Topic: Anybody ever attempt to make a fiberglass gas tank?

[mmtsquid]

I've searched around and haven't found any good "how to's" - my first thought would be to make a sacrificial slug out of foam, then use some kind of solvent to dissolve it afterward - does this seem feasable?

Anybody ever try it?

[Bob Wessner]

I seem to recall the subject coming up before, but can't recall any posts about success stories.

I have seen some references elsewhere about problems with fiberglass fuel tanks and gasoline-ethanol mixes and the deterioration of the tanks caused by the ethanol. It was a problem among  the boating crowd. I'm sure there are resins to prevent this available, might be worth doing some research.

[mmtsquid]

As much as I love some of Benjie's designs, I just can't get my head around spending that kind of money.

And I REALLY can't stomach the thought of taking a hammer to a perfectly sound tank just to get knee dents.

[cafe2be]

here you go. I saw this and read it all. Very interesting with a great result.
http://dotheton.com/index.php?topic=6339.0

[mmtsquid]

Cafe2B - you're the man!

That's EXACTLY what I needed!

[cafe2be]

no problem, I was preety amazed by the job that guy did on the tank. From start to finish, excellent job.

[Geeto67]

here is what I don't get - when he had the fiberglass covering the foam shell why didn't he just make a male-female mold of the tank? at least that way he could have made more than one tank in that shape. 

[mmtsquid]

Oh, there are several things that I would have done differently - I sure as heck would have made a mold (I know there are people on here that would buy a cool tank if it were reasonably priced).

I also would have not cut the tank - gasoline will eat the styrofoam out of there very quickly.

But yeah, if you're gonna make one, may as well make 2 or 3 and recoup some cost.

But he did answer all of the questions I had (gas cap and mounting points), and did a great job!

[Joksa]

here is what I don't get - when he had the fiberglass covering the foam shell why didn't he just make a male-female mold of the tank? at least that way he could have made more than one tank in that shape. 

There's more work and it would not have been one-off tank anymore.

[Geeto67]

here is what I don't get - when he had the fiberglass covering the foam shell why didn't he just make a male-female mold of the tank? at least that way he could have made more than one tank in that shape. 

There's more work and it would not have been one-off tank anymore.

not that much more work - the plaster of paris does all the hard work of making the mold. Seriously it is like an hour of extra work and you get like 5 tanks out of it before it degrades.

as for one off, the one time I made a fiberglass tank I actually made three, because that is how many times I needed to mod and adjust it and get it to actually hold fuel. There are definatly things I would have done different and one of them is to make a mold, even if I did not sell tank one it is nice to know that should I screw up I can just start over with minimal loss. The other big thing I would have done over is pay closer attention to my resins as some are not fuel safe to begin with and now many are not E10 fuel safe.

as for the filler neck there are two ways to do it - one is to cut out and graft the secton off a steel tank, the other way is to incorporate the filler neck into the mold and reinforce it with a section of pipe bonded into the tank with resin. for the petcock many of the older ones that use honda non bung style petcocks have nuts molded into the inside.

[super pasty white guy]

This is also a well documented thread from a guy who put together a carbon fiber tank for a SV.  Looks to be time consuming as all hell, but looks real nice at the end.


http://www.bayarearidersforum.com/forums/showthread.php?threadid=145975

[Geeto67]

This is also a well documented thread from a guy who put together a carbon fiber tank for a SV.  Looks to be time consuming as all hell, but looks real nice at the end.


http://www.bayarearidersforum.com/forums/showthread.php?threadid=145975

The reason it looks time consuming is because he is actually making a tank that mates the top shape of an MV agusta with the bottom of an SV in carbon fiber so he made a mold, then a plug, then a shape, then another mold then the tank thn the carbon fiber layup. Were you to do this one one of our bikes and custom shaping it the foam you start with and shape is the plug so you skip a few of his steps.

[j-conn]

just went through that carbon sv thread... wowza!

[Joksa]

  Looks to be time consuming as all hell, but looks real nice at the end.

Because he wanted to do some modifications to the original tank shape (narrow it). He needed to make a plug first and the modify then plug. If you wan't just replicate the form, you can use the original part as a plug. It still take some time as usually a motorcycle tank has "complicated" shape so you need to fabricate flanges for the mold in order to break the mold and release the fabricated part.

[mmtsquid]

The carbon tank is AMAZING!

Based on what I've read, I don't think I'll be able to tackle the tank this year - I'll just stick to doing the seat (the bike is currently in a million pieces, I just had a baby, and I'm taking differential equations this semester) so I have enough on my plate right now.

but next winter, it's on!

[Joksa]

not that much more work - the plaster of paris does all the hard work of making the mold. Seriously it is like an hour of extra work and you get like 5 tanks out of it before it degrades.

Nothing prevents making the mold from finished tank and save time from finishing the styrofoam plug. The part you are using as a plug has to be as flawless as possible otherwise all the imperfections will be shown in actual parts made out of the mold. So why using the time finishing (bondoing and painting) the styrofoam "tank" as you can make the mold afterwards. I would say an hour is a bit underestimate because you cannot replicate a tank with one piece mold (it would need atleast 3 pieces - upper halves and bottom).

The other big thing I would have done over is pay closer attention to my resins as some are not fuel safe to begin with and now many are not E10 fuel safe.

And what comes to the tank holding the fuel inside, I wouldn't count on just resin but use tank "cream".