[VeluM]

Originally Posted by dhanushs

This is NOT while emergency braking, this is while feathering the brakes. Any manufacturer who designs an ECU which pumps enough fuel to overcome emergency braking forces are just outright stupid.

Well, the quote is taken from the Emergency Braking section of the site submitted by SS-Traveller, so you should probably take this up with him.

As for manufacturers being stupid : I'm not going to argue about your opinion, but any vehicle's ECU is programmed to increase rpms when load is applied so as to prevent the engine dying. It is similar to switching on the AC when the car is at idle. The increased load increases the engine rpm to compensate. It is especially noticeable in smaller capacity cars like my Spark. Switch on the lights also has a similar albeit much milder reaction.

And PS. The ECU is not pumping enough fuel to overcome emergency braking. It is just enough to prevent the engine from dying when the rpms fall below a certain level. The impact can be negligible, depending on the brakes/engine.

Originally Posted by SS-Traveller

So downshifting is an option, no? Downshift and release the clutch!

If you check the sites, they also maintain that both hands have to be on the steering wheel during the entire manoeuvre in order to pass the test. And as you clearly believe that the UK site is neither outdated nor incorrect, I don't really see how that's going to be achieved. Unless one is driving an automatic, in which case the discussion is irrelevant.

[markmytravel]

May I request some of the experts to summarize the msot preffered action one should take in such a case both when your car is ABS equipped or non-ABS. I feel a good summarization will really help others to avoid situations like these.

[mayankk]

Muddy waters.
So tell me, in an emergency braking situation, i am definitely not looking at engine braking to gradually stop me.
I am aware of using it to gradually bring the car - when warned sufficiently as per my reflex abilities- to a stop.
Emergency situation, okay?
I want a slap-bang stationary car.
At this point , my only worry is to not hit XXXXXX.
I mash down both the clutch, and the brake, since by experience i have learnt that my car stalls at 34kmph(which frankly is still more than enough to cause expensive damage either to the car itself, or physical damage to the aforementioned xxxxx).


what exactly is so incorrect about that practice ?
compared to having non-steerable, non-braking stalled systems?


EDIT:@dhanushs that 34 kmph was just a figure i had picked from one of the earlier posts about an ikon.

[dhanushs]

Originally Posted by VeluM

The impact can be negligible, depending on the brakes/engine.

This is exactly what I mean, even in cars with bad brakes and high low end torque, under heavy braking, the interference of the ECU, when compared to the braking force is negligible.

In any case, assume you are in 5th gear, the ECU intervenes only below idle rpm. So, whats would be your speed below idle rpm @5th or 4th gear?. By the time the ECU intervenes or the vehicle stalls, you would have reached safe speeds.

EDIT:

Originally Posted by mayankk

since by experience i have learnt that my car stalls at 34kmph

Umm.. Mayankk, are you sure of that? You mean, your dash lights up at 34km/h @ 5th gear?. I assume its a Fiesta. Also, please note that here, we are not accelerating, but decelerating, and there is the momentum of the car propelling it further.

[suhaas307]

Originally Posted by noopster

I agree with suhaas that pressing clutch while emergency braking is not correct. This is something I have learned from experience and not by poring through manuals and Youtube videos . It seems intuitive that you would want to first bring the car to a complete stop and then worry about stalling. To address anilisanil's concern, stalling will happen only at very low speeds, not before, from practical experience. As someone before pointed out you can downshift from 5th to 2nd gear without stalling. At that speed, even if you do stall it will not cause much damage in terms of losing power steering and the like.

Also, engaging clutch puts the car in neutral which is not a great idea and counter-productive if the road is sloping gently downwards etc.

However one of the things I remember being taught in driving school back in 92-93 was "Emergency mein full clutch-brake!" My Dad (who learned driving only a few years before me) used to quote this often but I was never really sure it was the right way till I started driving extensively myself.

Sheesh! Finally, we have people on this forum who know a thing or two on the intricacies of driving a car with a manual 'box.

