Building a gas tank

[n1elkyfan]

Spyug your not raining on my paradie at all if anything it makes me want to do it more. I think I'm going to go with a Fiberglass tank because I don't want to buy the metal forming tools right now. I know I'll have to use Vinyl Ester resin which is designed to be resilint to gas. I was also planning on Por-15 the inside of the tank for an add layer of safety.

[tone]

AAAAGH ! whats this glass tanks are dangerous bull fella's 20 odd years in the industry tells me otherwise, as mentioned in a previous post they are fine & will if properly made stand up to far more abuse than a steel one, but making them is a bitch

As for the legality i cant say whats true in the us but in the uk the grp & abs tank laws were lapsed years ago to alloy certain ducati's & some small enduro bikes to be imported to this country

Rant over :-D

[Mark M]

AAAAGH ! whats this glass tanks are dangerous bull fella's 20 odd years in the industry tells me otherwise, as mentioned in a previous post they are fine & will if properly made stand up to far more abuse than a steel one, but making them is a bitch

I don't know if I would say they will stand up to more abuse, but they certainly aren't any worse.

Last option is to make a boxy aluminum tank and cover it with a sexy looking fiberglass or carbon fiber shell. It hurts your fuel capacity, but it sure is easier to build and looks great when finished.

FYI, you can also gas weld aluminum (a lot of tank builders do it this way), but it is non-trivial to learn and requires some practice. Of course, an oxy-acetylene torch is a fraction of the cost of a TIG welder, as well. You can trade $$$ for time if that works for you.

Mark

[TheCafeKid]

i was under the impression that glass tanks were illegal for road use in the US or at least most states but since have been told otherwise.

[spyug]

I'm still not keen on the idea of glass tanks for the street but I guess if done well they should hold up for anything other than a major crash. I still think you would have an issue with your DOT folks and it could make reselling the bike a bit of a chore, especially if a certification process is required. Having said all of that I'd be interested in seeing how this all turns out for you.

I have done some fiberglass work over the years and recently did a seat for my XS Tracker using the glass over foam technique. This requires the use of epoxy for the resin as it does not eat the rigid foam. Easy enough to do.

You could use this method for fabrication of your tank. Using rigid pink or blue foam glue up ( urethane glue i.e. Gorilla Glue) as many pieces as needed to make a rectangle big enough for tank. You can get rigid foam in different size sheets but use at least 2" or better 4" thick if you can get them. Rough cut to the size & shape you want with saw, surform and or files then smooth with progressive grits of sandpaper. It does not have to be 100% smooth as the tank skin will be formed around it. The "buck" should be about 3/16" to 1/4" undersize to compensate for the finished skin.

Now you will need some epoxy to paint the entire buck. Try and ensure there are no holes or areas nor covered. I'm not sure if it would work but you may be able to apply the POR-15 for this purpose. I think from what I've read and experienced myself the Phenol Novalac from Caswell plating may work better as it is a true 2 part epoxy. Do some trials first of course.

Once the epoxy is cured you can lay on your glass and resin and I'd think you would need a minimum of 2 glass coats. Vacuum bagging would also be a good idea to add strength to the build. There is a lot of information on this all over the net so do some studying.

Once the glass has hardened you can cut a hole ( gas cap area) to expose the foam. Using acetone, pour in a bit at a time to melt the foam. Pour out the sludge. Flush with a power wash if possible. Recoat the inside with POR or other liner if you didn't use the above method.

The exterior should be sanded as smooth as possible without breaking through the gelcoat and finished with bondo and skim coats of scratch filler. A good primer /surfacer befor paint would also be recommended.

Depending on your fittings you may need to build up some areas for some extra strength. For a nifty gas cap, go down to the local marina or boat store and see what they have.

The only issue I can see with this technique is it would be difficult to build any internal structures ( if you wanted baffles or something).

There are other variations on this method and depending on the shape of the tank you may be able to make a simpler buck out of thinner panels of foam if built in the shape of a 6 sided box ( i.e. like a "toaster" tank).

