OKA
BUYERS GUIDE – HEAVY DUTY
Japanese 4×4 light trucks dominate this category, but their shortcomings leave pace for niche marketers, including the once-troubled OKA Motor Company. In mid-2020 a new Australian-owned OKA All terrain Vehicles organisation gave this marque much-needed revitalisation.
At OTA, we were involved with the OKA project from 1993. At that stage, the Perth-based company was courting customers in the mining and recreation businesses, as well as seeking finance from various sectors, both here and overseas.
Along with the late Ian Glover, OTA’s Allan Whiting was asked to evaluate the OKA prototype and suggest improvements. The original machine had a small cab and we judged the payload insufficient.
At a conference in Sydney following our test drive, then OKA managing director, Mike Walker, confirmed that our criticisms echoed those already made by several mining companies and would be taken into account when the production vehicle was designed.
“All we need now is a good name for the truck,” said Mike Walker. After some thought, Allan Whiting ventured: “You can’t get more Aussie than ‘Okker’, so why don’t you call it that?” The idea resonated, but the spelling was made more professional!
The post-2021 OKA
The vehicle used the same production cab that was used on all previous OKAs. In standard form it met mining requirements for roll-over-protection (ROPS – AS1636-1984) and could be specified for falling-object protection (FOPS) if required.
Nice bush-compatible touches were hinged headlight mesh covers and vertically-stacked lights with easily-adjusted beam height.
The cab was formed from zinc-coated flat metal sheets, welded and glued over RHS tube frames, so repairs were low-cost. Also, all glass was flat-panel. The cab was isolation-bolted to the frame, helping front-end stiffness, but that design meant there was no tilt-cab function. However, engine access was via a large lift-up panel between the front seats.
Also carrying over were the stiff, parallel-rail chassis and long, supple leaf springs and this approach was at variance from the Japanese concept of a flexible frame and stiff suspension. In addition to providing a good ride quality the OKA approach also made it simpler to fit rigid bodywork, such as water tanks, without the need for complex three-point mountings.
Although the proved concept was retained, in-service experience led new OKA boss, Dean Robinson and his team to upgrade the powertrain, the axles and the brakes.
In this era of throwaway mentality it’s very refreshing to note that OKA had a refurbishing service for owners of existing vehicles. The rebuild process had its own series designation – ‘R’ – and usually involved replacement engine, transmission, transfer case and axles.
Having driven the original production vehicles we can understand why many owners would want a replacement powertrain, because we were highly critical of the choice of a four-cylinder Perkins Phaser, with only 106hp (79kW) and 354Nm, to haul a GVM of 5500kg. The popular replacement engine by the new OKA organisation was a Cummins 6BT mechanical-injection engine, with outputs of up to 160kW and 600Nm.
However, that engine was later changed to the upgraded Cummins ISBe5, four-cylinder diesel that was not only lighter, but had increased outputs of 136kW at 2500rpm, with maximum torque of 700Nm in the 1200-1700rpm band. The six-cylinder, 260kW/1020Nm version remained an option.
The new-build OKA range was designated ‘NT’ and consisted of single-cab, dual-cab and multi-cab pick-ups, plus a van body that could be specified for load-carrying, bus seating or pop-top campervan vocations.
All standard models were built on a common, 3190mm wheelbase, with 1664mm track front and rear. GVMs varied from 6500kg to 7100kg and payloads ranged from 1650kg to 2200kg, depending on body type and options. All variants could pull a 4500kg trailer.
The ISBe5 had selective catalytic reduction (SCR) exhaust after-treatment that relied on AdBlue urea dosing, fed from a large, 43-litre tank. AdBlue is readily available all across Australia these days, because all new heavy trucks need it.
The original transmission was a Spicer T5-290 five-speed, connected to an NP205 New Process transfer case, but the 2021 models scored a much heavier-rated Tremec TR4050 five-speed manual and an Allison 1000 Series torque converter, automatic six-speed was optional.
