2017 4X4OTY: Tough Dog Suspension

THE annual 4X4 Of The Year event pits the newest offerings from all the major manufacturers head to head on some of the most technical terrain Australia has to offer. The idea is simple, push them until they can’t be pushed any more.

After a week living out of these vehicles we’ve got a solid idea of what works and what doesn’t; what rises to the top and what sinks to the bottom. Sounds great in theory, and it’s the only true way to get an accurate representation of how each model compares against its peers. However, in most cases, any new 4x4 taken to these locations is going to be decked out with good quality rubber, a versatile suspension set-up and your usual off-road kit including bar work and winches.

In order to see how each stock vehicle compares against a modified 4x4 with all the fruit, we included in the rotation Tough Dog’s decked-out NP300 Navara space cab.

Tough Dog has been attending the annual 4X4OTY event for a few seasons now, normally because it’s finalising R&D on a kit before it hits the shelves. This year was no different with its prototype leaf-sprung NP300 Navara.

So how did it perform, and how does it compare against some of the most capable vehicles you can find on the showroom floor? In a word, flawlessly. The combination of purpose-built suspension and aggressive tyres made the Navara one of the most capable vehicles in our fleet, despite its workhorse underpinnings and lack of technological advantages some had.

The Navara handled the High Country’s undulating, winding terrain with aplomb, giving a ride quality comparable to many coil-sprung 4x4s while still retaining load carrying capacity and increased articulation for improved off-road capability. It’s the best of both worlds.

So what exactly went in to making a basic leaf-sprung ute outperform coil-sprung 4x4s with far superior tech? We asked Tough Dog front man David Cook exactly that. “Our Navara is equipped with a 30mm lift sitting on foam cell shocks all ’round,” he said. “Up front the springs are rated to carry a bullbar, with our comfort springs in the rear for 0-300kg weight. All up it allows for a 265 tyre to be fitted to a 17-inch rim and push things as far as you’re legally allowed.”

While the fine-tuning happens in the field, the actual process to design and construct a system like this can take months. Up front the NP300’s strut arrangement is similar but subtly different to the outgoing D40 model, while the rear end is entirely new for this generation, which essentially means Tough Dog was starting from scratch. “The first thing we’ll do [when designing a kit] is duck down to our local dealer and place an order for the first black 4x4 on the lot so we can get on top of the R&D here in Australia as soon as possible,” David told us. “From here we’ll rack up a few thousand kays in the vehicle in standard form to give us a good base line.

We do all our testing on standard wheels and tyres so the size of the tyre, size of the rim, or the weight of both, isn’t affecting what we’re feeling through the car. Then we’ll take the standard shocks out of the car and dyno them on our in-house dyno as a reference point. Using our experience and the data we’ve gathered driving it in standard form, we develop and go on to fine-tune a replacement shock absorber with the valving changes we believe will get the most out of the vehicle.”

The space cab Navara also serves as an R&D platform for further development of Tough Dog leaf springs. “When we design the leaf spring pack, theory and on-paper designs can only take you so far. Real-world testing is where the knowledge is gathered,” David explained. “We can make changes to the camber (arch) of the spring, as well as the number of leaves, their thickness and the overall length of the spring to achieve the lift, load carrying and ride quality we’re chasing.

Working out the most effective changes that will get the results we’re after needs to be done in real-world R&D, so we endeavour to purchase every leaf-sprung car that we intend to develop a kit for because it’s the only way to get it right. Modern turbo-diesel vehicles punch out plenty of power and torque, which has changed how leaf springs are designed over time. The design of the spring plays a crucial part in guarding against vibrations from excessive axle movement.”

David told us: “The leaf-sprung Navara is really designed around load carrying; it does carry a load better than the coil-sprung one (which is perfect for towing off-road caravans or decking them out with a camper back). If you’re someone who’s looking to carry a load regularly then that leaf-sprung version is probably going to be the better choice, but fortunately with this car you don’t compromise too much in terms of comfort because of the way the leaf spring has been designed.”

Despite feeling planted in every situation we took it in (including a little sideways action on a rally course), Tough Dog still has a few more tweaks to make to the rear shocks before they’re released in the first quarter of 2017. The full kit will be available through Tough Dog’s website and through its dealer network.

While the market has become flooded with newcomers, the Tough Dog options represent true value for money with a guaranteed solution that’s going to work for 99.9 per cent of people.

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