Building fiberglass adventure bike pannier boxes

Being a fan of hard luggage I decided to try something a little different and build some fiberglass pannier boxes. Rather than just build one-offs, the plan was to spend a little extra time building moulds so that boxes could be quickly and easily produced. Below is a photo of the finished product on a DRZ400 then followed by how I went about the process:

Using my previous set of pannier boxes to get the right size, custom wood was used to create the plugs for the pannier box mould and pannier box lid mould

Using my previous set of pannier boxes to get the right size, custom wood was used to create the plugs for the pannier box mould and pannier box lid mould

With a router the edges were given a 45 degree bevel not only for looks, but to remove all sharp edges

With the lid removed you can see the internal edges were given and extra lip (wet edge) to ensure water cannot make its way up and into the pannier boxes

The pannier box lid removed from the box

The pannier box lid removed from the box and flipped over

An automotive primer/filler is used on both the pannier box and pannier box lid to seal the custom wood so they can have fibreglass laid over them to create the moulds

Starting with the pannier box lid

First up Iíll go through the steps to complete the pannier box lid plug which creates the pannier box lid mould

The pannier box lid is then glued to a baseplate to complete the pannier box lid plug. This will produce a the mould that will have a ridged perimeter and will cast straight and true lids

In this photo the pannier box lid plug has been laid with fiberglass to create the pannier box lid mould

One the left is the pannier box lid plug and to the right is the newly created pannier box lid mould (cast with black gelcoat)

The final pannier box lid mould cleaned up and ready to layup pannier box lids

Next is the pannier box

The actual pannier box itself is slightly more complex as it needs to be a two part split mould to accommodate for the wet edge.

A cradle is created to help cast the pannier box in two sides. This cradle is made from custom wood

With a router the edges were given a shallow 45 degree bevel to allow the use of putty for a tight seal, and then primered

The pannier box is dropped into the cradle and putty is used to ensure the edges are snug and perfect. This will be used to create the first side of the pannier box mould

The fiberglass being laid over the plug to create the first side of the pannier box mould

Another view of the fiberglass being laid over the plug to create the first side of the pannier box mould

The box is then removed from the cradle. Both the pannier box plug and the fiberglass face of the pannier box mould are cleaned up and prepped for the laying up of fiberglass to create the second side of the pannier box mould

The fiberglass laid up over the second side of the pannier box plug to create the second side of the pannier box mould

Another view of the fiberglass laid up over the second side of the pannier box plug to create the second side of the pannier box mould

The two fiberglass mould halves are then split to remove the pannier box plug. The two sides that now form the final pannier box mould are ready for clean-up and then laying up actual pannier boxes. Note that before splitting the pannier box mould halves a series of holes are drilled so that the moulds are perfectly aligned when used

Laying up the final parts in the pannier box moulds

Now that the pannier box mould halves and the pannier box lid mould are complete and cleaned, it is time to start laying up the final parts

The main pannier box mould halves bolted together and then the inside is laid with three layers of 300grm chop-strand matt with black dye added to the resin mixture

The final pannier box after being pulled from the mould halves. Here you can see the wet edge that stops water getting in even though the lid does not seal in any way and simply sits in place by means of hinges and a latch

The final pannier box lid after being pulled from the lid mould

The final box with the lid sitting in place ready for cleaning up, adding the hinges and latch

The box after being cleaned up, hinge affixed, latch installed and luggage loops added

A close up look at the flush-mount/lockable latch. This was sourced from Comac

The hinge used was a continuous PVC hinge. This was sourced from Comac

An internal look showing the stainless bolts with nylock nuts for the hinge and the stainless capsrew bolts for the luggage loops

For the final fitting, six holes are drilled through once side to match up to the pannier racks. Six stainless bunthead M8 bolts and penny washers are used to bolt the box in place using clear RTV sealant to ensure a waterproof finish. Done!

DRZ400 pannier racks and top rack

Click here for an article on the DRZ400 pannier racks and top rack in the above images

Author of this article: ADVGD(366)