The Dmax gets a GVM Upgrade; what’s the choices?

Before buying the Dmax, I sat down and made a spreadsheet covering the accessories and modifications that I wanted to put on the 4WD, as part of building it into a comfortable, reliable and mildly capable tourer.

A GVM upgrade was never on the cards, but I’ve ended up with one.

About 2 months before our big 3 month trip up north I was getting into the swing of building the Dmax, and was thinking about the weight of everything in it. I made a decision to visit the local tip to check what it weighed.

With just the winch, AFN Bull Bar, aluminium Bull Motor Bodies canopy, a 45kg battery in the rear, baby car seat, a full fuel tank and myself in the vehicle it came back at 2380kg, which had be quite concerned, and that was without looking at the individual axle weights.

Keen to see the finished build? Here it is – Isuzu Dmax touring 4WD.

If you want to know how its fared after 3 years, check this out – Isuzu Dmax Review after 3 years.

Lastly, if you want to know how much the build cost, check this out – Dmax build cost.

Factory pay load

From the factory, our model Dmax is supposed to weigh 1925kg. We removed the rear tub, which should effectively reduce it to 1815kg.

The maximum GVM (gross vehicle mass) is 2950kg, giving us 1135kg of ‘payload’. In the scheme of things, this is a substantial amount. Many 4WD’s are only 650 – 800kg.

Dmax build up
Our saggy Dmax with the factory springs and barely any weight in the rear

Adding the weight up

After weighing the Dmax, I went home and made another spreadsheet, carefully adding up the weights of everything that would go into the vehicle. The result, without the tow ball weight of our camper trailer was a further 645kg, taking the vehicle to 3025kg.

Add the towball weight (somewhere between 80 – 130kg) and we would be over the maximum GVM by about 150 – 200kg). That, is a problem!

If you want to know exactly what the finished Dmax weighs, and what that comprises of, have a look at this; Isuzu Dmax touring 4WD build; a look into what it weighs.

What happens if you exceed your GVM?

Manufacturers give a maximum GVM for a reason; it’s only designed to carry so much. If you exceed your GVM, your insurance company can walk away from any claims because your vehicle was not roadworthy at the time of the accident.

Beyond that, a heavy vehicle puts all sorts of excess stress on the components of your vehicle, and will cause issues over time.

If you are unsure of how the weights all work, we wrote a simple guide that makes it all super easy; Towing capacity; a simple guide to keep you legal.

In regards to the suspension though, its common to have a Dmax suspension upgrade for towing as they are simply too soft on the rear end (like all new utes) to tow anything with a heavy tow ball weight.

What to do?

At this point, I was a bit annoyed; I’d made a spreadsheet in the past and thought the weights would be OK. I’d also bought bigger tyres, and had factored in the size lift I wanted in order to keep it all legal, and now a curve ball had come my way.

As the weeks passed, I rang pretty much every company in Perth offering suspension packages, and had a chat to them. I had originally decided I would run the Old man emu suspension from ARB, with the 600kg constant load springs for the rear.

Knowing now that even if the springs would cope, I wouldn’t be legal anyway meant I had to explore the land of GVM upgrades.

The factory springs in every dual cab ute on the market that I know of will not carry a big load, and definitely no where near what the specifications say without major sag.

The SX Dmax has the lighter duty springs, and I could see even with just a mildly loaded camper trailer and some gear on the back that the springs were no where near up to the job.

When installing a canopy on the back of a Ute, its super important that you think about total weight, how it is distributed and that you match the style of canopy to how you use the vehicle.

We’d already purchased the aluminium canopy as it was the best choice for us, and had to roll with the punches. If you want to know more about canopies, check this out; Buying a 4WD Ute Canopy; the ultimate guide.

GVM Upgrade options

There’s lots of options out there for getting GVM, and sometimes GCM upgrades. Below is the research I did, and why I ended up going with ARB. That said, please know that a GVM upgrade takes your vehicle beyond its original engineering intentions, and you are more likely to break something.

Some of the GVM upgrades on the market today are getting a bit silly, and this is made well known when you have rear differentials snapping in half, or major catastrophic failures with ultimately were contributed to by carrying extra weight.

If you need to increase your GVM by that much, perhaps you are better off starting with the right vehicle to begin with. Here’s two posts worth a read – GVM upgrades; how much is too much, and Is your 4WD really suitable, or do you need a truck?

ARB – Old Man Emu GVM Upgrade

ARB sell the Old Man Emu GVM upgrade which has a few different spring options, raises the vehicle by 30mm, has a 3 year or 60,000km warranty and you can buy spares pretty much all over Australia. The GVM goes from 2950 to 3220, giving you an extra 270kg of capacity.

Interestingly, if you add the front and rear axle capacities given by Isuzu, you get 3220kg, so ARB are staying in line with the manufacturers recommendations.

This helps when it comes to aftermarket accessories and warranty issues. They have also suggested that 25mm is the optimum lift height due to wheel travel and CV angles.

