what is coasting in the context of driving?

synchro

what is coasting in the context of driving?

djmarkus

synchro wrote:

what is coasting in the context of driving?

Going downhill in neutral so no fuel is used.

Coconut

As far as I remember from pre-driving test days, its travelling with the clutch down. For example, if you're slowing down, but put the clutch down much earlier than you need before braking.

(But, er, thats open to correction!)

jor el

Having your foot on the clutch while the care is in motion. Removes the drive force from the front wheels and also moves the center of gravity away from the front of the car. Bad thing to do in general. Probably better off in the motors forum too.

aodh_rua

djmarkus wrote:

Going downhill in neutral so no fuel is used.

The engine is still running so fuel is still used. As the other posters have metioned it means driving with the clutch down. Along with the problems already listed, you also have less control as there is no power going to the wheels.

synchro

thanks ppl

sprinkles

jor el wrote:

Having your foot on the clutch while the care is in motion. Removes the drive force from the front wheels and also moves the center of gravity away from the front of the car. Bad thing to do in general. Probably better off in the motors forum too.

I don't think putting the clutch down can alter the center of gravity, excepth for the fact that a small piece of metal has moved slightly lower, thus lowering the center of gravity minutely. The COG is to do with the shape of the object.

As has been said:

Coasting=clutch down or in neutral.

Boggle

I don't think putting the clutch down can alter the center of gravity, excepth for the fact that a small piece of metal has moved slightly lower,

It's more to do with where the force is coming from - coasting is moving purely on the cars own momentum while normally the car would be propelled/slowed by the drive wheels thus altering the centre of gravity albeit very slightly...

stevenmu

In a front wheel drive car, which most cars on Irish roads are, a lot of your grip comes from the force put into the front wheels by the engine, giving you better control of your car. If you coast into a turn you not only have less grip in your front tires, because the cars momentum is trying to push against your turn without any energy from the engine to pull it the direction you want to go, the cars weight also gets pulled to the front side away from the turn as you slow down giving you less traction in the back aswell.

RobertFoster

I was told 2 days ago it was travelling for more than 2 car lengths with the clutch down.

Red Alert

if you leave your foot on the clutch a lot to 'smooth' out driving you'll also burn the linings in your clutch - don't do it!

Lump

Driving with the clutch in... big no no when it comes to your test.

John

Sparky

the only time i ever used the clutch in when driving is to either stop when using the brake or to slow me down by using the gears.

Lump

SO you don't use the clutch when changing up the gears.... you'll really nacker your gearbox.

John

Wez

On bikes you can change gears up without the clutch.. It doesn't damage it at all if done right, meaning don't change from 1st to 2nd without the clutch.

Mercury_Tilt

This post has been deleted.

Sparky

Lump wrote:

SO you don't use the clutch when changing up the gears.... you'll really nacker your gearbox.

John

yeah sorry it was blatintily (sp?) obhious of a mistake that i forgot to say that aswell


So thats why its so noisy a 10mph

JackieChan

Did my driving test 3 years ago and passed but the tester did say to me to watch my coasting(when coming to a stop), he says it gets worse as you get older. Funny enough I don't do it anymore

Chalk

JackieChan wrote:

when coming to a surprise

how do you know when your coming to a surprise?

kluivert

Just a note to point - you use up less fuel in modern cars if a coast to a stop with the clutch pressed down than simple putting the car in neutral.

Proven fact especially with deisel cars.

GreeBo

Sparky_S wrote:

slow me down by using the gears.

tsk tsk tsk, very bold.
shouldnt do that, you are not in "full" control of the car.
Use the brakes to slow down, thats what they are for.
You'll also get rid of that big, dirty, amateur sounding rev that you get from slowing down your way as he engine tries to cope with the rev change.

saobh_ie

Shouldn't brakes and engine breaking aren't mutually exclusive, I would have though both should be used. On my bike I generally just use engine breaking, with a little front and a little back just to tweak the speed and to active my brake lights, most important.

Engine braking is evil if you don't have your break lights, especially if you shut the throttle or take your foot off the accelerator and your bike/car slows really fast without any external indicators.

However on twisty country roads you should use gentle engine breaking without brake lights to prepare you for the corners, we've all been behind people who slam on the brakes at every bend in a country road. Then the thirty fourth time he does it you just shake your head, "What a mupp... oh wait he's stopped... Argh!!!!" before you slam into him because he's stopped for some cows.

As regards coasting, it reduces your ability to control the vechile. If you need to stop suddenly the engine braking avalialbe might stop you a meter or two shorter than brakes alone. But if you find yourself in a position where you need shift your ass and fast you've got to clutch out and gas on at the same time, then your engine has to get back in synch with the wheels. If you hadn't been coasting your gearing, engine speed, wheel speed would have been ready so that when you put on the power the vechile would respond.

I think...

Also somebody mentioned cornering when coasting reduces grip. It makes sense to me but on Irish roads with irsh cars?. Your grip is used for going around corners, accelerating and decellerating. Obviously all three can't be done at the same time otherwise the universe would end but do too much of the other two at the same time cornering and accelerating or cornering and decellering in certain road conditions and your in trouble.

This possibly relates more to high performance vechiles than the average family car whose engine and gearing which probaly couldn't spin itself out on ice if the driver was trying. But essentially if your coasting around a corner there is no power to the wheels. No braking force, no accelerating force from the engine, but your also lacking constant even power which stops other forces from slowing you down.

However we don't drive that fast in this country, the roads don't allow us. Although the roads don't provide much grip at all do they in certain places so maybe it is a little relevant...

...that is if anyone can decode it?

stratos

Just a few things I disagree with here.
I don't believe front wheel drives gives you better control of a car.
If a car is front wheel drive you can only steer with the front wheels.
If a car is rear wheel drive you can steer with the rear wheels too using the throttle.
You might say ok this only for boy racers, but I can speak from experience. my car aquaplaned/understeered unexpectantly one evening on a bend.
Luckily being a rear wheel drive car. I was able to stomp on the throttle and pull the rear of the car around, thus avoiding a stone wall.

Engine braking is quite acceptable and gives you better control of the car as well, It saves your brakes from overheating which leads to fade as the pads aquaplane over the discs on their own gases.

clutching or even changing gears in a bend can be dangerous.
a cars theoretical weight shifts as it drives, during acceleration the weight is at the back over the rear wheel (a reason front wheel drives can spin their wheels so readily at take off).
The weight moves to the front under braking (front brakes do most of the work as the weight is over the front axle).
As you are driving through a bend the weight of the car is shifted over the rear wheels, this actually helps the rear tyres grip.
Lifting off the throttle or clutching, suddenly unloads the rear wheels and sends the weight forward, do this at a fast enough speed in a bend and you will spinout.
I personaly don't like coasting ever, it even feels uncontrolled.
By the way the next time your stopped at a junction waiting to turn right with your wheels turned and your foot on the clutch and your car in first.
Think about this, what would happen if you got rear ended.
Your foots gonna come off the clutch, and pitch you into oncoming traffic.

Sorry about long post.

SouperComputer

If a car is front wheel drive you can only steer with the front wheels.

tis OT: But incorrect you can use power and of course the handbrake to contol the rear of the car with FWD, depending on the situation.

Engine breaking can be handy, but there is a good reason for heel/toe in performance driving.

Stratos, I think you need to lay off the GT4. There are some gross simplifications with your physics there!