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Does ABS shorten stopping distance???
Jasper - 10/11/11 at 10:39 AM

So I went on a Speed Awareness Course last night, that's 4 hours of my life I'll never get back.

The guys giving the talk was your usual IAM instructor who clearly NEVER broke the speed limit for any reason. Anyway, he told us that stopping distances have not changed since the 1960's. He reckoned that ABS does not decrease your stopping distance at all, just allows you to manouver when you're breaking. And with cars heavier now than they used to be the better breaks we have just end up doing to same job.

I disagreed with him completely, saying than the combination of ABS, better brakes and better tyres must make a difference. He's trying to say that a 1970's Granada would have the same stopping distance as a modern BMW.

Your thoughts?

The other interesting thing was that they talked about collisions a lot. I asked the other instructor what percentage of collissions were caused by excessive speed. She could'nt/wouldn't give me a decent answer, and only said that a small amount. So why the hell did I have to listen to an hour talk about collissions when I was done for speeding - not dangerous driving?

There was a guy there who had been done for speeding rushing his bleeding wife to the hospital. They then went on to try to tell him he should have kept within the speed limit even in this situation - that he would have got there just as quickly. One bright spark then asked why ambualnces bother to drive fast with flashing lights if it makes no difference? They stuck to their line - there is NEVER a good reason to break the limit. If it was my wife bleeding I know what I would do - and in fact my father-in-law is only alive now because his wife drove a top speed to the hostpital when he had an anaphylactic reaction to a wasp sting - the hospital staff told her he only lived becasue she did.

Anyway, I could rant on and on, as you can imagine they did really like it when I kept tell them that the police should target bad driving - not just nick people for speeding in completely safe situations just as a revenue earner.


big-vee-twin - 10/11/11 at 10:51 AM

I think the combination of ABS, Tyres and better brakes have improved things dramatically.

I have also been on a course similar to the one you have been on I think the IAM man was towing the line, The IAM teach you to break the speed limit in certain circumstances especially when it gets you out of trouble.

The courses are a bit of a joke though and as you say they never seem to have the facts and figures to hand to prove what they say.

I was most amused to watch those who had been on the course with me scream out the car park and race off down the road afterwards!!

I was there for doing 33mph in a 30 zone, there was one woman who had got done for 31 in a 30 zone, the policeman there blamed the cameras as faulty - but that didn't help us, the cost of the course was £120.00- either that or three points.

What a total waist of time.


eddie99 - 10/11/11 at 10:53 AM

I did a small research project on ABS, and with regarding to stopping distances in a straight line I came to the conclusion that it depends on the driver. If the driver knows what hes doing and is pumping the brake pedal rather then pushing it harder then no ABS probably doesnt decrease them. However to the normal driver that just pushes the brake harder when they start skidding, then yes ABS is an advantage..........


designer - 10/11/11 at 10:56 AM

I'm no expert, but surely the brakes on cars today are a lot better than in the 60's.

If not, then there has been a lot of money spent with no improvements, we could have stuck with small drum brakes and asbestos brakes.

And, as this course was a 'penalty' they have to tell you what fits their argument.


coyoteboy - 10/11/11 at 11:00 AM

I personally find ABS increases stopping distance slightly in some situations (snow, gravel) but in most conditions it's pretty much the same as "good" braking technique. But overall tyres and brakes are a hundred times better than 40 years ago. Clearly your instructor was attempting to make a point to slow people down, shame telling porkies doesn't work with people who know more than you. I have found that most IAM members are sanctimonious know-it-alls who like to force their own (sometimes incorrect) opinions on you at every chance. Giving them the role as instructor in such a course is bound to make that worse.

I too did some research in my car with ABS in the snow. I found that I could stop in the shortest distance with good control and careful cadence braking and careful steering inputs, followed ABS at about 1 car length further without steering inputs with the ABS keeping the car straight, then finally without ABS and without steering I ended up sideways and about 3 car lengths further I drive with the ABS fuse pulled in thick snow.

