Safe Speed Forums

Had a run with my observer the other day, he said he felt safe and confident in my abilites (phew ).
One thing he did say would need work was the way I (and probably millions of others as well I suppose) am still braking when I change down to make (say) a right turn into a junction. No I don't go all the way down the box one gear at a time, just that one selection you need to make to execute the turn.
I've been practising hard ever since, and using techniques suggested (eg grip the wheel harder with your left hand as you brake and don't let go until you stop braking), but it still feels darned un-natural.
Any comments or advice would be appreciated.

IMHO it is unnatural, in the same way that strict use of pull-push steering is. I think they should concentrate more on developing a smooth approach rather than imposing strict rules like this. What if you were braking for a tight downhill hairpin? Would you be expected to get off the brakes and allow the car to surge forward whilst you frantically grab for the low gear?

As has been hinted at on other threads, with skilled use of heel & toe downchanges the whole maneouvre becomes one smooth operation with the downchanges an integral part, ie we can think of the entire process of slowing down as a sinusoidal curve on an imaginary g meter, that goes smoothly back to "zero g" as we commence the turn (though this too can be overlapped if you replace the "rule book" with an understanding of the "friction circle").

If you were driving really smoothly you'd be unable to discern where the gearchanges were on the plot, so it wouldn't really matter when they were done.

And if we were to aim for the ultimate perfection of a steady g level that simply moves around the friction circle through the process of braking, turning and acceleration, then under this regime there would never actually be an opportunity for the downchange at all!

That said, I understand the principle that they are trying to teach you to leave a safety margin between braking and manoeuvring, and having to leave time for a gearchange clearly achieves that, but nonetheless I'd have thought this was more a teaching method suited for "basic" motoring rather than advanced driving.

<Dons tin hat and waits for inevitable flak from IAM members... >

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Personally I think the idea of not braking whilst changing down is, basically, incorrect, and I don't care what the so-called 'experts' teach.
This was covered on here on a recent thread and the general consensus was that the best and safest way to change down for a corner, junction or potential hazard was to 'heel & toe' whilst always ensuring that the engine revs and gear match the speed. In other words, always keep the engine 'on the cam'. This technique means that you are always in the correct gear to accelerate smoothly if any problem arises, you minimise engine wear due to the oil pressure dropping and pistons tending to 'slap' at low revs whilst the transmission still has positive engagement, and your overall driving is smoother and more comfortable. A passenger should fell no sensation of braking, changing gear, braking and changing gear - it should all be one smooth and co-ordinated action.
My qualifications for saying this: 45 years driving in competition and a qualified aeronautical and mechanical engineer who now builds a lot of engines for classic cars.

(Great minds!)

Meanwhile another related conundrum...

If we accept that this "rule" is intended to build in a safety margin during braking, then which do we think is best? Assuming our car can safely brake at 0.8g, should we...

brake for a hazard at a full 0.8g, but do so a second early (ie the IAM way), so we then coast up to the hazard whilst changing down,

or

begin braking at the same moment, but brake for longer at a lower g level, so that we arrive at the hazard after one steady brake application, fitting in the downchange(s) wherever appropriate along the way?

My point is, should we build in a safety margin by braking hard and early, or by braking less but longer?

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

I think these 'slow' techniques are a great teaching device. When we learn to use them it raises our vision - our vision HAS to rise if we're to find the time to use the technique.

If we then progress to using fast and efficient techniques without letting our vision drop again we've got the best of both worlds.

I'm really certain that these factors are significant. They come from Hendon, and Hendon learned a very great deal about what works, without always discovering why it worked.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Surely the act of self-imposing a lower "g limit" achieves the exact same effect, but more smoothly? To go back to my previous question...



Either way you have to make your initial observation / decision at the same moment, but where one technique involves a relatively firm braking operation followed by a coast, the other involves a single, steady deceleration. But which one gives us the lower risk, in terms of dealing with the unexpected?

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

Yes, I agree and this has been my problem I think. I believe I was braking too late and not thinking far enough ahead - by raising my vision and braking a little earlier I find I'm getting more used to the technique.

I think that's true - but we haven't known the benefit of self imposed g limits. This is blue sky thinking. Hendon thought the techniques were important in their own right - all manner of complex constructs have been offered to justify them.




The long slow braking technique leads to less stress and more natural (subtle?) late adjustability. When the hazard is far ahead and requires a stop I won't even use full engine braking. (An example being a red light - by slowing gently and early I may well be able to keep speed until the light goes green.)

