Advanced Driving Hub

Posted: **Fri Jul 29, 2016 10:55 am**

GTR1400MAN wrote:I've had the EBA (Emergency Brake Assist) on my Civic activate when not required. I was braking quickly/firmly for a dog that ran into the road. The violent braking that ensued surprised/startled me ... and the car behind me! He was a reasonable distance behind (luckily) but still locked up as I came to an almost standstill. I'd not experienced it in action before despite having tried out the ABS. The difference was, I admit, I stabbed at the pedal, When I tested the ABS I used a smooth increasing pressure push.

EBA was designed by Lucas (originally - this is going back quite a few years when Lucas did ABS as well as the magic smoke that kept electrics working in 'old' cars) because the problem was that people would react (the sharp stab) to the hazard but not brake firmly enough. So if the system detected a rate of application above a threshold it would collapse the servo and give full ABS, whether you wanted it or not.

It was tested on the proving ground using the company secretaries. When they drove over a pressure line, a polystyrene dummy was fired out from between two walls. Most did exactly what was required. One drove straight through. Her reasoning? It was just polystyrene and rather than panic and have a crash I knew I could safely go strait through it. That's quality thinking.

Posted: **Fri Jul 29, 2016 11:59 am**

fungus wrote:
Horse wrote:
sussex2 wrote:I believe it is good to try these devices out but always when alone in the car.
My experience is that very few people are aware of how to use them, that includes ABS brakes.

Any of the ADIs here able to tell how DVSA have altered their test criteria to suit ABS? As Astraist posted recently (and, AFAIK he's correct) best practice e-braking with ABS is to declutch.

How does that square with the old 'if it locks, release and reapply, and delutch just before stopping' principles?

The advice from the DVSA has been for a number of years now "that the advice given for emergency braking in non ABS vehicles may not be correct. Refer to the vehicle manufacturers hand book for the correct procedure in vehicles fitted with ABS."

I teach my pupils to, as Reg would put it, muller the brakes, clutch down as soon as the brakes bite, keep increasing pressure on the brake pedal and DO NOT RELEASE IT UNLESS THE EMERGENCY PASSES. There may possibly still be instructors out there who still insist that the ABS should not be activated.

Nigel.

Yes, my instructor. He told me to perform an emergency stop. So when I did, I simply slammed the brakes on as hard as I could, and this activated the ABS. Not a problem, or so I thought.
He told me that it was completely uncontrolled. Made no sense to me, frankly, as I came to a halt very quickly, and thus, would have most likely avoided any impacts.

The next emergency stop I did, I braked firmly without activating the ABS, and came to a halt much more smoothly, but I travelled a bit further during the braking. The instructor was quite satisfied with it, which frankly made no sense to me. Why would I sacrifice safety (stopping in the shortest distance possible) for smoothness (not activating the ABS)?

Frankly illogical, but I ignored him on that particular aspect and instead chose to speak to a different instructor who told me that if you activated the ABS during a test, you would not gain minors or fail the test. So I took the test knowing I was allowed to use the ABS. Not that it mattered, as I never needed to perform an emergency stop anyway.

Posted: **Fri Jul 29, 2016 12:12 pm**

TheInsanity1234 wrote:He told me that it was completely uncontrolled.

I suppose the concern in your instructor's mind would have been what you'd have done in a car that didn't have ABS fitted.

A quick check shows that ABS was made mandatory on new cars reigstered after 1st July 2004, although at that time, I've read, there was an exemption for cars that sold less than 500 a year.

Posted: **Fri Jul 29, 2016 7:51 pm**

Gareth wrote:I suppose the concern in your instructor's mind would have been what you'd have done in a car that didn't have ABS fitted.

In which case the instructor should also provide a non ABS car for that exercise and explain why, giving students experience of the difference between ABS and non ABS.
Instructor doesn't deserve ADI status.
All that development and legislation to help safety for what, in this case?

Posted: **Fri Jul 29, 2016 7:59 pm**

WhoseGeneration wrote:In which case the instructor should also provide a non ABS car for that exercise and explain why, giving students experience of the difference between ABS and non ABS.

Certainly I'd go for explaining the difference, but practising an emergency stop without triggering ABS is pretty good practice for executing an emergency stop in a car without ABS.

Posted: **Fri Jul 29, 2016 8:14 pm**

Gareth wrote:
WhoseGeneration wrote:In which case the instructor should also provide a non ABS car for that exercise and explain why, giving students experience of the difference between ABS and non ABS.

Certainly I'd go for explaining the difference, but practising an emergency stop without triggering ABS is pretty good practice for executing an emergency stop in a car without ABS.

Rubbish, the point is, if it's fitted use it.
Your approach presumably means that, on a car so equipped, ESP should be turned off for a learner driver?

Posted: **Fri Jul 29, 2016 9:09 pm**

WhoseGeneration wrote:
Gareth wrote:
WhoseGeneration wrote:In which case the instructor should also provide a non ABS car for that exercise and explain why, giving students experience of the difference between ABS and non ABS.

