Take It To The
Next Level.
GVM upgrades are an extremely hot topic and generally the foundation of any touring or work vehicle setup.
We specialise in 4wd suspension and GVM upgrade packages to suit a wide range of applications.
Our staff are highly trained & knowledgeable when it comes to GVM upgrades and we perform all of the modifications in our specialist workshop.
To work out if your vehicles GVM is legal, try our free GVM Calculator.
GVM (Gross Vehicle Mass)
Maximum weight your vehicle is able to weigh
BTC (Braked Towing Capacity)
Maximum weight your vehicle can tow
GCM (Gross Combination Mass)
Maximum weight total of vehicle & trailer combined
Tow Ball Download (or ball weight)
Maximum weight a trailer can put on your tow ball
Vehicle Payload
Maximum weight you can load on/in your vehicle
Axle Load Capacity
Maximum weight that can be carried on a single axle
Wheel Load Ratings
Maximum weight the tyre and rim is rated to carry
From factory all vehicles have a standard GVM set by the manufacturer which is the maximum weight the vehicle can weigh, generally the GVM of a vehicle will be printed on the compliance plate and found in the owner’s manual. Performing a GVM upgrade is the process of modifying a vehicle to increase the GVM, once the GVM is increased the vehicle can legally carry more weight.
There are many reasons for needing a GVM upgrade however they generally all stem back to the need for carrying more weight. Exceeding the GVM of a vehicle can present multiple issues in regards to mechanical failure, legal implications, warranty and insurance. Vehicles may be over GVM due to the added weight of accessories, passengers, luggage or tow ball download from a trailer (generally a combination). Increasing the GVM of a vehicle will limit the potential issues by ensuring the vehicle can physically and legally carry the additional weight.
GVM upgrades will often incorporate a wide range of different components & modifications to achieve the higher GVM rating. Generally, it will depend on the model of vehicle, the intended use and the GVM rating that is required. Basic GVM upgrades normally involve an aftermarket suspension system including heavy duty springs and shocks which allow the vehicle to carry some additional weight whilst still being safe & legal. For a more serious GVM upgrade there will usually be other modifications required to achieve the higher GVM ratings such as upgrades to suspension arms, braking systems, diff housings, axles, driveline and chassis.
Performing modifications to a vehicle will physically enable additional weight to be carried, the GVM upgrade then needs to be engineered to make it legal & compliant. There are two main methods of engineering a GVM upgrade, it can either be done pre first registration or post registration.
Pre first registration means the modifications are performed when the vehicle is brand new prior to the vehicle being registered for the first time, this is done under SSM (second stage of manufacture) which means the manufacturer of the GVM upgrade package has already done the testing and engineering for the kit.
When the vehicle is registered, it gets registered with the higher GVM from day one which means it doesn’t need to be inspected. Post registration is when the vehicle is already registered prior to the modifications being performed.
Once the modifications are performed the vehicle will be inspected by an engineer who will provide an engineer’s report and fit a modification plate to the vehicle, once this is complete the vehicle will generally be required to undergo a generic roadworthy inspection.
You can always contact us if you have any questions.
GVM is very important but there are many other things to consider when looking at vehicle weights and legalities, especially when towing. Some of the notable numbers to take into account are the tow ball download, GCM, BTC, axle load capacities and wheel load ratings. It is very common for a vehicle to be within the legal GVM limit whilst exceeding these other weight ratings:
When you connect a trailer to your vehicle it puts weight onto the towbar, this weight is called ‘tow ball download’. The tow ball download weight being transferred onto the towbar is adding to the overall weight of your vehicle which is something to keep in mind when calculating your GVM. Some vehicles will be under their GVM without a trailer connected but then exceed their GVM when a trailer is connected due to the additional tow ball download weight.
Braked towing capacity (BTC) is the maximum amount of weight a vehicle can legally tow providing the vehicle has the correct towbar installed and the trailer has an adequate braking system fitted. Generally the maximum BTC of a vehicle can be found on the compliance plate or in the vehicles owner’s manual. When purchasing a trailer or towing with your vehicle it is important to know the weight of the trailer to ensure you do not exceed your vehicles maximum BTC.
Gross combination mass (GCM) is the weight of your vehicle and trailer added together, it is the total combined mass. Most vehicles will be issued with a maximum GCM rating which cannot legally be exceeded. Often people will only look at their GVM and BTC, if the vehicle is under GVM and the trailer is under maximum BTC they assume it is legal however this is not always true. It is common to forget about GCM however the GCM of a vehicle can easily be exceeded prior to reaching the GVM or maximum BTC.
Vehicle payload is the amount of weight you can legally put onto a vehicle without exceeding the GVM. To calculate your payload you will need to subtract your empty vehicle weight from the vehicles GVM, this will be your vehicles payload meaning this is how much weight you can carry. Payload is any weight added to the vehicle such as accessories, luggage, passengers etc. You need to ensure all of the weight you are adding to a vehicle is not greater than the vehicles payload, therefore not exceeding the GVM.
Axle load capacities are an individual maximum weight that can be carried across a single axle. Axle load capacities are generally based on the weakest limitation in the system which could be any of the load bearing components such as a diff housing, suspension, wheel bearings, wheel studs, brakes etc. It is common for a vehicle to be under GVM but exceeding an axle load capacity due to the load distribution. If the weakest components in the system are upgraded as part of a GVM upgrade it is often possible to increase the axle load capacities.