[Edited on 10/11/11 by coyoteboy]


AndyW - 10/11/11 at 11:02 AM

On certain sufaces like gravel, snow and ice ABS can make the braking distance longer, BUT, you can remain in control. ABS afterall is just another "driver aid" and helps maintain control rather than just simply shortening stopping distance.

Although i totally agree with the OP, the course I went on was full of flaws, and when questioned no reasonable explanation could be given. It was like, were right your wrong, and even if you can prove a valid argument, were still right and your in the wrong.

Again when I questioned one part, I was simply told, If you were right you wouldn't be here..... TOSSSERS

Waste of 4 hours and £60


deezee - 10/11/11 at 11:03 AM

Stopping distances in the highway code have been a joke for years. Everyones best friend, Jeremy Clarkson did a Topgear short on it. You can watch it, but his old 1997 Lexus stops at 70mph in 139ft, versus the 246ft in the highway code. Old Lexi (cheers Mr Partridge) are pretty heavy, right?

http://www.youtube.com/watch?v=KGkKDaYd3Mo


Bluemoon - 10/11/11 at 11:08 AM

I think it will depend mostly on the driver, the basic physics of friction has not changed, you need the wheels to be turning just under skidding (locking up) to get the maxim braking... But ABS can react much faster than a human, so there might be some advantage, but this is probably small. Stopping distances though have probably decreased for mr/mrs average though as they don't apply enough pedal pressure in an emergency but with high servo ratios and ABS of modern cars this is not a problem as light pressure is all that is needed; hence modern cars with brakes with no "feel" to them..

Dan

[Edited on 10/11/11 by Bluemoon]


Bluemoon - 10/11/11 at 11:10 AM

quote:
Originally posted by deezee
Stopping distances in the highway code have been a joke for years. Everyones best friend, Jeremy Clarkson did a Topgear short on it. You can watch it, but his old 1997 Lexus stops at 70mph in 139ft, versus the 246ft in the highway code. Old Lexi (cheers Mr Partridge) are pretty heavy, right?

http://www.youtube.com/watch?v=KGkKDaYd3Mo


Weight has nothing to do with it (if the correct tires are being used that is, i.e correct load rating and brakes sized properly), the coefficient of friction remains the same irrespective of weight.. Buses stop very well, and weigh 10's times more than a car..


mrwibble - 10/11/11 at 11:10 AM

wish we'd put money into driver education, and what to do when losing control instead of letting 17yr olds out after jumping hoops to get a licence.


mcerd1 - 10/11/11 at 11:12 AM

quote:
Originally posted by big-vee-twin
I think the combination of ABS, Tyres and better brakes have improved things dramatically.


I'd go as far as saying that the tyres probably make the biggest difference, especial if we're talking about half decent rubber and not £20 per corner rubbish


didn't those togear idots do some kind of tests over the years to see how modern cars performed against the stopping distance in the code....

infact here it is: http://www.youtube.com/watch?v=KGkKDaYd3Mo
not very scientific, but it give you some idea - and that was in 90's !



from my own experience I started out in a 1979 mk1 fiesta (730kg, 145/82 R12 first the michelin ZX's then modern budget tyres)

then 'upgraded' to a 1992 s1 pug 106 (760kg, 145/70 R13 also with michelin ZX's, then budget tyres of the same type)
so thats about as close a comparison as I can think of between 70's design and 90's design

obviously neither had ABS, both of them had rubbish stopping distances, but there was a big difference changing to the more modern tyres and even after that the 106 felt like it stopped quicker and safer (although I never got the chance to measure that really...)


[Edited on 10/11/2011 by mcerd1]


adithorp - 10/11/11 at 11:13 AM

Technically a car with ABS and the same vehicle without have the same stopping distance... when the driver is perfect enough to control the braking at the max without locking wheels. There are very few of us capable of that.

