Computers in cars....

Del Lardo · 17 Jan 2005 at 22:10

Originally posted by Entai
But the whole point is that given two identical cars in identical situations the car with ABS will take longer to stop that the car without ABS, even if the wheels lock on the car without ,this is a proven fact and is indisputable.

Please can you explain to me why I am sitting here watching a DVD recorded by Andrew Walsh who

belongs to the top 1% of Department of Transport Approved Driving Instructors

In this DVD he demostrates how to break properly using a Corrardo (VR6 I believe). When breaking hard with no ABS and the wheels locked the car is not under control and the breaking distance is increased. When using ABS breaking distance is reduced by around 1 car length and a further car length when using Threshold breaking.

CaPtBlaCk · 17 Jan 2005 at 22:24

Originally posted by Entai
They have already gone that way.

ABS is already electronically independent if the electronics fail you will have no brakes there is no mechanical link between the brake pedal, and the calipers on the wheels, on any modern car with ABS, it all goes through the pump, if that stops working YOU HAVE NO BRAKES.

Your statement is complete and utter rubbish.

ALL ABS systems are independent of the hydraulic system, therefore failure of the ABS control module, pump or modulator block will not have a direct effect on the hydraulic system.

Arc · 17 Jan 2005 at 22:28

You have to remember that the general numpty in a car will simply hit (stand on) the brakes and hope for the best when their faced with a potential accident and have minimal thinking time. Thats why ABS is fitted.

Same with most other drivers aids. Some (like tc) are needed, its not like you could go out 15 years ago and buy a 200bhp family saloon for the prices you can now. Its brought performance cars to a new target audience.

Its always the same, whatever the mass market wants is what the manufacturers produce, especially in todays so called "safety culture" world.

CaPtBlaCk · 17 Jan 2005 at 22:35

Originally posted by Entai
But the whole point is that given two identical cars in identical situations the car with ABS will take longer to stop that the car without ABS, even if the wheels lock on the car without ,this is a proven fact and is indisputable.

So unless you teach people to steer while braking which is very hard to come to terms with and takes an awful lot of practice to master, cars with ABS are more dangerous than cars without, as they take longer to stop.

Dear oh dear, yet more nonsense.

Not everybody is a driving God, although there seems to be a few in this thread. Whilst in ideal conditions with a driving God behind the wheel, your statement may well hold true. But sadly for the other 99.99% of the population that don't learn to drive on race tracks, and drive whilst tired and distracted and under varying road conditions, ABS will always be the safest option

Entai · 17 Jan 2005 at 22:37

When we test ABS equipped cars they only have to be 80% as efficient (by regulation) as normal unassisted braking sytems, that is they are allowed 20% more room in which to stop the vehicle compared with a non assisted vehicle.
I agree in some circumstances they may actually be better than unassisted systems but most of the time they are not, this is a proven fact.

As for the guy who said the hydraulics are seperate, I would like to ask him if he has stripped and studied more than 100 ABS systems from different manufacturers installed in different cars over the last year or two as I have. I have not come across one system where they are linked.

Bobbler · 17 Jan 2005 at 22:37

Originally posted by CaPtBlaCk
Your statement is complete and utter rubbish.

ALL ABS systems are independent of the hydraulic system, therefore failure of the ABS control module, pump or modulator block will not have a direct effect on the hydraulic system.

I would have thought so too, overwise how come I can still apply brakes when the car is not running? Surely the ABS cannot be on while the car is off?

CaPtBlaCk · 17 Jan 2005 at 22:40

Originally posted by Entai

As for the guy who said the hydraulics are seperate, I would like to ask him if he has stripped and studied more than 100 ABS systems from different manufacturers installed in different cars over the last year or two as I have. I have not come across one system where they are linked.

If that had been the case, then you would know what you are talking about, clearly you do not.

I still stand by what I said ~ YOU ARE TALKING COMPLETE AND UTTER RUBBISH!

moss · 17 Jan 2005 at 22:46

Originally posted by Entai
They have already gone that way.

ABS is already electronically independent if the electronics fail you will have no brakes there is no mechanical link between the brake pedal, and the calipers on the wheels, on any modern car with ABS, it all goes through the pump, if that stops working YOU HAVE NO BRAKES.

My ABS unit has failed on my 106, all thats happend is basically the ABS has stopped working, the brakes still work fine.

edit: misread what you said, its kinda different, my mistake

Simon · 17 Jan 2005 at 22:53

Originally posted by Entai

As for the guy who said the hydraulics are seperate, I would like to ask him if he has stripped and studied more than 100 ABS systems from different manufacturers installed in different cars over the last year or two as I have. I have not come across one system where they are linked.

You have earlier claimed that they are though.

All braking systems use hydraulics, The action of pressing the master cylinder then forces fluid through the system and operates the brakes by pushing on the caliper pistons.

The ABS system will simply block the flow of fluid to the brake which is locked up vby closing the solenoid inside the ABS module. This stops the wheel locking, there is no mechanical pump. And certainly your claim of the 'brake pedal and caliper not being mechanical linked' is certainly false.

CaPtBlaCk · 17 Jan 2005 at 22:56

Originally posted by Bobbler
I would have thought so too, overwise how come I can still apply brakes when the car is not running? Surely the ABS cannot be on while the car is off?

Of course that is the case, each vehicle still has a brake pedal which is directly connected to the brake master cylinder via a rod/linkage and then via hydraulic circuits to the road wheels.

Out of all the new technology on a motor vehicle in the last 20 years, I would state that ABS is the single most failsafe system out of them all.

Simon · 17 Jan 2005 at 23:09

Originally posted by Entai
But the whole point is that given two identical cars in identical situations the car with ABS will take longer to stop that the car without ABS, even if the wheels lock on the car without ,this is a proven fact and is indisputable.

