I’ve coached many drivers who are fast driving away from the apex, and able to reach the exit point of a curve at a good speed (ie, using most of the available longitudinal/lateral grip). But the drivers who are fast up to the apex are less plentiful.

That’s because transitioning from the initial application of the brake pedal until that point where longitudinal G force changes from a negative value to a positive one is the zone where the great drivers hang out.


There’s no doubt that it takes much more skill and finesse to brake well, as opposed to accelerate well.


Over my years of coaching with VBOX dataloggers I’ve come to realise there are four distinct (but paradoxically, with blurred edges) phases in the braking process. I call them Preload, The Big Squeeze, Modulation, and Unsqueeze. I’ve been lucky to have access to data from Clint Weston of the AMG Driver Academy and observing what he does and how he does it at the wheel of an AMG GT has been educational. However, it has only been possible to make accurate assessments thanks to the VBOX HD2 supplying me with G forces (calculated from GPS) and throttle/brake position (this information being extracted from the vehicle’s CANbus).






Let’s dissect them.


· Preload. These nanoseconds are where you’ve moved from accelerator to the brake and taken up the slack. The duration where there is neither brake nor throttle being applied is as little as three-hundredths of a second in Clint’s case, when braking for Turn Two at Zwartkops. The slack in question is in the pedal but also the rest of the car. When talking stock road cars, it includes every rubber bush in the suspension and steering. It is, ultimately, a heads-up to the various mechanicals and systems that a big change is coming to the dynamic state of the vehicle. On the pedal pressure data, you can usually see this as a little up-tick when the pedal position goes from nothing to about five percent - and then very rapidly into The Big Squeeze.

· The Big Squeeze. This is where 90 percent of the action happens. The name sums it up. When I look at the negative G curve and pedal pressure data of a skilled driver, this reveals a rapid build up to maximum forces – in other words, they create a near-vertical G-force line, with the pads squeezed hard against the discs. It is still a squeeze and not a stomp though – compressing the suspension as evenly as possible is still an important goal in the first part of the process. You want the car to hunker down against the tarmac so that each brake can deliver maximum contribution.

· Modulation. Some way into The Big Squeeze you’ll see the G-force start to level off- or even reduce slightly. This is the driver controlling his input as the car slows and the risk of a lock-up or ABS intervention increases. It is a subtle process but you can see it clearly when you overlay Clint and Joe Average. You’ll see a high plateau in the former instance, with an occasional dip. Lesser drivers often have a series of jagged spires, suggesting multiple ABS interventions. Also, the phasing of the process differs, with Clint doing the hardest braking earlier in the entire process.

· The Unsqueeze This phase is critical. More commonly known as trail braking, this is the release of the pedal in a controlled manner up to the point where the foot can be transferred to the gas. The objective is to keep the front end of the car sufficiently loaded to aid steering grip, the first, subtle movement of the steering already having been made. With the car starting to pivot/swivel around its front axle (aided by the rear being slightly unloaded), the final release of the brake pedal can be made. Get the "Unsqueeze" wrong and you’ll overload the front tyres at some point on your way to the inside of the corner, creating an initial understeer and moving the car away from the target enough to make hitting the apex impossible. Miss the apex and it is virtually impossible to get on the gas soon enough and hard enough to get perfect drive onto the next straight.


Further around the lap, the process starts again but it isn’t identical. Turn Four at Zwartkops, with an apex speed of 110/115 km/h - versus just on 60 km/h for the hairpin - is a momentum corner and the G-force curves Clint creates are very different - understandably so, when you consider they have little in common other than being right-handers.


What he does at two totally different corners has convinced me that braking is of the essence and that it becomes even more of a delicate art when driving a traditional manual, and a car that doesn't have ABS. I'm keen to get the VBOX onto something like a Backdraft Cobra with a Reghard Roets at the wheel, or a Lotus Challenge car with Jeffrey Kruger driving and take a close look at their data when they're working the middle pedal...



119 views

Do you know what ADAS means? It’s an acronym for Advanced Driver Assistance Systems. It is the umbrella term for everything from ABS to adaptive cruise control.

Slowly becoming part of the general motoring lingo, ADAS is – I suspect – more of a term coined by engineers and those who create the tech that defines modern cars and modern driving. It ultimately embraces traction control and ABS anti-lock braking (systems which were still relatively novel when I first started testing cars as a cadet motoring journalist in the late 1980s) all the way to torque vectoring.




Devon Scott touches on ADAS as part of an excellent intro at the Jaguar Driving Experience and it is a theme which is reintroduced repeatedly in the course of a fascinating morning at the brand’s facility in Lonehill. It has (sadly in some ways) been well over a decade since I got to park a Jaguar in my driveway so to have the likes of the F-Type, F-Pace, all-electric I-Pace and latest XE and XF sedans at my behest was novel and exciting, to say the least.


Since I last drove cars in anger, 400-plus kW seems to have become the new normal and a hot hatch with less than 150 kW is now merely a warm hatch, which is why ADAS systems are not nice-to-haves but must-haves. The kW numbers have certainly brought out my inner conservative though, and I can’t help wondering whether the speed and acceleration numbers being talked about have become absurd and whether it is time for Big Brother to step in?


With 18-year-olds having ready access to 250 km/h cars, isn’t it overdue? After all, human reaction time has remained unchanged and while braking distances are amazing thanks to advances in tyres, electronics and hardware, the results published in roads tests are based on ideal everything - including reaction time.


