2023 Ford Ranger build: GVM upgrade

GVM (Gross Vehicle Mass) upgrades seem to be a subject of constant conversation whenever you’re hanging out with anyone building up a new 4x4 to carry lots of gear and tow large trailers.

What is GVM and why does it matter? And do you really need to upgrade the GVM on your vehicle? After recently jumping through the hoops of a GVM upgrade on our Ford Ranger build we thought it time to look at the topic again, and get the facts straight.

Gross Vehicle Mass is the maximum weight your vehicle can legally be when driving on the road, including fuel, accessories, passengers, cargo and any weight on the towbar. The GVM is not a figure that the authorities pluck out of the sky to ping you on, but is set by the vehicle manufacturers as to what they have designed and engineered the vehicle to safely and competently carry on and off road.

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The figure relates to many things including the weight of the components, the driveline’s capability, the rating of the axles, the tyres fitted to the vehicle, which have their own load rating, and what the vehicle is designed to do.

Load your vehicle in excess of the stated GVM and you are taking it beyond its safe rating, and should anything go astray when driving over weight, you could be liable for any damages, injuries or even deaths that might occur as a result of your actions.

It’s up to the driver to know the GVM of the vehicle they are in control of and the weight it is carrying at any time. Pleading ignorance on the side of the road after an accident won’t hold sway with authorities, or your insurance company, and you could be in for a world of pain as a result.

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Before we go on we’ll mention Gross Combined Mass (GCM). This is the maximum weight your vehicle and trailer can be including all cargo, passengers, fuel, accessories and everything else. Again this weight is set by the vehicle manufacturer and must be strictly adhered to for all the same reasons as with GVM.

Let’s look at our 2022 Ford Ranger V6 Sport as an example here. Ford lists the kerb weight of the Ranger at 2264kg and gives it a GVM of 3280kg, so theoretically you can put 1016kg of people, luggage, cargo, and ball weight on and in it. But that doesn’t always correspond with the rated payload, which in the case of the Ranger is listed at just 934kg. Confusing? Yes, but this is the grey world we live in.

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Building it big

Four-wheel drive accessories are big business, and we all love to equip our rides to tackle more difficult tracks and rugged terrain, protect them against animal strikes and tree branches, and to extract ourselves from tricky situations.

We also like to take everything away with us when we travel, including the kitchen sink, and also load the family into the vehicle, and all this stuff quickly adds up and eats into your payload and GVM.

A bullbar with winch and steel underbody protection adds a heap of weight to the front of the vehicle and much of it is hanging out in front of the axle where it’s really felt when driving. Throw in some scrub bars and a few spotlights and an extra battery in the engine bay, and you could be looking at a couple of hundred kilograms on the front axle.

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The same out back; replacing the ute tray with a canopy like we did on the Ranger not only adds weight but moves the mass rearwards so it’s behind the rear axle.

Mount a spare tyre or two up high on the back of the canopy and it’s in the worst place you could want it, hanging off the back of your chassis. Where you put your fridge, drawers, water tanks and everything else inside the canopy also needs to be considered, and ideally mounted forward of the rear axle. Even your oversized mud-terrain tyres add to the vehicle’s overall weight, even though they are carrying the vehicle and not being carried by it.

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Weighing it up

When we built the Ranger we left the suspension selection and installation until as late as possible so that we knew what we were dealing with, and could choose the ideal suspension kit accordingly.

The replacement springs and shocks supplied by Tough Dog were chosen to carry the weight comfortably, and were the components used in the brand’s GVM upgrade kit for Rangers.

The Tough Dog kit includes 500kg rated rear leaf springs and complete replacement front struts with new springs and foam cell shocks on all corners. A centre bearing kit is part of the package to accommodate the raised ride height, and we chose to add Tough Dog’s replacement upper control arms to keep all the alignment angles in check.

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Once equipped with its new suspension the vehicle was wheel aligned, and it rode better than ever over all the terrain we could throw it at. We were happy as Larry!

But when we put the Ranger on the scales it came in at 3152kg, which didn’t leave a lot left of our 3280kg GVM. More worrying was 1436kg across the front axle, which is only rated to 1450kg, and 1716kg across the 1959kg rated rear axle. If we loaded up the Ranger with any gear we would soon be exceeding the legal limit. No worries, we thought; the upgrade kit takes the GVM up to 3750kg so we’ll just get it certified and be right as rain… or so we thought.

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Pre- or post-rego upgrades?

When people talk about GVM upgrades you might hear them refer to both pre- and post-registration approvals.

As the names suggest, the main difference here is one is performed before (pre) the vehicle is first registered, while the other is done at any time post registration. Pre-rego upgrades are the way to go if you have your kit in order as this is a nationally approved deal, and done as part of the SSM (Second Stage Manufacturer) scheme.

Post-rego GVM upgrades are done at a state level, and need to be approved by a local state-approved engineer or company. The approval still goes on a national register against the vehicle’s VIN but the certification may need to be updated if you move or sell the vehicle interstate.

