I need some help with this one ..

At a party last night with my family with the usual mixture of guests and .....

The ABS debate cropped up (as these things do in the kitchen at parties...) a very large debate inssued with the most of the men and a couple of women taking part .... ABS brakes, a good or bad thing ?? was basicly the debate ... Am I correct when I stated that with ABS ...

a. Your stopping distance is increased slightly ?
b. When you have to use them for real, you stand on them and let the ABS system sort it out while you get on with the business of avoiding the accident .. rather than lifting-off and re-applying to avoid a skid ( a contensious issue last night I can tell you !)
c. In snow it's actually a bad thing to have ABS as the snow build-up that occurs at the front of the tyre normally doesn't with ABS so harder to stop ?

One of the guys there was on the design team for Dunlop who invented an anti-jacknife sytem for trucks in the late 70's and early 80's and knew his stuff, he was adamant you lift-off and re-apply in a hard braking situation to avoid the use of ABS ?? I thought this was with traditional non-ABS systems ?? This went on for over 2 hours on and off everytime I went back for a top-up I got pulled into the debate as "you have a performance car" ?

This might be question for Simon our resident "Oracle" on the subject of car control ....

Kev

 

Hmmmm,

The stopping distance may get longer, but usually with ABS the disks all round will have improved the stopping distance a great deal anyway !

The whole point of ABS is to stop you having to cadence brake, ie lift off and reapply, the ABS system does this all for you, you just plant the brake pedal to the floor and then try to avoid the incident !

This is the way i understand it, usual disclaimers apply !

 

ABS doesnt stop you in snow as you have said due to the lack of build up by the wheels, its also like any other safety device, your not meant to use it to reduce your risk of skidding or braking, if it kicks in then your too close or have ***** up.
I think all cars with abs have also got disks all round so your brakes are better than some other cars that dont (astra mk4 for instance)
Too many people take abs for granted nowerdays, it is good and was developed for aircraft years ago, it can save your car from getting crunched too, but its still a combination of disks, pads and tyres that has more affect on your stopping.

(ps if this sounds cr@p its cos i need some sleep )

 

Tony, yep, i dont think i have ever activated the ABS on either of my scoobs !

 

I think Tony's right. Most cars these days have ABS and yet there is no requirement to learn how to use it properly. I did a driving course a few months ago where I was taught to use ABS. I can say that you do not lift and reapply. Once you're in a situation that requires ABS - you keep it applied.

The biggest mistake people make (myself included before the training) is to brake and steer at the same time. All this does is upset the balance of the car, making it much more difficult to control.

When you apply ABS, stay in a straight line and then steer to avoid the obstacle. This takes time to get used to because your natural reaction is to try and avoid the obstacle in your path. The difference though is staggering - you keep complete control of the car and you can stop safely.

There are situations where it will not benefit you (ice and snow etc) and it is not so good if you are on a race track, but having now been taught to use it properly, I would not buy another car without it.

Chris

 

Hi

As were on the ABS debate got a question, is it my imagination or does scooby ABS come on really early.

Thanks
Simon

 

Cars do not have disc brakes on the rear to reduce stopping distances but because they increase the ability to loose heat so the brakes can perform numerous stops without fading.

For example the handbrake on the Impreza operates a small drum inside the rear disc.This tiny drum is more than capable of locking the rear wheels even at high speed however it would overheat if you tried to use it to stop from 90 mph.

Or to put it another way the Impreza Turbo would need very large drums to be able to disapate the heat thats generated and the weight/cost/performance makes discs a much better option.

As to weather ABS is good for a road car pull the fuse and see for yourself,you will be shocked at just how much better the car is with ABS,I certainly was.

Surprisingly the benefit was not shorter stopping distances in good conditions but was that the car remained much more controlable in average/bad conditions.

I tried stopping on a piece of dual carriageway with a fair bit of camber.With no ABS the car slid down towards the curb very fast and also went sideways. With the ABS it stopped in a dead straight line.

Down bumpy country lanes the wheels locked easily over bumps and again the car slid towards the ditch.By the time I released and reapplied the brakes I travelled miles further than with the ABS on.

Also with no ABS I couldn't brake hard as quickly for fear of locking the wheels, with the ABS you hit the pedal as hard as you can as fast as you can so you gain a fair bit as you first start to brake.Most drivers don't do this.

