TrailTop modular components are designed to work as an easily modified system. Think of these parts as building blocks that you can customize and assemble to build exactly what you want!
This page will give some basic information on how the system works and what to expect in terms of the build process.
1 – Components
The TrailTop system simplifies the process of building a structural framework for your camper project. Our unique fiberglass pieces are easy to customize to build exactly what you want. The straight rail parts can be cut to the exact lengths required, and corner parts can be used to complete the structure.
2 – Fitting
There is some simple fitting required to get the straight rail pieces to mate properly with the corners. The straight parts are cut to the exact length required (see note below about cutting our parts). Measure the width of the flange on the corner piece, and transfer the measurement to the flange on the straight section.
Draw lines lengthwise at the top of the flanges just below the curve to complete a rectangular section that will be removed.
These steps will get you 90% there, but some minor sanding along the edges will be necessary to get a square, tight fit.
I like to use a detail sander with 40-60 grit paper along the cut edges to finish fitting the straight piece with the corners. I find this to be easy to control and still very quick to get the desired result. I will also have some sandpaper around that I can wrap around a block or piece of angle iron to get into the corners neatly.
This is definitely a step to be patient on, the better the parts fit together dry the easier it is to bond everything together neatly later.
Notes about cutting TrailTop parts
There are several acceptable methods for cutting parts. Regardless of the method used, we suggest that you put masking or painting tape on the fiberglass surface and mark your cut lines on top. The tape will help minimize chipping/cracking of the gelcoat.
Preferred method
Use an abrasive tool (such as a cutoff wheel on an angle grinder, a die grinder, etc.). We have found this to be simple, fast and leaves the cleanest edge.
Alternatives
Saw tools with a blade designed for cutting metal are acceptable (jigsaw, circular saw, hack saw, etc.) The edges generally are not as clean as what you get with an abrasive cutting tool. Very fine tooth blades will wear out fast, a medium tooth blade is the best compromise between smooth cuts and blade durability. It is highly recommended to test your chosen method before proceeding to ensure an acceptable result. Regardless of how the fiberglass is cut, plan to do a bit of sanding along the edge to smooth out the finish.
3 – Bonding
Several products are possible for bonding the parts together, each with their own pros and cons. We are always testing different ideas, this page will be updated if any of our recommendations change.
Epoxy (Best)
Epoxy is the best overall option in terms of performace. It will give the strongest joint, and will resist cracking if you plan to fill and smooth everything for a seamless look. It is suitable for fiberglass-fiberglass bonding between TrailTop components as well as fiberglass-wood bonding for the plywood walls so only one product is needed for the entire project. It is the more expensive option but will give the best results. A standard epoxy (like West Systems 105) can be used but is pretty thin and not gap filling, relatively inexpensive fillers are available to thicken the epoxy for different purposes (West Systems 406 for structural bonding of parts for example). Another great option and our preference is a pre-thickened product from West Systems called Six10 Epoxy Adhesive which comes in a standard caulk-gun tube. For a single project, the Six10 is the go-to option for how easy and clean it is to work with.
Construction Adhesive
The greatest benefit to construction adhesives is that they are readily available locally at home improvement centers and very inexpensive. They are generally thick enough to fill gaps as well and are easy to use by loading the cartridges in to a caulking gun. The downside is that generally these adhesives are designed to not cure rock hard. If your project requires all the seams to be filled and smoothed, using a slightly flexible adhesive will almost certainly contribute to cracks along the seams over time. However a shell where the walls are bolted or riveted in place and the seams are visible is a great application for construction adhesives.
Joint Preparation
Regardless of the product that is chosen proper joint preparation is critical. The gel coat side of TrailTop parts need to be sanded with rough sandpaper for maximum tooth, minimum 80 grit and coarser paper is even better.
The resin side of the parts should be sanded in a similar fashion, but that side should also be cleaned with acetone to remove waxes in the resin that migrate to the surface when the parts cure.
Once the parts are prepped and ready to be bonded, the epoxy can be applied and parts can be clamped in place with light to moderate pressure until the epoxy cures.
4 – Framing
Once the TrailTop shell is complete some additional framing may be desired.
Most projects will require a wood sill plate around the bottom that ties the 4 corners together. Epoxy, through bolts or both can be used. The exact setup will depend on the project and what the requirements are.
Framing around doors, windows, mounting points for accessories, additional support for wall/roof skins, etc. If the plan includes a roof rack or roof top tent, additional support at the mounting points for these items will be necessary.
More project specific details can be seen on our project build logs.
5 – Skinning
The TrailTop framework has been designed with a flange that is recessed to accept 1/4″ plywood for the walls and result in a seamless final appearance. The best method is to epoxy the plywood into place, but screws or bolts could be used as well for a less permanent solution.
Dry fit the plywood panel in place. The seam between the plywood and TrailTop rails will be filled in with body filler later so a tight fit will make this easier but is not absolutely necessary.
Sand the TrailTop flanges, the framework and the plywood with 80 grit or rougher sandpaper thoroughly, then wipe everything down with acetone.
Lay a bead of epoxy on the TrailTop flanges and the wood framing and bring the plywood panel into place.
With a box of wood screws, secure the panel into place. In the picture we cut some scrap 1×2 and pre-drilled holes through it so it would act as a large clamp along the glue line. This is not necessary but works well to ensure more even pressure between plywood and TrailTop flange.
Once the epoxy cures, the screws can be removed if desired. Our preference is to leave in the mechanical fasteners in addition to the epoxy, so there are two methods used depending on the situation.
If there is wood framing behind the screw, it can be countersunk just below the surface of the plywood so it can be covered with body filler later.
If there is no wood backing, the hole can be drilled and countersunk for a flat head bolt with a washer/nut on the inside. The head of the bolt can still be covered with body filler using this method.
This is not meant to be a detailed step-by-step guide but hopefully gives an idea of how easy it can be to build a strong, structural shell for you project.