Why do some people say ABS *DOESN'T* shorten the braking distance?

[ndee]

Unless you have the UBER-take-the-foot-off-the-brake-before-they-slide-feeling, ABS WILL shorten your braking distance, right?

 

[iamwiz82]

ABS is designed to help the driver maintain control of the vehicle during emergency braking situations, not make the car stop more quickly. ABS may shorten stopping distances on wet or slippery roads and many systems will shorten stopping distances on dry roads. On very soft surfaces, such as loose gravel or unpacked snow, an ABS system may actually lengthen stopping distances. In wet or slippery conditions, you should still make sure you drive carefully, always keep a safe distance behind the vehicle in front of you, and maintain a speed consistent with the road conditions.

http://www.nhtsa.dot.gov/cars/problems/Equipment/absbrakes.html

 

[zixxer]

Noone said it didn't shorten the braking distance.

ABS increases confidence, and people with ABS statistically follow people closer than people without ABS.

(as in, your car w/ ABS stops in 60 feet, but your false sense of security lets you follow at 30 feet. Someone else who doesn't have ABS stops in 90 feet, but follows at 85 feet.. or whatever..)

 

[Kremlar]

If you're not skilled at avoiding locking your brakes, yes.

If you're on a dry, stable surface, yes.

 

[Zenmervolt]

Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

 

[ndee]

ok, that's what I meant, on dry stable surfaces the stopping distance shortens.

I just got irritated because I read "ABS doesn't shorten breaking distance".

 

[tnitsuj]

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

What he said.

 

[PlatinumGold]

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

thank you. i was trying to say that but i couldn't seem to get it right.

i have two cars with abs, i can induce the abs to activate in wet conditions but usually i can stop without abs.

i've never really induced abs in dry conditions but i suspect that it wouldn't necessarily stop me faster than what i'm capable of doing without it.

 

[ndee]

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

 

[PlatinumGold]

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

abs is grabbing and releasing grabbing and releasing. if you look at the treadmark of a car stopped using abs on dry you will see dash blank dash blank where the abs is activated.

brakes without abs would leave a solid skid mark.

 

[ZeroNine8]

Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

 

[ndee]

Originally posted by: PlatinumGold

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

abs is grabbing and releasing grabbing and releasing. if you look at the treadmark of a car stopped using abs on dry you will see dash blank dash blank where the abs is activated.

brakes without abs would leave a solid skid mark.

yes, I know that they dash-blank-dash-blank. But don't the brakes absorb more energy when they're not sliding?

 

[LAUST]

Originally posted by: ndee
Unless you have the UBER-take-the-foot-off-the-brake-before-they-slide-feeling, ABS WILL shorten your braking distance, right?

Not ALWAYS

 

[LAUST]

Originally posted by: ndee
ok, that's what I meant, on dry stable surfaces the stopping distance shortens.

I just got irritated because I read "ABS doesn't shorten breaking distance".

oh you mean like this?

In what circumstances might conventional brakes have an advantage over ABS? There are some conditions where stopping distance may be shorter without ABS. For example, in cases where the road is covered with loose gravel or freshly fallen snow, the locked wheels of a non-ABS car build up a wedge of gravel or snow, which can contribute to a shortening of the braking distance.

Okay you be "Irritated" I'm going to go ahead and just get PISSED!!! when people think that some feature on their car is going to automatically make them think they are covered.

 

[ndee]

Originally posted by: ZeroNine8
Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

but couldn't ABS be made that one thousands of a second before the tires start to slide, they release the break a little bit?

 

[DougK62]

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

Why WOULDN'T it increase stopping distances? ABS is just a computer pumping the brakes - just as a person with a non-ABS car would pump the brakes manually. Do you really think that letting OFF of the brakes is going to give you a shorter stopping distance than if you just stay on them? It just doesn't make sense.

 

[Zenmervolt]

Originally posted by: ndee

Originally posted by: PlatinumGold

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

abs is grabbing and releasing grabbing and releasing. if you look at the treadmark of a car stopped using abs on dry you will see dash blank dash blank where the abs is activated.

brakes without abs would leave a solid skid mark.

yes, I know that they dash-blank-dash-blank. But don't the brakes absorb more energy when they're not sliding?

