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Off-roading in a pick-up – what should you know?

We look at the specific features you should be looking for in a pickup if you need genuine off-roading capability.

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With just six manufacturers selling new pickup trucks to the UK market, one of which of which only offers an electric model, there’s not a lot of choice when it comes to selecting the right pickup for your business. If you have serious off-roading needs, your choices shrink further.

Isuzu has long offered its versatile D-Max pickup range in the UK, which is available in a variety of flavours to suit every business and personal need. We’ll be exploring the full range over coming weeks. The D-Max family starts with the UK’s cheapest entry-point to a new pickup at £25,995 (plus VAT) for its two-wheel drive Utility specification. For drivers who need to regularly travel off-road the rest of Isuzu’s range comes with four-wheel drive as standard. All four trim levels – Utility, DL20, DL40, and V-Cross – come with a 1.9-litre diesel engine. 

If you’re serious about off-roading, Isuzu UK has put together a one-off Mudmaster model that shows what the D-Max is capable of when fitted out with some specialist accessories, most of which are official Isuzu parts that can be fitted by your local dealer.

Today, we’re looking at the specific features you should be looking for in a pickup if you need genuine off-roading capability.

Tell me about this Isuzu D-Max Mudmaster

Created as a one-off demonstration of how robust an Isuzu D-Max can be with a little help, the Mudmaster is based on the top-spec D-Max V-Cross trim, but adds around £14,000 of additional accessories to complete the package. We’ll detail all the extras below.

Apart from the unique ‘Mudmaster’ stickers, you can pretty much create your own version of this truck from any 4WD D-Max model.

How much does the Isuzu D-Max Mudmaster cost? 

If you wanted to build your own Mudmaster to the same specification as the Isuzu UK press office, you’d need to start with the top-specification D-Max V-Cross model. That starts from £36.5K with a manual gearbox or £38.5K with an automatic transmission. These are commercial vehicle on-road prices, which includes vehicle registration, the first year of road tax and number plates, but excludes VAT. If you don’t like solid white, add £600 + VAT for one of seven alternative colours.

On top of the regular V-Cross, the Mudmaster package seen here adds around £14K plus VAT. So you’re looking at roughly £50.5K plus VAT for a manual or £52.5K plus VAT for an automatic for a D-Max that looks like this one. But there are plenty of different choices in the sprawling Isuzu accessories catalogue, let alone the aftermarket possibilities, if you want something a bit different.

While the Isuzu D-Max Mudmaster gets an exterior makeover, most of the useful mechanical functions for off-roading are available on the rest of the range. If you’re doing regular work away from sealed tarmac, these are the things you should be thinking about for your next vehicle.

Two-wheel drive vs four-wheel drive

It’s no surprise that the majority of pickup trucks in the UK spend most of their lives on tarmac roads. For most of this driving, a two-wheel drive (2WD or 4×2) vehicle will cover most needs with ease. But there’s certainly still a need for plenty of pickup owners to venture onto unmade tracks, whether it’s for work or pleasure, and this is where four-wheel drive (4WD or 4×4) tends to provide a significant advantage.

The logic is sound enough. In a 2WD pickup, all of the engine’s drive is sent to the two rear wheels. If conditions are slippery, the torque from the engine can easily overwhelm the traction available from one or both wheels, causing them to spin uselessly. With a 4WD pickup, the same amount of torque is spread around all four wheels, so the engine is less likely to overwhelm the traction available and the vehicle will move forward rather than simply spinning its wheels and churning mud/dirt/snow/sand everywhere.

A 4WD pickup will still be able to move forward even if only one of its four wheels has grip. With a 2WD pickup, you’re relying on one of two (rear) wheels having sufficient grip to move the vehicle. If you’re on a nice tarmac road, it’s likely that all four wheels will have plenty of grip so this is not a major issue. When you’re off-road, however, grip levels can vary dramatically across all four wheels at any time.

But it’s not just when you’re mud plugging that it makes a difference. Consider towing a loaded boat trailer up a ramp and out of the water. The rear wheels might be on slippery, slimy wet concrete with limited grip, but the front wheels are on dry concrete with more grip. A 4WD vehicle will be able to pull the heavy trailer up the ramp more easily than a 2WD model.