An less skilled/normal driver just applying max pedal effort (ie causing the ABS to opperate) against the "perfect driver" in the non-ABS car will take further to stop. The ABS releases the brake afterall, but it thinks far faster than us so it's very marginal. The normal driver trying to stop the non-ABS car will take even further to stiop due to either skidding or not applying max braking force.
ABS is designed to allow you to steer when emergency braking (even our imaginary perfect driver above can't do that). In most cases you only need to do that if you're driving within your stopping distance.
Yes, a modern cars stopping distance has decreased. What increases in technology haven't done is reduce to thinking/reaction time and that is a bigger factor than the actual breaking distance.


alistairolsen - 10/11/11 at 11:14 AM

ABS cant change physics, given the same tyres and weight the theoretical stopping distance cannot change, it just lets drivers who panic and mash the pedal into the floor come close to that physical minimum whilst steering. That said, i challenge even a good driver to beat it (and there arent as many good drivers as people who think they are;-) )

Modern tyres have massively reduced stopping distances.

Modern brakes havent really, they tyres always have been and still are the limit. If you can lock your wheels, your brakes are better than your tyres.

Speed awareness courses are a good way of making money. First you get done for speeding and should have the right to a fair trial. Then they bully you into 3 points and a £60 fine if you go quietly and dont question it, then they offer to drop the points if you pay them another £60. Its a shocking indication of the way this country is going.


jossey - 10/11/11 at 11:18 AM

Why is that important?
When your brakes lock up on wet and slippery roads or during a panic stop, you lose steering control and your vehicle can spin. Rear wheel ABS prevents wheel lockup so that your car stays in a straight line. If your car has ABS control on all four wheels, you also keep steering control. If you have steering control, it is possible to avoid a crash by steering around hazards if a complete stop cannot be accomplished in time.



Agriv8 - 10/11/11 at 11:18 AM

Most cars in 1960 were fitted with drum brakes on the rear and in most cases wouls cause most cars of the era to nose dive. but I suppose were a lot lighter.

Personally I cant se the stopping distances being the same. one pratting arround in my A6 ABS and Brake assist .

did a simulated emergency stop and avoid ( no cars about ) on A59 from the national speed limit to 0 on a crud peice of tarmac stopped on a sixpence it even fired the hazards on to warn other vehicles.

regard

Agriv8


Ivan - 10/11/11 at 11:21 AM

Just checked a 1990 South African "Car Magazine" comparative road test of a 1990 VW Golf GTS and Mazda 323 and stopping time from 100kph was an average of 3.6 secs with a best of 3.4 for both - modern Golfs stop in around 2.9 secs or thereabouts - a huge difference, so he doesn't know what he is talking about.

In fact modern hatchbacks are now commonly achieving stopping times that where the preserve of supercars pre 1990s

ps - for those who don't know - South Africa's Car Magazine's tests have always been at the cutting edge of car testing using the most modern measurement systems available at the time.

[Edited on 10/11/11 by Ivan]


deezee - 10/11/11 at 11:24 AM

quote:
Originally posted by alistairolsen
ABS cant change physics


Awww man! Seriously? Well there goes my faster than light space ship, based on physics bending ABS technology..... might as well bin the whole project now


MikeFellows - 10/11/11 at 11:29 AM

my understanding is that stopping distances where based around a ford anglia as that was the most popular car at the time

I guarantee that abs or not, my fiesta van could out brake it


MikeFellows - 10/11/11 at 11:30 AM

not scientific but....


chrisxr2 - 10/11/11 at 12:08 PM

The woman done for 31 could have chosen to go to court were i suspect she would have won.


quote:
Originally posted by big-vee-twin
I think the combination of ABS, Tyres and better brakes have improved things dramatically.

I have also been on a course similar to the one you have been on I think the IAM man was towing the line, The IAM teach you to break the speed limit in certain circumstances especially when it gets you out of trouble.

The courses are a bit of a joke though and as you say they never seem to have the facts and figures to hand to prove what they say.

I was most amused to watch those who had been on the course with me scream out the car park and race off down the road afterwards!!

I was there for doing 33mph in a 30 zone, there was one woman who had got done for 31 in a 30 zone, the policeman there blamed the cameras as faulty - but that didn't help us, the cost of the course was £120.00- either that or three points.

