How to build a Jayco Silverline

There are more than 150 RV brands in Australia, with involvement ranging from complete built-up imports to partial local assembly to almost fully Australian manufactured, from the chassis and suspension up.

The range of RV construction types also vary widely, from traditional stick-and-tin (Meranti timber frame and aluminium cladding) to fully composite body structures.

Here we’re looking at what is involved in building a composite caravan, specifically a range-topping Silverline model, from its bare bones up at Australia’s largest RV manufacturer, Jayco.

The Jayco Silverline has been in production since 2014 at Jayco’s 50-acre site in Melbourne’s Dandenong South. Like most Jayco vans, almost everything on the Silverline is built on-site from the chassis up.

Busy factory

Nine Jayco Silverline caravans are built each day out of a total of 49 Jayco camper-trailers, caravans and motorhomes produced at the Dandenong South site.

Up to 180 workers are involved in building a Silverline, from welding the chassis to handling the completed caravan over to a delivery driver to take it to the selling dealer.

The Jayco Silverline is put together in six main construction buildings, which include the Chassis shop, the Lamination workshop, the Saw section and the Caravan line. Each main factory takes up roughly 10,000 square metres of floor space.

The crucial element of a Silverline build is of course its run sheet. This sheet is unique to each caravan, with its VIN number as well as all details needed for the manufacturing process, from chassis dimensions to the cabinetry layout and any options involved with the order.

The Chassis shop cuts the raw chassis sections of Australian steel and then the chassis is welded together according to the run sheet requirements, which takes about an hour.

The welds are smoothed off and the chassis then sent to an off-site supplier for hot-dip galvanising. When it returns to the chassis shop, the chassis is put upside down on a trolley and wheeled around to the various assembly stations for fitment of items such as the suspension, wheels, stabiliser legs and coupling.

Jayco’s J-Tech independent suspension subframe and trailing arms (fitted to off-road models) are made by AL-KO and the springs and shocks by Pedders. They're assembled in the chassis shop and then the suspension unit fitted to the chassis.

Other items, such as the drop-down steps, rear bumper, mudflaps and water tanks, are added to the chassis before it is flipped over onto its wheels and towed over to the caravan assembly line. From the time the chassis is returned from galvanising until it's fully ‘dressed’ takes about 45 minutes.

Meanwhile, in the Lamination workshop the walls and roof are being built, again according to a run sheet that allows workers to make the panels according to the length, layout and wall/roof cut-outs and wiring required for any optional equipment in the specific caravan order.

The sandwich construction walls and roof consist of an aluminium frame and high-density polystyrene insulation that is layered over with plywood inner and outer sections and an outer fibreglass skin all vacuum bonded together.

Firstly the aluminium is pre-cut to the lengths required so that then the pieces can then be welded together to make the frame. Then the frame is moved to an area where the high-density polystyrene insulation is cut and fitted to the apertures in the frame.

Sections of timber and galvanised sheeting are glued to the inner walls/roof to allow furniture to be secured into later. Inner and outer plywood is glued to the frame and an outer layer of fibreglass rolled out and added to the top.

The sandwich wall or roof section is then vacuum bonded in a vacuum press for 40 minutes and the excess (around the frame) is trimmed off and window apertures are cut out with a router.

There are four vacuum presses -- each a four-tier unit (that can laminate four sections at a time) -- and each wall or roof section takes three hours to produce from start to finish. When complete, the wall/roof sections are taken to the caravan line.

The interior cabinetry and ply floor panels are cut in the Saw section building, again each set of panels are made-to-order according to the individual requirements of the run sheet with CNC cutting machines.

It takes five hours to complete one caravan’s cut order. The furniture is then built on the caravan line in the Cabinet section, a day or two before the caravan is on the line.

The caravan line is where the dressed chassis and interior and exterior components all meet. Workers are given 45 minutes to complete each stage before the caravan must move to the next stage.

The chassis rolls into the shed and stops at two fitting stations.

The first is to install the plumbing required under floor level and 12v trailer wiring for the lights.

Then the chassis is rolled forward and sealant added to the top of the chassis rails in preparation for the floor install.

Then the waterproof marine ply floor sections and wheel wells are added to chassis, bonded by the sealant, aligned with staples and then secured to the chassis with screws.