Retail price is around $3400 fitted, and this reduces your towing capacity if towing at maximum GVM.

If you sell a the vehicle to another state, the engineering becomes null and void, and it needs re-certifying.

Lovells GVM Upgrade

Lovells GVM kits are sold by a huge number of companies around Australia. I rang a lot of places, and got pricing between $4200 to $5200 fitted. No idea how it varies by so much, but there you go. The warranty is 3 years or 70,000km on the shocks, and unlimited on the springs.

This kit is supposed to lift the vehicle 50mm, raises the GVM to 3600kg (an extra 650kg of payload), changes the axle ratings and most importantly, still leaves you with a 3500kg towing capacity.

The Lovells kit also changes your GCM (Gross combination mass) to 7100kg, although I’m a bit suss about how this is being done, and think there may be some very upset people in the near future when the rules and regulations get a bit stricter.

Pedders GVM Upgrade

Pedders Dmax GVM upgrade increases it to 3450kg, giving you an extra 500kg of payload. It does not increase your GCM, retails for about $3500, has a 2 year/40,000km warranty and there are a lot of stores around the country for spares.

I enquired about the lift amount and got various answers from different branches. Some suggested 30 – 50mm increases, whilst others said it is no lift at all. They also couldn’t tell me what rating springs would be run in the rear in kilograms.

Dobinsons and West Coast Suspension

I did get pricing from Dobinsons and West Coast Suspension, along with the various data, but can’t remember it off the top of my head, and to be honest pretty much dismissed it as soon as I was told it would lift the vehicle by 50mm, which is too much for the setup I had planned.

Who did it boil down to?

Having already committed to bigger tyres, and being limited to a maximum of 33mm increase in suspension lift, it came down to ARB or Pedders. I seriously considered Pedders, but the sheer size, engineering backing and availability of parts in Australia made the ARB GVM upgrade the better choice.

They were the smallest of GVM upgrades in terms of increase, but stick within the factory axle weight ratings, use good quality gear that I’ve been happy with in the past and are very reputable.

Getting the GVM upgrade fitted

ARB had to freight front springs from Tasmania over for me, and fitted me in with just 3 weeks before our trip was due to leave. Their service was absolutely flawless from start to finish*. I was regularly updated, clearly communicated to and even slotted in the fitting of a Safari snorkel while I was there.

I’ve bought things from ARB in Canningvale before (their old premises), and had good service, but this time around it was 10/10. I picked the vehicle up 2 days later, with all of the paperwork and was asked to bring it back in 500km to check everything was tight and good to go.

This is part of the Old man emu warranty process, and even though we were running out of time I obliged.

* Whilst tinkering around under the bonnet, I found the air box was fairly loose, which seemed a bit strange to me. I grabbed a 12mm socket and extension, and found that the two rear air box bolts were finger tight.

The front one was tight, but for some reason not clamping it down properly. I removed the collar which seemed too big for the job, and checked the other two were the same length, then reinstalled it all with washers to space it out.

I don’t know what was changed at the front, and its a shame that they forgot to tighten the bolts. Still, better to pick it up in the driveway than end up with a busted air box!

Diff drop

I should quickly mention that a friend pointed out my CV angles were a bit suss after the GVM upgrade. I purchased a Roadsafe Diff Drop kit from Coastal 4×4, and installed it in about an hour, which has lowed the angles a fair bit.

ARB do not do this as part of their kit, but I reckon it really needs to be done. You can read about the diff drop here – Dmax diff drop installation.

Dmax’s don’t have the best reputation for strong CV’s, and having a bad angle definitely won’t help this.

Loading her up

As I type this, we are sitting not far from the Northern Territory border, with a 4WD that’s pretty well loaded, and a camper trailer that follows us around when we move spots. We weighed the vehicle before we left, and it came in at about 2900kg without the towball weight.

It rides well, and I’m pretty happy with it. I suspect that the front springs may be a little too high load rating, despite having a winch, steel bull bar, catch can, secondary fuel filter and bigger battery in the front. The car sits level, even when towing, which is fantastic.

Kalgans Pool with the GVM Upgrade
Travelling out of Kalgans Pool
ARB GVM Upgrade Dmax
Loaded up without the canopy
Isuzu Dmax Suspension GVM
Sitting nice and level, legal and with decent clearance
Isuzu Dmax GVM Upgrade
The front of the Isuzu Dmax

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  1. Hey John,

    Yep, there’s different rules for different places. You can still get GCM upgrades in Australia in various states, but not all. I have a post coming out soon that will cover this in more detail.

    You are correct that the towing capacity reduces at full GVM with a GVM upgrade, but a lot of people don’t need more towing capacity, they just need a higher GVM and that’s where it can be useful. We fell in this boat; I don’t care that our towing capacity is reduced to 2730kg at our new GVM of 3220 as we are never anywhere near that anywhere.

    I have heard some interesting conversations about GCM upgrades, so it will be fascinating to see how that all rolls out, and what changes happen going forward.