You're absolutely right. Engaging the clutch would mean the gears are free to be changed. Which also means that the car isn't in gear. When a car is doing 140 km/h and the anchors are dropped, and it isn't in gear, it would only mean you have less control of your car.

When one is doing 140 and you slam the brakes, the car will take a couple of seconds to shed the speed and slow down to 10-20 km/h, so before it falls out of the power-band in 5th gear, which should be around 1500 RPM, and the car is doing about 30 km/h, is when one must press the clutch and change to the gear appropriate for the car's speed and the engine's speed.

ABS helps you keep the car in a straight line when you shed speed like that. What it does is, it assists your braking and ensures that the wheels don't lock, thereby allowing you to turn the wheel and avoid a collision or come to a halt without skidding into something on the road.

Originally Posted by noopster

--> Suhaas you're just 22? I thought you were my age hehe!

And what made you think I'm your age, Noop? I'm sure you're pretty young yourself!

[VeluM]

Originally Posted by suhaas307

Sheesh! Finally, we have people on this forum who know a thing or two on the intricacies of driving a car with a manual 'box.

Wow, a loaded statement as any I've ever read. Just because people disagree with you doesn't mean they're wrong or "ignorant" as you so kindly implied.

On the other hand just because they agree with you doesn't mean they know a thing or two about the intricacies of driving a car with a manual 'box either

The relative impact of engine braking will be nearly immaterial in an emergency. Especially since we're discussing a vehicle with ABS and a high-speed emergency. Therefore, even if we assume that your opinion is correct for arguments sake, IMHO it is a whole lot of "technique," "finesse" and "intricacy" for not much benefit; while attempting to follow what is described as the "Correct" way may actually cause more confusion for some, myself included.

[suhaas307]

Originally Posted by VeluM

Wow, a loaded statement as any I've ever read. Just because people disagree with you doesn't mean they're wrong or "ignorant" as you so kindly implied.

On the other hand just because they agree with you doesn't mean they know a thing or two about the intricacies of driving a car with a manual 'box either

Oh no, I've had several people agreeing and disagreeing with me on several opinions of mine.

But this is not an opinion. It is a technique that one adopts while driving. And it is the technique that is recommended, advised, and observed all over the world. It's the difference between a fact, and something that is, well, not.

Originally Posted by VeluM

The relative impact of engine braking will be nearly immaterial in an emergency. Especially since we're discussing a vehicle with ABS and a high-speed emergency.

Engine braking has nothing to do with this. Engine braking, simply put, is an art wherein one switches from a higher cog to a lower one while dabbing on the brake-pedal gently, and letting the engine fall out of its power-band gradually, and going through the gears, one by one, until you come to a halt. This is the practice that I've adopted if I see a red light at the traffic signal in the distance. I'm not completely perfect at it, but I'm trying to get it right.

Originally Posted by VeluM

Therefore, even if we assume that your opinion is correct for arguments sake, IMHO it is a whole lot of "technique," "finesse" and "intricacy" for not much benefit; while attempting to follow what is described as the "Correct" way may actually cause more confusion for some, myself included.

It's a technique. And it isn't a 'whole lot of it'. it's as simple as delaying the depressing of the clutch while braking suddenly. I've done it with just 40k of driving experience, and don't me mistaken, I'm far from being an exceptional driver. So how hard can it be?

There isn't much to benefit from this practice, except maybe, with your life? Okay, that might have been a bit drastic, but seriously; simultaneously depressing the clutch while hitting the brakes while doing high speeds isn't advised, for the simple reason that when the clutch is depressed, the car is theoretically not in gear, and therefore, you have lesser control of the car.

Sometimes, depressing the clutch and hitting the brakes simultaneously may lead to consequences you're better off not facing. I've not been in that position, and I don't know what exactly happens in such situations (when the clutch and brake is pressed simultaneously)

What you should be worried about is stopping in time, rather than hitting the clutch for the fear of stalling.