Holes for plumbing, wiring and the door step were already pre-cut in the floor at the Saw section, but the floor joins are now sanded smooth.

The vinyl flooring is pulled out from a roller and cut to length. Then half of the vinyl is pulled back and glue troweled out and spread onto the ply.

Then that side vinyl is laid down onto the glue and the process repeated for other side.

Then the vinyl is trimmed to shape around floor edges, the step, wheel wells and holes are cut though the vinyl for plumbing and wiring.

The caravan is now wheeled onto the tracked section of the line, with the wheel sets mounted onto trolleys that follow the tracks. It’s a clever system, because it’s easy for the workers to move the caravans along to the next stage.

The first stage is to fit all of the internal cabinetry. This includes large appliances such as the fridge and hot water service, which are installed into the furniture in the Cabinet section.

The 12 volt, 240 volt and gas wiring/plumbing is also routed through the section between the walls and cabinets. The front boot enclosure is also installed at this point.

Then the caravan slides across to the next station, where the sidewalls are fitted. The sidewalls have come down their own mini-line within the caravan line to meet the caravan at this point, with workers fitting windows and decals to up to five side walls sitting on this dedicated line.

The sidewalls are clamped onto a suction cup rig and with a remote control to operate the rig are lifted over to the caravan, where they're temporarily clamped onto the chassis and roof bars mounted to keep them in position.

Workers have a datum point on the chassis to line the walls up to when installing. The side walls are secured to the chassis and furniture.

Like the walls, the roof comes down a dedicated mini-line to meet the caravan. There are up to five roofs in various stages of construction, with all fixtures and fittings (such as air-conditioning units, roof hatches, solar panels) installed during this stage.

The roof is lifted on a remote-control gantry into position over the caravan, where it (like the walls) is lined up against datum points to make sure it is square.

Around the time of the roof assembly stage, electrical work continues with items such 240volt power points and options such as gas heater now fitted.

The batteries are connected as is the Battery Management System, although the fuse is removed to avoid the risk of short-circuit as further electrical items continue to be added to the build. It’s also the time to round-off fiddly operations such as fitting RCA plugs, strip and fit 12 volt wiring connections, CD players and the like.

If a slide-out model, this is then fitted to the caravan. Like the walls and roof, the slide-out is built on a mini-line on the caravan line and joins the van at this point of its manufacture.

It’s now time for the roof/ side extrusions to be installed, after the joins are glued and screwed.

After the rear inner wall is installed, the one-piece fibreglass rear mould section is added. Following the theme of the other major exterior components, the rear section is fitted up with decals and lights behind the main caravan assembly line before being fitted. Sealant is applied to the periphery and two workers lift the section into position.

Then the front inner wall and insulation is installed, followed by the fibreglass nosecone. The front window is already installed to the nosecone behind the main assembly line. As with the rear section, sealant is applied to the nosecone before two workers carry it into position.

Because the assembly building is not long enough for one continuous line, at this point the van is taken off the trolleys and moved forward to the final part of the assembly line. Here it's fitted on trolleys again in preparation of being moved on the rails back the other way across the factory and towards final completion.

It’s time now for the door, final hatches and awning to be installed as well as final touches such as rear view camera.

Then a final cleanup of excess sealant and any swarfing or material from cabinets is cleaned up. Then the electrical equipment is tested and 240v electrical and gas are signed off and soft furnishings like dinette cushions and mattresses are now added.

The van is given a final quality inspection and if any problems is reworked to get it right.

The van is now ready to be removed from the caravan line building, where it has spent four days being built. A completed Silverline leaves the caravan line every hour.

The completed caravan is towed by a tractor over to the water test area -- which are dedicated wash bays where high-pressure water is directed at the van and the interior then checked for leaks.

Then the van is taken over a weigh bridge and the weight added to the compliance plate, which is then fitted. The gas and electrical certification is then lodged and the caravan is ready for dispatch.

Although the complexity involved with building RVs at Jayco is much to do with its sheer volume and wide range of products, it's also in part because of the intricate and innovative process of making composite wall and roof sections.

It's a process that can’t be done by just anyone: it involves an investment of time, money and expertise.