06 May dB25: The Tank – Part 1

Making a fuel tank is a complicated process with many factors needing to be considered. Due to the nature of petrol and its ethanol content, the ways in which we can manufacture our tank are limited. We decided on a polymer fuel cell with a carbon fibre skin. Manufactured by Aero Tech Laboratories, who specialise in fuel cell systems, we’ve created a fuel tank that is strong, relatively easy to manufacture, 100% fuel resistant, (meaning it will last indefinitely, unlike a carbon fibre or fibreglass tank) and, in the event of an impact, the moulded tanks are in fact flexible, absorbing impacts and ensuring that the material does not split.

Firstly we created a steel mould, this was hand-fabricated and made larger than required to allow for shrinkage which happens as the plastic cools inside the mould. We added all the features necessary including mounting faces for the fuel cap, breather, fuel pump and a small channel for a drain pipe.

After a number of prototypes and mould adjustments to optimise capacity and overall design, we have our first tank and we’re very happy with the results. We’ve now begun the process of creating the fuel tank skin. This is a panel that will float 10mm away from the tank and will define the overall design. The plastic fuel tank will not be visible at all giving the impression of a conventional metal fuel tank.

Above you can see our fuel tank adapter. This has a number of roles: the fuel cap mount, breather mount, and skin mount. Once designed in CAD we move to 3d printing helping to refine our design. As you can see, we printed 3 versions before moving to aluminium.

Below, the final CNC aluminium part. In our next newsletter we’ll dive into how we incorporate this into the final tank skin (we promise you won’t have to wait so long this time!).

We’ve also been working on some of the finishing touches. We had originally planned a folded sheet metal part for our exhaust hanger but decided to change to a CNC aluminium part. This is stronger and has a much cleaner more attractive design. Again starting with 3D printing, we refine and check the design before moving onto CNC aluminium.

An optional extra on the dB25 is a suspension upgrade from Maxton Suspension. We’ve fitted their RT10 mono shock with remote reservoir to our prototype; this is a bespoke built unit, set up specifically for this bike. The remote reservoir we’ve fitted on the side of the bike, on show, as we love the look of the Maxton products. We’ve also designed a lightweight and strong aluminium bracket to mount to the engine.

We’ll be back with an update on our tank skin very soon. Then we’ll be off to paint!

Thanks for reading

Calum