And how confusing can it be? With a little practice, perseverance and awareness, you can get it right It's no big deal. If it causes confusion, then it's akin to a student who has a doubt about something being taught in class.

The argument on people who have poorer reflexes is also moot. If you have poor reflexes, you ought not be driving at 140 km/h in the first place, and put yourself in a situation that requires you to brake suddenly.

Stick to the highway speed limit in that case. There is a reason why it is 80 km/h, and it is because 99% of the road users don't know these little 'intricacies' that would actually make a difference.

Originally Posted by markmytravel

May I request some of the experts to summarize the msot preffered action one should take in such a case both when your car is ABS equipped or non-ABS. I feel a good summarization will really help others to avoid situations like these.

May I?

Well, it's quite simple really. The brakes on a non-ABS car will tend to lock up when the brakes are applied suddenly. It's a phenomenon where the calipers bite the discs that haul the car down. In a non-ABS car, sometimes, the caliper does not let go of the disc and holds onto it for a period longer than desired. In such a situation, one must have the presence of mind. You know that you've locked up when your steering inputs don't yield benefits. So what one should do is pump the brake-pedal repeatedly so that the calipers let go of the disc.

In an ABS equipped car, when the brakes are applied suddenly, the ABS activates immediately depending on the condition and one will know when the ABS kicks in when the brake pedal kicks back violently. This might throw some people off guard and they might even let go of the brakes. At this point, one must remember that the foot on the brake MUST be planted and buried into the carpet. Resist the violent kick-back and allow the ABS to do its thing. the car will come to a stop and you will be able to turn the car in whichever direction, and you can even accelerate out of the situation, once the coast is clear.

[cranky]

The argument on people who have poorer reflexes is also moot. If you have poor reflexes, you ought not be driving at 140 km/h in the first place, and put yourself in a situation that requires you to brake suddenly.

Stick to the highway speed limit in that case. There is a reason why it is 80 km/h, and it is because 99% of the road users don't know these little 'intricacies' that would actually make a difference.

Thank you. This is exactly what I've been trying to say since my first post.

This forum may have a large proportion of experienced drivers. The world outside it does not.

The relative impact of engine braking will be nearly immaterial in an emergency

My experience leads me to believe that engine braking is most effective at the same rpm that the engine develops maximum power, down to the point where the engine develops its maximum torque. This needs one to downshft through the power band while braking, exactly as you shift upward while accelerating.

In a manual with a paddle shift I'm hopeful this may be possible to use in an emergency situation. In a stick shift, it's probably better to forget the clutch exists as all your concentration should be on avoiding the obstacle/vehicle/child in front of you using your steering and brakes.

The human brain works best at serial tasks, and it is not a good idea to be thinking of your left foot, the engine note and the correct gear when in serious danger.

[suhaas307]

Originally Posted by cranky

Thank you. This is exactly what I've been trying to say since my first post.

This forum may have a large proportion of experienced drivers. The world outside it does not.

You're welcome!

Originally Posted by cranky

In a manual with a paddle shift I'm hopeful this may be possible to use in an emergency situation. In a stick shift, it's probably better to forget the clutch exists as all your concentration should be on avoiding the obstacle/vehicle/child in front of you using your steering and brakes.

Exactly! So forget about the clutch. Don't bother pressing it along with the brake. Hold the steering tight and brake hard when the time comes. When the car is doing slower speeds is when one should think about pressing the clutch. Or when one feels the engine 'knocking'.

Originally Posted by cranky

The human brain works best at serial tasks, and it is not a good idea to be thinking of your left foot, the engine note and the correct gear when in serious danger.

Exactly. All this should happen by reflex. And for it to happen by reflex, one needs adequate practice and experience behind the wheel. One should not 'think' about it, because one you've thought about it, there is perhaps no time left for you to 'think' anymore at all, God-forbid!

[mayankk]

Frankly,it won't make one tiny bit of difference when you have seconds to stop,whichever school of thought you belong to.

So let's not knock a different reaction as incorrect off the cuff.

