The major drawback with almost every 4WD currently sold in Australia is the lack of load carrying capacity. It means that adding a few accessories and loading up for a trip not only puts these vehicles over their maximum legal Gross Vehicle Mass (GVM), but can also make the vehicle unstable and unsafe under those conditions.

Installing aftermarket suspension goes some way to improving things, although without including a legal increase to the vehicle's GVM, it can still leave you liable for overweight infringements, insurance claim refusal and even prosecutions if something goes wrong.

With the 300 I decided to get this situation rectified from the very beginning, installing a federally approved TJM XGS suspension system, with their GVM Plus upgrade, prior to first registration.

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Tare The standard unladen weight of your vehicle as specified by the manufacturer, with all oils and 10L of fuel. You'll find it on your rego papers.

GVM Gross Vehicle Mass. The maximum legal weight of your vehicle, including any accessories, passengers, cargo, fuel and any downweight bearing on the vehicle via the towbar. The GVM is specified by the manufacturer and appears on your rego papers. In the case of the LC300, the standard GVM is 3280kg.

BTC Braked Towing Capacity. This is the maximum mass of a trailer (with brakes) that can be towed with the vehicle. In the case of the LC300, it's 3500kg.

GCM Gross Combination Mass. The maximum combined mass of the vehicle and any trailer it's towing. Can be a published figure or simply the sum of the GVM and the BTC. At the time of writing, GCM and GCM increases are in a grey area for light vehicles, and I will not discuss them in this article.

SSM Second Stage Manufacturer. This means that a company has obtained federal approval for a modification. In this context, it means a suspension modification to allow a GVM increase.


Exceeding your maximum GVM is not only illegal, but can void your insurance and leave you open to civil and criminal liability in the event of an accident. Fortunately, the GVM of many vehicles (including the LC300) can be increased with the right modifications.

Upgrading the GVM of a vehicle typically involves replacing the suspension (springs/shocks/struts), and may include other components such as control arms, indicators etc depending on the vehicle and the increase.

The upgrade process includes extensive testing at the increased mass to ensure the vehicle is structurally sound and safe to operate at that mass. Tests typically include handling and braking assessments, structural strength assessments and computer modelling. After successful testing, the modification is approved and can be sold to the public. There are two methods by which this can occur:

Federal Approval (pre-rego)

As the heading implies, a federal approval (also known as a Second Stage of Manufacture or SSM) is a nationally approved modification which occurs before the vehicle is registered for the first time. A second ADR compliance plate is added to the vehicle, and it will always be recognised with the higher GVM values. SSM kits must be fitted by an authorised installer to obtain approval. This means transferring interstate in the future is no issue, and you're not subject to the whim of future changes to state regulations. If you are buying a new vehicle and planning a suspension upgrade, then having a pre-rego SSM GVM upgrade done is very worthwhile and preferable to a post-rego upgrade.

State Approval (post-rego)

If the vehicle is already registered, the only option is to go with a state-based approval. For a federally-recognised kit (such as the TJM XGS kit I have installed), the only real difference is that an approved engineer must sign off on the installation of the kit. Moving interstate means a new engineer must sign off on the installation again at that time. If you want to install anything different to a federally-approved kit, the state engineer will have to undertake testing to satisfy him/herself of the capability and safety of the upgrade before approving the upgrade. This is the path I took with my 200-series, but rules have changed somewhat since then.


There are plenty of suspension options on the market these days. Lots of brands, lots of options and lots of price points. You can spend anywhere from $3,000 to $18,000 on suspension for a 300-series.

I've run various twin tube shocks on my 4WDs for over 30 years and never had an issue with them. In most situations, they are a perfectly acceptable shock and you'd never reach their limits. The thing about the suspension industry is that manufacturers will often claim that the option they offer is the only one to have. This is particularly true for companies offering only one type of shock. There's a particular retailer of twin tube shocks out there claiming that their twin tube foam cell shock outperforms a remote reservoir monotube. Conversely, there are retailers of $15,000 remotes implying that anything less is hopeless. Neither claim is true.

So, what are the pros and cons of different shock absorber types?