It was Mercedes that discovered most people apply the brakes slowly even in an emergency situation so they developed a system called brake assist.This monitors how you normally brake and if you suddenly brake harder than normal the computer put the brakes full on for you.Apparently this makes a big difference to stopping distances especially at slower speeds(where most pedestrians are run over).

Modern ABS also has the ability to adjust each wheel independantly which has a lot of benefits.
It also measures weather you are stopping in a straight line or in a curve,and adjusts the rear brake force accordingly to keep the car stable whilst increasing the effort at the rear.

Everybody likes to think they are very good drivers and therefore do not need things like ABS but the truth of the matter is that ABS has many benefits and will be much better in the vast majority of situations than the unaided driver.

IMHO the difference between a car with and without ABS is a bit like the difference between an Impreza and a TVR down a wet country lane in the middle of the night.I know which one I would prefer to be driving.

Andy

 

<B>As to weather ABS is good for a road car pull the fuse and see for yourself,you will be shocked at just how much better the car is with ABS,I certainly was</B>

So with a little bit of wiring work and giving the bright button a new name (lockup switch) we can put a smile on thoose track day faces .

Simon (going to bed now honest)

 

so am I

 

I use to work for Ford motor co. (thats why I have a Subaru WRX) and thought I would check with a friend in the R&D department who has knowledge of this area and heres what he said:-

a. Stopping distances are shorter in the wet AND in the dry but like TonyB and the Subaru manual says (c.) snow gives a longer stopping distance, but then you shouldn't be going that fast in snow really (unless your Richard Burns).

b. ABS only works to your advantage if you push the pedal down and hold it down till the car comes down to the speed you require. If you push and release the pedal and reaply then your stopping distances will be longer because your breaks will never really retard your speed enough.

as an aside to this when ABS was first introduced in to America many drivers were driving there cars off bridges and the sides of the road because with ABS you should still be able to steer and control the car under sever braking.

Trev.



[This message has been edited by tizard99 (edited 23 October 2000).]

 

I'm sure for all those who understand the nuances of cadence braking etc ABS is bad news.

But for us ordinary mortals it is a God send.

I have had the misfortune to be involved in 2 situations in the last year where, if it weren't for ABS I think I'd be history now, one in a Focus and one in the Scoob.

On each occasion someone pulled in front of me on a wet road, whilst I was doing legal, but high speeds. Both times I was able to steer round them. I dread to think what would have happended in a non ABS car.

Cheers

Simon

 

<B>a. Your stopping distance is increased slightly ?</B>

depends on the spec of the system, the early ABS systems were poor compaired to a skilled driver, the current multi-chanel systems are very good for road use, can be a pain for track driving as some drivers find benefits in using the brakes to balance the car, sometimes ABS makes this dificult. They banned ABS in F1 for a reason, the modern stuff is very impresive.

<B>b. When you have to use them for real, you stand on them and let the ABS system sort it out while you get on with the business of avoiding the accident .. rather than lifting-off and re-applying to avoid a skid ( a contensious issue last night I can tell you !)</B>

Keep it planted, do not let off. It feels weird as the pedal continues to drop and pulse, just keep the presure on.

<B>c. In snow it's actually a bad thing to have ABS as the snow build-up that occurs at the front of the tyre normally doesn't with ABS so harder to stop ?</B>

ABS in snow is deadly IMHO, there should be a switch on the dash to disable it, you get far more braking control without it in these conditions.

ABS is fitted to cars with disk or drum brakes, My Impreza Sport has drums on the rear and ABS.

I prefer driving cars on the road with ABS and on track without ABS. For the average driver it is a huge help. For the above average driver it is too in road driving as most good drivers in an emergency will probably still panic and lock the wheels.

 

a) The early systems weren't as good as a skilled driver, hence these rumours about ABS still circulate today.

b) Step on the brakes as hard as you can and STEER! The Dunlop system might have worked differently, but all modern systems react to a single press on the brakes. If Mr. Dunlop still disagrees, just take him out on a wet road and show him!

c) Some Audis used to have a switch to disable ABS when on snow/loose gravel. I think the problem is that most drivers would forget to switch it back on.


Skilled or not, a driver cannot control the brakes with the same accuracy as a modern ABS controller because ABS can independently adjust the braking force to each wheel. Moving the brake pedal affects all four wheels at the same time.