Certainly I'd go for explaining the difference, but practising an emergency stop without triggering ABS is pretty good practice for executing an emergency stop in a car without ABS.

Rubbish, the point is, if it's fitted use it.
Your approach presumably means that, on a car so equipped, ESP should be turned off for a learner driver?

Explaining the difference between ABS and non ABS and how to identify whether your vehicle has ABS or not is essential. A learner should experience ABS in action as most will now have ABS on their first car and they need to feel the pedal pulsing and the noise of the brakes being released and re-applied rapidly. If they don't, it'll frighten the hell out of them when it happens, and they'll release the brakes because they'll think they've broken the car.

Idealy it would be nice to be able to de-activate ABS as an execise but whether it would achieve anything positive I don't know. The sensitivity of the brakes differs considerably between cars as does the presure required to activate the ABS. My 1.9tdi Ibiza had very sensitive brakes but you had to realy hammer them to activate the ABS. My Fiesta on the otherhand has less sensitive brakes, but the ABS activates under less presure than the Ibiza.

I would imagine that the brakes on most modern cars would pull up in a straight line at 90mph +. I demonstrated this in my Ibiza at above the NSL on the B3081, one of the roads used on the Shaftesbury driving days. I hammered the brakes, and the car pulled up perfectly straight. This is not something I would relish in a 1960s Ford Anglia or a Morris Minor at that speed. The driver would have to fight to keep one of those cars straight at 60 let alone anything above that.

Nigel.

Posted: **Fri Jul 29, 2016 9:27 pm**

fungus wrote:I would imagine that the brakes on most modern cars would pull up in a straight line at 90mph +. I demonstrated this in my Ibiza at above the NSL on the B3081, one of the roads used on the Shaftesbury driving days. I hammered the brakes, and the car pulled up perfectly straight.
Nigel.

I really can't be bothered to research all the systems fitted to your Ibiza but that ability you describe could be due to EBD.
Again, perhaps another system that should be switched off for learners?

Eta, I drove a few 1960s cars, because I started then and, no, you didn't have to fight to keep them straight when braking from 60mph plus.
They did have hydraulic systems, not rods, you know.

Posted: **Fri Jul 29, 2016 9:37 pm**

TheInsanity1234 wrote:
fungus wrote:
Horse wrote:
sussex2 wrote:I believe it is good to try these devices out but always when alone in the car.
My experience is that very few people are aware of how to use them, that includes ABS brakes.

Any of the ADIs here able to tell how DVSA have altered their test criteria to suit ABS? As Astraist posted recently (and, AFAIK he's correct) best practice e-braking with ABS is to declutch.

How does that square with the old 'if it locks, release and reapply, and delutch just before stopping' principles?

The advice from the DVSA has been for a number of years now "that the advice given for emergency braking in non ABS vehicles may not be correct. Refer to the vehicle manufacturers hand book for the correct procedure in vehicles fitted with ABS."

I teach my pupils to, as Reg would put it, muller the brakes, clutch down as soon as the brakes bite, keep increasing pressure on the brake pedal and DO NOT RELEASE IT UNLESS THE EMERGENCY PASSES. There may possibly still be instructors out there who still insist that the ABS should not be activated.

Nigel.

Yes, my instructor. He told me to perform an emergency stop. So when I did, I simply slammed the brakes on as hard as I could, and this activated the ABS. Not a problem, or so I thought.
He told me that it was completely uncontrolled. Made no sense to me, frankly, as I came to a halt very quickly, and thus, would have most likely avoided any impacts.

The next emergency stop I did, I braked firmly without activating the ABS, and came to a halt much more smoothly, but I travelled a bit further during the braking. The instructor was quite satisfied with it, which frankly made no sense to me. Why would I sacrifice safety (stopping in the shortest distance possible) for smoothness (not activating the ABS)?

I've never understood this idea that the ABS should not be activated. To threshold brake takes good feel and practice, something most drivers don't have because they haven't developed it. Basically you need to stop the bloody car if someone steps out in front of you. There's no time for the niceties of not activating the ABS.

Nigel.

Frankly illogical, but I ignored him on that particular aspect and instead chose to speak to a different instructor who told me that if you activated the ABS during a test, you would not gain minors or fail the test. So I took the test knowing I was allowed to use the ABS. Not that it mattered, as I never needed to perform an emergency stop anyway.

Posted: **Sat Jul 30, 2016 10:47 am**

WhoseGeneration wrote:
Gareth wrote:Certainly I'd go for explaining the difference, but practising an emergency stop without triggering ABS is pretty good practice for executing an emergency stop in a car without ABS.

Rubbish, the point is, if it's fitted use it.
Your approach presumably means that, on a car so equipped, ESP should be turned off for a learner driver?

Please either explain with what you're disagreeing, or re-read what I wrote without a preconceived filter.

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