The Sheet Metal Shop .Com

Sheet Metal Automobile - tank for my bike

sheetmental - Jan 13, 2005 - 11:05 PM
Post subject: tank for my bike

i have been considering building a "coffin" tank for my bike.
i was wondering if any of you have made a gas tank before.
my idea was to use .063 aluminum to make the tank, and have my buddy tig weld it. the part that worries me is, will the aluminum weep gasoline? how about excepting paint? is there some other metal i might use that would be better suited to making a tank? we have no english wheel, or any other tools
that you might use for making things that are round. that is why i am making a coffin tank. it's all straight lines, so i expect the layout/forming should be a peice of cake.

Bunzo - Jan 14, 2005 - 06:58 AM
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Gday sheetmental,
Aluminiums fine for making fuel tanks for anything except methanol. If you do want to make a curved tank, the easy way is a leather bag full of shot (no 6) or a block of hardwood with a hollow in it work wonders when you use a wooden mallet with nice round ends. Just take it slowly, make your blanks bigger than you need and trim them to size when youve got the shape you want. You will probably have to make it in at least 4 pieces-left and right side , top strap and bottom to fit over your barwork. Anyhow aluminiums good to work with for tanks and doesnt present any problems that Ive noticed when painting it either.(one word of caution, dont cut it or touch it where it is going to be welded with any angle grinder discs cos it makes it a bugger to weld.)Hope I could be some help.

marky - Jan 14, 2005 - 04:08 PM
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Depending on how your aluminium sheet comes i.e hard ,half hard or annealed,if you are going to beat it ,it may need annealing as you work it .Iuse Zirconium flap discs for weld removal or the old tried and trusted dreadnaught files i think somefolk call the flat a pansar file ?,[i could be wrong and thinking of something else entirley].good luck with the tank biggest problem i had was always with the filler neck and getting the cap to fit [no jokes please about getting a smaller head]aw ra best Marky

sheetmental - Jan 14, 2005 - 09:34 PM
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oh hell! i never considered the cap! man, am i lucky i consulted you guys first.
i know you can't weld dissimilar metals, so that would mean my cap has to be aluminum too.
unless one of you knows where i might find one, i wonder if mebbe the boat guys would know what i might use.
thanx for all the help, anything else y'all might think of i would greatly appreciate.
i am liking this place more and more every time i come here!

danski0224 - Jan 15, 2005 - 02:17 PM
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An internet search for "gas tank cap" or something similar should get you somewhere. Places that cater to the custom street rod (cars or motorcycles) folks might have tank parts for sale.... unless you really want to make your own.

Those parts are probably available in aluminum or steel.

Bunzo - Jan 16, 2005 - 01:54 AM
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Dont know if you have Earls products over there but I think they have weld on ally fillers, or failing that some of your truck supply places may be able to get them for you. (they can over here anyhow) Forgot to mention maybe having to anneal the ally, it pretty much depends on exactly how deep you form it( which is why I like to make them in 4 pieces, so you dont have to hollow any of the sections that deep) anyhow hope that is of some help.

sheetmental - Feb 06, 2005 - 02:19 PM
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ok, this is either gonna be a question that you will laugh that i actually asked it, or is a good question. you decide....
i was talking to a guy the other day at a dealership. i was there trying to figure out something else i am doing. i told this guy about my plans for my bike, including the tank and he said, if i don't put the holes in the tank before i have it welded, the air inside will expand from the heat and will not allow the weld to seal liquid-tight. part of me thinks he is full of sh_ _, another part me of me says i better ask someone who knows.

Bud - Feb 06, 2005 - 03:12 PM
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I think he is absolutly right. If the air cannot escape, it may blow your welds out as it expands? At least it is this way in soldering. In small applications and real quick soldering or brazing jobs, you can get away with it, otherwise your risking a weak joint if it will solder at all. I think the welding would be the same? IMHO

BobLuland - Feb 06, 2005 - 04:21 PM
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The answer is yes to the vent. If not just for safety since this is a coffin tank you will be using flat panels, which will deform from the pressure. Just drill a quarter inch hole wherever your going two put your petcock or filler neck. Rules of thumb learned over twenty–five years of Harley and Indian restorations. Always wipe down the inside of the metal with lacquer thinner before you start assembling. Do not use spirits it leaves residue. When you’re done with welding your project seal with two-part tank sealer. Make sure you use the prep. NOTE; make sure that you put a pipe plug in the petcock hole and masking tape on the top flat of the filler neck so sealer doesn’t get in the treads or on the sealing surface of the filler neck. I like to throw in some aluminum hardware (washer etc) with the prep to really clean off any scale. If you don’t use the prep the sealer will not stick and gas will get under it and you will be pulling out globs of the stuff. Usually on the road cursing (Bin there, done this). Try to seal the tank before you prime the outside. Sealer and paint don’t like each other. On tank repairs (This is a future note.) The only thing we found that dissolves tank sealer is Keytone. Good luck. Sounds like a fun project. Bob

sheetmental - Feb 13, 2005 - 12:11 PM
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cool, i appreciate the tips! with all the good advice i am getting, this should come out pretty nice in the end.

burninbriar - Feb 14, 2005 - 07:31 PM
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I assume tou want to use aluminum becouse it can be cut with wood working tools.If the english wheel is whats preventing you from useing sheet steel or trying to shape the aluminum I would not let that hold me back.since you will more than likely paint the tank you can cover hammer marks with body putty.

sbworks - Feb 15, 2005 - 08:19 AM
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i would not recommend the use of anything less than 0.080 3003h14 aluminum for your tank. rubber isolators on the tank mounts are mandatory if it is hold up to vibration.when you have it welded use a half lap weld joint on the lower tunnel section ,butt welding the rest of the tank is fine.the cap you need is available from independant gas tank co. also you will need a fuel petcock weld in bung possibly 2 depending on how far down on the backbone it is dropped . make sure you pressurize the tank with air at 3psi after its welded completely then squirt a little soap and water on all the weld seams hope this helps you build a safe and long lasting tank. good luck