 

Hi All

Don't know how I missed this one!!

I have only read the first few posts, so forgive me if this has already been covered but...

Braking Distance.
The older versions of ABS definately increased the distance it would take a skilled driver to stop a car. Some of the more modern however ones are unquestionably superior to any human being in road car.

The main reason for this the introduction of independent 4 wheel ABS. This means that each wheel can be braking at (almost) it's optimum braking at ALL times during the stop.

The problem with non-ABS road cars (my Type R included) is that the brake set-up includes lots of front brake bias. The reason for this is that most people find it far more challenging to control a car with rear brakes locked. Therefore it is safer to lock the fronts (this is not always the case however).

The upshot of this is that the rears don't do nearly as much work as they could.

In a competition car you often have a brake bias control which alters the bias of the brakes front and rear. It is staggering what a difference in braking you get by moving the bias back even a couple of percent.

------

Having said all this, the main reason for ABS is not stopping distance reduction, it is for the reduction of skids....

It is true that deep snow and gravel pose a problem for ABS as the "digging in" effect causes the main part of the braking on loose surfaces, but, ABS will still do it's main job of helping you to avoid a skid. It just won't stop you!!!

There is no benefit in cadence braking with ABS that I can think of.

True perfection in stopping without ABS does not require cadence braking anyway...

The only way a human could beat modern top of the range ABS would be by a highly skilled driver left foot braking in a rear wheel drive car with enough rear brake bias to lock the rears under normal circumstances...

The reason for the LFB is that you can use the throttle to alter the effective brake balance of the car all the way through the braking zone.

Cheers

Simon

PS. Kev, you are too kind re the 'Oracle' thing . Anyway, I am a Microsoft man through and through

 

Even if it was possible for a highly skilled driver to stop more quickly without ABS (on track testing for example), I doubt even the same driver in the same car would be able to repeat that feat if he was braking from high speed on a wet road (maybe leafy and greasy as well) while approaching a large tree for example. Just try not to lock up in that sort of situation! Try having to steer at the same time and it's even more difficult. That's why it's much safer to have abs on road cars, even for very skilled drivers.

 

agreed

 

I dont have ABS on my Type RA to my cost at the weekend. Lack of concentration (babies in the back), turned back round and the car in front had unexpectedly stopped - After lots of driving training, I still just stamped on the brakes - idiot ! - nice imprint of man's tow bar right through the grill and radiator !!
I have had ABS for about 8 years until now and have perhaps got complacent, but unless you are as good as Mr Schumacher, then I suggest it is best.

 

Thanks all ..

Thought I might get Simon's input somewhere in the thread I've just printed the thread out to pass on to my old man to show his cronnies !!

I might of been wrong on one or two but eh .... I'm human, at least we all agree on the two most important, bury the pedle and let the sytem sort the braking while you concentrate on avoiding the obstruction etc and the snow issue.

I agree with DavidRB, I'd have taken him for a spin down a damp lane and prooved the point but as I'd drunk a few large glasses of "The Dogs B*****ks" wine I thought better not.

On an interesting close, I had to use the ABS system today down a long open private drive, I got a bit carried away and as I approached the main enterance to the site a car nudged out and I had to take two wheels to the nice fancy turf under heavy braking, interesting with two wheels on tarmac and two on grass .... stopped brilliant, no fuss, no back stepping out etc just stopped ....... did'nt even chew-up the fancy lawn ...... much

K

 

I had a nasty near miss Saturday just gone. Going up the A329(M), as I came upon the slip road joining from the large Wokingham roundabout, a Sierra decided to pull out in front of me. Although I had slowed down for the hazard of a slip road, I was still pressing on (late for a wedding, but no excuse for speeding). Anyway, just as I thought the Sierra was going to stay in the left hand lane, he swerved (as opposed to normal lane changing) in front of me and I had to slam on the brakes very hard. As I have a MY93 WRX, I don't have ABS, and locked up quite badly. I can't quite remember how I regained control, but I managed not to hit him, or totally lose it - but it was close to being a big accident. Having got used to ABS with previous cars, it was very unnerving to lock up and it took me a while to realise what was happenning and sort it out. I was even going slightly sideways at one point. Had I had ABS I would not have locked up and would have made a far better job of avoiding said Sierra. Whatever the disadvantages of ABS, I still think it is a life saver for the average driver, possibly even for many above average drivers.

