BUYERS GUIDE - MOTORHOMES
Earthcruiser’s first Extreme XTR330 6×6 was exactly that: extreme. A true go-almost-anywhere motorhome, with the expected top-shelf Earthcruiser home comforts, it was built on a greatly modified LandCruiser 79 cab/chassis.
For a start, if you haven’t got a big bag of money, don’t even think about annoying Earthcruiser for an Extreme XTR330 6×6: it’s around double the price of a ‘normal’ Earthcruiser Extreme 4×4…and they’re not cheap.
The 2023 XTR330 was developed in conjunction with Bob James’ 6×6 Australia that’s well known for its innovative 6×6 conversion on ute and light tuck cab/chassis. We’ve covered the James’ 6×6 process in our Modifications section.
The 6×6 Australia conversion was similar to the design approach used by some European OEMs, employing a single main prop shaft – not the power take off used by some after-market converters – and a load-sharing beam that distributed rear tandem weight evenly between the rear axles.
Although based on the Toyota 79 Series, there was not much left of the original beast’s chassis and running gear. The cab looked standard, but the rear wall had been cut to allow a crawl-though into the motorhome body.
The chassis under the cab was retained, albeit with considerable ‘flitching’ for additional strength, but the chassis aft of the cab was extended and ‘joggled’. This frame ‘waisting’ was done using ‘lobster back’ tapering and joining, and was CAD modelled and CNC laser cut.
This aft narrowing of the custom box-section chassis rails allowsed installation of a James walking beam that provided 50:50 weight distribution between the two rear axles and space for outboard-mounted air springs, for optimal handling and sway control. Also limiting sway were military spec anti-sway bars with in-cab remote disconnect function that allowed the sway bars to detach and give more axle articulation off road.
Needless to say, the narrow-track standard Toyota rear axle had been discarded and replaced by two fabricated axles, with chrome-moly half-shafts and 3600kg capacity each. Rear axle track matched the front axle dimension – a task that still seems too difficult for Toyota to manage. The front axle was a fabricated design, with a load rating of 1980kg.
The rear diff centres were Ford 10-inch and nine-inch, respectively, fitted with diff locks and controlled by a power divider that let the third axle ‘idle’ unless a loss of traction occurred. All three diff locks could be engaged simultaneously, if required.
Some 6×6 conversions make turning circles vast, but the James design incorporates a ‘bogie roll steer’ function that provides self-steering assistance from the rear bogie, based on the radius and speed of the turn.
The centrifugal force action when cornering causes a slight bogie wheelbase increase on the outer wheels and a corresponding decrease in the bogie wheelbase of the inner wheels. (Bogie wheelbase is the distance between the forward and rearward rear-axle hubs.)
If looked at from above, the diff centres hardly move, but the two rear axles develop a slight angular difference and this angle aids the steering action of the front wheels: the greater the vehicle load and the centrifugal cornering force, the greater is the steering input from the rear axles.
Air suspension was done by six air springs, with custom-designed Bilstein dampers. A side benefit of the air suspension was automatic 100mm load levelling when travelling and up to 250mm static. The air springs were fed from 52 litres of on-board compressed air storage.
The XTR330 also had four hydraulic rams for self-jacking on slopes
The chassis and axle/suspension additions saw GVM increase to 7000kg, under the second manufacturer SSM scheme that’s nationally recognised, but painfully slow in process, despite the much-vaunted new ROVER initiative.
Earthcuiser maintained the standard V8 powertrain, with a choice of the Toyota five-speed manual, with heavy-duty clutch, or a six-speed Aisin auto from the LandCruiser 200 Series.
As OTA knowns only too well, a wheelbase extension compromises belly clearance. (Our 75 Series 4×4 has a wheelbase extension to 3700mm and that sometimes sees the belly touching the deck.) The first XTR330 has an even longer ‘mean’ wheelbase of 4130mm (measured from front axle to centre of rear axle group), so belly clearance was potentially debilitating.
The cure was simple, if somewhat pricey: portal axle hubs. A portal hub is a ‘drop box’ with a gear set in each hub that lowers the axle centre line, thus allowing the axle to be mounted higher in the vehicle. At the same time, some gear reduction is included, thus lowering the torque loads on the axle half shafts.
In the case of this XTR330 the ground clearance under the axle diff bowls was increased by 120mm to 390mm and the gear reduction in the hubs was 16 percent. The lowest chassis point was 610mm above level ground. Total vehicle height was 2600mm at suspension ride height.
Portal hubs have a side benefit, making it easy to accommodate an air feed though the hubs, into each tyre, allowing inflation and deflation via touchscreen controls while vehicle is in motion. The CTIS (Central Tyre Inflation System) reacts to road speed by implementing automatic pressure changes, based on road speed.
The downside of portal hubs is heat caused by gear friction and that’ was countered in the XTR330 by fitment of remote oil reservoirs for the hubs.