What a total waist of time.


britishtrident - 10/11/11 at 12:43 PM

ABS increases stopping distances by a very skilled driver by a very small margin when compared with those that can be achieved --- but ABS allows a maximum G stop under control. The more modern ABS systems are considerably better than the early systems as the wheel sensor on the most recent systems are more sensitive and the resultant control of the break pressure by the ABS ECU is less coarse, this is why modern ABS system are better than the older generation systems in ice and snow.

Modern cars can stop in a slightly shorter distance than 1970s cars mainly due to having more rubber on the road, the big improvement in braking performance came in the 1960s when front disc brakes started to be fitted to entry level cars.
Not so much because of brake fade issues as the main problems with front drum brakes fore everyday motoring was they were prone to snatching at slow speed, pulling to one side, suffered from leaking wheel cylinders and always needed regular adjustment. front drum brakes also gave a very non-linear pedal response because the brake shoes and drums distort under the force exerted by the wheel cylinder.

When entry level cars like the Anglia, Escort, Viva and Marina had drums on the front come MOT time they would more often than not fail on brakes pulling to one side for no obvious reason. A trick we worked out was to swap over the brake drums left to right often that would fix it.


MikeRJ - 10/11/11 at 12:52 PM

Even the most skilled driver in the world can not control every wheel individually. If one wheel locks up he has to judge whether it will be advantageous to release pedal pressure and regain traction on the wheel (losing braking effort from all the other wheels in the process) or whether to just leave it locked. A good ABS system will release pressure only on that wheel so no braking effort is lost on the others.


MikeRJ - 10/11/11 at 12:54 PM

quote:
Originally posted by big-vee-twin
I was there for doing 33mph in a 30 zone, there was one woman who had got done for 31 in a 30 zone,


I've heard this claimed a few times but no one has ever produced a speeding ticket with 31mph on it (in a 30mph limit); I just don't think it would happen.


bartonp - 10/11/11 at 01:01 PM

My 1964 Morris Traveller will happilly lock all 4 wheels from 30/40/50/60 ... drums all round, 155 R 14 tyres ... does squirm a bit, and I wouldn't like to do it more than once! It's probably under the 'stopping distance' quoted too!


pajsh - 10/11/11 at 01:13 PM

I can't understand people bleating on about the Driver Awareness thing.

Before it came along you would get a fine, 3 points, a hike in your insurance premium and no choice.

At least now you have a chance to keep the points off for when the renewal comes round.

The course is just an alternative punishment, like making you sit in the corner or on the bottom step with maybe the odd person picking up something they didn't know. It would be cheaper for the government just to make you pay the fine rather than have centres and instructors all over the country.

As Normal Stanley Fletcher said "Can't do the time then don't do the crime"

ABS has saved my life more than once both in stopping power and being able to steer whilst braking. Doesn't matter how good a driver you are, when the unexpected leaps out at you very few people will be as quick and efficient as an electrical circuit.

But as stated above the tyres are the limiting factor in the end and cars being heavier put more demand on them for stopping adhesion. My MK2 Scirrocco only has a book weight of around 900kg. Compare that with the new Mk3.

Speed doesn't cause accidents, drivers do. Speed just makes the results potentially more significant as I=MV²


russbost - 10/11/11 at 01:18 PM

I think the main point is difference in tyres. Having the best brakes in the world or the most incredibly efficient abs system controlling each wheel separately (the only sort of abs really worth having if comparing with a good driver) is absolutely no use if the coeffecient of friction between the tyre & the road is low.

Modern tyres are much better than they used to be & I think particularly in the wet, not so much so in Winter tho' hence why Winter tyres can make an incredible difference to both handling & stopping in the cold months - & note I said cold not icy, temp only has to drop below around 7 degrees for most tyres to lose significant amounts of grip


MikeFellows - 10/11/11 at 01:21 PM

quote:
Originally posted by pajsh
I can't understand people bleating on about the Driver Awareness thing.

