Focus on tech
Geared down for better performance
Some modern 4×4s are too clever. With state-of-the-art automatic gearbox technology, the makers of these 4×4s claim there is no longer a need for a transfer case; with an extra low first gear, these vehicles can handle some off-road driving. This month we focus on transfer case technology. And if the so-called kort stokkie really has become redundant and irrelevant.
There we were, on a mountain in Lesotho. It was 11pm and we were utterly lost. We were driving a shiny new Volkswagen Amarok 2.0BiTDI 4Motion AT and a Nissan Patrol 3.0TDi.
We had taken a 60km track which supposedly led to Semonkong, a road labelled ‘bad road’ on a Lesotho map. In the beginning, it was indeed a bad road. Later, it evolved into a ‘very bad road’. As the hours ticked by, the going got increasingly tricky, and the track turned into a grade four 4×4 obstacle course.
By then it was dark. We were on the side of a mountain on a track that made Sani Pass look like a four-lane national highway. It was not quite what we had in mind with the whole ‘bad road’ deal.
Still, we had no alternative other than to push on, regardless. The Volkswagen was fitted with the ZF eight-speed automatic gearbox that, around town and on the open road, had proved absolutely brilliant. But this mountain... this was something quite unlike what the VW engineers in Germany had in mind when they said this gearbox, with its lower-than-normal first gear, was a handy replacement for the traditional transfer case, as used in a pukka 4×4.
Take the Nissan Patrol, for instance. It has a transfer case, connected to a traditional kort stokkie, or short(er) second gear lever, in the cabin. For normal driving you leave the part-time 4WD system in 2H, with only the rear wheels providing propulsion. For gravel roads and slippery driving conditions, you can select 4H, and the drive is split 50/50 between the front and rear axles.
And for the really, really tough 4×4 bits, where speed is not important but low-down grunt is, you select 4Low, for five low-range ratios and a top speed of around 60km/h. The rest of the Nissan was equally old school: there was the ladder-frame chassis, the excellent wheel articulation and a complete lack of electronic driving aids.
The Nissan and VW represented the two different ends of the 4×4 driving
spectrum. One is all oldschool driving skill, the second is a technological piece of equipment with fancy traction control and the low first gear which is supposed to provide forward momentum.
Driving the two cars on that dangerous track proved to be a watershed moment. The Nissan was really tricky, requiring just the right gear, the right momentum, precise throttle inputs and delicate steering inputs.
The VW was completely different. Point it in the right direction, add throttle – and keep the throttle at a constant input point – and the traction control sorts it all out, almost miraculously maintaining forward momentum.
The VW proved much easier to drive on that type of extreme terrain than the Nissan. The short first ratio in the automatic gearbox certainly did its job on that mountain.
But here’s the thing: if we had to drive a mountain track like this on a daily basis, we’d opt for the Nissan, every time, every day. Even though the VW may flatter the driver with its electronics – and it may last a few years doing it, too – it was never intended as a hardcore 4×4 replacement. Instead, it’s aimed more at aiding the occasional bundu basher.
The Nissan’s drivetrain, on the other hand, was designed for this type of driving from day one, and it will take this kind of beating day in and day out.
What is it about a transfer case that makes it the better option for hardcore 4×4 driving then?
Shifting the focus
A transfer case is connected to the vehicle’s gearbox and receives its drive from the gearbox, too. This power transfer between the gearbox and the transfer case can be done through gears, hydraulics or a chain drive.
The driver can, in most cases, select between 2H (rear-wheel drive only), 4H (four-wheel drive high range with the drive split 50/50 between the front and rear axles) and 4Low (four-wheel drive low range with the drive split 50/50 between the front and rear axles).
Essentially though, the transfer case reduces the gearbox ratios to increase low-speed torque, to enable the 4×4 to crawl over rough terrain at the slowest possible speed with the most torque at the driver’s disposal. These ratios vary from 4×4 to 4×4.
For instance, a Jeep Wrangler Rubicon’s transfer case ratios are lower than those of the Jeep Wrangler Sahara. The Rubicon can crawl at an even lower speed than the already very capable Sahara over those large boulders, offering better control and more precision, and less chance of expensive damage.
Then you also get cases like older generation Subaru Foresters: the non-turbocharged versions were fitted with what Subaru called reduction gears. This transfer case was not designed for hardcore 4×4 driving but rather for dragging a caravan out of a muddy campsite.
Opposite page, top: The Jeep Wrangler Rubicon’s transfer case ratios are lower than those of the Sahara model, enabling it to crawl along at lower speeds. Opposite page, left: The gear lever in a VW Amarok automatic. No transfer case here but rather a shorter first gear and an off-road mode with all sorts of electronic trickery. Top: The Nissan Patrol represents everything we love about old school driving, as it relies on driver know-how rather than electronics. Above: The traditional layout of a 4×4: main gear lever in the middle and the famous kort stokkie next to it. Some people reckon it’s a thing of the past but interestingly, Suzuki binned its push-button system to return to this arrangement on the 2018 Jimny.