ABS releases the brakes _completely_ when it pulses. So those "blank" areas are when the car has _zero_ braking force.

ZV

 

[ndee]

Originally posted by: LAUST

Originally posted by: ndee
ok, that's what I meant, on dry stable surfaces the stopping distance shortens.

I just got irritated because I read "ABS doesn't shorten breaking distance".

oh you mean like this?

In what circumstances might conventional brakes have an advantage over ABS? There are some conditions where stopping distance may be shorter without ABS. For example, in cases where the road is covered with loose gravel or freshly fallen snow, the locked wheels of a non-ABS car build up a wedge of gravel or snow, which can contribute to a shortening of the braking distance.

I read that this "build up a wedge of gravel or snow" was a myth.

 

[ndee]

Originally posted by: Zenmervolt

Originally posted by: ndee

Originally posted by: PlatinumGold

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

abs is grabbing and releasing grabbing and releasing. if you look at the treadmark of a car stopped using abs on dry you will see dash blank dash blank where the abs is activated.

brakes without abs would leave a solid skid mark.

yes, I know that they dash-blank-dash-blank. But don't the brakes absorb more energy when they're not sliding?

ABS releases the brakes _completely_ when it pulses. So those "blank" areas are when the car has _zero_ braking force.

ZV

oh, not only releasing it a little bit, so far that you stop slidding? That's what I thought would ABS work.

 

[ndee]

Originally posted by: DougK62

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

Why WOULDN'T it increase stopping distances? ABS is just a computer pumping the brakes - just as a person with a non-ABS car would pump the brakes manually. Do you really think that letting OFF of the brakes is going to give you a shorter stopping distance than if you just stay on them? It just doesn't make sense.

if you slide, breaking distance increases.

 

[Zenmervolt]

Originally posted by: ZeroNine8
Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

Yes, this is faster, everyone knows that. But fully locked brakes are actually better than ABS under some conditions. That's the point I was making.

ZV

 

[Zenmervolt]

Originally posted by: ndee

Originally posted by: ZeroNine8
Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

but couldn't ABS be made that one thousands of a second before the tires start to slide, they release the break a little bit?

Not without somehow knowing the exact amount of traction available at that instant. That's something that cannot be programmed into the computer or even truly monitored.

ZV

 

[ndee]

Originally posted by: Zenmervolt

Originally posted by: ZeroNine8
Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

Yes, this is faster, everyone knows that. But fully locked brakes are actually better than ABS under some conditions. That's the point I was making.

ZV

ah ok. Under some circumstances ABS is shorter, under some longer, right?

 

[ndee]

Originally posted by: Zenmervolt

Originally posted by: ndee

Originally posted by: ZeroNine8
Actually you can stop a car faster if you don't lock up the brakes because tires, like most things, have higher static friction than kinetic friction. By keeping the tires just on the verge of breaking loose from pavement you will have greater stopping force than just locking them up. ABS works better than non ABS for the average driver, however it is possible to stop faster without ABS for skilled drivers who know how to keep the tires closer to that break point. The other big thing, as was already said, locked up tires don't allow any real steering, so you essentially have no control while skidding.

but couldn't ABS be made that one thousands of a second before the tires start to slide, they release the break a little bit?

Not without somehow knowing the exact amount of traction available at that instant. That's something that cannot be programmed into the computer or even truly monitored.

ZV

I see, I thought it could

 

[DougK62]

Originally posted by: ndee

Originally posted by: DougK62

Originally posted by: ndee

Originally posted by: Zenmervolt
Because it doesn't. It increases stopping distance in favor of keeping control. Fully locked brakes actually stop a car very quickly on dry pavement, but you don't have any control while that is happening which is a very bad thing. ABS very slightly increases stopping distance under _most normally encountered conditions_ in favour of allowing the driver to maintain control. This is a good tradeoff for most people.

ZV

why would it increase stopping distance? Because you don't "slide"?

Why WOULDN'T it increase stopping distances? ABS is just a computer pumping the brakes - just as a person with a non-ABS car would pump the brakes manually. Do you really think that letting OFF of the brakes is going to give you a shorter stopping distance than if you just stay on them? It just doesn't make sense.

if you slide, breaking distance increases.

Well I'm just going to give you a big "DUH" on that one. Where did I say anything about sliding?