Before it came along you would get a fine, 3 points, a hike in your insurance premium and no choice.

At least now you have a chance to keep the points off for when the renewal comes round.

The course is just an alternative punishment, like making you sit in the corner or on the bottom step with maybe the odd person picking up something they didn't know. It would be cheaper for the government just to make you pay the fine rather than have centres and instructors all over the country.

As Normal Stanley Fletcher said "Can't do the time then don't do the crime"

ABS has saved my life more than once both in stopping power and being able to steer whilst braking. Doesn't matter how good a driver you are, when the unexpected leaps out at you very few people will be as quick and efficient as an electrical circuit.

But as stated above the tyres are the limiting factor in the end and cars being heavier put more demand on them for stopping adhesion. My MK2 Scirrocco only has a book weight of around 900kg. Compare that with the new Mk3.

Speed doesn't cause accidents, drivers do. Speed just makes the results potentially more significant as I=MV²


I refused the driver training course last year and took the 3 points and £60 fine

the course was £75 and no hike in insurance - no brainer


Agriv8 - 10/11/11 at 01:37 PM

quote:
Originally posted by bartonp
My 1964 Morris Traveller will happilly lock all 4 wheels from 30/40/50/60 ... drums all round, 155 R 14 tyres ... does squirm a bit, and I wouldn't like to do it more than once! It's probably under the 'stopping distance' quoted too!


a further point of the lack of 'progesive ' braking on drums as they tend to be on or off.

regards

Agriv8


coyoteboy - 10/11/11 at 01:54 PM

quote:

If one wheel locks up he has to judge whether it will be advantageous to release pedal pressure and regain traction on the wheel (losing braking effort from all the other wheels in the process) or whether to just leave it locked.



Though in reality you can release just enough effort to unlock the one wheel while maintaining a good deal of effort through all the other wheels, your point is valid. No human can individually control all 4 wheels at ~25hz or so as ABS does. ABS is a win win situation generally, apart from the odd situation where it, by definition, can't sense what it needs to and can't deal with the consequences (once all wheels have locked it can't identify whether it's still sliding or not very easily, I did once dump my car into a grass bank at 5mph because the ABS went mental on the gravel as soon as I touched the brake (admittedly fairly hard))


britishtrident - 10/11/11 at 02:00 PM

quote:
Originally posted by mcerd1
quote:
Originally posted by big-vee-twin
I think the combination of ABS, Tyres and better brakes have improved things dramatically.


I'd go as far as saying that the tyres probably make the biggest difference, especial if we're talking about half decent rubber and not £20 per corner rubbish


didn't those togear idots do some kind of tests over the years to see how modern cars performed against the stopping distance in the code....

infact here it is: http://www.youtube.com/watch?v=KGkKDaYd3Mo
not very scientific, but it give you some idea - and that was in 90's !



from my own experience I started out in a 1979 mk1 fiesta (730kg, 145/82 R12 first the michelin ZX's then modern budget tyres)

then 'upgraded' to a 1992 s1 pug 106 (760kg, 145/70 R13 also with michelin ZX's, then budget tyres of the same type)
so thats about as close a comparison as I can think of between 70's design and 90's design

obviously neither had ABS, both of them had rubbish stopping distances, but there was a big difference changing to the more modern tyres and even after that the 106 felt like it stopped quicker and safer (although I never got the chance to measure that really...)


[Edited on 10/11/2011 by mcerd1]



Small entry FWD hatches are at a big disadvantage under braking because all the braking is done by the front wheels and tyres, add the fact Michelin ZX was well known for being extremely lacking in grip on slipper & wet surfaces.

