russbost
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| posted on 10/11/11 at 01:18 PM |
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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
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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MikeFellows
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| posted on 10/11/11 at 01:21 PM |
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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
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Agriv8
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| posted on 10/11/11 at 01:37 PM |
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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
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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coyoteboy
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| posted on 10/11/11 at 01:54 PM |
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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))
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britishtrident
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| posted on 10/11/11 at 02:00 PM |
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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.
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hughpinder
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| posted on 10/11/11 at 02:12 PM |
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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
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britishtrident
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| posted on 10/11/11 at 02:14 PM |
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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.
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 10/11/11 at 02:20 PM |
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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.
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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bartonp
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| posted on 10/11/11 at 03:38 PM |
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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.
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Phil.J
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| posted on 10/11/11 at 03:49 PM |
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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.
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cliftyhanger
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| posted on 10/11/11 at 04:08 PM |
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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.
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Confused but excited.
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| posted on 10/11/11 at 04:14 PM |
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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. 
Tell them about the bent treacle edges!
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MikeRJ
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| posted on 10/11/11 at 05:13 PM |
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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?
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Ninehigh
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| posted on 10/11/11 at 05:22 PM |
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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)
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coyoteboy
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| posted on 10/11/11 at 05:35 PM |
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I have a '90 car that can be run with and without ABS - I can see a confirmation of the obvious coming along...
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cliftyhanger
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| posted on 10/11/11 at 05:44 PM |
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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
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mcerd1
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| posted on 10/11/11 at 05:57 PM |
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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]
-
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dhutch
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| posted on 10/11/11 at 06:32 PM |
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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
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NigeEss
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| posted on 10/11/11 at 08:53 PM |
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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 ?
Time is an illusion. Lunchtime doubly so.................Douglas Adams.
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mrwibble
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| posted on 10/11/11 at 09:23 PM |
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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.
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britishtrident
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| posted on 10/11/11 at 09:50 PM |
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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.
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britishtrident
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| posted on 10/11/11 at 10:09 PM |
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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.
[I] What use our work, Bennet, if we cannot care for those we love? .
― From BBC TV/Amazon's Ripper Street.
[/I]
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SteveWalker
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| posted on 10/11/11 at 11:34 PM |
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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.
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Ninehigh
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| posted on 11/11/11 at 12:01 AM |
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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
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Browser
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| posted on 22/11/11 at 09:53 PM |
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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.
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