There have been a couple of times when I have purchased a motorcycle from a private party and the seller has thrown in an old helmet to boot. Helmets have a half life of only a few years and the older they get, the more likely they will not protect your head in a crash. So when I get an old helmet, of course, I… use them. I use them until I can purchase a new helmet. Then comes the question of what to do with the old helmet? I have held on to a couple of full face helmets with the idea that I would convert them into a motorcycle trunk. I know what you are thinking, “a helmet isn’t going to hold enough stuff to be of any use.” There is where you are wrong. I did a “stuff-it-full” test and found that a full face helmet will hold three full sized bath towels! I estimate that a person could carry in the full face helmet trunk; a sweat shirt, a pair of gloves, some odds and end tools, water bottle, power bar and a pair of sunglasses.
Today I was working on my GS 850 Suzuki bobber project, but wanted to take some time and consider a few things I was going change, so I decided to work on my helmet trunk idea. Choosing the best one of the two useless full face helmets kicking around in “Motorcycle Stable,” I removed the inside padding and foam. The padding just snaps in and came out very easily, but I had to break the foam loose from the shell with a chisel.
To make the helmet into a trunk I figured it would have to have a bottom plate in it so my stuff wouldn’t fall through luggage rack onto the road. There are a couple things you could use for a bottom plate, wood, metal, or plastic. I used plastic from a 55 gallon barrel. Wood would have been much easier, but I’m a plastic barrel guy. The top of the barrel is the thickest plastic, so that’s where I cut out the bottom plate. Just set the helmet on the top of the barrel and trace around it.
Most helmets taper inward at the bottom opening. I cut the plastic slightly larger than the opening, so when I put the bottom plate into the helmet and pushed it down, it would be too large to pass through the narrower bottom opening, It took several trips to the grinder to get the bottom plate just the right size. Once I was satisfied with the fit, I pushed the plate down to the bottom of the helmet shell and stuffed the shell full of towels to hold the plate in place. Using a good epoxy glue, I secured the plate to the helmet shell from the under side and then from the inside after I removed the towels.
The top of the barrel where I cut the plate is slightly concave. When I attached the plastic plate to the helmet, I put the curve so it was bowed up into the shell. I did this because motorcycle trunks are usually secured to the luggage rack with a couple of bolts, a bracket with two holes in it and two nuts. With the bow up, when the nuts were tightened they will pull that bow down, putting constant presser on the nuts so they would be less likely to come loose.
To mount the helmet trunk to the luggage rack, drill two holes through the bottom plate about 4″ apart or so the holes with the bolts through them will fit though the luggage rack with at least two rack bars between the bolts. Drill two holes in a metal bar that match the holes in the truck bottom plate. Put the bracket with two corresponding holes under the luggage rack, drop the bolts through the plate, between the bars on the luggage rack and through the bracket holes and secure with two nuts.
The helmet was pretty ugly and beat up, but some sanding and a coat of black spray in bed liner dressed it up. I sprayed the face shield too so no one can see my stuff in the helmet trunk. I padded the bottom of the trunk with a cut to shape piece of rubber yoga mat that I picked up at Goodwill one day. So that’s pretty much it. I now have a trunk that I can easily attach to any luggage rack, carry my stuff in and gave an old helmet a second useful life.
Anyway… for what it’s worth.