Jerome.

 

As has been said, I think a very big issue is the driver's concentration and ability. Non ABS is fine if you are concentrating (it's great without it on the track) but as Jerome just said, if you arent and you are used to having it, in the time it takes your reflexes to realise what's happening, you are in trouble (well I was). My preference would be for ABS on the road - and a switch to turn it off for the Track.

 

I posted a comment about ABS and snow in the winter, the consensus seemed to be that it IT comes in too soon and especially on pre97 Car like mine. My old MR2 was a better stopper in the snow.

I wouldnt be without it on the road, provided you plant it in an emergeny it will stop you better than most other drivers could manage. However if you want to really enjoy a drive it can be a bad thing, this is why the Lous elsie (which does not even have a servo) is so popular.

Anyone who thinks that can cadence brake faster than ABS is just daft.

I would liek to be able to turn off my ABS for the track/snow, so any of you aftermarket manufacturers out there could think about developing a kit????

 

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Anyone who thinks that can cadence brake faster than ABS is just daft.<HR></BLOCKQUOTE>

cadence braking does not give the best stopping distances, it is used purely to unlock the wheels in a skid situation.

If you want to stop quickly you need to be good at threshold braking, where the tyres are at there absolute limit of adhesion keeping a constant pressure on the brakes and not pumping them.

Someone who is good at threshold braking is a match for ABS. ABS is unbeatable in a panic situation though.

 

Grand Turismo

I stand to be corrected (not au fait with Scooby fuse boxes) but I believe you can just take the fuse out!

Hey presto, no ABS.

Nick

 

I guess that's one of the main points really. In a panic situation where a car pulls out in front of you or a person steps out, etc. it's very difficult to exhibit the control and skill required to not lock up (especially in the wet). That's why I like having it. It's different on a track because you know where the next braking point is and how slippy the track is etc. You may only get one chance on the road and it's very hard to tell how hard you can brake before you lock up in exteme situations. It's also psychologically very difficult to take your foot off the brake after locking up, or use self control to not lock up, if you are heading for a big accident or a pedestrian. ABS rules because it does the braking thinking for you, while you can concentrate on things like steering around the obstacle.

 

A skilled driver could well match ABS in a straight line, but not in a corner.

When braking and cornering, ABS allows more braking force to be applied to the outer (more heavily loaded) wheels than the inner ones. The brake pedal can only reduce the force on all the wheels at the same time.

Racing with ABS takes a bit of guts as you have to trust the system when you turn into a corner with your foot still on the brake pedal.

It's just like having traction control, but on the entrance to a bend and not the exit.

 

Just another 2 cents worth - the reasoning behind banning ABS in various sports for instance British touring Cars, was because the cars with ABS stopped too quick for the cars who's manufacturers didn't fit ABS so in a (cheaper) effort to keep things equal they band ABS on all cars. Same as 4WD in touring cars some were better than others (like SCOOBYS in the wet).

p.s. I also recall something about F1 cars not having ABS because of this reason also, but I maybe wrong about this.


Trev.

[This message has been edited by tizard99 (edited 27 October 2000).]

 

I used to have an old Audi Quattro Turbo (big, wide, heavy...thing) which had switchable ABS. For a test I attempted an emergency stop in snow with and without ABS.

First without ABS....slid to a halt with a mountain of snow under the wheels, occaisionally cadence braking to straighten the car back up.

WITH ABS..forget stopping you're just not going to. Very scary. Car turned into a big white sledge which I couldn't stop. Turned ABS off to stop.

Granted in the wet and during normal circumstances ABS is a lifesaver ~ just be aware it has limitations.

PS during hillclimbing ABS fuse was usually pulled as the pedal feel was frightening when standing on the brakes with the ABS chirping away.

It takes huge b@lls as well to come off the brakes when in a lock up situation to re-apply the brakes. Something I can't say I've mastered on the track let alone the road.

ABS for me ! Unless its snowing.

Cheers


Mark.

 

It's also a matter of prefernce.
My team autocrosses a VW, and my older driver hates ABS brakes because he feels like he can't stop.
I think it may be partially that a lot of people are very used to cars w/o ABS.
This, of course, has nothing to do with the technical reasons