New TerraGlide caravan suspension raises the bar

The Melbourne-based automotive outfit behind some of Australia's most desirable off-road and performance vehicles, has released a unique new semi-trailing arm independent suspension for caravans that it describes as the "perfect off-road suspension".

Melbourne-based Premcar is best known for bringing to life the tyre-shredding Ford Falcon-based FPV performance sedans of the early 2000s, and more recently mud-bashing 'Warrior' variants of the Nissan Navara ute and Patrol 4x4 wagon.

Not to mention the eye-catching Gateway Ford Bronco restomod show-stopper recently unleashed in the US.

But now it's turned its extensive automotive design, engineering and testing know-how to the design of an all-new off-road caravan suspension, with its new TerraGlide subsidiary recently releasing a new range of coil spring and airbag suspension set-ups targeted at buyers of off-road caravans.

Head of Engineering Joshua Wood said the Premcar team believes there's a gap in the Australian off-road caravan suspension market between the extreme, bespoke off-road set-up offered on Brisbane-built Bruder expedition vehicles, and more mainstream offerings from the likes of Cruisemaster and AL-KO.

"We wanted to bring our automotive skill-set into the caravan industry, and make something we could sell to all off-road caravan manufacturers but with higher capability off-road," Wood said.

As part of the 12 month design and development program, Premcar says the unique semi-trailing suspension geometry inspired by the automotive industry was carefully optimised using sophisticated computer modelling and mechanical simulation, including the use of sophisticated MSC Adams Virtual Engineering software.

"We actually had control over the camber and toe as the suspension moved up and down (with the use of this software)," explained Premcar's Principal Chassis Engineer Andrew Lynch.

"So with a little bit of body roll (around corners), you're actually changing the camber on both wheels, and essentially keeping a flat contact patch between the tyre and the ground. It's similar to any vehicle with front independent suspension," Lynch said.

"A lot of (other caravan suspensions) run toe-in on the front axle to help with stability, but (with the TerraGlide) as the wheel goes up and it rolls it's actually toeing in as well, to pull the caravan back in rather than let it drift out further.

"Semi trailing arms have been around for a long time but not on a caravan... the current Ford F-150 Lightning has the same rear suspension as this."

Premcar says its new TerraGlide suspension boasts a class-leading 230mm of total wheel travel, and features custom-designed jounce bumpers that provide progressive wheel deceleration, to help reduce the impact of large shocks on the chassis and caravan body.

The use of an anti-roll bar on each axis also allows softer spring rates for a more forgiving ride, as well as a less jarring 'bounce' frequency that's similar to the tuning on the Warrior Patrol wagon.

"The wheels actually move up and down and not the chassis (over corrugations)," he said.

A single specially tuned, high-performance Monroe twin-tube shock absorber fitted alongside each wheel is similar to dampers fitted to some Walkinshaw-fettled Cheverolet Silverado pick-ups.

"Two dampers per corner (as seen on many off-road caravans) doesn't make any sense," Engineering Director Bernie Quinn said during a media presentation at Premcar's Melbourne headquarters. "To me it's purely a marketing ploy as there's no reason why you can't have one good automotive damper on each corner, like you do with a car, and tune that perfectly."

Premcar said the patented TerraGlide suspension outshone some rival products during benchmark and durability testing at the Anglesea Proving Ground in Victoria.

"We delivered two to three times less load into the chassis than a leading off-road competitor, which we believe is likely to deliver less shock load into the caravan and improve the durability of the whole van," Wood said.

Premcar also believes the new suspension's inherent stability particularly when cornering on gravel roads, will make secondary safety systems like trailer ESC less important.

"It's providing a more stable fundamental platform so those band-aids don't have to be as active," Quinn said.

Tapping into its global supply network, other automotive-grade components used include sealed, dual roller bearings and maintenance-free bushes. The TerraGlide comes with electric drum brakes but a disc brake option is in development.

"You still have to maintain your brakes but other than that it should save you money over the life of the suspension," Lynch said.

The TerraGlide suspension is being produced at Premcar's engineering and production facility in Epping, Victoria. It's currently available in 3500kg and 4500kg rated coil spring and airbag tandem axle set-ups, with a single axle version coming soon.

Premcar says it will be "competitively priced" and available for fitment to a wide range of caravan chassis, with Melbourne-based Urban and Masterpiece Caravans among the first to adopt it for their 2024 range. The new suspension could also find its way on to other trailer types, as well as eventually be available overseas.

In the meantime, Quinn said TerraGlide is a potential game-changer as it's the first time within the Australian RV industry that leading automotive design, engineering and testing principles have been applied to an off-road caravan suspension.

"(The TerraGlide) outperforms anything in the market, there's nothing even close to it," he said.