Many drivers make the mistake of thinking that a 4WD vehicle will be safer in all conditions, but this is not really the case. A 4WD vehicle will provide better and more stable traction, which only applies under acceleration. When cornering or braking, however, there’s no significant difference in how the vehicles will behave. This is amply demonstrated by the number of Range Rovers that end up in ditches every winter…

Transfer case

The D-Max 4WD range (everything apart from the base Utility specification) has a transfer case, which allows you to switch between 2WD and 4WD as needed. It also features high- and low-range modes when driving all four wheels. This is all controlled from a dial on the dashboard.

The 2WD mode is used for everyday on-road driving, although you can leave the D-Max in 2WD mode for light dirt or gravel roads. This gives best performance, best economy and lower noise at speed.

The 4WD High mode is designed for slippery surfaces such as grass or mud, where you’re still maintaining a reasonable pace but need extra grip. Rather than just driving the rear wheels, you’re now dividing power equally between front and rear wheels. You do suffer some loss in performance and fuel economy if you leave the pickup in 4WD High in normal road use, but you won’t damage the vehicle.

4WD Low is a specialist set-up that reduces vehicle speed and increases the torque available to each wheel. It’s designed for situations where you have grip but need more torque to get the truck moving – like climbing a steep, rocky hill with a fully loaded tray. It can also help with fine control in slippery conditions, as you have more throttle control for delicate applications.

You can switch between 2WD and 4WD High on the move in the D-Max models, but you need to stop momentarily to change into 4WD Low. You also don’t want to use 4WD Low at anything more than very slow speeds, so you’ll need to stop again once you’ve got to flatter ground to switch back to either 4WD High or 2WD mode.

Manual or automatic?

Most pickup manufacturers will still offer manual gearboxes on most, if not all, of their models. Automatics tend to sell better for road-biased customers, while those frequently heading off-road or towing will often prefer the control of a manual gearbox.

Traditionally, off-road drivers have tended to prefer manuals because you can select a higher gear in slippery conditions – taking off in second gear rather than first, for example, to minimise wheelspin. You can also use the gears to slow the vehicle downhill, with lower gears naturally limiting the speed of the wheels.

In newer vehicles, modern automatic transmissions can overcome some of their previous limitations. Most allow you to manually shift up or down for controlling your speed, and many vehicles will have multiple driving modes for different conditions.

Another useful function that helps automatic vehicles cope well on steep inclines is hill descent control. This is standard on all Isuzu D-Max models, for example. When you’re starting down from the top of a hill, you use the brake pedal to slow the vehicle to a speed you’re comfortable with. You then hit the hill descent control button and lift your foot off the brake, and the car will continue descending the hill at the same speed. It’s like a basic form of cruise control for low-speed off-road driving, and achieves much the same results – if not better – than holding the vehicle in a specific gear.

Locking differential

The 4WD modes described above split the engine’s torque equally between the front and rear axles, so 50% goes to the front wheels and 50% to the rear. However, drive on each axle will vary depending on the resistance at each wheel. That means a wheel with less grip is likely to spin, as there’s less resistance.

All D-Max models, including the 2WD Utility version, include a locking rear differential. This means you can ensure that both rear wheels get an even share of the torque going to the rear axle. So in 2WD mode, each wheel gets 50% of the total drive while in either of the 4WD modes, each rear wheel gets 25% of the total drive (there’s no locking front differential on the D-Max, so the 50% of the torque to the front wheel will still split according to resistance at each front wheel).

A locking differential helps in very slippery conditions, where one side of the vehicle has more grip than the other. If your right-rear wheel is on a slippery, muddy surface but the left-rear wheel is on a grippy surface, more engine torque will naturally go to the right wheel as it has less resistance. But all that does is make the wheel spin as it has no grip. And the more you try to accelerate, the more wheelspin you get with no forward movement as all the torque goes to the spinning wheel. By locking the rear differential, you make sure that both rear wheels get equal grip, so the left wheel can drive the car even if the right wheel is still spinning.

Some hardcore off-road vehicles also offer the ability to lock the front differential, but this is much less common. The D-Max doesn’t have this and neither do most pickups sold in the UK.

Approach and departure angles

Isuzu D-Max V-Cross Mudmaster

In a road car, you generally get best performance when the car is as low to the road as possible. This lowers the centre of gravity, so the car will roll less through corners and generally handle better. That’s great on a fairly flat surface, but is no good when you’re covering rocky terrain and ditches. Here, you need ground clearance.