Twin tube (Eg XGS Roamer):

Twin tube shocks -as the name implies- have an inner cylinder which contains the piston, and an outer cylinder which acts as an oil reservoir and contains some nitrogen gas. A foam cell shock is a variation on the design, where the outer cylinder contains a closed cell foam rather than gas. Twin tubes are the most common and affordable type of shock absorber installed on vehicles today.

Their primary advantages are cost and durability. The twin tube design means they are less susceptible to impact damage, and they also run lower gas pressures, reducing stress on seals. Foam cell shocks often have no gas pressure at all. Twin tube shocks typically offer more piston travel than monotube (non remote) shocks.

Their primary disadvantages are that they are more susceptible to performance degradation from heat. They rarely offer any form of adjustability, so must be valved well to suit the vehicle, although this will always be a compromise depending on operating weight and conditions.

Monotube (eg XGS Rugged):

Monotube shocks are a single cylinder construction, with a high pressure gas charge. They are commonly found in high performance sports cars and in premium aftermarket brands. Their larger piston allows for more precise damping and the single tube improves heat dissipation, reducing fade under extreme conditions compared to most twin tube shocks. The larger piston means potentially higher damping force can be applied.

Their primary disadvantage is that the single wall increases susceptibility to impact damage. Some monotubes (such as the Rugged) have thicker walls to allow for this, but particularly in a vehicle such as the LandCruiser (which has its rear shocks in front of the axle), it's important that they are protected from stone impacts. Another downside is that high gas pressure in monotubes puts seals under more stress than twin tubes.

Monotube Remote Reservoir (eg: XGS Remote):

The remote reservoir version of the monotube design improves on the advantages of the monotube, and adds a few more. The biggest advantage from my perspective is the addition of full damping adjustability. For a vehicle operating at various weights and in different conditions like mine, the adjustability is what sealed the deal on choosing remotes for this build.

The reservoir increases total oil volume and surface area, reducing fade. It also increases gas volume, reducing stress on seals. Compression adjusters like those on the XGS Remote shocks allow for a further reduction in gas pressure, reducing stress on seals.

The main drawback of remote reservoir monotube shocks is typically the cost. Some systems for the 300-series can top $18,000. I honestly would never consider spending that sort of money on suspension, unless I had a sudden desire to enter the next Finke Desert Race! The XGS Remote system costs around $5,900 at the time of writing That's fully installed with a pre-rego GVM upgrade. This makes them excellent value. For about double the cost of a twin tube system, they offer substantial feature and performance advantages.

After considering the pros and cons of the three shock types, I decided that a remote reservoir monotube setup would be my preferred option for the 300. I researched some of the more reasonably priced remote reservoir systems, aiming for a known brand with good after sales support and a solid reputation. That eventually led me to TJM and their newly updated XGS Remote system.

For less than a third of the cost of some alternatives, the XGS Remote offers spectacularly good performance and easy adjustability of both the compression and rebound damping (many alternatives only offer compression adjustment). Plus you get a 3-year 100,000 KM nationwide warranty, and when the shocks eventually do wear out in the future, they are fully rebuildable.

GVM Increase: How high can we go?

The other consideration before choosing a system is the amount of GVM increase required. TJM offer two mass options in every XGS range for the 300-series: 3925kg or 4100kg. The main difference between the two is the rear springs, with the 3925kg option having springs designed for a constant 275kg of additional load, and the 4100kg option having springs designed for a constant 500kg of extra load.

I decided on the 3925kg option, because I try to keep the car as light as possible most of the time, only loading up for trips. I don't plan on installing a drawer system, or tow a heavy van. That meant the 275kg springs would be fine for my needs, and the 3925kg total would be more than enough to keep me legal. On the other hand, if you plan on having a drawer setup, roof rack and perhaps a large offroad van with a 350kg ball weight, the 4100kg version would probably be a better choice. The cost is the same, so it just comes down to personal preference based on your needs.

Take a look at the table below to see just how necessary a GVM upgrade is, if you plan on equipping your 300-series for outback touring:


As I write this, I've had the 300 for a little over a month. In that time I've travelled about 3,000km, including local roads, highway driving, some towing duties (1500kg trailer), plus some offroad testing on fast dirt and on some slower 4WD terrain.


