Ron & Viv Moon put Terrain Tamer’s GVM upgrade to the test over three tough outback trips

It’s been over a year since we fitted a Terrain Tamer GVM suspension upgrade to our Troopy, and since then we’ve done three pretty long and hard trips, including along the Canning, a jaunt to Cobourg Peninsula in the NT, and another trip through Outback SA and the NT, following much of the Binns Track to the Gulf of Carpentaria.

With the Troopy wearing an ARB bullbar with a Carbon winch up front and a Kaymar rear step/towbar down the backend with drawers and a water tank to add to the weight, I knew I had to do something with the suspension. Even though Toyota upped the ante as far as GVM was concerned with this model, it was just a token addition, and most people would want more.

In recent years parabolic springs have seemingly become the flavour of the day for those wanting to replace their normal leaf springs. Parabolic spring packs typically contain less leaves than the normal leaf spring, while also featuring less unsprung weight with better flex and articulation—something that 70 Series Cruisers aren’t well known for. As well, in a parabolic spring, the tapered design of each leaf allows the stress to be distributed more evenly across the spring, while each leaf is allowed to work independently with enhanced flex, and importantly, without sacrificing load-carrying capacity, while keeping all four wheels on the ground.

With some great reports from my son with his 79 Cruiser and the many tough, heavily loaded trips that vehicle is subjected to as part of his tour company’s (moontours.com.au) travels in Cape York, the Simpson and western deserts, along with the Victorian High Country, a set of parabolics for the rear of the Troopy quickly went to the top of my most wanted list.

My timing was right as well, as Terrain Tamer released a GVM upgrade for the 70 Series Cruisers late in 2023 that included parabolic springs. The GVM upgrade was pretty impressive as well, lifting the GVM to 3,950 kg in this case (they have other variants as well) from the standard 3,300 kg. While the Troopy has a kerb weight of 2,308 kg, it does not include (as per normal with any kerb weight figure) any fuel, passengers or additions such as bullbars, dual batteries, etc.

The whole GVM upgrade kit, designed in conjunction with the well-known and well-respected Multidrive Technology company (multidrive.com.au) based in Geelong, Victoria, includes new springs and shocks front and rear, along with a new sway bar for the rear, plus shackles and poly bush kits. The Installation Guide and associated info are first-class—easily the best and most comprehensive I’ve ever seen and obviously aimed at the DIY handyman. And, as with anything these days, there’s the paperwork that must be completed and a sticker to go on the driver’s side B-pillar informing those who need to know of the GVM upgrade.

It’s a lengthy process to change a suspension with some heavy lifting involved. It really necessitates a well-set-up workshop, equipment, and expertise, so I left that for the crew at Outback 4WD in Bayswater, Victoria (outback4wd.com.au), to do the job.

The front suspension is relatively easy, with the original coil springs and shocks painlessly replaced with the new Terrain Tamer product. The biggest issue at the front end is the changing of the caster bushes on the trailing arms, which requires a good, gutsy hydraulic press for the removal of the old bushes and the fitting of the new ones.

The back end of the Cruiser and the leaf spring packs are a bigger and heavier matter requiring a couple of people and a few support stands to make the job easier and safer. Once the new parabolic springs were in place, the new shocks were fitted, and then it was time to also fit the new heavier-duty sway bar.

Having a quick look at the TGS Series twin-tube shocks from Terrain Tamer themselves, you’ll quickly realise they are, in both the front and rear shocks, bigger than the OE versions with a 40 mm bore and 20 mm chrome-hardened shaft, the bigger body allowing more oil in the shock, which is a good thing. There are double-welded eyelets for added strength and a multi-stage valving system for a responsive but comfortable ride, while the nitrile seals that keep the oil where it should be are German-made. The shocks for the rear are not only bigger but also more firmly valved than what would be required for a normal leaf spring pack, as parabolic springs do not offer any frictional resistance to the spring’s oscillations, so that work has to be done by the shock—a bit like a shock that controls a coil spring.

We also fitted a new steering shock to the Cruiser, while earlier model 70 Series have to have bigger side indicators fitted to comply with ADR requirements, but our rig, being pretty new (but the old V8 model), had the right size lights.

The price for this suspension upgrade comes in at $6,367 plus fitting, so it’s not a cheap addition, but I reckon it is well worth it. Warranty-wise, the shocks have a three-year cover, while the springs are covered for the owner’s lifetime. For more details, go to www.terraintamer.com

With the new suspension fitted, the Cruiser sits a lot taller, especially in the rear, and we’ve given it more than a fair test over the last 12 months. The ride, even when empty, is very comfortable over a wide variety of surfaces—I’m always surprised at how good it is. And it carries the load you end up with when on a long remote desert jaunt easily with little difference to the ride and handling quality. I’m more than impressed, and it’s a worthwhile GVM upgrade that offers top-notch equipment and a good ride whether loaded or empty!

By Ron & Viv Moon