A close look at what's new under the skin for Isuzu's first completely new ute in almost a decade.
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After six years of development, the all-new 2021 Isuzu D-Max has finally landed in Australia. Taking over from the long-serving and outgoing model (which arrived way back in 2012), this new model enters a segment that’s more competitive than ever.

Aside from the big jumps in terms of safety, interior and technology, the 2021 Isuzu D-Max also brings a lot of changes and updates under the skin. In this instalment, we look into the new nuts and bolts of the new D-Max.


2021 Isuzu D-Max engine

While a 3.0-litre diesel sounds familiar at first glance, there’s a whole lot of new metal under the bonnet of the new D-Max. Gone is the 4JJ1-TC, replaced the new 4JJ3-TCX. It carries over the same bore and stroke, but has a new block, head, pistons and fuel injection system.

Power and torque have improved for the 4JJ3 – 140kW @ 3600rpm and 450Nm @ 1600-2600rpm. Beyond that, 400Nm is available from 1400rpm to 3250rpm, and 300Nm is available from 1000rpm. For the full rundown on Isuzu’s new 3.0-litre Diesel engine, click here.

4JJ3-TCX

Behind the engine

The Isuzu-sourced six-speed manual gearbox (MVL-6S) carries over the same 275 millimetre clutch plate, but now has a dual-mass flywheel. Isuzu tells us it also has a pull ring selector, allowing for easier gear changing.

The automatic gearbox, from Aisin, is an updated version of the previous automatic transmission. Like the previous generation, it can lock up the torque converter between third and sixth gears for better fuel economy, and hold lower gears on downhill sections for gradient braking.

Important improvements for this automatic transmission include a new transmission cooler/heater (particularly for towing), and 0.2-second faster shift speeds.

Next up is a 2.482:1 transfer case, which uses a part-time 4x4 system with shift-on-the-fly 4x4 engagement. This is all familiar stuff, but shifting between two-high and four-high (up to 100kmh) and into low-range (at a stop) have all been sped up, with a new electric actuator.

Crawl ratios are a respectable 45.71:1 for the manual-geared D-Max, while a taller first gear in the automatic gearbox yields less reduction: 33.3:1. Beyond there, a typical steel tailshaft has been replaced by a stronger and lighter aluminium unit.

Diff breathers have also been ‘snorkelled’ to help with reducing water ingress, and a new engine air intake yields an 800mm wading depth, 200mm higher than the outgoing model.

In a much-needed first for the breed, the 2021 D-Max now scores a locking rear differential. Sourced through GKN Driveline, this is standard across the 4x4 range. Using an electro-mechanical engagement, the diff lock operates in low range only. It can be engaged on the fly (up to 8kmh), and disengages automatically above 28kmh.

Isuzu tells us the new D-Max gets a retuned and improved off-road traction control system, which gets turned off when the rear differential lock is engaged. The outgoing D-Max had one of the least effective systems in the segment, but our first off-road test will find out how improved this new one is.

2021 Isuzu D-Max chassis

The chassis has been reworked, with an additional crossmember (making eight in total) and now comprises of 46 per cent high-tensile steel, making it stronger and lighter. This saves eight kilograms, while adding 20 per cent more rigidity. Ultra-high tensile steel is used in key areas such as pillars and crossmembers for better crash protection.

The body, an all-new redesign with zero carry-over panels or glass, has new dust sealing throughout, with plenty of corrosion resistance added during construction. And thanks to a stronger roof design, the D-Max has a 100kg roof load.

The wheelbase has grown from 3095mm to 3125mm, but overall length is slightly shorter: down from 5295mm to 5280mm. Wheel track stays the same (1570mm), but the new D-Max is 20mm wider: 1880mm.

Claimed ground clearance improves by 5mm, to 240mm on 18-inch wheel models and 235mm on 17-inch wheel models. Steel bash plates are used around the sump and transfer case for protection.

Perhaps most importantly for this segment, this new chassis allows a higher overall GVM: 3100kg for all 4x4 models. That means with the heaviest kerb mass (X-Terrain, 2130kg), you’ve still got 970kg of payload left over. On the lightest 4x4 model (SX single cab-chassis, 1780kg) the payload is huge: 1320kg.

For those who love to really crunch the numbers, the independent front differential has a 1450kg rating, while the rear (banjo style) diff is rated at 1910kg.

With a 3500kg braked towing capacity and 350kg towball mass limit across the range, the D-Max also has a decent 5950kg gross combined mass (GCM). That means at full GVM you have 2850kg of towing capacity left over. And with the heaviest X-Terrain at maximum towing, your effective payload drops down to 320kg.

On models with a lower kerb weight and higher payload, this number will correspondingly increase.

2021 Isuzu D-Max suspension

It’s the same story of independent front suspension and leaf-sprung rear end, but both have been reworked for the 2021 D-Max. Upper control arms on the front have been moved higher, allowing for better roll-centre geometry. The anti-roll bar has been to the gym, 17 per cent thicker for the new D-Max, further improving on-road dynamics.

The three-leaf spring pack remains at the rear end, but it’s not a carryover part. Stronger ‘SUP9’ spring steel is used for this application, with a higher chromium content and requiring less weight overall for the same given spring rate.

New rear dampers have been mounted more upright for two benefits: more on-road ride comfort and better off-road articulation, 30mm better than the outgoing model.

Isuzu has two different sets of rear suspension available for the 2021 D-Max. Most dual cab models come with a standard rear leaf suspension, but single cabs and other work-oriented models have a heavy-duty rear leaf suspension.

On this subject, the D-Max also gets beefier brakes: 320mm diameter disc brakes up front, along with 295mm rear drums. Electric power steering is employed, and despite the increased wheelbase, the new D-Max scores a 10cm tighter turning circle: 12.5 metres.

Front wheel bearings have been changed, using a sealed cartridge-style bearing that don’t need periodic greasing or tensioning. This has potential benefits for off-roaders who spend lots of time in mud and water, but time will ultimately tell in this regard.

Wheels and tyres come into two flavours for the new D-Max: 255/65 R17 all-terrain tyres on either steel (SX) or alloy (LS-M) 7-inch wide wheels. Higher specification LS-U and X-Terrain get 265/60 R18 highway-terrain tyres on a 7.5-inch wide alloy wheel.

The 18-inch wheels are slightly taller (30.5 inch diameter) and wider (10.4 inches), while the 17-inch wheels measure in at 30.1 and 10 inches. All models get a full-size steel underslung spare, regardless of specification.