[Suess]

Originally Posted by Thad E Ginathom

Your dad knew how to get it into your head! Never depress the clutch when braking, except to actually slow down, or just before stopping. If it is an emergency stop, no time for gear change, let the engine stall rather than touch that clutch.

In case of emergency braking, you should slam the clutch n brakes together!IMHO.

[longhorn]

Originally Posted by vina

Wouldn't engine stalling be bigger trouble than it is worth - I mean wouldn't you lose both the power steering and power brakes? Most of us don't have any experience steering/braking without the assistance provided by the engine power so I'm not sure it is a good idea to have a stalling engine - can you tell more.

By the way, by the time engine starts to complain about stalling, speed will be so low engine anyway can not help you brake (in fact once the rpm is that low it'll try to make the car move) - I guess depressing the clutch will not harm

Firstly to stall you engine you should be in a gear other than neutral. The stalling will happen when you are moving too slow as there is no pressue given to the accelerator and are almost going to reach a complete halt. So no issues w.r.t. power steering /brakes.

[vina]

Originally Posted by longhorn

Firstly to stall you engine you should be in a gear other than neutral. The stalling will happen when you are moving too slow as there is no pressue given to the accelerator and are almost going to reach a complete halt. So no issues w.r.t. power steering /brakes.

I don't think that is true, in an emergency braking situation in the fifth gear in a Figo engine will stall around 28kmph (roughly 700rpm) and at that point you still need the power brakes and the power steering to get out of the way of vehicles coming towards you on the rear and in front (stopped vehicles or vehicles swerving in your lane, or incoming vehicle who decides your lane is made for him to overtake)

[rki2007]

Originally Posted by Suess

In case of emergency braking, you should slam the clutch n brakes together!IMHO.

Holding the clutch and brakes is not that efficient. To control the speed of the car, braking in the existing gear or shifting down and braking is more efficient. What i do normally is that just brake in the existing gear and if possible continue or if required shift downwards and to stop the car to still obviously clutch+ brake.

If at all it is totally an emergency situation then slamming the clutch and brake is the only option.

[lucifer1881]

I agree with Thad. Clutch is a strict no-no when it comes to emergency braking. You will not stall the engine if you use the clutch, but you will definitely hit whatever it is you are wishing to avoid. Ideally this is what one must do:

1. Slam the brakes.
2. Press the clutch. If in fifth / sixth / top gear, downshift to third or even second if the gearbox allows it. Do this as quickly as possible.
3. De-press the clutch.

The engine will stall. The car will come to a complete halt in less than half the distance needed otherwise. The brake vacuum reserve holds enough for two full applications. So don't worry about losing brakes in case the engine stalls. Power steering will go. But that really is not that much of a problem. It will take effort to turn the wheel. That is all.

[Thad E Ginathom]

Originally Posted by Suess

In case of emergency braking, you should slam the clutch n brakes together!IMHO.

Originally Posted by lucifer1881

I agree with Thad. Clutch is a strict no-no when it comes to emergency braking.

It's a no, no, NO, and our instincts should be trained to this, as, in any real-emergency stop what we do will be mostly instinctive, with no thinking time. Emergency stop is a one-foot job.

It is not only a case of needing every ounce (or even milligram!) of help to actually stop, but the engine braking contributes to the stability of the car, and it is more likely to remain under control.

Power steering: forget it, unless driving a truck. We don't need it anyway. Not relevant.

[Suess]

Originally Posted by Thad E Ginathom

It's a no, no, NO, and our instincts should be trained to this, as, in any real-emergency stop what we do will be mostly instinctive, with no thinking time. Emergency stop is a one-foot job.

It is not only a case of needing every ounce (or even milligram!) of help to actually stop, but the engine braking contributes to the stability of the car, and it is more likely to remain under control.

Power steering: forget it, unless driving a truck. We don't need it anyway. Not relevant.

"from lucifer1881:
..The brake vacuum reserve holds enough for two full applications. So don't worry about losing brakes in case the engine stalls. Power steering will go. But that really is not that much of a problem. It will take effort to turn the wheel. That is all."

you may be right when we are talking about the cars without ABS..but if you want to use ABS effectively, you should be pressing both clutch and brakes with full force together. stalling the engine will affect the power and electronics of car ABS/EBD.

in case of cars without ABS, i would also suggest to press clutch but only at the last moment of emergency braking.so, first brakes only and then just before the car stops press the clutch.

