Behind the Scenes: Jayco Endurance Chassis

Strong, lightweight, home-made: Jayco’s Endurance chassis is just one of its unique construction points. 

The Jayco Process

There are many points of difference between a Jayco caravan and other vans on the market, and Jayco’s signature ‘Endurance’ chassis is a significant one. Unlike the vast majority of RV manufacturers, Jayco build its own chassis, rather than buying them from an external supplier. But it hasn’t always been this way – manufacturing operations manager Chris Ryan said Jayco only brought the chassis shed back in-house about 15 years ago.

“We brought it in-house for a number of reasons,” Mr Ryan said. “Obviously there are operational efficiencies we can gain by bringing it in-house. And we also have control over it and we can bring new developments in quicker than if we used an external provider, because we control the whole process.

“At Jayco, we like to think we’re a dynamic company and we like to bring new things in quickly and, hence, that’s why we like to do as much in-house as we can.” 

The chassis shed is exactly the type of place you’d expect a chassis to be made. It’s a cavernous workshop, buzzing with the sounds of angle grinders, hammers, and other power tools. Everyone is kitted out with ear-plugs – it would be impossible to spend more than a few minutes in here without them – and the chassis shed completes 45 chassis every day.

BUILDING THE ENDURANCE

Lengths of steel come in from Jayco’s supplier, pre-cut to size. These are laid out on a table like a giant jigsaw puzzle before being clamped, then welded together to create the chassis main rails, cross members and A-frame. 

The Jayco Expanda Outback sits on a 6.01m chassis, made from strong rectangular hollow section (RHS) steel. The Outback packs beefs up the Expanda’s credentials with 6in (150x50mm) main rails (compared to the 4in used on non-Outback models) and a 125x50mm (5in) A-frame. This gives the van greater strength and a higher ground clearance.

The Expanda Outback’s chassis has pressed-hole steel C-section cross members between the main rails. Hence the name, these rails are shaped a bit like a ‘C’ and have holes cut out of them, which reduces their weight. It’s still very strong and the holes allow the under-floor plumbing and wiring to be run through and stay protected.

All Endurance chassis are hot-dip galvanised, which involves submerging the steel chassis in a bath of molten zinc. The zinc reacts with oxygen and carbon dioxide to form a layer of grey zinc carbonate over the steel, protecting it from corrosion.
Hot-dipping is one of the few processes Jayco outsources to another company.

J-TECH DEBUT

JTECH signals a new era for Jayco, which had never before used its own suspension setup on its huge fleet. Previously, all vans and campers were fitted with beam-axle, leaf spring suspension, with optional heavier-duty Simplicity suspension. But, in this new era for Jayco, JTECH is now fitted to all Silverlines and all other RVs with the optional Outback pack.

Designed wholly in-house, J-TECH and its components, while out-sourced, are made to Jayco’s detailed specifications.

The chassis module (sub-frame), control (hub) arms and brakes come from Al-Ko, while the heavy-duty telescopic off-road shock absorbers and coil springs are custom-made by Pedders, especially for Jayco. All the components come together at Jayco where they’re fitted together and inserted into the Endurance chassis.

Finally once everything has been signed off, it is hitched up to a tractor and towed, like a regular caravan, over to the production line, ready to be turned into a caravan.

Suspension components

Modular sub-frame 

• This is the frame in which the whole suspension kit sits. It has been designed to complement the Endurance chassis and can be bolted and welded directly between the chassis rails. The frame is electro-coated to help protect it against corrosion and stone chips.

Trailing arm

• Located on the A-shaped hub arm, or trailing arm, the wheel hub sits roughly parallel to the ground. This arm is attached to the sub-frame ahead of the wheel and allows it to move vertically to smooth the ride.

Independent stub axle

• These replace the single beam axles used in non-independent suspension systems. Helping the wheels move independently of one another, allowing for more a accurate reaction to the road surface. Creating greater stability and a smoother, safer ride.

Coil springs

• Coil springs are one of the most important features of the suspension system. Their role is to absorb the shocks that are created when driving, and to maintain correct downward pressure on the road for optimal tyre/road surface contact. 
• They do this by absorbing energy through their coil shape and releasing it when required.

Shock absorber

• The name is a bit misleading and, while coil springs are actually doing the shock ‘absorbing’ in a suspension system, shock absorbers have two other, equally important, roles.
• The shocks, which are, effectively, a hydraulic pump, actually control the movement of the coil springs, and they keep the tyres in constant contact with the road.

See the full review in issue #531 of Caravan World.