But it’s not as simple as sitting higher up to clear obstacles. For serious off-roading, you also need to look at a few other dimensions. These are approach angle, departure and and breakover angle. So what are these and why are they important?

Your approach angle is the angle of the hill you’re trying to get your front wheels onto. If you drove straight up to a solid wall, that would be an approach angle of 90º and you wouldn’t be able to climb it. You wouldn’t even be able to get your front wheels onto the wall because the nose of the car is in the way. Vehicles with more ground clearance and/or shorter front overhang (the bit of the car ahead of the front wheels) can get their front wheels onto a steeper incline without bashing the front bumper.

Departure angle is essentially the reverse – the angle of the hill you’re trying to leave to get back onto a flat surface. Again, a vehicle with more ground clearance and/or shorter rear overhang (all the section of the pickup that’s behind the rear wheels) will have a higher maximum departure angle, as you won’t bang the back of the truck on the hill as you try to leave it.

Breakover angle is the steepest angle you can drive over without touching any part of the bottom of the car against the ground. Once again, ground clearance helps here but so does having a short wheelbase (that’s the bit of the vehicle between the wheels).

Roads tend to be fairly flat by definition, so these angles are rarely something you’d notice unless you’re in a Lamborghini approaching a speed hump. But off-road vehicles have to deal with changing topography on a regular basis, so it’s something worth considering when you’re choosing a new pickup.

The D-Max Mudmaster has more ground clearance than regular D-Max models, so it has better approach, departure and breakover angles despite being the same size vehicle.

What off-road extras do I really need? 

The Isuzu D-Max Mudmaster demonstration model takes the basic mechanical capabilities of the regular models and extends them further for more specialised off-road functions. These go beyond the average owner’s needs, but will help in specific circumstances.

A snorkel from ARB feeds air to the D-Max’s diesel engine from above the cabin, rather than taking air through the large radiator grille in the nose. This allows the vehicle to tackle deeper water (as shown in the image above) without fear the engine will cut out and leave you stranded waist-deep in a river.

An electric winch by Winch Systems is housed behind the front bumper, with the front number plate folding up to allow access. This can be used to either pull heavy objects – or other vehicles – towards you; or as a tool to pull your truck if it gets stuck.

For low light conditions, the Mudmaster augments the D-Max’s regular headlights with nine-inch central driving lights attached to the grille and a lightbar above the windscreen, both supplied by Lazer. Between them, these powerful LEDs can turn night into day for safe operation in darkness or poor visibility.

The Mudmaster’s suspension is an upgraded carrying and towing kit from legendary Australian suspension specialists, Pedders. This beefs up the D-Max’s load carrying and towing capability, as well as raising the ground clearance. Bolted to the suspension are 20-inch ‘Hurricane’ alloy wheels from the Isuzu catalogue, fitted with Scorpion all-terrain tyres.These will give extra grip off the road, but are less responsive (and noisier) on tarmac.

Underneath there’s a hefty Isuzu steel underguard set, designed to protect mechanical bits from impact with even the heftiest rocks. On top, there’s official Isuzu plastic cladding that covers the wheel arches and bonnet, to protect against flying stones.

As befits a manufacturer demonstration vehicle, the D-Max Mudmaster deploys almost every accesssory in the Isuzu catalogue. Here’s a quick run-down:

  • ARB Base Rack roof rack
  • rubber floor mats, front and rear
  • heavy duty seat covers, front and rear
  • door visors, front and rear
  • door handle protectors
  • Alpha XS-T canopy (which includes silver roof bars, central locking and a heated rear window)
  • black steel side steps
  • Isuzu tow bar set

So although the Mudmaster is not an official D-Max production specification, you can essentially build your own with about £14K of accessories from your friendly Isuzu dealer. Even a lot of the third-party equipment, like the Pedders suspension kit, can be ordered straight from the Isuzu catalogue, while most dealers will be able to sort any of the other equipment for you as well.

Additional reporting by Stuart Masson.

Trinity Francis
Trinity Francishttps://www.trinitygfrancis.com/
Freelance automotive journalist and motoring writer focusing on all aspects of automotive content, with particular attention to emerging trends, industry innovations, tech and consumer advice.

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