[dhanushs]

Originally Posted by Thad E Ginathom

Power steering: forget it, unless driving a truck. We don't need it anyway. Not relevant.

Hydraulic power steering still work as long the vehicle is moving and in gear. (Meaning crank shaft rotating)

Originally Posted by Suess

.. you should be pressing both clutch and brakes with full force together.

Not a good idea. The part of engine in emergency braking is not only provide power assistance, but in FWD cars, it provides better control than braking without it.

This is why you have to downshift simultaneously. So that the car does not stall till low speeds, and you have assistance from the engine.

[Suess]

Originally Posted by dhanushs

Not a good idea. The part of engine in emergency braking is not only provide power assistance, but in FWD cars, it provides better control than braking without it.

This is why you have to downshift simultaneously. So that the car does not stall till low speeds, and you have assistance from the engine.

Actually, i think the discussion started about emergency stop/braking..so, in that case you wont be having time for down shifting or anything else.

on straight line for emergency braking, your goal is to stop the car in minimum distance..and that is best achieved with full braking. and also, not stalling the engine is important because we might need to steer away too to avoid collision. so the clutch!

[Thad E Ginathom]

Originally Posted by Suess

you may be right when we are talking about the cars without ABS..but if you want to use ABS effectively, you should be pressing both clutch and brakes with full force together.

Again, no. This is a serious misunderstanding that could be dangerous

stalling the engine will affect the power and electronics of car ABS/EBD.

I don't think that is true. Most of us stall a car once in a while. Even if it is true, when you are about to kill someone, or smash your car up anyway, who cares? We are talking about emergency stops.

For less-than-emergency heavy breaking: it is still a one-foot job, except one probably has time to change down.

[Suess]

Originally Posted by Thad E Ginathom

Again, no. This is a serious misunderstanding that could be dangerous
I don't think that is true. Most of us stall a car once in a while. Even if it is true, when you are about to kill someone, or smash your car up anyway, who cares? We are talking about emergency stops.

For less-than-emergency heavy breaking: it is still a one-foot job, except one probably has time to change down.

I fully agree with the heavy braking being an one-foot job in less-than-emergency situation. But i wanted to point out that when we are braking in emergency we want our car working properly(not stalled or turned off). That will help in avoiding the collision becasue it's not always necessary that car will stop before hitting the obstacle. on the other hand, in case of slippery road(wet/ice/snow/oil) engine braking can put the car in skidding.

(in fact you will fail the driving test if you stalled the car during "Emergency Braking Test"!..at least that's how it is in Germany. it will stall if don't press the clutch at right time...and i think because in emergency situtation you are not in the position, usually, to find that "right time" so, press the clutch and brake together!)

Actually, when you have floored the brake padel, all wheels stops moving(rotating) so, i don't think engine braking will be of any use anyway. Braking shouldn't be confused with engine braking (which is primarily used to slow down not to stop..essentially a brake function.). in fact you will be needing more power through braking system because car engine is still providing power to wheels! (remember more powerful engine requires more powerful braking system).

[Thad E Ginathom]

We disagree. I am almost certain (it's been quite a while since I did it) that hitting break and clutch for an emergency stop would fail you in a UK test.

Engine breaking is less likely to cause skidding, due to not throwing the weight forward.

There's nothing wrong in hitting the clutch at stalling point, but, with that child a few metres in front of you, you hope you have stopped before you had time to even think about it!

Afterthought...

Of course, stalling is not ideal. Ideally, we would declutch before stopping. I don't mean to argue that point; my point is that the, whatever, we should not declutch before that point, and that, in a real emergency, stalling is the least of our worries. Yes, in a UK driving test, they would expect you not to stall.

Lets look at this way:

Stalling: not perfect.