The nice thing about foam is it is easy to work and infinitely shapeable. It might make the project a bit easier as the alternative would require 2 moulds. The two sides would then need to be seam joined which might add another level of complexity to insure a good fit and tight seal.

Just some thoughts.

I'll be looking forward to hearing how you will proceed & let me know if I can help.

Cheers,
Spyug

[tone]

OOOh someone's been reading up then :-D good info there spyug but a little more complicated than it needs to be

My way is to make a 2 peice buck (top & base) slightly undersized as you said, there's many materials you can use for this foam is only one, timber is another for example

The next step depends on what the buck is made from, foam will need covering, i'd use sheet wax in this case & polish any imperfections from the mold, with smooth well polished & waxed timber it is possible to make the mold directly off that, if the buck has undercuts (the laminators enemy lol) the mold may need to be in more than 2 peices the worst ive done is 7 :shock:

Presuming you can get a good top & bottom half from your molds joining the base of your new tank into the top half wont be a problem

hope this helps & good luck with it n1elkyfan :-D

[n1elkyfan]

I think It will be in at least two part because I was thinking of using the lower part of the other side, The one oppisite of the petcock, for housing the electronics to try and clean up the bike a little bit. And this would be harder if I used the method were I dissolved the foam, and I would like to build at least two tank one I can beat on to see how strong it is.

[spyug]

Tone,
I'm interested in your mould making. Can you give some more detail. I'm sure lots of us would benefit from some more info.

I'm thinking you will finish you buck to mirror smoothness then paint with release agent then a gel coat followed by lightweight cloth backed up by mat and reinforcements of cardboard or light wood. Would that be close? How do you prep the mould prior to making the part.

As far as the actual part what would you recommend for layup ?

You mention undercuts as the bain of the fabricator anything else to guard against?

I've always found that you can never have too much info so if you and anyone else would care to share it would be appreciated.

Cheers,
Spyug.

[8trackmind]

I've been thinking of building a gas tank for my gs and was wondering If I should make it out of fiberglass, which would be easyer, or making it out of steel, which I'm thinking could be safer. My questions are has anybody on here ever built there own gas tank or have anybody had experiance with a fiberglass gas tank.

Here's exactly what you're looking for. This fellow even went so far as to make one for an SV650...Out of carbon fiber... A feat I would have considered unlikely for a home made job.

Read all about it here:

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

[drhach]

Read that whole thread, that is the standard that your work should be judged by. The last page of the thread shows an easy way to do the whole thing using a male mold. Try it, let us know how it works.

[Billy Ricks]

Carbon fiber would be my choice. This guy makes it look reasonably easy.

http://www.mci.i12.com/carbon/index.htm

http://www.mci.i12.com/carbon/petrol_tank.htm

[n1elkyfan]

I'm in the middle of reading that thread right now. He makes it look easy. I don't know if I will use carbonfiber but I'm definitly going to be using kevlar for reinforcment.

[spyug]

Amazing thead. all the information you will need. Notice that they also touch on my lost foam method.

Now ( despite my misgivings) I'm starting to think carbon fiber tank. I can lessen the weight and increase the capacity. How about a 10 gallon "Iron butt" tank:-D

Good thread guys.

Cheers,
Spyug.

[n1elkyfan]

Ok I just read the whole thread and my brains now mush from info overload. Definitly will have to revisit several times but looks like I will have to go get some foam to start designing the new gastank. I hate when an Idea sticks on you and you can't get rid of it untill you finally decied to do it.

[drhach]

Try a couple of smaller projects first. I know many of the concepts of the layup process. I have to say though, that I learn something that makes my next project better each time. I would like to do a fiberglass tank. I need a bit more practice though. To me the thing that matters most is that it is safe and professional looking. Nothing looks worse that an amateurish job. I recently made a tail section for my bike and a lot of the work that I am doing to make it look right has to do with my choice of layup methods. I didn't vacuum bag, I didn't make a female mold. Now I'm doing a lot of surface prep. I figured since it wasn't a production part, I'd save a couple of steps. I'm starting to doubt if I really saved anything. This is like anyhting practice practice practice. The cool thing is that fiberglass is relatively cheap. If it doesen't turn out right you can start over.