In the UK many small fwd hatch backs also suffer from having the brake master cylinder on the wrong side of the car the resultant pedal cross linkage acts like a torsion bar and robs the brakes of any feel. LHD VW Golfs have much better brakes than the RHD equivalent but the actual brakes are identical.


hughpinder - 10/11/11 at 02:12 PM

ABS can significantly increase your braking distance in some circumstances. I did a skid control course, and the guy give the lectures was an ABS tester for toyota. He stated that for a 4*4 pickup towing a maximum weight trailer, the stopping distance was 3 times as long as for the same setup without ABS(both on ice). I do think its an advantage for most people most of the time, so the statistics must come out in favour of ABS generally. There's also the ability to keep control of the car too!
Someone earlier posted that the coefficient of friction of a tyre does not change with vehicle weight - this is actually wrong.
I posted the formula Avon gives for its track tyres - for a kit car with say 150kg per corner car coef of friction comes out as about 1.7 dry, 0.8 in the wet, for a tintop at 350kg/corner 1.4 dry.0.65 in the wet.

Regards
Hugh


britishtrident - 10/11/11 at 02:14 PM

quote:
Originally posted by bartonp
My 1964 Morris Traveller will happilly lock all 4 wheels from 30/40/50/60 ... drums all round, 155 R 14 tyres ... does squirm a bit, and I wouldn't like to do it more than once! It's probably under the 'stopping distance' quoted too! [/quote}

Nothing in this world would make try a test emergency stop in a Morris 1000 from anything over 30mph
From long bitter memory the Morris 1000 probably had the most troublesome brakes of any BMC car.


britishtrident - 10/11/11 at 02:20 PM

quote:
Originally posted by hughpinder
ABS can significantly increase your braking distance in some circumstances. I did a skid control course, and the guy give the lectures was an ABS tester for toyota. He stated that for a 4*4 pickup towing a maximum weight trailer, the stopping distance was 3 times as long as for the same setup without ABS(both on ice). I do think its an advantage for most people most of the time, so the statistics must come out in favour of ABS generally. There's also the ability to keep control of the car too!
Someone earlier posted that the coefficient of friction of a tyre does not change with vehicle weight - this is actually wrong.
I posted the formula Avon gives for its track tyres - for a kit car with say 150kg per corner car coef of friction comes out as about 1.7 dry, 0.8 in the wet, for a tintop at 350kg/corner 1.4 dry.0.65 in the wet.

Regards
Hugh


Weight distribution has a big effect because tyre friction is not classical linear Coulomb friction a Porsche 911 can out brake any other road car on comparable rubber. because each corner can contribute approx 25% of the braking effort.


bartonp - 10/11/11 at 03:38 PM

quote:
Originally posted by britishtrident
quote:
Originally posted by bartonp
My 1964 Morris Traveller will happilly lock all 4 wheels from 30/40/50/60 ... drums all round, 155 R 14 tyres ... does squirm a bit, and I wouldn't like to do it more than once! It's probably under the 'stopping distance' quoted too! [/quote}

Nothing in this world would make try a test emergency stop in a Morris 1000 from anything over 30mph
From long bitter memory the Morris 1000 probably had the most troublesome brakes of any BMC car.


...but then, it IS brand new end-to-end - master cyl, fixed pipes, flexi pipes, cylinders, linings, drums, tyres - you get the idea? And then the shoes have been adjusted up on the drums very carefully by me to balance the braking forces at each corner, and THEN it's not driven very much so it all stays in balance (otherwise I'd be adjusting it every 5 mins).

I had the same setup on a Wolseley Hornet (Mini) I was using as a daily driver. Got changed rapidly for a set of 1275GT disks!!!

Phil.


Phil.J - 10/11/11 at 03:49 PM

I remember someone had ABS fitted to his single seater Hart engined hill climb Pilbeam back in the eighties. It was completely hopeless compared to a normal brake setup in hard use. Lasted two meetings I recall, one of them a wet Wiscombe where it should have been in it's element.
In the few instances ABS has engaged on my road cars it's frighted me to death with the increased stopping distances involved, particularly in snow. Given a choice I would not specify it on a new car purchase.


cliftyhanger - 10/11/11 at 04:08 PM

quote:
Originally posted by designer
I'm no expert, but surely the brakes on cars today are a lot better than in the 60's.