Declutching before or at the same time as braking: wrong and dangerous

[longhorn]

In an emergency situation, the only thing you should do is to slam the brakes as hard as possible and control your direction with the steering. This will come as a reflex action mind you. You won't even remember that there is a clutch pedal (assuming it to be a reflex action). I disagree on pressing the clutch part. I'd say forget the stalling part as your aim is to bring the car to a safe halt in the minimum distance and disengaging the clutch will not do any good to reduce the stopping distance, far from it. Loss of power steering is a non issue unless you are driving a truck. You will be able to turn the steering as usual with a bit more effort at most as long as the car is in motion. The only issue will be for vehicles equipped with hydraulic braking system.

[vina]

Originally Posted by longhorn

... Loss of power steering is a non issue unless you are driving a truck. You will be able to turn the steering as usual with a bit more effort at most as long as the car is in motion. The only issue will be for vehicles equipped with hydraulic braking system.

While I agree that every car owner must practice braking without pressing the clutch (thus training his reflexes) - anybody who habitually presses clutch while braking will do so (without realising) even in emergency situations.

Coming to steering being a non issue - the steering becomes hard the moment power steering is lost. In emergency situations this will only serve to confuse the driver probably increasing the chances of accident in case steering was needed in the first place - you want the driver's attention on the road not on the confusion that is created.

The same will happen to gear shift - when your mind is grappling with a sudden possibility of mowing down a child I'm not sure it'll remember to shift any gears at all.


For diesel cars (perhaps not petrols) at least once you are at stall speed, engine will do the opposite of braking - it'll try to mave the car forward. This is thanks to the huge torque generated. I have seen this happen in 3rd gear on my car - speed becomes stubborn and deceleration is lost once rpm goes below 1000, unless I press clutch.

Also in diesels (may be petrol too - but may be not) once you reach stalling speed in high gear, even if you downshift, the engine braking you gain is insignificant - speed is already too low.




the most common example everyone is giving - that of a child in front - is not always relevant. If you do see children on the road and are still driving too fast then the best advice is - learn to drive responsibly. If the child shows up suddenly then in most cases swerving out is the best response - and you don't want the car to stall. If swerving is not possible due to any reason then you go straight line anyway and forget steering start praying.

In addition child in front is more of a way of shutting up your critics - if you believe in your thesis give more relevant example - like an idiot biker taking an announced sharp turn right in front of your car (and without him having wife and kid riding pillion) - that is relevant enough for the discussion and doesn't bring in "you should do everything to save kids" factor - let's leave that for advertising folks.

[Suess]

Originally Posted by Thad E Ginathom

We disagree. I am almost certain (it's been quite a while since I did it) that hitting break and clutch for an emergency stop would fail you in a UK test.

Engine breaking is less likely to cause skidding, due to not throwing the weight forward.

There's nothing wrong in hitting the clutch at stalling point, but, with that child a few metres in front of you, you hope you have stopped before you had time to even think about it!

Afterthought...

Of course, stalling is not ideal. Ideally, we would declutch before stopping. I don't mean to argue that point; my point is that the, whatever, we should not declutch before that point, and that, in a real emergency, stalling is the least of our worries. Yes, in a UK driving test, they would expect you not to stall.

Lets look at this way:

Stalling: not perfect.

Declutching before or at the same time as braking: wrong and dangerous

In UK they are asking you not to use clutch when emergency braking becasue they also asking you not to press brake too hard so, you don't lock the wheels. so, when you ease the brake padel a little to come out of locking your engine can help in rotating the wheels again. but as Vina said when you speed is reduced to quite low as in emergency braking situation, there won't be any engine braking and further in case of diesel engines engine braking is anyway insignificant. So, engine braking is not reason for it.

See, as you said yourself you did it (UK Test, i guess) long back, this practice might be good and true when there was no ABS. But with ABS you don't worry about wheel locking. so, you apply the as much as pressure on brakes using your upper body(pushing it to back of your seat) and simulatenously you press clutch so, you don't have to worry about "that last moment i.e. stalling point" when you have to press clutch.

UK driving test also want you "not stall the car" as you mentioned, so my point is, you should not be thinking anything else then stopping and also steering away if need arise in case of emergency braking. that's why ABS/EBD and valuable innovations, you won't be worrying about stalling point, wheel locking, easing brake pressure etc. when emergency arrives.