[VeluM]

Originally Posted by suhaas307

Oh no, I've had several people agreeing and disagreeing with me on several opinions of mine.

But this is not an opinion. It is a technique that one adopts while driving. And it is the technique that is recommended, advised, and observed all over the world. It's the difference between a fact, and something that is, well, not.

I agree with you that it has been advised on some sites, however how it has been advised on this forum is a little misleading IMHO in both the method as well as the method being the Only way.

For one, in the sites quoted earlier, it states that the brake pedal should be pressed before the clutch and later states that the clutch should be pressed before stalling. This could mean anywhere in between, including immediately after pressing the brake. It doesn't however state that the clutch should not be pressed immediately after the brake. Second, both hands should be on the steering wheel, so as mentioned by you below down shifting is not an option:

Originally Posted by suhaas307

Engine braking has nothing to do with this. Engine braking, simply put, is an art wherein one switches from a higher cog to a lower one while dabbing on the brake-pedal gently, and letting the engine fall out of its power-band gradually, and going through the gears, one by one, until you come to a halt. This is the practice that I've adopted if I see a red light at the traffic signal in the distance. I'm not completely perfect at it, but I'm trying to get it right.

Since engine braking has nothing to do with the technique during panic braking, what other advantage do we gain by not pressing the clutch? Directional manoeuvrability with maximum retardation is the primary objective of ABS, which is achieved by standing on the brakes. Therefore, I am still to understand how not pressing the clutch helps.

Originally Posted by suhaas307

It's a technique. And it isn't a 'whole lot of it'. it's as simple as delaying the depressing of the clutch while braking suddenly. I've done it with just 40k of driving experience, and don't me mistaken, I'm far from being an exceptional driver. So how hard can it be?

I'm not sure how better to explain this: During an emergency, one is not predisposed to think about or use engine retardation to slow the vehicle by changing down through the gears. The sites quoted earlier also recommend keeping both hands on the steering wheel, which makes changing down impossible.

Therefore, in high gears the engine will quickly fall out of the retardation rev-range to a point where we can agree that it doesn't help much either way. This is at best a fraction of a second in ABS equipped vehicles, especially since the issue being discussed is a smooth, dry highway with no gravel/sand/oil that is visible, and where ABS would have been considerably better equipped to stop the vehicle in the shortest distance. Again not sure how not pressing the clutch helps.

In any emergency, be it of any nature in any field, the idea is always to design processes and procedures that are least complicated and most effective. Thinking about pressing the clutch just before the engine stalls or even trying to be aware of the engine rpms is just adding to the complexity of a situation that requires it the least.

Originally Posted by suhaas307

There isn't much to benefit from this practice, except maybe, with your life? Okay, that might have been a bit drastic, but seriously; simultaneously depressing the clutch while hitting the brakes while doing high speeds isn't advised, for the simple reason that when the clutch is depressed, the car is theoretically not in gear, and therefore, you have lesser control of the car.

Control over the car via gears when not applying any accelerator input is Only due to the natural retardation that occurs in such situations. This retardation is in simple terms the wheels being made to rotate slower than the momentum of the vehicle would naturally force it to. It isn't anything more complex than that.

At high speeds, leaving the car in gear would help as much as keeping the car in 5th gear on a downhill slope. In order to gain any control from the engine, one has to be in at most the same gear as is used to drive up the same slope (at sane speeds), and preferably a lower gear. Since we aren't going to be changing down to a lower gear during an emergency, I again do not understand how not pressing the clutch would help. The brakes are already providing the required retardation, while ABS ensures that the vehicle remains manoeuvrable throughout.

