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 Post subject: SKID CONTROL
PostPosted: Wed Jul 21, 2004 02:12 
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Location: West Scotland
Paul,

what about linking up with one of these types of organisations to promote active road safety, in particular younger drivers, who think they are invincible and will be saved by "technology" in the event of any problems?

http://www.activitypoint.co.uk/en/e01/01441.htm

I'm considering it myself as I would really like to experience and learn the control techniques if ever there was a situation where the inevitable may happen as so often does with most drivers, causing accidents.

Andrew


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 Post subject:
PostPosted: Sun Aug 01, 2004 17:03 
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Location: Wokingham, Berkshire
When I bought my Mazda RX-8 I was offered a day at ProDrive included in the price.
I am in the process of booking my ProDrive day for August/September.
It is a sensible thing for sports cars manufacturers to do.
Especially in a car, like the RX-8, where the difference in handling between 50 and 80mph is negligible, and tends to let you drive much faster than you think you are going.
Again, people that promote scameras have only probably driven their granfather's volvo, once or twice... :-(


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 Post subject:
PostPosted: Sun Aug 01, 2004 19:35 
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Most of the pro-scammers haven't even drove a car or are kidding themselves about promoting cameras if they do drive, this is the reason we have cameras. Any sensible driver knows that always sticking to the speed limit is not inherent in road safety, these people think otherwise. I would love nothing more than to catch those so called safety camera proponents speeding.

Andrew


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 Post subject:
PostPosted: Tue Aug 03, 2004 11:26 
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Posts: 116
I dont wish to be sexist but....... I am :-)


it seems, that men are by far and away the most likely to get caught speeding, some 84 percent of tickets are for men.

I dont think ladies and fellas drive in the same way.. I am not saying one way is better than the other.

there are to many ladies in the partnerships.. different style of thinking different style of driving..

Is there anything in this..?

rgds
bill humble apologies if I have offended..


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 Post subject:
PostPosted: Tue Aug 03, 2004 11:31 
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Location: Wokingham, Berkshire
It seems that what you are saying is indeed the case.
Women and men have different attitudes towards driving.
My wife for example refuses categorically to drive my RX-8. My fear is that, the day she needs to (emergency or else) she will have an accident.
I am trying to get her to drive my car when we go out together, but haven't yet succeeded.


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 Post subject:
PostPosted: Fri Aug 13, 2004 12:36 
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Joined: Mon Mar 08, 2004 19:41
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Location: North East Wales
I learned skid control the hard way - trying out car control on any icy and forest gravel roads that I could find in N Wales.

I was lucky not to bend the car much.

But feel structured training is maybe a better route and have been looking for a skid pan or some sort of venue unsuccessfully in N West / N Wales for daughter. Can anyone help ?


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 Post subject:
PostPosted: Sat Aug 21, 2004 09:40 
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Skid control, is old world motoring.

ABS & traction control is now becoming the standard.

Tuition for a controlled skid, is a completly differant world to controlling a skid in an emergency.

If a vehicle is fitted with the above, it will be controlled automaticly.

The better solution is for our Government to enforce the fitment as standard by manufacturers.

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 Post subject:
PostPosted: Sat Aug 21, 2004 11:26 
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Location: Saltburn, N. Yorks
It has been shown that on a dry road locked wheels stop a vehicle faster than an A.B.S. system! We had skid-pan training on our tankers before I retired and could switch between an A.B.S. fitted vehicle and one without. In a panic brake situation, the standard one always stopped in the shorter distance. Main use for A.B.S is on a slippery surface, allowing steerage, but I suggest that under emergency braking that most of us don't think to try and steer. The ads. showing the car swerving safely around an object are obviously set up. I'd like to see one where an obstruction is presented without warning, I suspect the result would not be the same! :?


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 Post subject:
PostPosted: Sat Aug 21, 2004 19:33 
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I also seen an article in the magazine 'Professional motor mechanic' where a test by the German road worthiness organisation TUV showed that an ABS car with worn shockers required an overall longer stopping distance as compared to a non-ABS car.

Andrew


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 Post subject:
PostPosted: Mon Aug 23, 2004 13:24 
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What you're saying is that drivers need to be prepared for the unexpected on the roads and they should be trained for it.

I learned the hard way:

Travelling along long straght road when tractor driver copmletely mis-judged distance and pulled out infront of me. Two choices: driver under trailer and get decapitated OR brake and steer into wall without bouncing off into tractor and trailer!

My passeneger and I were extremely lucky. I had a number of years driving experience, am a careful motorist and was driving a high performance car (therefore with high performance breaks).

Make me wonder, therefore, how many other motorists wouldn't have been able to make the choice and how many other cars wouldn't have stopped.

Fact is, if everyone drove a little more carefully and put time into better judgement (in right situations) we'd stand less chance of needing to be prepared for these kinds of situation!


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 Post subject:
PostPosted: Wed Aug 25, 2004 08:56 
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I agree that people should drive more carefully but there are situations where we could all do with a little extra help, and where ABS and traction control will be of little , if any, assistance.

Maximum braking is achieved when the wheels are on the point of locking up. ABS tries to mimick this by very rapidly releasing and reapplying the brakes. Even if it doesn't improve a car's braking distance, it allows steering that a non ABS car won't have and thus gives at least a chance of avoiding an accident. Newer systems are ever improving, but there are still many cars without it (my own latest acquisition included).

Traction control works in much the same way, but trying to maintain maximum grip for acceleration without wheelspin.

Neither of these systems will help that much on black ice on a corner, or for any sudden loss of grip on a corner. For this reason, skid pan training can be useful for most drivers to learn how to regain control of their car in an emergency and better still, how to better control it in the first place.


