes) necessary. And that leads to the question of how much flexibility do you need, which leads to the need to be in the appropriate gear for the circumstances. Staying in whatever gear you're in until you drop out of the operating range of the engine or until you need to accelerate, has the advantage of reducing the driver workload (compared to dropping down through the gears as the speed drops) but means you sacrifice this flexibility. If you're absolutely confident that you are not going to need engine braking or acceleration in the near future then being in the wrong gear is not a problem. But in other circumstances it's worth retaining that flexibility. And by that I mean being in a gear which gives you enough flexibility to respond promptly to reasonably forseeable events, rather than waiting for those events and having tio change gear before you respond.

It seems to me that the arguments FOR deferring the gear change until the stop/go decision has been made are IMO largely the same as the ones FOR coasting. Both may be perfectly acceptable in some circumstances but not for all circumstances.

[ijd]

GreenV8S said:

R_U_LOCAL said:

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

Not what I was leading up to. Back to the question: coasting with the clutch dipped and/or out of gear, views for / against and why?

In a modern diesel car this uses more fuel than slowing down on the overrun, the engine management system cuts off fuel injection completely if you're on the overrun but has to keep the engine running at idle if you dip the clutch -- the opposite to a petrol engine where lower revs (idling) = less fuel than on overrun.

I noticed this on my 525d which had one of those annoying little "instantaneous mpg" gauges, dip the clutch and it went up to maybe 50mpg, overrun it went off the end of the scale to "infinite mpg" (would be 0 l/100km with a sensible gauge :-)

Ian

[GreenV8S]

ijd said:

GreenV8S said:

R_U_LOCAL said:

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

Not what I was leading up to. Back to the question: coasting with the clutch dipped and/or out of gear, views for / against and why?

In a modern diesel car this uses more fuel than slowing down on the overrun, the engine management system cuts off fuel injection completely if you're on the overrun but has to keep the engine running at idle if you dip the clutch -- the opposite to a petrol engine where lower revs (idling) = less fuel than on overrun.

I noticed this on my 525d which had one of those annoying little "instantaneous mpg" gauges, dip the clutch and it went up to maybe 50mpg, overrun it went off the end of the scale to "infinite mpg" (would be 0 l/100km with a sensible gauge :-)

Ian

Yes, but with respect the fuel consumption gains are not sufficiently important to determine whether and when an advanced driver should change gear or coast.

[TripleS]

ijd said:

GreenV8S said:

R_U_LOCAL said:

I'm anticipating a "what happens if the revs drop to the point where the engine starts to judder?" question - am I right?

Not what I was leading up to. Back to the question: coasting with the clutch dipped and/or out of gear, views for / against and why?

In a modern diesel car this uses more fuel than slowing down on the overrun, the engine management system cuts off fuel injection completely if you're on the overrun but has to keep the engine running at idle if you dip the clutch -- the opposite to a petrol engine where lower revs (idling) = less fuel than on overrun.

I noticed this on my 525d which had one of those annoying little "instantaneous mpg" gauges, dip the clutch and it went up to maybe 50mpg, overrun it went off the end of the scale to "infinite mpg" (would be 0 l/100km with a sensible gauge :-)

Ian

I don't think you're right in suggesting that fuel supply is maintained to petrol engines on the over-run. We had Jaguar XJ series 3 models, a 4.2 litre six cylinder and a 5.3 litre V12, and both of those would cut off the fuel supply on over-run.

Incidentally, it is my understanding that this is done to reduce the emissions (which are bad on over-run) rather than for fuel economy reasons.

Best wishes all,
Dave.

[WhoseGeneration]

GreenV8S said:

Playing devil's advocate for a moment, what's your position on coasting either with the clutch down and/or out of gear, while approaching a hazard? There's a follow-on question that you can probably guess, but I won't ask it yet because I don't want to presuppose your answer.

ETA: this was really a response to instructormike's post, not Vonhosen's.

Edited by GreenV8S on Friday 10th August 18:05

Who has a copy of the book about the original BSM HPC course?
I remember discussion and differing views on this by the co authors.
Alas, I read a library copy a long time ago.

[uriel]

One thing I've never seen discussed when reading discussions on gear changes and engine braking is the effect of the engine impeding the braking progress. It seems like common sense to me, so I'm wondering whether I'm looking at things wrongly.

If you are in gear with the clutch engaged, wanting to slow down at a rate greater than that at which the car would engine brake without the brakes being applied, then if you were to slow at that rate using the brakes, aren't the brakes working against the motion of the engine as well as the forward motion of the car? When reading discussions on engine braking, it seems as though people consider the effects of the brakes and the engine braking as a cumulative affect. But the way I see it, that's only true if the engine braking is slowing the car more than the brake pads? I hope that makes some sense!

[R_U_LOCAL]

uriel said:

One thing I've never seen discussed when reading discussions on gear changes and engine braking is the effect of the engine impeding the braking progress. It seems like common sense to me, so I'm wondering whether I'm looking at things wrongly.

If you are in gear with the clutch engaged, wanting to slow down at a rate greater than that at which the car would engine brake without the brakes being applied, then if you were to slow at that rate using the brakes, aren't the brakes working against the motion of the engine as well as the forward motion of the car? When reading discussions on engine braking, it seems as though people consider the effects of the brakes and the engine braking as a cumulative affect. But the way I see it, that's only true if the engine braking is slowing the car more than the brake pads? I hope that makes some sense!

I don't see how the engine is hindering the brakes. If you lift off the accelerator, the compression of the engine starts to slow the car down. Pressing the brakes slows the car more quickly, but the engine is still helping, albeit in a very small way. It would only be going against the brakes if there was still some throttle applied.

[TripleS]

R_U_LOCAL said:

uriel said:

One thing I've never seen discussed when reading discussions on gear changes and engine braking is the effect of the engine impeding the braking progress. It seems like common sense to me, so I'm wondering whether I'm looking at things wrongly.

If you are in gear with the clutch engaged, wanting to slow down at a rate greater than that at which the car would engine brake without the brakes being applied, then if you were to slow at that rate using the brakes, aren't the brakes working against the motion of the engine as well as the forward motion of the car? When reading discussions on engine braking, it seems as though people consider the effects of the brakes and the engine braking as a cumulative affect. But the way I see it, that's only true if the engine braking is slowing the car more than the brake pads? I hope that makes some sense!

I don't see how the engine is hindering the brakes. If you lift off the accelerator, the compression of the engine starts to slow the car down. Pressing the brakes slows the car more quickly, but the engine is still helping, albeit in a very small way. It would only be going against the brakes if there was still some throttle applied.

I suppose in an emergency braking situation the rate of retardation provided by braking could be greater than the rate at which the engine loses its rotational momentum and slows down - if you know what I mean- in which case it would have been better to declutch at the same time as the brakes are applied.

Best wishes all,
Dave.