Originally Posted by suhaas307

Sometimes, depressing the clutch and hitting the brakes simultaneously may lead to consequences you're better off not facing. I've not been in that position, and I don't know what exactly happens in such situations (when the clutch and brake is pressed simultaneously)

I do know, because I was in a situation where I had to brake in an emergency. No lives on the line, just some possible vehicular damage (brand new Sparky, and I had my heart in my mouth!). The comparison may not apply since my car isn't ABS equipped, while the Captiva is/was, but the control comes completely from the traction or friction between the tyres and the surface on which they ride. In panic braking (with ABS), maximum possible traction with maximum braking effort is already achieved (in the given good surface being discussed), therefore we don't again have evidence of not pressing the clutch being better.

Originally Posted by suhaas307

What you should be worried about is stopping in time, rather than hitting the clutch for the fear of stalling.

Partially agree, and I'm glad you agree that one shouldn't be worried about hitting the clutch for fear of stalling. When braking in an emergency, one is only thinking about stopping in time, before the obstacle/obstruction. Panic braking is different because one generally isn't just slowing down, but stopping. Therefore worrying about the clutch later on - when much closer to the obstacle - to prevent the vehicle from stalling is still diverting one's attention. Initially it is a reflex, whereas later it is a learned response. There is a big difference between these two especially in emergencies.

Stalling the vehicle does have negative effects of lack of power assist in steering and braking and hence ABS; and we are gladly agreed on this.

These are critical issues, which IMO can be resolved by pressing the clutch by reflex.

In my personal opinion when to press the clutch is best left to each. I choose reflex simply because I am yet to see evidence of any benefits of not pressing the clutch immediately after the brakes.

And as I said earlier, complicating things in an emergency is best avoided.

Originally Posted by suhaas307

And how confusing can it be? With a little practice, perseverance and awareness, you can get it right It's no big deal. If it causes confusion, then it's akin to a student who has a doubt about something being taught in class.

Learning how to react to an emergency in the method you describe as better is something that will not be instinctive to me. I can spend time practising it, but I know I will never try it in a real emergency because I'd be rather afraid of making a blunder. In theory everything is perfect, but in practice, not quite. And though practice makes perfect, I'd rather not take chances with my family's lives unless I am given evidence of my instinctive reaction being wrong.

Originally Posted by suhaas307

The argument on people who have poorer reflexes is also moot. If you have poor reflexes, you ought not be driving at 140 km/h in the first place, and put yourself in a situation that requires you to brake suddenly.
Stick to the highway speed limit in that case. There is a reason why it is 80 km/h, and it is because 99% of the road users don't know these little 'intricacies' that would actually make a difference.

I agree with this. One has to know one's limits, and part of those limits include knowing how one reacts in an emergency. For example in the Army they put recruits through such vigorous and intense training in the most extreme of situations so that the person is trained as best as can possibly be to react as trained. However, there are still soldiers who crack, react badly or plain freeze in fear in war. We on the other hand can get a license without being anywhere near meeting the requirements laid down in those informative websites quoted earlier.

In the case of the driver of the Captiva, he obviously wasn't trained, and knew neither his nor the vehicle's limits - which resulted in this thread.

PS. I do use engine braking, and advise all to do so in normal braking situations.

[Samurai]

Originally Posted by suhaas307

Engine braking has nothing to do with this. Engine braking, simply put, is an art wherein one switches from a higher cog to a lower one while dabbing on the brake-pedal gently, and letting the engine fall out of its power-band gradually, and going through the gears, one by one, until you come to a halt. This is the practice that I've adopted if I see a red light at the traffic signal in the distance. I'm not completely perfect at it, but I'm trying to get it right.

I don't know whether you can call it an art, considering most of the work is done by the engine and gear ratios. But you don't have to cycle through every gear before you come to halt. Once you spot the red light, you can start braking while staying in whatever gear you are in, but you can do it so that you fall out of power band just before coming to halt, then you can directly switch to neutral. But if you fall out of power band little earlier, you can switch to most appropriate lower gear and continue braking. This usually happens in highways where you can see the congestion from a far distance. Anyways, no hard and fast rule here. As long as you don't coast, you are fine. For example, in my Jeep I don't even bother touching the brakes for slowing down, just releasing the A-pedal does the drastic slowing down required, that is because of the gearing of the Jeep.