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We bought our Ranger as an ex-demo model and it was already registered with 6000km on the clock, so a pre-rego GVM upgrade was obviously not possible.

But this gave us the benefit of building up the Ranger first and knowing exactly what weights we’d be working with. Whether pre- or post-registration, your approval goes through the relevant state and national bodies and, as with any big show, things are never as simple as they should be. Our Ranger was fitted with all the correct components for the Tough Dog GVM upgrade but as they were ordered individually and not as the approved GVM kit (which carries its own specific part number) we couldn’t get approval.

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This meant we had to get the Tough Dog GVM-upgrade kit with its specific kit part number and show that that was what was fitted.

It also had to be fitted by someone approved to fit the GVM-upgrade kit; unless you are an approved GVM-upgrade kit fitter you can’t do it yourself. Luckily for us the team at Opposite Lock in Epping is a Tough Dog approved fitter and took on the job of replacing our suspension. The front struts, rear shocks and leaf springs all carried the exact same part numbers as those that were removed, but they were now from the GVM-upgrade kit.

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What we didn’t have, which is included in the kit, were the blue approval sticker, the replacement tyre placard, and the new vehicle weights sticker, which were all affixed to the driver’s door jamb.

The kit also includes the front side indicators that are needed for vehicles with a GVM of 3500kg or more, and these come with the patch wiring and a template to suit the vehicle that makes it easy for the guys to drill the holes and fit them in the right place on the front guards. All in a day’s work for the proficient team at Opposite Lock, Epping. Once the GVM upgrade hardware has been fitted, it needs to be inspected and approved by an approved engineer, who in our case was Linda Hitch of Hitch Engineering Services.

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Linda first checked the vehicle’s VIN and chassis numbers, to make sure they match what is in the system, then she sighted all the part numbers of the suspension components to make sure they matched those that are approved in the upgrade kit.

She also checked the ride height of the vehicle at each wheel to ensure it is within the allowed specification, sighted that the new placards and indicators were in the correct places, and checked the tyres for clearance on the body, ensuring that they don’t rub on anything at full steering lock and suspension travel.

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Driving tests are not required at this point as the kits are approved for beforehand by the manufacturer, in this case Tough Dog Suspension.

This federal pre-approval and certification means that individual vehicles needn’t be put through test drives provided that all the exact components of the kit are utilised; you cannot mix and match parts in a GVM-upgrade kit.

Once Linda had all her information logged into the system, it was just up to us to take the paperwork and vehicle to Vic Roads, where an inspector again gave it a once over before the updated weights were entered into the system.

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Do you need a GVM upgrade?

Spending the day with Dave Hadley and the team at Opposite Lock, Epping, and later with Linda, it gave us a chance to ask what sort of people were asking for and fitting GVM kits.

Dave was quick to tell us that GVM upgrades were some of the most common products he gets asked about, but first he questions customers why they think they need one, and what are their plans for the vehicle.

“People come in and say they have bought a new 4x4 and that they need a (pre-registration) GVM upgrade,” said Dave. “I ask them what they are going to be fitting to the car, what are they towing and what sort of use will the car get.”

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Installing a GVM upgrade with its heavier rated suspension to a vehicle that is not carrying a load will ruin the factory ride quality and dynamics.

In the case of our Ranger’s Tough Dog kit the rear springs are rated for a constant 500kg load and as such are very firm and stiff, but they are perfect for the weight of our canopy and everything that is permanently carried inside it. The Tough Dog kit even comes with a recommendation to have a “permanent payload of no less than 300kg to assist in safe and stable driveability”.

“Some people fit a GVM upgrade because they read online that they need it, and then they complain that the car rides like a old cart,” said Dave.

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It pays to speak to the right people before you get your new 4x4, go through your plans for it and what you plan to fit and carry in it, and get a true indication of what your vehicle needs.

Linda does a lot of work with Caravan Industry Victoria, so she deals with van manufacturers and the people who tow vans. She pointed out that someone towing a heavy van might want to look at a GVM upgrade.

“If you have a big van and are putting 300kg download on your towball, that (weight) comes straight off your GVM”, said Linda. For many new 4x4 wagons, 300kg is a large percentage of the payload.

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Final thought

The thing we took away from this experience, and we hope we’ve passed on to you here, is that before you book your new 4x4 in for a pre- or post-registration GVM upgrade is to know what’s involved in the upgrade, and what to expect of the modified vehicle.

Do your research and find out the weights of the accessories you plan to fit to the vehicle, how many passengers you will be carrying and how much cargo you will load up with. This will give you a rough guide as to the overall weight of your built 4x4, and how close you might be to its GVM.

If you are not close to GVM or won’t be carrying the weight all the time, you might want to reconsider the upgrade to find an alternative that better suits your needs, rather than impacting negatively on the ride and handling of your vehicle.