Long braking can finish late too. I reckon trail braking is a worthy technique in road driving although it can be risky to learn. Once learned it becomes indispensable and invaluable. Late adjustments become second nature and the disaster recovery options are excellent. I have very strong reservations about teaching and learning, however. See:
http://www.safespeed.org.uk/braking.html

I definitely don't recommend anyone tries to learn trail braking on the public road.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

On a slight digression, an equally useful "forward planning" lesson is to aim to use a constant braking rate.

For example, next time you are in a situation where you can see you have to stop or slow down by a significant amount, take note of how your braking varies as you constantly reassess the situation and readjust the pedal pressure to stop at the required spot. You will probably be amazed how much it does vary.

So try judging what steady rate of brake application you need to make right from the outset, in order to stop at the required place without needing to increase or decrease the braking force as you pull up.

With practice it can be done with a fair degree of accuracy, but the amount of forward planning and judgement you need in order to do so is quite substantial.

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

Trail Braking appears to be what I know as Left Foot Braking - the initial approach is right foot braking with heel and toe as the driver gets into the correct gear for the corner, once in gear the left foot is free, to take over the braking while the right slides onto the accellerator giving right foot for power and left foot for brakes, and the purpose to maintain balance and control. There is no sudden movement or change of pressure, and it is basically a rally technique (pace notes give the driver the required gear in advance). There was a great demonstration on Men and Motors, but I can't remember exactly what program.

As I also said on another thread, and to back up SafeSpeed - do not try this on the public road because:

a) your left foot has only been trained to floor the clutch, and has no feel - you will press too hard.
b) you have to move both feet in order to get into an emergency stop position (brake and clutch both depressed), and unless this is second nature through a lot of off-road practice it cannot be achieved - in rallying the road ahead is certain to be clear.
c) it is pointless unless you are applying braking all the way up to the apex (by that I mean HARD braking not just covering the brake), which you shouldn't be doing because there is no safety margin

Having said all of that, I suppose that some of my arguments are countered with a single word: "Automatic". No clutch negates a and b, but I think c is still true. Most racing cars these days fall into the category of automatics including WRC and F1, and left foot braking is used in both very widely. They both involve pushing the car to the absolute limits of grip, and at that point the subtle advantage of balancing between brake and throttle are apparent. No point to it at all unless the .1 of a second you save is more important to you than being able to stop for an unforseen hazard.

My understanding is that trail braking can be with right or left foot, and merely describes the process of overlapping the braking and turn-in phase of the corner to a high degree.

The aim is to keep good front wheel grip and steering response through weight transfer, whilst simultaneously maximising use of the total available grip (see "friction circle").

The downside is that it is very easy to either (a) lock the front wheels and understeer off into the scenery, or (b) unweight the back wheels too much and oversteer off into the scenery. But between the two there is an oh-so happy medium...

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

That probably explains a bit of my confusion - personally I haven't got used to the braking abiity of my current car and tend to find that I have braked too much too early - but better that than finding out the wrong way that you have braked too late!

Not a recommendation for safe driving, but for those interested in learning more, there is a nice discussion about H&T and LFT on the ScoobyNet site which naturally has input from those that really know what they are doing, and a few entries from those that possibly shouldn't be on the road at all (not everybody even owns a car; some just like to dream and pretend that they are over the age of 16) - it includes links to videos (for those with broadband) including closeups of the feet in action. At one point the rally car driver goes from 5th to 2nd with H&T and double-declutching in less than 1.5 seconds.

http://bbs.scoobynet.co.uk/showthread.php?t=314866

As for constant braking... wel i am currently getting ready to do HPC, and on my 1/2 day pre MDC assessment, it was said to me as in Roadcraft that braking should start off minimal, then increase in the middle phase and then be realesed very gently so as not to jerk when stopping. What i find i needed to do was practice this, and also declutch quite early as from 5th gear to 2nd for a roundabout i need to declutch at around 25 mph to stop the car stalling.

I think some in the IAM make too much of this, and insistence on total separation is distinctly anal.

This is what I said on the www.advanced-driving.co.uk forum (as someone who has passed an advanced test but wouldn't claim to be a real driving enthusiast):


Hope this is useful.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

My normal style is braking that starts early and gently, and I think it is especially helpful to do this if you have another vehicle behind you. This means that you can prompt the following driver to slow down in an orderly manner along with your own speed reduction. Having twice been hit in the tail early on in my driving career I'm a bit sensitive to that sort of thing! These days I do not rush up to a stopping point braking late and hard, because if the following driver is not paying attention at the critical moment a shunt becomes highly likely, and we don't need that.

Best wishes all,
Dave.

Yeah, that's an excellent point. Far better than mine in fact. That's the real answer to your question JT!

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Thank you Paul, but one little afterthought:

Let us not take it to extremes such that the following driver might think we're being deliberately obstructive. Happy medium again, eh?

Best wishes all,
Dave.