Blow molded gas tanks.

After searghing fleabay for aluminum tanks to modify, I came up with an Idea. Why not have blow molded plastic tanks made. Many new bikes use plastic tanks that are impervious to ethanol and other nasty's. I know they would not be show quality pieces. But for daily use, why not. I can't imagine once setup, it would be too expensive to produce. On the plus side they would be durable. Any thoughts or people to take on the challenge. I would be up for a Lyta or Dunstall one if it could be had for under $300.

bwolfie said:

After searghing fleabay for aluminum tanks to modify, I came up with an Idea. Why not have blow molded plastic tanks made. Many new bikes use plastic tanks that are impervious to ethanol and other nasty's. I know they would not be show quality pieces. But for daily use, why not. I can't imagine once setup, it would be too expensive to produce. On the plus side they would be durable. Any thoughts or people to take on the challenge. I would be up for a Lyta or Dunstall one if it could be had for under $300.

Click to expand...

That's what Ducati thought...

It would be easier to cut the bottom out of a Norton tank then build a steel gas tank (doesn't need to be pretty) that fits under the outer fiberglass shell, glue the two together and there you have it, steel for weird fuels and fiberglass for looks.

Jean

Sounds good to me but want it in SS and explosive formed inside a mold. Nothing compostie seems impervious to the spiked gasoline, especially in summer.

There is no real problem manufacturing composite tanks which are 100% resistant to all common pump fuels. However those in the business of making these tanks, dont seem to have bothered to look at the reasons why improperly made GRP corrodes with modern fuels, and have little or no understanding of how to make usable products. This has meant the problems persist with recently made tanks, and effectively means that its not feasible to sell GRP tanks now, even if they are properly constructed!

In terms of bikes such as Commando's whose owners generally do not want to pay for high quality exact replicas of OE tanks in aluminuim, it seems that the only viable option at the moment are shoddily made Indian or Pakistani tanks. These tanks may well be perfectly ok after a little work has been carried out, and its obviously rather silly to expect perfect parts at such low prices.

HDPE plastic tanks are probably possible, but tooling costs are likely to rule this production process out for low volume niche market parts such as Norton tanks, but all in all the introduction of a thin wall plastic fuel cell within an existing steel or GRP fuel tank, seems more interesting, as it would be highly effective and far cheaper than all other alternatives.

Commandos such a niche market who'd foot the bill tooling up anyway. Maybe someone with a feel for what can be done might give a few tank makers a buzz to test their desire for rather long term return. After the dramatic images of explosive formed SS tank has faded, the print it out 3D technology, maybe in a ceramic to bake floats to mind.

"Honest officer I've not had a drink just syphoned some my buddies gasoline to get going again"

the new nortons have plastic tanks

I don't know one plastic from another, but my friend has a Suzuki DR400 that has an aftermarket tank. Opaque plastic, and it looks like the same material that my mower gas can is made out of. Is this blow molded? My 2001 Speed Triple has a plastic tank that Triumph described as "polymer". It's a hard plastic. I've heard of some problems with plastic Ducati tanks, and whenever that subject comes up on forums, people mention that Triumph has had problems with theirs as well. I've never spoken to anyone first-hand with a problem with the Speed Triple tanks. Mine has had fuel in it since 2001, and still seems to be fine, but I've never knowingly added ethanol to it. I suppose it gets whatever is left in the hose, when I fill it with the good stuff, but I try and run it low before filling to avoid much of that. BTW, Nebraska just let the bill die in the legislature that would take ethanol labels off of the pumps. At least for now.

HDPE which is what nearly all fuel tanks are made from has no known solvents at room temperatures, so ethanol is not likely to cause any problems. HDPE tanks are used in pretty nearly all the cars and LCV's currently being made, and I would imagine a fair number of motorcycles.

bwolfie said:

After searghing fleabay for aluminum tanks to modify, I came up with an Idea. Why not have blow molded plastic tanks made. Many new bikes use plastic tanks that are impervious to ethanol and other nasty's. I know they would not be show quality pieces. But for daily use, why not. I can't imagine once setup, it would be too expensive to produce. On the plus side they would be durable. Any thoughts or people to take on the challenge. I would be up for a Lyta or Dunstall one if it could be had for under $300.

Click to expand...

I was trying to figure out how hard that would be to do a while ago... There were a few other possible solutions as well such as vacuum forming the tank in two parts and welding it together, this is cheaper solution for a one off or small numbers, the finished part would be kind of ugly but you could always put a fiberglass cover over it. There are also people who make flexible fuel bladders so it may be possible to stuff one or two of them into a fiberglass shell as long as they are ethanol resistant.

As for stainless, that would be a right pain in the arse, the austenitic and duplex grades would strain harden something stupid during forming and you get a lot of grain growth in the HAZ which leads to fatigue failures. The ferritic grades will be better but dont have the same corrosion resistance.