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 Post subject:
PostPosted: Sun Sep 05, 2004 16:58 
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Skid pan training would be great. People need to know what skids feel like and what steering into them means and how it works. knowing the difference between the handling of a front and rear drive car when it is wet would be use full too. You could learn cadence breaking too. If we drove better we woukld not need to fork out of ABS and traction control.


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 Post subject:
PostPosted: Fri Sep 17, 2004 08:34 
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Oscar wrote:
It has been shown that on a dry road locked wheels stop a vehicle faster than an A.B.S. system! :?


I have read some silly statements, but that has to be a cracker.

A wheel being braked that has grip on the road will stop a vehicle far quicker than a vehicle with locked wheels.

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 Post subject:
PostPosted: Fri Sep 17, 2004 09:05 
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bmwk12 wrote:
Oscar wrote:
It has been shown that on a dry road locked wheels stop a vehicle faster than an A.B.S. system! :?


I have read some silly statements, but that has to be a cracker.

A wheel being braked that has grip on the road will stop a vehicle far quicker than a vehicle with locked wheels.


When you lock the wheels on a car on a dry road the increase in heat at the contact patch increases the coefficient of friction of the tyre compound. Under some fairly common circumstances the increase in the coefficient of friction is greater than the loss of efficiency associated with 100% slip - i.e. locked wheels. So it's true - locked wheels sometimes stop you shorter. Or at least - that's the way I understand it. I do see frequent mentions in the press of this effect, but I haven't seen proper science.

Locked wheels always stop you FAR more quickly on gravel and on freshly fallen snow, as a wedge builds up in front of the tyres. And I have seen proper science for this effect.

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 Post subject:
PostPosted: Fri Sep 17, 2004 13:17 
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bmwk12 wrote:
Oscar wrote:
It has been shown that on a dry road locked wheels stop a vehicle faster than an A.B.S. system! :?


I have read some silly statements, but that has to be a cracker.

A wheel being braked that has grip on the road will stop a vehicle far quicker than a vehicle with locked wheels.


I read somewhere that the coefficient of friction between a tyre and a good, dry road surface is 0.7
Which, I think means (because 1g is the theoretical max) that you'll get 0.7g deceleration with locked wheels.
I'm prepared to be corrected on this point.

But, this means that, as maximum braking is achieved at the point of lockup, this 0.7 is the maximum you can achieve - if you don't take 'keying' of the tyre to the road surface (a la F1) into account.
As, with ABS, the wheels are sometimes not being braked, this maximum cannot be achieved (excluding the point above).
Without ABS, while the wheels are turning the brakes do the work, and when the wheels are locked the tyres do the work that the brakes should be doing.
The big advantage with ABS is that you can steer the car - locked wheels cannot be steered.


Regards
Peter


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 Post subject:
PostPosted: Fri Sep 17, 2004 13:43 
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Pete317 wrote:
I read somewhere that the coefficient of friction between a tyre and a good, dry road surface is 0.7
Which, I think means (because 1g is the theoretical max) that you'll get 0.7g deceleration with locked wheels.
I'm prepared to be corrected on this point.


F=(mu)R

R on a horizontal road is mg
(mu) is the 0.7

therefore max breaking force is mass times 0.7g

as F=ma then a is 0.7g

0.7g is the decelleration

that's correct then.

Simon


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 Post subject: Locked Wheels?
PostPosted: Sat Sep 18, 2004 12:24 
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Surely you get better retardation when the wheels are still turning but on the verge of loosing grip as in kadence braking or when the ABS operates?


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 Post subject:
PostPosted: Wed Sep 22, 2004 12:27 
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As far as I understand it, if you lock a wheel, it generates lots of heat, sound and smoke. This is all energy that is being taken from the car. This energy isnt being taken from the car when you dont lock a wheel. The only energy in this case is heat in the discs/pads. The hotter rubber gets, the stickier it gets too, so it will try and 'glue' itself to the road. This, in dry conditions will stop you quicker.
ABS was developed for aircraft over 30 years ago to stop them falling off of a runway/taxiway during ground manouevers in the wet. You could lock the wheels of a modern jet solid, wind the throttle up and still take off! It was never intended to stop planes and now cars any quicker. It was always about having control (steering).

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 Post subject:
PostPosted: Wed Sep 22, 2004 12:33 
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Pug205GRD wrote:
ABS was developed for aircraft over 30 years ago to stop them falling off of a runway/taxiway during ground manouevers in the wet. You could lock the wheels of a modern jet solid, wind the throttle up and still take off! It was never intended to stop planes and now cars any quicker. It was always about having control (steering).


It's handy in Montreal when you're driving on top of two foot of snow. If you need it in the UK, your are driving like a chump anyway.

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 Post subject:
PostPosted: Thu Sep 23, 2004 09:56 
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simon h wrote:
Pete317 wrote:
I read somewhere that the coefficient of friction between a tyre and a good, dry road surface is 0.7
Which, I think means (because 1g is the theoretical max) that you'll get 0.7g deceleration with locked wheels.
I'm prepared to be corrected on this point.


F=(mu)R

R on a horizontal road is mg
(mu) is the 0.7

therefore max breaking force is mass times 0.7g

as F=ma then a is 0.7g

0.7g is the decelleration

that's correct then.

Simon

I think the theory is ok but the numbers are suspect.

1g is in no way a theoretical maximum - its not a magic number! F1 racing cars routinely pull 2 to 3g under cornering and braking, modern road cars will typically pull 1 to 1.5g depending on the performance profile of the car and the quality of its braking system etc.

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