My other interest in ADAS comes via my involvement with Racelogic, the provider of the VBOX hardware used by virtually every car manufacturer to validate ADAS systems. As you can image, when developing the likes of Active Cruise Control or Autonomous Braking, you need to be sure the system reacts timeously and appropriately…it would be inconvenient if the car unnecessarily and excessively when you're cruising the fast lane and it would be even worse if it didn’t slow the car sufficiently or soon enough when closing in from 120 km/h on a car doing 80 km/h.


Another point well-made by Devon is that these electronic aids should be considered an integral part of the dynamic package. They’re not there to mask shortcomings but form part of the whole. So turning them off in the pursuit of glory – even on a skidpan – proves little. They react significantly faster than even the most skilled race drivers so let them save your bacon and make you look more talented than you might be.


ADAS is what make it possible for tall SUVs like the F-Pace to handle a slalom with such precision and for a sports car like the F-Type to corner like a race car…



It becomes clear again on the skidpan when despite armfuls of opposite lock applied at quickly and as soon as possible, it is all but impossible to prevent a car from spinning out on a wet surface. A similar exercise with the Jaguar’s standard systems engaged result in a reasonably undramatic reduction in power and the ability to stay safely between the cones which define the road…


But one thing remains startlingly clear: despite the advances in technology and the almost insane ability to bring a car back from the brink, the laws of physics continue to play an important role and remain the final arbiter as to whether you crash or not. The final part of the lesson therefore, is not to rely on the electronics too much. They too have limitations.


Jaguar Land Rover EXPERIENCE Johannesburg features a range of facilities ideal for use by special arrangement by other businesses for product launches, events, conferences, casual meetings or team-building days. A 52-seat cinema room can be used along with a selection of conference rooms and private boardrooms with seating for between eight and 50 guests.


It is situated at 1 Capricorn Drive, Lonehill and can be reached at 010 023 0462, info@experience.jaguar.co.za or info@experience.landrover.co.za.

14 views

My father was tuning a Group One Datsun 1200 GX for a young racer, Bill Schipper.

But I was usually to be found some way from where Bill’s little sedan pitted – I just followed my ears and honed in on the noise from the rotary-engined Mazdas. They were easy to find. Of course, it wasn’t only the bark-to-howl-to scream I loved – they were giant-killers on the track too, thanks to the ease with which extra power could be extracted from these “showroom stock” race cars.

Handling and braking were relatively rudimentary, although coil springs all round and trailing arms with a Panhard rod was certainly superior to the leaf-sprung axles of most Fords, Datsuns and Toyotas of the era. Discs (non-ventilated) and rear drums were pretty much de rigueur. If there was a handling advantage, it came down to the fact that the light and low-slung engine aided both weight distribution and centre of gravity.

Their nemesis was ultimately the likes of the Golf GTI and by the mid-1980s the rotary was a spent force in production car racing though far more entertaining to watch than the Golfs. Imagine if they had built a rear-drive 323 with a rotary powerplant! In Star Modifieds and then Wesbank Modifieds they soldiered on until well into the 1990s, Ben Morgenrood building incredible three and then four-rotor race cars in various Mazda-based shells – he must’ve had some useful contacts in Japan and the USA.

No surprises then that my first road car was a Mazda RX2 and my first race car a Capella Rotary. Actually, the latter started life as a Capella 1600 but even in the late 1980s (when my father and I built the car for Castrol Super Saloons) coupe shells were in short supply and we picked up the donor for the princely sum of R40 at a municipal auction. It was a bit of a wreck, truth be told, but it had two doors.

Fast forward two-and-a-half decades and I’m driving the latest Mazda CX-5 – a crossover or an SUV, depending on the engine/drivertrain details.

It would be pointless to say something like: “it’s amazing how far they’ve come”, because if they hadn’t, it would be really worrying. But what is apparent – and there are plenty of landmark cars from the intervening years which give truth to the statement – is that Mazda remains a fundamentally innovative and engineering-driven brand.

No one has quite matched the authenticity of the original MX-5. Successive generations have been faithful to the recipe of a lightweight, modestly powered sports car with the emphasis on driver involvement. Also remember, Mazda won Le Mans with the quad rotor 787B in 1991. More than a quarter-century would pass before another Japanese brand repeated the feat.

When it comes to styling, my eyes say Mazda leads – you only have to compare the likes of successive generations of Corolla, Almera and Mazda3 to see who has the most daring styling. This is still evident in the CX-5 and its smaller stablemate the CX-3 when you compare them to rival brands. It arguably also applies when it comes to driving enjoyment – a quality which Mazda sums up with Jinba Ittau.

Mazda refers to their design language as KODO, and it can be summed up in three keywords: speed, tense, and alluring. I get it, and there are elements of those qualities in the CX-5, which is pressed into service for a Cape town involving moving belongings out of a university rez and storing them in anticipation of the 2020 academic year.

There’s so much that impresses me about the medium-sized family holdall. It is good to drive. The transmission and Skyactiv a 2.2-litre turbodiesel are perfectly matched in all but one respect: when the start/stop kicks the engine back into life there’s a notable jolt as the oilburner fires up. It is at odds with the impressive refinement of the rest of the package. A solution would be to opt for the 2.5-litre petrol version, which will also save you nearly 30K.

After a weekend with a CX-5, would it be my choice if buying in the segment? My days of requiring a five-seater with this much luggage volume have long gone but in this four-wheel-drive guise (it is an on-demand system, driving the rears only when the fronts slip, but to my mind it deserves to be considered an SUV rather than a large crossover) it straddles a lot of turf. Natural rivals are the Honda CR-V and Toyota RAV but I think if buyers think carefully enough also makes more sense than a Fortuner for many – and it has much more class.

I think if families took the time to consider their needs, then this will make as much sense 98 percent of the time. The other two percent being when you need seven seats and/or low range...

3 views