Fuel Tank Bladder

We have all seen the posts about ethanol in gasoline dissolving fiberglass tanks. And rusted tanks with failed cream linters. And aftermarket tanks with wrong shapes that don't hold fuel.

Maybe I missed it, but I haven't seen a discussion about using a fuel bladder or liner in an original fiberglass or steel tank. These shouldn't be that hard to make or fit. They are used in marine and aero applications: http://www.marinefuelbladders.com/

Thoughts???

Stephen Hill

Stephen Hill said:

These shouldn't be that hard to make or fit.

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In prinicple fuel bladders are a very good solution to the problem as they are usually constructed of FKM fabrics and this is one of the very few materials which is Ethanol proof. However fitting fuel bladders is a potential major PITA. These are mandatory in all main motorsport classes and usually they reside in the rear of the monocoque. As this is the main "structural bracket" the designers tend to keep the access openings for installing the fuel bladders as small as possible - however these are way bigger than a tank cap in relation.
ATL is the dominant company for these things.

It would make sense to change the fuel tank into a two part cover however this means a slight loss of capacity, and also the construction of a relatively complex bladder to follow e.g. the Roadster tank will make it quite expensive. For a PR style tank I'd say it's a good solution.



Tim

Interesting idea, I know these tanks from my aviation background. (and I know these tanks can sometimes leak also)
imo, difficult to fit into the Norton tank, given the relatively complex shape of a motorcycle tank.
Installation in an existing motorcycle tank would be problematic also, given the size of the filler cap.
Also the max fuel capacity will be reduced significantly.
Quality replacement tanks are a better alternative, however,unfortunately, the market seems to be flooded with barely useable material from India.

I remember bladders in aircraft to be thick walled and rigid. And heavy. I have a hard time imagining getting it in through the filler neck. Would it be possible and legal to make much thinner more flexible bladders as the existing tank structure would
provide some strength? Or at least it would with the steel tanks maybe not so with the glass ones.

Also think that in fairly short order the Emgo tank will drive the hand knocked tanks off the market. If Emgo decides to add an Interstate tank to their line then it really is game over.

Having changed many aircraft bladders I think they'd be much more trouble than they're worth. Fuel bladders are attached to the supporting structure by snaps or by lacing so they won't collapse as fuel is used. There would need to be a large access hole somewhere to stuff it in and fasten it to the inside of the tank. Better to spend money on one of the new non-India tanks.