The wheel ends were finished off with upgraded brake packages, backed by hydraulic brake boosting and 17-inch Earthcruiser Exclusive forged aluminium wheels with dual inflation valves for the 35 x 12.5-inch Federal Xplora Mud terrain tyres that were 137Q load rated (2300kg per tyre). Toyota’s 3500kg towing capacity was retained.
Comfort and convenience
The gang at Earthcruiser are hands-on remote area travellers, so they know exactly what’s required for extended trips away from support. That degree of necessary equipment starts with tank options for fuel and water, and this first vehicle had twin 275-litre water and fuel tanks, plus a 27-litre grey water tank. An Integrated high pressure water blaster delivered a 1500psi stream.
An optional ‘Arctic’ package, for operation down to minus 40 degrees C included heated water tanks and batteries, and a drying compartment for clothes and wet goods.
The spartan Toyota cab received an upgrade in the form of repadded and leather-reupholstered driver and passenger seats, plus a leather-covered console. Earthcruiser-quality insulation was also incorporated the cab and Clearview power-fold electric mirrors. There were also optional cab seat heaters and multiple USB outlets.
Behind and above the cab sat Earthcruiser’s one-piece, infusion-moulded structural foam roof, closed with double seals, bonded to moulded, structurally-insulated foam walls and floor. The insulation is rated for -30C to +70°C ambients.
A moulded, structurally-insulated and sealed entry door was fitted with a dead lock and all the body latches and locks were flush-mounted or recessed. Access was made easy by Earthcruiser Exclusive, automatically-retractable cab entry steps.
A triple-layer block-out roof curtain incorporated PVC windows, insect and full privacy screens.
Although best reserved for sleeping two, a third person could be accommodated and the XTR330 featured four seat-belted positions: two in the cab and two in the camper.
Body skirts with four lockable toolboxes were fitted to this vehicle and a lockable, pass-through rear hatch allowed storage of items such as fishing rods, skis and camp chairs.
The camper featured leather dinette seats, CNC-routed Corian bench tops, stainless steel sink with purified drinking fountain and taps; instantaneous diesel hot water; diesel cabin heating; electric-slide-out Thetford chemical toilet ensuite and internal and external showers.
The XTR330 had a lithium battery system for starting and house batteries: a whopping total of 1110Ah and that’s around three to five times what’s normally provided in motorhomes.
Standard were 810-watt mono-crystalline solar panels and up to 1152w panels could be accommodated. Also standard were a 3000w Victron Inverter with 6000w peak power and a 50-amp Multi Country (variable frequency and voltage) Victron battery charger.
The standard alternator was replaced by a 200-amp high output, fully sealed and water-cooled brushless alternator (mine spec).
This high-capacity electrical system meant that there was no need for any LPG on the XTR330. Even the roll-out BBQ was 240V electric and the kitchen cooker was a 3500W two-plate induction cooktop, supplemented by a microwave oven.
There was also ample battery capacity to run a 12-volt split air-conditioning (90amp/1800w/5800 BTU/h) without the need for mains power.
The twin fridges were a main 122-litre model and a 68-litre rear fridge/ freezer.
Other electrical equipment included a chargeable cordless mini wet and dry vacuum cleaner; chargeable toolkit with chain saw and impact wrench; 2160w, 12-volt continuous duty air compressor that provided 14CFM at zero psi and 8CFM at 100 psi.
This first XTR330 was equipped with a pair of GME XRS connect UHF radios and Hella HID driving lights, delivering comfortable light temperature, but other options were available.
The purpose-designed recess in the nose of the camper moulding neatly housed a 52-inch, dual row, curved Roadvision LED light bar and fog lights were integrated into the bullbar.
Other exterior lighting was 360-degree flood lighting on all sides and rear of vehicle, with an emergency lighting” function. An optional internal/external security camera system with 24-hour DVR system was available.
A Space-X Starlink internet system was integrated into the vehicle, offering global internet connection. The satellite dish was flush mounted with the roof, to prevent damage. There was also an optional Cel-fi cellular phone signal booster.
A touchscreen Garmin head unit featured digital switching of all motorhome functions with wireless capability of up to five metres range. It also had an inbuilt pitch and roll meter and TPMS display.
It was loaded with Hema Mapping and had audio with radio, AUX, USB and Bluetooth connectivity. It played audio through an additional speaker system in the camper.
A DVR/GPS/4G solid state digital video recorder was also on the options list, along with cellular hot spot and GPS tracking in real time, with 60-day recording loops.
The Garmin system Interfaced with three 10-inch touchscreens, of which two had removable wireless docks.
Protection and recovery
Protective kit included a hammer-tone winch-compatible steel bullbar, with steel scrub rails and side steps, colour-coded to the bullbar. Two 13,000lb 12-volt electric winches were fitted, front and rear, along with heavy duty front and rear recovery points.
There were two spare wheel carriers with electric lifters, to help make tyre changes effortless.
A dual-purpose Maxtrax/firewood box carried up to four sand ladders and a load of firewood simultaneously.
Given the incredible equipment levels in this Earthcruiser initiative, it’s possible we’ve missed something, but we can’t think what it could be. Yes, it did have a kitchen sink…