What Drive Where

As more and more Members acquire or build off-road 4WD motorhomes, it seems timely to discuss what can realistically be driven where, with the overriding qualification that this article is written primarily for newcomers to off-road driving. Those with extensive previous experience may perceive specific situations differently from those lacking it. Common to most however will be the realisation and acceptance that, especially with big vehicles, 4WD needs to be reserved for getting out of trouble – not just a few hundred metres further into it.

This article is relevant to all those innumerable tracks mapped in solid red that criss-cross Australia’s interior. It relates also to many of those tracks shown in broken red lines, but I advise against driving on those until you gain experience.

Four-wheel drive itself is very rarely, if ever, needed for travelling across virtually any track shown in solid red; it is more likely to be needed when attempting to enter or leave a desirable camp site. Then, as covered later in this article, it can be valuable indeed. What is required most of the time on dirt tracks includes:

Adequate ground clearance: This should ideally be 300mm minimum. Without that, damage to the exhaust system and fuel tank is likely, and to the differential housing/s possible, but less probable. This is a serious requirement. I am bothered by a few vendors offering converted 4WD European delivery vans with inadequate ground clearance and tyres unsuitable for off-road use. With these, the 4WD function was probably intended primarily for icy conditions (where front-wheel drive lacks traction), not off-road use.

Given a choice, I would far sooner have a high ground clearance 2WD, with adequate weight over the driving axle, than a low-slung 4WD anything. Without good ground clearance, that 4WD function is useless. As are low profile, high pressure tyres off-road.

Suitable and regularly maintained suspension: Particularly on long corrugated roads (e.g., Tamaki Rd, Plenty Highway etc) the suspension takes a hammering. Shock absorbers must be of adequate size and in top condition. Few survive more than 50,000km. In particular, the rubber bushes are likely to need replacing every 10,000 - 15,000km.

Here again, most 4WD campervan conversions are likely to have suspension intended for slippery, but not rugged, going. I strongly recommend upgrading the suspension from the start.

U-bolts need checking every 5,000km. Wheel nuts likewise (many truckies check daily).

Suitable tyres of recent build: Use top quality, high profile All Terrain tyres, not more than five years old. Avoid rugged macho tread tyres - they are noisy, wear fast and are less effective in sand.

Long-range fuel tanks: Within reason, the bigger the better! My now-sold OKA held about 380 litres. This comfortably allowed us to drive from Broome to Alice Springs without refuelling, and to buy fuel where it was less costly. If planning to do a lot of such driving I recommend a minimum 1,000km range, assuming strong head winds. Ideally more.

Water: Obtaining drinkable water is a major problem in SA and much of WA. You either need big tanks (which add a lot weight) or very good filtering, so that you can use marginally suspect water. Washing water is easier to find. It’s well worth adding an extra external pump and carrying a long collapsible hose to enable you to fill up from streams etc.

Rugged interior construction: By and large, 4WD truck chassis are far tougher than what’s built on to them. Insufficiently rugged construction (with allowance for chassis flexing) is the downfall of many (even commercially built) 4WD motorhomes. Many designers and builders underestimate this – and also the difficulty of truly sealing against dust.

All interior furniture must be secured firmly to strong frame members (Sikaflex alone is ideal as it allows some movement), but not simply attached to a plywood wall, or, as in the case of one notorious caravan example, glued to the outer thin veneer (amazed owners would open the door to what looked like an explosion in an Ikea factory, and they had no recompense, as attempting to fix the many failures bankrupted the maker).

Lightness: Many breakdowns are caused by overloading. If travelling off-road, you really must keep weight to the absolute minimum that is consistent with carrying the essentials. This can be hard to achieve, as most 4WD chassis not only weigh more, but are also substantially de-rated in terms of load carrying, relative to a 2WD truck of similar type.

Realistic size: Many of the more remote National Parks, State Forests and even roads, are only cleared sufficiently to allow fire truck access. In our experience, many are impracticable in anything higher or wider than a pop-top standard OKA coach (about 2.1 metres wide and about 2.3 metres high). Even then the OKA was often a tight squeeze. Were we to do it all again we would probably use the somewhat smaller Volvo or Pinzgauer (both 6WD). Also necessary is a good turning circle, but here again this tends to be much wider than with most 2WDs.

Good, up to date maps: Very important. Many shops have maps in stock for years and not all maps include the date of printing or previous updating.

Adequate tools and major spares: This is essential. Even if you have no idea how to use them, or replace vital bits, someone invariably comes along who does. Consult one of the vehicle’s factory-associated service agents for advice on possible needed spares. Definitely carry all routinely-changed items, like filters. This enables routine servicing to be done speedily and almost anywhere.

Given the above, you are sufficiently well-equipped for all but a few tracks. Unless very experienced, those tracks to avoid are:

The Old Telegraph Track (top of Cape York) – some parts not drivable in anything larger than a Toyota Troopy.

Simpson Desert crossings – the ‘shorter’ Simpson crossings are very hard on the transmission and frankly boring. The Rig Road alternative is far more interesting and easier on the vehicle, but much longer. Unless very experienced, do this one in truly experienced company.

Canning Stock Route – best avoided unless travelling in a convoy – it requires a minimum 2400km fuel range (this is possibly about to change).

The Gibb River Road on the other hand is often described as only for the full-on 4WD brigade. This is total nonsense. Apart from the Pentecost River crossing, it is usually no better or worse than most good outback tracks. My wife Maarit travelled it routinely until recently (using a 4WD Toyota 100 Series) when visiting remote outback Aboriginal communities. The track to Kulumbaru is like a three-lane dirt highway. We suspect its reputation is due to the more macho types needing to maintain their image when back home!

Virtually every other major solid-red lined track is passable in a vehicle set up as described.

Probable Bogging

Where you are most likely to run into trouble is when getting in and out of otherwise appealing camp sites, so be extra careful. Be aware that big 4WD trucks are close to impossible to deflect from a straight line when reversing in sand (unless you drastically drop front tyre pressures, and even this may not help). This is especially so if you have a limited slip, or locking rear differential. Take this one seriously. If accessing a soft surfaced site involves turning whilst driving in, make totally sure you can get out by driving forward. Ideally reverse in. If you can do that you can easily drive out forwards. If not, you probably can’t!

A final word of caution; big 4WD truck chassis and transmissions are very tough, but they are not unbreakable. Be cautious when using a lot of torque in 4WD low range, as the torque multiplication in low first gear is sufficient to twist the chassis and break drive shafts before the engine stalls. Avoid using first gear low-range if possible. If the vehicle starts dragging in a low gear in soft going, drop the tyre pressures to ease the load. This typically makes at least ‘one gear’ difference.

I should perhaps mention that Maarit and I have travelled extensively across and around Australia. I have driven from Broome to the east coast and back, always via the Centre, over ten times, and also across virtually every major interior route except (so far) the Canning and the Gunbarrel Highway. I have also driven twice across the length and breadth of Africa, including two Saharan crossings. Much of our travelling has been in our previously owned OKA, but prior to that we travelled extensively inland using our ground clearance increased 2WD VW Kombi.

I prefer not to recommend specific brands of big 4WDs, but this is an area where engineering is not usually overly compromised by bean counters. There are substantial differences in noise, harshness and ride quality, so insist on a trial run before committing to buying.

Finally, I recommend against big 4WD’s unless you have a really positive need (or simply want a big toy!) They are costlier, rougher and have less weight carrying capacity than their 2WD equivalents.

Collyn Rivers is the author of several books in the above and related fields. Some of his books are available directly from the Head Office of the CMCA.