If not, then there has been a lot of money spent with no improvements, we could have stuck with small drum brakes and asbestos brakes.

And, as this course was a 'penalty' they have to tell you what fits their argument.


I believe asbestos brakes are in fact VERY good. Sort mintex 1144 standard. Modern friction materials not as good, hence the need for big servo's and discs. In fact I saw a figure of 30% difference banded about on one forum a while ago.

And I know this because using asbestos pads on my (old) cars makes them stop much much easier than with modern pads. I don't have a servo either.


Confused but excited. - 10/11/11 at 04:14 PM

Modern tyres must improve breaking distances since 1960.
According to the latest Michelin advert, their new tyres stop you at least 3M shorter that the sh1t they were selling lus ast year and according to said advert, you fit two of the new ones to the offside only.


MikeRJ - 10/11/11 at 05:13 PM

quote:
Originally posted by cliftyhanger
I believe asbestos brakes are in fact VERY good. Sort mintex 1144 standard.


I might have misinterpreted this, but Mintex 1144 is asbestos free. I'm not even sure you can buy asbestos based pads these days?


Ninehigh - 10/11/11 at 05:22 PM

quote:
Originally posted by Jasper
I disagreed with him completely, saying than the combination of ABS, better brakes and better tyres must make a difference. He's trying to say that a 1970's Granada would have the same stopping distance as a modern BMW.

Your thoughts?



Let's test it.

I have a 2001 Pug 106 and a 2005 Mondeo.

I know there's one person on here who has a 1970 something Datsun Z, and I'm sure we have some people here with cars less than a year old.

Let's mark out the various stopping distances and see how short/over each car is. If that guy's right then they should all stop around the same place (accounting for worn brakes)


coyoteboy - 10/11/11 at 05:35 PM

I have a '90 car that can be run with and without ABS - I can see a confirmation of the obvious coming along...


cliftyhanger - 10/11/11 at 05:44 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by cliftyhanger
I believe asbestos brakes are in fact VERY good. Sort mintex 1144 standard.


I might have misinterpreted this, but Mintex 1144 is asbestos free. I'm not even sure you can buy asbestos based pads these days?


No asbestos is sold by shops any more, or indeed for years. However, I have acquired a fair stock of asbestos pads for my old car

I meant the asbestos ones have a similar friction coefficient to that of mintex 1144, ie much better than "normal" ones.
And in reality little danger to health, just wash the brakes down rather than using an airline


mcerd1 - 10/11/11 at 05:57 PM

quote:
Originally posted by britishtrident
Small entry FWD hatches are at a big disadvantage under braking because all the braking is done by the front wheels and tyres, add the fact Michelin ZX was well known for being extremely lacking in grip on slipper & wet surfaces.

spot on, it was a bit like driving on ice every time it rained

thats why I changed, of course I didn't have much choice in 12" 'standard profile' tyres..

quote:
Originally posted by britishtrident
In the UK many small fwd hatch backs also suffer from having the brake master cylinder on the wrong side of the car the resultant pedal cross linkage acts like a torsion bar and robs the brakes of any feel. LHD VW Golfs have much better brakes than the RHD equivalent but the actual brakes are identical.


Its the bulkhead that flexes on the RHD 106 - the cross linkage is stiffer than the chassis

mind you I could still lock its wheels anytime I liked...

[Edited on 10/11/2011 by mcerd1]


dhutch - 10/11/11 at 06:32 PM

quote:
Originally posted by Jasper
So I went on a Speed Awareness Course last night, that's 4 hours of my life I'll never get back.

The guys giving the talk was your usual IAM instructor who clearly NEVER broke the speed limit for any reason. Anyway, he told us that stopping distances have not changed since the 1960's. He reckoned that ABS does not decrease your stopping distance at all, just allows you to manouver when you're breaking. And with cars heavier now than they used to be the better breaks we have just end up doing to same job.