Wheel load ratings are a weight rating for an individual wheel (rim & tyre). Manufacturers will provide a maximum load rating for individual rims and tyres based on how much weight they can handle. With any vehicle you need to ensure the rims and tyres fitted have a load rating equal to or higher than the minimum required load rating, this is specifically important if you are increasing your GVM and axle capacities. The required load rating will usually be found on a vehicles tyre placard or can be calculated from axle load capacities.
We can perform GVM upgrades on most common makes and models of 4wd, however there are a few specific models that we don’t have anything available for. Generally, this will be due to a unique suspension geometry, factory limitations or a lack of aftermarket options for that vehicle model. Some vehicle models have complete systems available from manufacturers and others require a custom package to be put together. These are some of the common vehicles we can perform a GVM upgrade on:
Note: For the 70 series Landcruiser we can incorporate a GVM upgrade with a Coil Conversion.
We have access to a wide range of suspension brands and GVM upgrade options. The brands we recommend for a GVM upgrade will depend on the vehicle model, intended use, required GVM and budget of each individual application. These are some of the common brands we can utilise within a GVM upgrade package:
(If you can’t see your vehicle model listed or the brand of products you would like to use, we may still be able to offer them, our sales team will be happy to chat about any options that are available for your vehicle model).
Want to see some GVM upgrades in action? Check out the full builds below, or visit the main gallery find more inspiration.
Does a GVM upgrade increase the vehicles GCM?
Not always, most generic GVM upgrades will increase the GVM but will not alter your GCM. Essentially this allows you to carry more weight on the vehicle but if you are utilising this type of GVM upgrade you won’t be able to access your full towing capacity. For some makes and models we do have specific GVM upgrades available that will increase your GCM.
Do I maintain my towing capacity with a GVM upgrade?
Yes and No. You will always technically maintain your full towing capacity however some GVM upgrades do not change your GCM which means you can only tow your maximum towing capacity if you are under your factory GVM weight. If you are utilising your new GVM upgrade then the amount you can tow will be reduced to stay within your GCM. However, if you have a GVM upgrade that also increases your GCM or does maintain a full BTC then you can generally be loaded to your new GVM and still maintain a full braked towing capacity.
Does fitting a GVM upgrade reduce my towing capacity?
No, it does not reduce your towing capacity, your towing capacity will remain as per factory. But you do need to keep your GCM in mind, if your GVM upgrade does not increase your GCM then you may exceed your GCM if you are towing a trailer equal to your maximum braked towing capacity.
Are aftermarket rims and tyres required for a GVM upgrade?
This will depend on the GVM upgrade, most of the time it depends on whether the GVM upgrade is changing your axle capacities. If it is a basic GVM upgrade that does not alter your axle load capacities then you will not require aftermarket rims and tyres. If it is a higher GVM upgrade and the axle load capacities are being raised then you technically do legally require higher load rated rims and tyres.
Can I fit bigger tyres to my car once I upgrade the GVM?
Tyre size is dependent on the specific GVM upgrade fitted to your vehicle. Most GVM upgrade testing is done with standard rims and tyres, this means for the GVM upgrade to be compliant you must run factory rims and tyres. Some specific GVM upgrades do have their testing done with bigger tyres, if the GVM upgrade you purchase has had testing done with bigger tyres then it is completely legal to run that bigger tyre size.
Are GVM upgrades recognised in all states & territories?
If your GVM upgrade is done pre rego under SSM then yes, it is a nationwide federal approval and the vehicle has a legal GVM upgrade for the remainder of its life. When a GVM upgrade is done post registration it will be a state based engineering approval, the vehicle is still legal to drive in other states with a higher GVM but only whilst the state of registration matches the state of engineering. If the vehicle ever needs to be registered in a different state, then the engineering may need to be done again.
Does a GVM upgrade change my vehicles ride height?
Generally, yes it does, this will depend on your vehicle and what GVM upgrade you are fitting. Most GVM upgrades include a suspension system that raises the ride height of the vehicle slightly.
What is the highest suspension lift I can fit to my 4wd?
Completely vehicle and GVM package dependant, rule of thumb is 2 inches (50mm) in most states and territories. On some specific models of vehicle, we can do 3 or 4 inches of suspension lift.
Will my vehicle ride rougher with a GVM upgrade fitted?
It can, however it depends on the selection of springs and shocks fitted to the vehicle. High quality components that are well matched to the load carrying requirements of the vehicle will generally provide respectable ride comfort (often better than factory).
How much does it cost to upgrade my vehicles GVM?
How long is a piece of string? There are so many options on the market, the price range is huge. Basic GVM upgrades with entry level components can be a couple thousand but the sky is the limit, some serious GVM upgrade packages can be in excess of $50,000 if they are a full vehicle conversion.
Does my vehicle need to be roadworthy for a GVM upgrade?
Technically yes, the whole point of doing a GVM upgrade is to make your car legal and compliant. If your vehicle is already unroadworthy then you are being counterproductive by fitting a GVM upgrade, we always recommend to keep your car as roadworthy as possible.
How long does it take to install a GVM upgrade to my vehicle?
Basic GVM upgrades consisting of a simple suspension upgrades can be less than a day in the workshop. Some serious GVM upgrade packages involving a whole vehicle conversion with upgrades to the suspension, brakes, diffs, chassis, driveline, steering etc can take a few weeks to complete.
JACKSONS 4X4
Call us on 08 8532 2550
Email us via our contact form
61 Chris Collins Court Murray Bridge, South Australia
Monday – Thursday: 8:00am to 5:00pm
Friday: 8:00am to 3:00pm
Closed: Weekends & Public Holidays
SISTER COMPANIES