    All the best!

  2. John Phillips says:

    Hi Aaron,
    Great write up.

    Regarding light vehicles with a current GVM not exceeding 4500kg in QLD.

    Increase in ride height (vehicle lifts).
    The Queensland Code of Practice: Vehicle Modifications (QCOP) LS09 and and LS10 indicate that a vehicle may be lifted by (a) up to 50mm by suspension, or (b) up to 25mm by tyres i.e. 50mm diameter increase or (c) a combination of (a) and (b) to a maximum of 75mm without certification. This is deemed a basic modification.
    Design and modification certifications are required for ride heights over 75mm to 150mm achieved by (a) up to 75mm by suspension, or (b) up to 25mm by tyres (c) up to 50mm by body blocks or a combination of these to a maximum of 150mm. Increase in ride height above 150mm requires specific approval.

    Gross Vehicle Mass re-rating (GVM upgrade)
    QCOP LS11 and LS15 outline requirements for GVM re-rating.
    The vehicle must be able to safely operate at the re-rated GVM. All affected components including the chassis frame, drive-train, axles, suspension, brakes, steering, rims and tyres must be assessed individually to ensure that they can safely support the loads resulting from the re-rated GVM.
    A modified vehicle (includes a pre-ADR modified vehicle) must also comply with the applicable in-service requirements of the Transport Operations (Road Use Management—Vehicle Standards and Safety) Regulation 2021 (the Regulation).
    Compliance with the Australian design rules (ADRs) is understood.
    These codes must not be used for the re-rating of either Gross Combination Mass (GCM) or Towing capacity of a vehicle. These have previously been determined by the original Vehicle Manufacturer (OVM) and appropriately approved.
    It would appear that an increased GMV will most likely reduce the towing capacity as GCM is unchanged.
    GCM upgrade for new (pre registration) vehicles was banned by the federal government in 2018. GCM upgrades to in-service vehicles are not currently permitted in Qld.

    Reference “Queensland Code of Practice: Vehicle Modifications (QCOP)” Department of Transport and Main Roads, September 2021.

  3. Hi Derek,

    Old man emu is the brand of suspension that ARB sells, and they should do a GVM upgrade kit, but perhaps its not valid in Queensland?

    Are you sure you’re asking about a GVM upgrade and not a GCM upgrade?

    If neither Lovells or ARB can help you might be out of luck in Queensland.

    All the best

  4. Derek Gruending says:

    Hi Aaron,

    Regarding the GVM upgrade, I have a 2017 BT50 and I’ve been to my local ARB in town, and they’ve advised me that Old Man Emu doesn’t do GVM upgrades?? I’ve tried speaking to other manufacturers including Lovells, and they’ll only touch a new, unregistered vehicle. Still waiting to hear back from Pedders though.


  5. James Bailey says:

    Thanks Aaron. I’ll contact Packard.

    How would another Colorado model allowed with bigger tyres help out in combination with a lift? If I still go over 50mm higher than my original roof height?

  6. Hey James,

    I believe anything over 50mm requires a lane change test, so its not as simple as just getting an engineer to say its fine.

    Interestingly Pedders wouldn’t tell me how much lift I’d get, and ultimately it really depends on how you have it loaded. It could be 40mm increase when loaded or 75mm increase when unloaded.

    Do any of the Colorado models that only have cosmetic changes come with larger tyres? If so, you might have an option there.

    Alternatively, you can speak directly to the engineers in Perth – there’s a list on the DOT website, or Packard Automotive seem to get a good wrap

    All the best

  7. Hi Aaron
    When ARB/Pedders do the GVM upgrade and lift, could you not have got a slightly higher lift + tyres over 50mm and got that engineer to certify it all?

    That’s what I’m hoping to do (40mm Pedders GVM + 14mm from bigger tyres) – not much in it really but if 50mm is limit id be over until the tyres ware down :p

    Some stores say they wiol/can but not sure if they are just telling me what I want to hear and they will only really certify the suspension and GVM change


  8. Hi Bruce,

    Please don’t take my comments out of context, or to heart. They are just my opinion, and you don’t have to agree with them.

    There were a number of reasons I decided to go with ARB over Pedders, and the size of the business, involvement in 4WD testing and distribution around the country were only a small part of this.

    I’m sure they are both reputable businesses. ARB is far better known in the 4WD industry, and their engineering skills are nothing insignificant. Pedders absolutely specialise in suspension, for all types of vehicles. ARB are focused on 4WDing only.

    All the best

  9. Bruce Brander says:

    So you think ARB has a better engineering background than Pedders who have specialised in suspensions for years. You lost me there.

  10. Hi Anthony,

    This is a bit of a grey area, and specifically depending on where you live. You can still get GCM upgrades, but not in all states of Australia.

    All the best

  11. I’m certain that updated legislation says you can only achieve a GCM upgrade pre-registration. You cannot legally get a GCM upgrade post-registration anymore.