I ended up on an all day course, during which mine said that the speed limit signed in the below link where a) 8ft tall, 3ft wide in an orange border, b) Before the junction, c) Not at odd heights and d) more than 100ft from the tunnel. Given the below image its fairly clear he was just on a rant. I wasnt caught speeding and the aledged incidenet wasnt even the same country i was only asking out of curiosity as to why the limit was there and what he thought of it. but yes, clearly sometimes they just get invovled in being econmical with the truth.

http://maps.google.co.uk/maps?q=st14&hl=en&ll=52.978791,-2.107637&spn=0.009948,0.018539&client=opera&oe=utf-8&hnear=Uttoxeter+ ST14,+United+Kingdom&t=m&z=16&vpsrc=6&layer=c&cbll=52.978836,-2.107781&panoid=s9gcQGBg-qGeGrx7y7d5YQ&cbp=12,115.92,,0,14.9

But as said, bleating aside, much rather the £120 a day of work than 3points.


Daniel


NigeEss - 10/11/11 at 08:53 PM

quote:
Originally posted by coyoteboy
I have a '90 car that can be run with and without ABS - I can see a confirmation of the obvious coming along...


Audi 80 perchance ?


mrwibble - 10/11/11 at 09:23 PM

forgive my ignorance, but surely ABS is about control rather than braking effort, else motor racing cars would use it? instead they lock a wheel when asking too much of the car.


britishtrident - 10/11/11 at 09:50 PM

quote:
Originally posted by mrwibble
forgive my ignorance, but surely ABS is about control rather than braking effort, else motor racing cars would use it? instead they lock a wheel when asking too much of the car.


F1 used untill it was banned along with other driver aids.


britishtrident - 10/11/11 at 10:09 PM

quote:
Originally posted by cliftyhanger


No asbestos is sold by shops any more, or indeed for years. However, I have acquired a fair stock of asbestos pads for my old car

I meant the asbestos ones have a similar friction coefficient to that of mintex 1144, ie much better than "normal" ones.
And in reality little danger to health, just wash the brakes down rather than using an airline



Any non-asbestos friction material is a substitute but in terms of cold stopping power in normal road use there is zero difference.

The main problem with non-asbestos friction material in normal urban is disc wear and the adherent nature of the dust.

I suspect with non-asbestos pads the performance differential between non OEM quality pads and second line or lower quality pads is greater than it was in the old asbestos days.


SteveWalker - 10/11/11 at 11:34 PM

quote:
Originally posted by mrwibble
forgive my ignorance, but surely ABS is about control rather than braking effort, else motor racing cars would use it? instead they lock a wheel when asking too much of the car.


I'd have thought that ABS equipped cars would stop quicker than non-ABS in most circumstances - not because the ABS stops them quicker, but because an ABS equipped car can have more powerful brakes as the ABS can cope with any lock-up that might occur during over-enthusiastic braking during normal driving. More powerful brakes without ABS can provoke lock-up, while, even in an emergency, many people don't apply full pressure to the brakes and thus will tale longer to stop with less powerful brakes.

Sorry that's not come out well - I was trying to say that most people will take longer to stop with less powerful brakes, but will tend to lock up too easily with more powerful ones. ABS allows the more powerful ones to be used by anyone.


Ninehigh - 11/11/11 at 12:01 AM

quote:
Originally posted by dhutch

But as said, bleating aside, much rather the £120 a day of work than 3points.


Daniel


Me too, the points punish you for 5 years


Browser - 22/11/11 at 09:53 PM

I've done the speed awareness course and I'm sure when someone asked where the braking distance data came from they said a drum-braked '60's Ford Anglia

Yes, they have to toe the line and tell you there is never a good excuse for speeding, that is what they are there for. I went because I didn't want three points on my license.
ABS does not shorten braking distances, that's not what it's for as legions of owners of dented 4x4's would have irately told you after last winter's snows, but as other posters have said it is intended that you should be able to brake and steer at the same time. Trouble is, someone should have told the police/govt./motor manufacturers that you have to be trained to use an ABS-equipped car to (a) know what it's doing when the ABS kicks in, (b) know what it is for and (c) get the best out of it.