Hi Gang, part of this was published in the October club Magazine and after seeing all the effort that went into this trailer, I thought why not post it for all to see.
Forum member sabre (Garry) along with Richard are both talented fellas IMO. 
As Corvette owners and enthusiasts, we are all familiar with the difficulties of carrying a bit of extra luggage or an esky to keep the "Honey' cool in our beloved cars. Not since the C1 has the Corvette had a true boot and although a lifting hatch was introduced from '82, space remained pretty limited until the C6. If you are the owner of a roadster and choose to have the roof down you're pretty much limited to a handbag and small travel bag, making an extended trip a real problem. When Lady J and I started discussing a trip to the Barossa for the Convention last year this seemed to be a major obstacle for doing more than a dash there and back, which seemed to be a pity since it was our first trip post retirement. In a moment of absolute madness, and lack of real thought I said "Why not make a Vette trailer to take all the gear we needed?". So began the secret project.
I had the C4 convertible project on hold awaiting paint due to a small engineering issue so this was an ideal time to lift a mould of the body. My original intention was to have the front and rear of the trailer the same as the late C4s with an opening top like the C4 hood. Effectively I would be joining the front and rear at the centre of the respective wheel arches. The connection at the rear of the hood would have been "interesting" but it would have looked like a shortened car which was my initial intent.
It had been quite a few years since I had worked with fibreglass but having previously built a few boats I started with the lifting of a mould from the C4 rear bar. After purchase of fibreglass, resin, gelcoate and some various rollers and brushes, it was a nervous moment when I covered my new rear bar with gelcoate to make the first mould. Two weeks later saw the removal of the six piece mould and another week of repair had both the mould and bar back in finished state.
It was now January and reality kicked in. The original design required moulds for the front bar and the hood before I started to modify the components to fit together. Additionally, I had concern over the amount of available space in the finished product and the low profile hood would restrict height considerably. It was at this stage I started questioning my sanity for ever starting the project.
As coincidence would have it, I was discussing my concerns with Richard Stones who said he had had the same idea for some time, however he had intended making the front and rear of the trailer the same. Adopting this approach meant I gained internal volume and could use the one mold for front and rear. It looked more like a trailer than a shortened car, but it did mean I needed to make the 'lid' from scratch. With time being the biggest factor I went with Richard's recommendation.
The next challenge became the chassis. I wanted to keep the height the same as the car, but internal volume was still a concern. If I used a conventional flat chassis the internal depth was reduced to about 200mm or the trailer would have been about 300mm higher. A stepped chassis, shaped to the taper of the rear quarter was the answer but this put the axle in the middle of the storage area. I considered using a duratorque suspension or struts but both had little gain for great expense and both would take more time than a standard slipper leaf spring and solid axle. The final chassis was shaped to suit the simple axle design with the floor following the lower line of the front and rear bars. There is a tunnel over the axle which sacrifices a flat floor for maximum load volume.
The chassis dimensions were defined for me by the car. The length was twice the distance from the rear axle to the bar plus a draw bar. The width is the distance between the rear wheels less clearance for travel (20mm per side). The biggest challenge was keeping the heavily shaped chassis parallel and true during welding which took a while and some rework. Once tacked together with some temporary bracing, the look of the final product became apparent by locating the two bars I had on the chassis. The enthusiasm returned and I started on the next challenge, the upper deck.
To create the upper deck I needed the profile of the rear deck of a convertible between the mid-point of the wheel arch to the attachment point of the rear bar, made twice and joined at the wheel arch. This seemed simple but left only twice the size of the soft-top compartment lid as an opening. So the mould was taken from the rear deck of the project car with the full length of the lid aperture being included as the opening would need to be extended in the final deck. I also took an additional mould of the aperture gutter to aid in the eventual join of the two deck halves. The final deck was formed by initially laying only the lid aperture section then removing it and placing it in position in the mould to make the opening as large as possible. Two of these were made and then joined resulting in the final shape which looked a little Frankensteinish, but final shaping would fix this.
Next came the lid. I returned to the rear of the car and taped all of the seams including the fuel access cover and took two molds of the same area. These were joined and braced and with copious quantities of filler shaped to the double convex curve required. Although I could have used a similar method to the deck ie one mold to produce two haves and join the final product, making two half moulds and joining them proved a better option as this gave the opportunity to remove the join marks in the mould meaning a reduction in filler and reduced weight in the final lid.
The final items for manufacture were the mud guard and filler panels to seal the lower half of the trailer. I made these from an assortment of pieces of offcut and timber to form 'plugs' for the manufacture of the 6 final pieces.
It was now just two weeks before the scheduled run to the SA convention. Richard again came to the rescue. We started with a lot of filler and block sanding followed by a polyester spray putty to remove the sanding marks and natural gelcoate porosity. At this stage the little trailer had its first road test by getting towed to Richard's spray booth for undercoat and topcoat.
The final product rolled out of the spray booth on the Monday before the scheduled departure on Wednesday for the Convention. Tuesday was spent with final assembly, fitting brakes and Richard again came to the rescue with a final buff and polish, despite the paint still being too soft. Jakki did her absolute best to fill the trailer prior to departure but failed as there was plenty of room available. Most of this room was taken up by the time we got home!
The trailer's road test covered about 3000km. Three days running to the Barossa then back through Adelaide and across the Great Ocean Road before heading home. The only defects were a couple of latch nuts coming loose and a lot of stone chips showing on the soft paint. The trailer tows well to 150kph and the electric brakes make stopping as good as not having the trailer on the back. I consistently got 600km out of a tank of fuel with a increase of only 0.8 l/100km, so the streamlined shape is not loading the car much. Overall I was very impressed by the finished product and I'm sure my award at the Convention was in recognition of the trailer as it commanded lots of interest wherever we went.
Garry, I hope I managed to arrange the pictures in the correct order of the build.