Given that the car is still devoid of accessories and their associated weight, I'd really expected the ride to be very harsh. The kit was installed with the expectation of a bullbar, winch, rear bar, long range tank and dual spares. Essentially an extra 300-400kg of weight. With this in mind, I immediately set the shocks to their softest settings for both compression and rebound. This ability is one of the great advantages of the remote reservoir shocks, and is no gimmick. The difference between the softest and firmest settings is substantial.

The ride from the new suspension is incredibly good. Better than the factory suspension, which I had never imagined possible given the fact there is over a tonne of available payload. Handling is also on par with the factory suspension, despite the extra height. I'm planning on stiffening the shock settings up as more weight is added from accessories, or when loaded for a trip.


On fast dirt and corrugations the excellent ride remains. Far better than any suspension I've had before. The 300 is comfortable and well controlled, with no skipping over the corrugations and no bottoming over larger depressions.

On slow offroad work, the suspension has good levels of comfort, compliance and travel. Like most 300s, mine lacks the KDSS system that now comes only on the GR Sport, so travel is limited by the sway bars in unloaded situations. If maximum travel is your goal, then the GR Sport would be the pick of the LC300 range, or consider some swaybar disconnects.


After a month running around on the new suspension, driving almost 3,000km on local roads, highways and offroad, plus some towing duties, the XGS Remote has exceeded all my expectations. Despite the huge available payload, the ride is better than the factory suspension and handling is on-par.

Offroad, the suspension delivers a supple ride and plenty of articulation, even without the advantages of factory KDSS. It will improve further once more weight is added to the car, and as with most 4WDs, travel would would also benefit from swaybar disconnects, if you plan on doing serious offroad work.

The GVM increase which comes from the 3925kg upgrade is substantial. The payload of the 300 is now a massive 1445kg, a very impressive 645kg increase over standard. That will be more than enough to keep the 300 legal with every accessory I plan to install, plus passengers, luggage and towball weight.

I was very impressed with the quality of the installation by TJM Northern Beaches (in Sydney). Accessory installs by some major retailers can be a bit hit and miss. But in this case, Ed (the installer) was thorough and showed excellent attention to detail.

Thanks to the suspension, Project 300 is off to a great start. As with all the modifications and accessories, I'll provide updates on the suspension's performance well into the future.

LandCruiser 300 Suspension Installation

Normally, I'd post a complete DIY guide here, but as the installation for the pre-rego GVM upgrade needs to be professionally installed by a TJM store, I'll just provide a brief overview of the process. You can also see the installation in the video here.

Pre-Rego process overview

  • The vehicle must not be registered before suspension installation.
  • Have the vehicle transported from the dealer to the TJM installer. This will need to be done on 'trade' plates, on a truck/trailer, or using an unregistered vehicle permit. The exact rules vary from state to state.
  • TJM will install the suspension, which takes about half a day. The vehicle will also need a new weigh-bridge slip, and a wheel alignment.
  • After installation, the vehicle will need to remain with TJM for a few days while the required documentation and compliance plates are obtained. This will take a few days.
  • You can then register the vehicle at the nearest registry or return it to the Toyota dealer for any final pre-delivery etc.
  • The vehicle will be registered with all the upgraded weights on the registration certificate.

Promotional and advertising content declaration

Undeclared promotion is rife in the 4WD "influencer" industry. Project300 is different. In the interests of full transparency, every page on Project300 will contain disclosure of what -if any- benefits were received in the process of choosing and installing the listed product(s).

I plan on owning and driving the Project300 LandCruiser for at least a decade. I'll only ever choose and install products which I believe to be of the highest quality, and which will serve me reliably throughout the life of the vehicle.

Disclosure for this article:

  • TJM supplied and installed the complete suspension kit at no charge to me, after I chose this product;
  • No monetary payment was or will be received from TJM or any other company to use or recommend their product;
  • I have no obligation to only make positive comments, and am free to say or write whatever I choose about the products, now and in the future;
  • This page contains affiliate links to eBay and/or Amazon. If you click on a link and then purchase any product at eBay/Amazon within a 24hour period, then I will receive a small commission on the total sale amount. The price you pay is not affected;
  • This page contains advertisements from Google Ads, for which I receive a small payment. I do not control the content of the advertisements and do not necessarily endorse the products being advertised.

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