GVM Upgrades are all about Legal Compliance and Safety. Whether you’re a Tradie with a heavy trailer and tools, or your towing a heavy van or camper, it’s all to easy to breach a modern vehicles legal GVM.

GVM Gross Vehicle Mass
CTM Gross Towing Mass
GCM Gross Combined Mass

GVM Upgrades | JMACX 4×4 Off-Road Solutions

The GVM is the maximum weight of a vehicle when fully loaded. This includes everything bolted to it and ALL load in it, such as fuel, water, bull bar, tow bar, recovery gear, tray body, canopy, even the passengers.

When considering these issues, note that many manufacturers advertise a particular GTM, commonly 3500kg in recent times. This 3500kg is only available with a stock vehicle, and as you add accessories, load or passengers, this extra weight needs to be calculated and taken OFF the advertised maximum figure.

The GTM is not able to be increased, and may have to be reduced in some circumstances.

The GCM is no longer able to be increased, and this is a very important limit. If the GVM is upgraded, and the vehicle set-up takes up to the maximum weight, then the practical Towing capacity is reduced, as the Combined Mass is a fixed limit.

200 Series Landcruiser Standard

  • GVM Total 3350kg
  • GTM Total 3500kg
  • GCM Total 6850kg

OME GVM has 2 options, 3650kg or 3845kg.

If the vehicle weighs 3800kg loaded for a trip, after GVM is fitted, then the practical Towing Mass is only 3050kg, not the standard 3500kg, ie 3800 – 3350 = 450kg. Then 3500 – 450 = 3050kg.

This is a VERY important concept to come to grips with if you are approaching the limits of your vehicle’s capacity.

To discuss specific GVM issues surrounding your model 4x4, please make contact with one of our experienced staff.

We can increase the GVM either before or after registration.

All vehicles have a legal GVM as part of the vehicle manufacturer’s overall Australian Design Rules (ADR) approval. If your vehicle exceeds the GVM it will be most likely be uninsured and cannot be driven when detected, ie If you are found to be over-weight on a trip, the vehicle will need to be made compliant by reducing weight before it can be driven from that point. Unhook the Van and leave it or take gear out of the vehicle, or both! Highly inconvenient.

Old Man Emu, in its capacity as an Approved Secondary Manufacturer, has a range of GVM options for an ever increasing range of vehicles. This approval is gained by Old Man Emu engineers submitting detailed tests, not only on the OME suspension components and Kits, but the rest of the vehicles mechanical systems as well. Usually Braking Systems and Axle Loads.

It is possible to increase the GVM further by upgrading these other mechanical parts, which come with separate engineering compliance from other approved Secondary Manufacturers.

Once the approved OME suspension system and GVM upgrade Compliance Plate has been fitted by us, it can then be registered according to its new increased GVM. This process ensures that your vehicle is GVM legal across all states.

For registered vehicles, our SA Dept of Transport ‘Approved’ engineer will assess compliance.

After providing some basic vehicle details, the existing suspension components may require replacement with a new OME GVM Upgrade Kit, or it may be that some level of GVM Upgrade is possible with the existing aftermarket components.
At the end of the process, a SA Compliance Plate is fitted by us. At this point the vehicle will need to undergo a complete inspection by the Department at one of its testing stations. Note: If the vehicle has been registered for less than 12 months, this requirement is waived.

The SA Compliance is currently recognised in all States.

GVM rules have recently changed significantly, and further substantive changes are planned, so please consult with us before moving ahead.

As mentioned earlier, if GVM upgrade is required beyond just Suspension or if individual axle loads are greater than the Original Equipment (OE) specification, then there are Secondary Manufacturers that have replacement engineered mechanical components that will render the vehicle compliant once fitted.

JMACX 4x4 Off-Road 4x4

We recommend and fit the JMacx Off-Road Solution range of components.

JMACX Engineered Uprated Rear Axle Housings

Landcruiser 70 Series and 200 Series

Strengthened rear axle housings are available for 70 Series, 200 Series, with other models like Ranger, Hilux, Colorado being progressively released, for loads in excess of the OE Manufacturer’s specification.

These replacement engineered differential housings compliment GVM upgraded vehicles where the new GVM is above the axle housing capacities.

The Replacement Differential Housings make the vehicles compliant, not only in GVM/GTM/GCM but also for individual axle loads.

Consider the 70 Series Single or Dual Cab

  • Front Axle Load Maximum 1480kg
  • Rear Axle Load Maximum 2300kg
  • Standard GVM Total 3300kg

Old Man Emu (OME) has 2 GVM options, 3780kg, which equals the Total Combined axle load of 3780kg, or with the rear sway bar kit and 600kg constant load rear leafs, the GVM can go to 3950kg. This is based on Finite Element Stress Analysis of the axle housings that establishes the maximum load at 3950kg or greater.

However, using a JMACX Off-Road Solutions Engineered Uprated Rear Axle housing, a GVM of 4180kg is available, as the replacement rear housing is rated to 2700kg, 400kg more than standard.

The Brake Booster also needs to be changed, to a Double Diaphragm type to compliment this GVM Rating.

This is especially useful for the Dual Cab version, the rear axle is located right at the rear of the cab, so ALL the rear payload is carried by the rear axle. In the Single Cab version, weight is more evenly distributed over both axles as the tray starts around the middle of the wheel base.

There is another feature worth mentioning on these 70 Series housings

  • The track width is increased to match the front track on the 4.5Li TDi models, 2007-on. This is a tremendous advantage for vehicle stability plus performance off-road. So much energy is lost pushing the rear tyres through new track, rather than following in the path of the front tyres.
  • The strengthened housing will not catastrophically fail as occurs on some vehicles. See the image!

Similarly the 200 Series GXL Landcruiser

  • Front Axle Load Maximum 1580kg
  • Rear Axle Load Maximum 1980kg
  • Standard GVM Total 3350kg

OME GVM has 2 options, 3650kg or 3845kg. This is based on Finite Element Stress Analysis of the OE axle housings.

The JMACX Off-Road Solutions replacement rear differential housing is rated to 3000kg, bringing a total GVM to 4200kg.

HD Upgrade Engineered axle housing for leaf Rear Summary

  • 400kg Increased Load Capacity Rear
  • Differential Housing
  • Fabricated 6mm housing with increased axle tube trusses and 6mm brackets with chrome moly spindles
  • Track Corrected to align with front
  • 4340 Chrome Moly 2 Piece Axles with Drive Plates, Stronger than OE axles
  • Brakes, seals, hubs, bearings etc all remain standard
  • Factory Locker compatible
  • Sway Bar Compatible
  • Direct Bolt in, no modifications required
  • Comprehensive Kit
  • Includes extended Brake Line and Handbrake cable extension
  • Anti corrosive undercoat with external high quality Powder Coat black
  • Full FEA Tested
  • Supporting Certification available, LB2, to Approved Engineer or Dept
  • Compliance Plate required/provided
  • Installation takes 5 to 6 hours
  • Experienced Technicians available for fitting
  • 3 Year Unlimited Km Warranty

If you would like any further information or to discuss specific GVM issues surrounding your model 4x4, please make contact with one of our experienced staff.