Thursday, June 29, 2006

L#29: Them’s the brakes…

In the last couple of weeks I have changed my heel and toe technique. This was, in the spirit of complete disclosure, prompted by the ask the experts section of Evo magazine.

The basic principle of heel and toeing is to match engine speed with road speed and gear selection when braking and downshifting, and you do this by blipping the throttle after you’ve disengaged the higher gear and before you engage the lower one. The heel and toe part refers to the fact that you’re doing this whilst applying the brakes at the same time; although, as it is customary to point out, this is a bit of a misnomer because it’s the ball of your right foot that you use in most modern cars, rolling it from the brake pedal onto the accelerator (the name referring instead to the more vintage variety of motor vehicle, which required you to use the heel of your foot on the throttle while standing on the brake with your toe).

The advantages to employing this “fancy” (it really isn’t) footwork are smoothness – see the way most flappy-paddle gearboxes do this for the driver automatically – and potentially safety, particularly in rear wheel drive cars, as it prevents a disparity between wheel speed and road speed that could have the slightly unfortunate side effect of sending you off the road. It also sounds cool, which, if I’m honest, is probably the principle reason I taught myself how to do it in the first place.

I’ve always been aware that there are two methods – basically the same, but until recently I’ve used the more traditional approach. This includes the additional step of releasing the clutch between gears in time with the throttle blip: double de-clutching as it’s called. I’m not entirely sure what the point is, but having previously been informed this was the “correct” way of going about things, then this was the way I was going to do it. I suspect it puts less stress on the transmission – especially the clutch – but what the hey, you never know until you try the alternatives.

I was pretty happy with this method, even if I didn’t get right quite a lot of the time (still potentially a little jerky), until I read Evo’s John Barker advising someone on the merits of h&t, but without extolling the virtues of the double de-clutch. Simply raise the revs while the clutch is disengaged, he was saying – and I thought, if it’s good enough for him, then it’s good enough for me.

The result is a revelation. As you might expect, this variation is loads faster than the ponderous full monty, but also far smoother as a consequence. I’m getting it right a much greater percentage of the time, too. Rapid-fire downshifts and a silkier ride – learning new stuff is great.

Which leads me very nicely into what I was doing on Monday of this week.

Thanks to the ever generous Steve Cropley, editor-in-chief of Autocar (and Haymarket’s other motoring titles), but also Vauxhall’s press office, who paid for the thing, myself and my trainee auto-j colleagues spent the day at Millbrook test and development centre, guinea-pigging a Motoring Journalist Driving Course. Put on by Ian Halton and Richard Bott this was a day’s instruction in defensive driving and an education on how to make swift, safe progress.

As you can imagine, Millbrook is a fascinating place, not only for the number of heavily clad prototype vehicles gallivanting around its testing facilities, but also because of the sheer variety of driving experiences that these facilities offer. We predominantly spent our time on the Alpine road course, but also took in the highspeed bowl, the handling circuit, and city course, as well as going out on the actual road – driving a trifector of VXR Vauxhalls: the Astra, the Vectra, and the Monaro.

Lapping the bowl – a two mile constant radius circle – at 130mph was certainly fun, though you might be surprised to learn that Vectra was a steadier ship than the Monaro at this speed, the big Aussie import being somewhat more softly sprung than the executive express. Less surprising probably is how much more comfortable it feels to be in control of the vehicle at this speed, rather than a passenger in the back. Biggest grins came on the Alpine course though, which loops and rolls up and down a series of steep inclines and dips, and especially in the Astra – which benefited from being the last car that we drove, and the most nimble. It also makes some fabulous, if slightly weird, noises. Talking to a coursemate, I compared the BAARRPP sound it bellows in the last few rpm before the redline to a spaceship arriving through a jump gate; he looked at me a little funny, but admitted he got what I meant.

The Astra wasn’t as unruly as expected either. The boost from its turbocharged two litre four-pot certainly isn’t as linear as in the Golf GTi, nor does it quite feel as fast (to be fair, we had all driven the 400bhp Monaro by this point), but there was no sign of rampant torquesteer unless seriously provoke. I personally found the aggressive delivery, where the power seems to arrive in lumps, pretty entertaining. But the gearbox isn’t the most cooperative or consistent I’ve ever tried, and seems to be set quite far back in relation to the driver.

The Vectra was hugely competent, the Monaro not so scary as you might imagine – though its controls are other-era heavy. If anything is going to drive you nuts about these cars, it’s the indicator stalks, which in the Astra and the Vectra are these new-fangled rocking stalks that trigger a switch rather than staying in position. Struck us all as a bit like reinventing the wheel – what exactly was wrong with the original design? – but even having said that we all got used to them by the end of the day.

The instruction itself was a useful mix of laidback encouragement and fantastically incisive, experience driven know-how. The day kicked off with a powerpoint presentation that lasted about an hour, and did an excellent job of convincing us – if such were actually needed – of the value of the information about to be imparted. This was peppered with memory-friendly phrases, but for the sake of brevity, I’m only going to paraphrase one of these for the moment. And since I started this off talking about brakes, this is where I’m going to stop: when driving – and especially quickly – it’s not so much about how fast you can go, but how fast you can stop.

In modern cars, the presence of ABS brakes is practically taken for granted. But as our instructors pointed out, hardly any ever really takes complete advantage of this system when forced into making an emergency stop; with ABS if you want to stop quickly stamp on the brakes, and stamp on them HARD – but not everyone is accustomed to doing this, and not everyone has the strength to apply maximum pressure.

So, practically on the quiet, various manufacturers have been implementing an accessory to ABS, and in Vauxhall’s case this is known as Brake Assist. With this in place, assuming you whack the brakes suddenly enough, the car’s electronic brain will detect that there is something of an emergency going on and summon up the absolute maximum crash stop capability of the brakes fitted to the car.

The Vectra VXR’s case – and I know because not only was it demonstrated, but we all tried it for ourselves – if you hit the middle peddle hard enough to trigger this electronic aid, the car will force itself to a stop within a length and a half if you’re travelling at 30mph. That is a phenomenal achievement, and I think we can look forward to such systems saving lives the lives of pedestrians everywhere.

Worth knowing even more than this, however, is what happens if you try the same trick from 40mph – a speed that easily creeps up on you if you’re not paying proper attention when driving around town. A 10mph difference results in practically double the stopping distance, even with a system as advanced as this fully engaged. Keep it in mind.




Millbrook Engineering


Post a Comment

<< Home