Braking

Topics relating to Advanced Driving in cars
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StressedDave
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Re: Braking

Postby StressedDave » Wed Nov 18, 2015 1:07 pm

Horse wrote:
Mr Cholmondeley-Warner wrote:There are just some hazards where you need the brakes to slow enough, regardless of whether you start to slow down half a mile before them


And there's the contradiction: for whatever the reasons (good aerodynamics, autoboxes going into 'neutral', etc.), just easing off the throttle won't actually slow the car too much from higher speeds. As I said earlier, I'll save fuel by easing off and losing a few mph, before braking - but I'll choose my moments and won't p1$$ off other drivers.

Told you we agreed... losing a few mph is significantly different from trying not to use the brakes.

Sometimes you get lucky and don't need the brakes at all, at which point you get to award yourself IAM points (Like man-points but only able to be redeemed against jam recipes)
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waremark
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Re: Braking

Postby waremark » Wed Nov 18, 2015 5:42 pm

Horse wrote:And there's the contradiction: for whatever the reasons (good aerodynamics, autoboxes going into 'neutral', etc.), just easing off the throttle won't actually slow the car too much from higher speeds. As I said earlier, I'll save fuel by easing off and losing a few mph, before braking - but I'll choose my moments and won't p1$$ off other drivers.

I drove a Porsche Macan the other day, which had a free wheeling gearbox. In default mode, if you lift off, the engine is disconnected from the wheels. I did not notice this at all except via the rev counter - when you lifted off the rev counter needle dropped to idle. Obviously there was no engine braking, but the disengagement and re-engagement were so smooth that I was not aware of the feature until I noticed the rev counter.

I think I read that if you switch off auto stop-start it also switches off this feature.

Astraist
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Re: Braking

Postby Astraist » Thu Nov 19, 2015 10:25 pm

I do wonder, apart from the safety aspect and fuel economy, what impact do you all belive should those different braking habits have on the rate of brake pad wear and brake fluid deterioration?

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Horse
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Re: Braking

Postby Horse » Fri Nov 20, 2015 9:36 am

There used to be a Soviet bloc motorcycle manufacturer called MZ, who made some wonderful - if, at times, quirky- bikes.

They were often limited by materials quality, with tyres being the most obvious example. The 'Pneumant' brand was not renowned for superb grip [ < an understatement ].

As a result, riders were reluctant to use the front brake with any force. The knock-on effect was that the brake linings became glazed, and the result of that was that the bikes gained the reputation of having poor front brakes!
Your 'standard' is how you drive alone, not how you drive during a test.

WhoseGeneration
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Re: Braking

Postby WhoseGeneration » Sat Nov 21, 2015 1:53 am

Horse wrote:
Which brings us squarely back to the 'Games' and using no brakes to explore better long-distance planning.

There's another aspect to this long-distance stuff. People (as in 'humans') simply can't assess well at long distances, it's a limitation of our eyes that we can't work out exactly how fast something is approaching, via looming and other cues. The worst case for this is high speed overtaking, in the face of oncoming traffic. Actually, it's worse the smaller the object in the distance is, e.g. motorcycle rather than car.



I remember vonhosen posting, I can't remember where, that his experience was that people overestimated the distance needed to stop at low speeds and underestimated the distance needed at high speeds. He didn't define what was low or high speed but if related to his sphere, I suspect we're considering low to be up to 50 mph and high to be well above 70 mph.

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akirk
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Re: Braking

Postby akirk » Sat Nov 21, 2015 8:34 am

That makes sense... I think it surprises people that distance increase is not directly linear
Alasdair

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Adamxck
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Re: Braking

Postby Adamxck » Sat Nov 21, 2015 10:31 am

As speed doubles, braking distance quadruples. Id say that was linear. Hard to calculate on the fly though. Unless my understanding of linear is flawed like my understanding of braking graphs.
Adam.

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StressedDave
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Re: Braking

Postby StressedDave » Sat Nov 21, 2015 10:43 am

Look, I only pointed out that the start of your curve meant infinite deceleration ...phht
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akirk
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Re: Braking

Postby akirk » Sat Nov 21, 2015 10:50 am

Adamxck wrote:As speed doubles, braking distance quadruples. Id say that was linear. Hard to calculate on the fly though. Unless my understanding of linear is flawed like my understanding of braking graphs.


because one doubles and the other quadruples, it should be a curve, not a straight line...

e.g.
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Alasdair

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Adamxck
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Re: Braking

Postby Adamxck » Sat Nov 21, 2015 10:59 am

Its flawed then. At least I understand the principal. Its the application thats the difficult bit. And dealing with the embarrassment of being shit with graphs.
Adam.


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