Decent ABS systems will surely be more effective as when a wheel locks up it only reduces the brake force to that wheel, allowing the other 3 to maintain maximum braking.

A non ABS system would require the braking to be reduced on all 4 wheels to stop one wheel from locking.

CaPtBlaCk · 17 Jan 2005 at 23:20

Originally posted by Simon
Decent ABS systems will surely be more effective as when a wheel locks up it only reduces the brake force to that wheel, allowing the other 3 to maintain maximum braking.

A non ABS system would require the braking to be reduced on all 4 wheels to stop one wheel from locking.

Your statement is sadly negated when dealing with driving Gods.

However to the ordinary bod (99.99%) cadence braking is not an option, even if it was far superior to the latest four channel ABS systems which as you state, only release the locked wheel and not all four as with other old as the hills, worked great on Morris Marina’s blah, blah...........

Mickey_D · 17 Jan 2005 at 23:40

Man, oh man I wish my wife's car was running right now.

I would take it out and show every one of you that in a straight line, ABS will take slightly longer to stop a car than cadence braking. Especially in low traction situations like snow or ice.

The ONLY purpose behind ABS is so that you can maintain steering capability while having maximum available braking.

And Entai, normally I'd be right beside you in any argument about cars, but your statement about ABS cars separating the mechanical (hydraulic) link between the pedal and the calipers is wrong. If the fuse blew to the ABS computer on any system you're suggesting, the car would have NO brakes and would become a ballistic steel missile. There HAS to be a completely functioning braking system in place WITHOUT the ABS being operational. There's no way a car would be allowed on the road with a completely "brake by wire" system only.

And no, that's NOT what the emergency brake is for. It shouldn't really be called an "emergency" brake, but more a "parking" brake. But that's another thread.......

Del Lardo · 17 Jan 2005 at 23:48

Originally posted by Entai
But the whole point is that given two identical cars in identical situations the car with ABS will take longer to stop that the car without ABS, even if the wheels lock on the car without ,this is a proven fact and is indisputable.

Originally posted by Mickey_D
I would take it out and show every one of you that in a straight line, ABS will take slightly longer to stop a car than cadence braking. Especially in low traction situations like snow or ice.

I think we all agree that ABS will take longer than Cadence breaking, the disagreement rose after Entai claimed that locked wheels would stop quicker than ABS.

The_Dark_Side · 17 Jan 2005 at 23:53

Originally posted by Del Lardo
I think we all agree that ABS will take longer than Cadence breaking

im still unclear how ABS takes longer to stop than cadence braking when its actually cadencing anyway,just doing it faster than a human being can

Simon · 17 Jan 2005 at 23:57

Originally posted by The_Dark_Side
im still unclear how ABS takes longer to stop than cadence braking when its actually cadencing anyway,just doing it faster than a human being can

Yeah exactly, and it only reduces the force on one wheel and not all of them

ABS is only as good as the 'control system' within it i guess.

moss · 17 Jan 2005 at 23:59

Ive just been doing a little reading on the ABS subject and found this...

http://www.elises.co.uk/components/s2/brakes/

This site claims that no matter what ABS is quicker at braking (Anti-lock Braking System (ABS) section)

http://www.gmfleet.com/us/products/specialized/police/safety/abs.html#2

From what ive read most claim that under normal conditions ABS will almost always stop you quicker but on soft or icey road conditions it can increase stopping distances, this is what ive personally found myself also.

Del Lardo · 18 Jan 2005 at 00:01

Originally posted by The_Dark_Side
im still unclear how ABS takes longer to stop than cadence braking when its actually cadencing anyway,just doing it faster than a human being can

To be honest all I am going on is what I was told when I was learning to drive but I'd imagine modern ABS systems would be somewhat more efficient. Threshold breaking on the other hand......

CaPtBlaCk · 18 Jan 2005 at 00:03

Originally posted by Mickey_D

I would take it out and show every one of you that in a straight line, ABS will take slightly longer to stop a car than cadence braking. Especially in low traction situations like snow or ice.

Mickey, you kind of hit the nail on the head there, in a straight line and low traction conditions.

How many situations involve no steering input and on snow and ice, surely appropriate speed is more important than cadence braking or applying the brakes with such force as to actually operate the ABS?

There are certain circumstances were by method A is better than system C and so on. But apply these to 'real' World situations and ABS will always be the safer option.

Mickey_D · 18 Jan 2005 at 00:15

Originally posted by The_Dark_Side
im still unclear how ABS takes longer to stop than cadence braking when its actually cadencing anyway,just doing it faster than a human being can

Because in a perfect world, a fully functional and properly working ABS system that could interpret every situation it would be called on to perform in would cost about 2500 quid.

No matter what anyone says on here, or what experience they have with systems on cars, the ABS system on a car involves about $25 worth of electronics and $50 worth of hydraulics components and the computing power of these things can be summed up in two lines of code. And the car companies charge us $400 and up for those little add-ons.

ABS systems are supposed to be set up to handle hundreds of possible situations where a tyre may lock, but they don't have the computing power to figure out just which one of these situations they are currently under. All they do is sense that one tyre is turning slower than the others and they momentarily push brake fluid away from that wheel cylinder / caliper. These are binary systems that just react quick enough for us to "think" they are more than that. The system doesn't know if you're on snow or ice and that moderated, non-sudden movements are what's required. It just slaps the pedal back up at your foot and allows it to drop again to the point of locking the tyres. When all that was needed was a gentle nudge to let the wheel start spinning again.

When ABS systems start using a little more computing power than you'll find in a light switch, and the car companies actually start putting $400 worth of equipment in for our $400 worth of payment, I might actually begin to think that ABS is a good idea. Until then, it's a marketing gimmick that fools most people into thinking it's a safety device.