Originally Posted by suhaas307

May I?

I am no expert, in fact I didn't know car driving at your age. But I have to correct couple of errors in your explanation.

Originally Posted by suhaas307

Well, it's quite simple really. The brakes on a non-ABS car will tend to lock up when the brakes are applied suddenly. It's a phenomenon where the calipers bite the discs that haul the car down. In a non-ABS car, sometimes, the caliper does not let go of the disc and holds onto it for a period longer than desired.

Not that simple. The brakes on non-ABS don't just tend to lock up when brakes are applied suddenly. When the traction between wheel and the brake pads exceeds the traction between tyre and road surface, the wheels get locked or stop turning. That is why wheels lock lot easily on slippery surfaces like gravel, grass, snow, ice or slush, where the road surface offers very little traction.

Originally Posted by suhaas307

So what one should do is pump the brake-pedal repeatedly so that the calipers let go of the disc.

Releasing the brakes makes the traction between wheel & brakepad nil or lesser than the traction between tyre and road surface, and wheels start moving again. From this you can also understand that you don't have to release the brake fully, just release it enough to bring the brake traction below that of the road traction. Continue to brake and release to imitate the ABS action.

Originally Posted by suhaas307

In an ABS equipped car, when the brakes are applied suddenly, the ABS activates immediately depending on the condition and one will know when the ABS kicks in when the brake pedal kicks back violently.

Again, the ABS doesn't activate unless wheel lock is detected. I may brake suddenly, but if the road traction is very good, wheels may not lock at all and ABS won't activate. But in slippery roads, wheels can lock at every braking action, activating the ABS. That is why offroaders don't like ABS at all, it will cause a riot in slushy conditions. High-end offroad vehicles usually have a ABS switch-off option for slippery conditions.

[simplyself]

Originally Posted by suhaas307

Google this topic for more info. Team BHP also has a thread dedicated to the same. Do read up about it and understand the issues regarding the same.

While appreciating the trouble you have taken to touch upon a few points, what I have observed is, getting into neutral a short distance from a speed breaker is indeed a good idea. Engine revs fall to the idling speeds, albeit for only a few seconds. Coasting is not meant to be done while cruising. What I meant is to come to the neutral a few metres ahead of the unavoidable object which necessitates compulsory slowing down. I would strongly advice against coasting in neutral just to reduce fuel consumption, as also when on a decline.

At this stage, though I do love to know about new things, including tips on driving, I, even at the risk of sounding immodest, am not in need to google up for driving tips. Theory is different, Sir, and not all the tips provided are good. Some are downright ridiculous.

[honeybee]

In my experience, braking while the car is in gear and NOT depressing the clutch, is better than braking while the clutch pedal is depressed, whether the braking is gentle or sudden. Not to mention the added advantage that if you can, you can steer away or around the obstacle if the car is in gear and clutch pedal not depressed (yes, while braking!).

I don't understand why people would want to keep the clutch pedal pressed when there's no need. As for downshifting you can wait till the speeds drop to 40kmph or below before shifting down from any gear, and most of the situations being discussed here seem to be well over that speed limit. So you have a precious few seconds in which the car slows down to around 40kmph and you have to downshift. Literally any lower gear would do here, for eg. even the first gear (assuming it's synchro). The only issues with downshifting into the first would be the excessive engine whine and lack of outright acceleration if you had the opportunity to drive away. So literally any gear, the fourth, the third, or the second, could do the job. And then you could use the clutch to control the engine stalling. Is this procedure so difficult that it should only be attributed to a minority of 'experts'?

Pressing the clutch when you don't want to downshift is plain unnecessary. Shifting down every second is plain unnecessary. I hope we can agree on these two points.

[vb-saan]

Wow, in just one day, this thread has changed colours. Highly informative discussion/arguments.

Lot of arguments ‘for’ pressing clutch while emergency braking, but I still cannot figure out how it is beneficial.

Suhaas: I thought you’re much younger