The new transfer case was a BAE HD150 variant that was built specifically for OKA, using proved defence-product engineering. (BAE is internationally recognised for its off-road componentry.)
The axles were also modified BAE parts and OKA later moved to Dana 130 axle centres. Central tire inflation (CTIS) was optional on OKA’s new axles. Standard wheels were steel disc 19.5-inch tubeless and that wheel size is a popular medium-truck fitment.
Original OKAs had four-wheel disc brakes, with vacuum-hydraulic actuation, but the new range had air/hydraulic braking, with air supply from an engine-driven compressor. That compressor could also operate the optional CTIS.
The options list was extensive, including cruise control; winches; differential locks; different wheels and tyres, including beadlocks and an additional fuel tank.
Our assessment of the upgraded OKA was that it was a greatly improved package, with significant performance and braking benefits over its predecessors. It was also pleasing to see a company prepared to upgrade pre-loved machines, rather than expecting people to buy new.
On the subject of ‘buy’ it’s important to note that all this custom building and performance doesn’t come cheaply: a typical single-cab pick-up with commonly-sourced options was around the $290,000 mark.
Earthcruiser compatibility
In late-2024 OKA was approved for fitment of Earthcruiser motorhome modules by this Wollongong (NSW) based company. Earthcruiser is recognised as one of the best off-road motorhome producers in Australia and can build on Japanese-brand, Iveco Daily and Mercedes-Benz Unimog cab/chassis.
The OKA cab/chassis’ relatively high initial price levels out when mated to the Earthcruiser bodywork, because there’s no major modification required to the chassis, brakes and suspension.
Many potential Earthcruiser buyers don’t want to be tied to European truck brands that don’t have widespread support outside major population centres and can’t put up with the ride quality of Japanese 4x4s.
Cummins, Allison and Dana parts and service support is Australia-wide.
On and off road
We had a brief gravel-road drive in a 2024 model, but didn’t get to check it out off-road. However, given that the cab, chassis, suspension and dimensions were unchanged, we expect its off-road ability to be at least as good as its predecessors.
Getting into and out of the OKA is something of a climb, so the truck won’t appeal to the infirm, but it did have three points of contact – two grab points for hands and a wheel-hub step for the left foot.
Because the engine tunnel is between the front seats the cab isn’t a walk-through design, but we found getting comfy quite easy. Vision was excellent and ergonomics were first-rate: all controls fell readily to hand.
The rationale of the OKA is no-frills, so the interior was relatively stark, but highly functional.
Ride and handling were ute-like and vastly superior to those of the Japanese 4×4 brigade. Performance from the Cummins/Allison combination was also way beyond the capability of Japanese or Iveco Daily vehicles.
Here is our off-road experience with the original pre-2021 model.
‘Being purpose-built the OKA had impressive off-road dimensions, with a 3.2-metre wheelbase inside overall length of only 5.3 metres resulting in approach and departure angles of 41 degrees, and a belly angle of 150 degrees when loaded.
‘Suspension travel – left wheel bump and right wheel rebound – was 359mm front and 488mm rear.
‘Vision was very good, thanks to the OKA’s forward-control layout and flat screens, but the rear view mirrors were small – a compromise between good vision and offering tree branches a smaller target.
‘The stubby gear lever had light, short action and the ratios were well chosen.
‘Town and country road handling was very good, albeit with some steering wander on the mud tyres.
‘A manoeuvering limit was the 12.8-metre kerb to kerb turning circle.
‘The OKA really hit its stars when the bitumen turned to dirt, where we found its gravel road handling was predictable, with straight and grab-free braking.
‘On a mine site the OKA’s supple, long-travel suspension worked quietly to cope with bumps and holes that stretched its oscillation to the maximum.
‘The gearing and low-speed torque combined to give it impressive climbing power with minimal need for gear-changing.
‘This truck has abilities beyond the experience of many who will drive it.’
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