Fresh water & air tank in OEM spare location?

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

r2m, Frontrunner already manufactures the aux tank and system similar to what you are describing. Problem is, legality (US) and safety issues of a gravity fed aux gasoline tank. It relies on a section of soft hose to retain 16+ gallons of fuel.

FTTL001_1881_20131212182621.webp
 

Attachments

hoser said:
r2m, Frontrunner already manufactures the aux tank and system similar to what you are describing. Problem is, legality (US) and safety issues of a gravity fed aux gasoline tank. It relies on a section of soft hose to retain 16+ gallons of fuel.
Click to expand...

Regarding legality, here in California, I believe it is illegal to install a second (auxiliary) tank unless it's by some authorized manufacturer like TransferFlow. So that being said, this would be a covert install and hopefully something that would not be caught when when getting smogged. (Or just drop the aux tank via the spare tire hand crank, and plug the 2 hose lines on the factory tank when getting smogged. Auxiliary tank?? What Tank???)

Hoser: I'm not sure I understand your safety issue with gravity flow, can you please clarify?:confused:

Thanks.
 
Last edited:
r2m, it's best to discuss this in a different thread but here is what I'm talking about:


CODE OF FEDERAL REGULATIONS:

49CFR393.67, Liquid Fuel Tank (partial): “c) Construction of Fuel Tanks, (5) Fuel withdrawal fittings. Except for diesel fuel tanks, the fittings through which fuel is withdrawn from a fuel tank must be located above the normal level of fuel in the tank when the tank is full.”

You wouldn't store your full jerry cans in your garage, upside down with the spout on the bottom either, would you? They might seal 100% but if they do leak, that is likely where they will leak first.
 
hoser said:
r2m, it's best to discuss this in a different thread but here is what I'm talking about:


CODE OF FEDERAL REGULATIONS:

49CFR393.67, Liquid Fuel Tank (partial): “c) Construction of Fuel Tanks, (5) Fuel withdrawal fittings. Except for diesel fuel tanks, the fittings through which fuel is withdrawn from a fuel tank must be located above the normal level of fuel in the tank when the tank is full.”

You wouldn't store your full jerry cans in your garage, upside down with the spout on the bottom either, would you? They might seal 100% but if they do leak, that is likely where they will leak first.
Click to expand...

Ahhhh. Understood. Thanks!
 
SanDiegoCruiser - I really like that custom tap on the rotopax! That's what I'm looking for, something relatively inexpensive yet easier to use. I've got the same jerry can setup inside the cabin like you do, trying to avoid having to unstrap, remove, add spout, pour, replace and restrap 100 times per weekend!

Any tips on the tap? Pretty straightforward to make it work? I said it above and I'll say it again, rotopax needs to make a 4 gal water container!

Am I correct in that the 2x2gal rotopax can be connected for storage purposes, but not actually linked together?
 
r2m said:
Hey Fireball,

This is an idea I've been thinking about for a while and it could manifest itself into several different options.
If you could get someone to fabricate (or do it yourself) a hexagonal or octagonal (heck, it could even be round) tank about the diameter and height of a stock spare tire, have a hole down the middle of the tank (think torus or doughnut shape but with vertical sides), then one can use their factory spare tire chain and crank to hoist it nice and snug into the stock spare tire position!

?
Click to expand...

This is exactly what I was thinking! If we take the factory spare location, assume a 32" tire (which we know fits pretty easily) and a 9" height, that would give us 4.2cf of space. 1cf = ~7.5 gal of water. So you would have plenty of space down there for a decent amount of water and either some extra fuel as others seem to be keen on, or for my preference a small air tank.

9" height should keep it tucked up a bit higher than the OEM spare, still affording good clearance and departure angle. So there would be plenty of space for 10gal of air and 10gal of water! Someone should make this!
 
fireball said:
This is exactly what I was thinking! If we take the factory spare location, assume a 32" tire (which we know fits pretty easily) and a 9" height, that would give us 4.2cf of space. 1cf = ~7.5 gal of water. So you would have plenty of space down there for a decent amount of water and either some extra fuel as others seem to be keen on, or for my preference a small air tank.

9" height should keep it tucked up a bit higher than the OEM spare, still affording good clearance and departure angle. So there would be plenty of space for 10gal of air and 10gal of water! Someone should make this!
Click to expand...

I just modeled that size on SolidWorks here at work, and you were correct that it does come out to 4.188657407cf (Okay, I got a little carried away...:D) But you're wrong about the gallon volumne. 4.2cf = 31.33 gallons!:clap:
 
My rough calcs were 4.2 cf of space and 7.5 gal per cf. I then rounded fine to 20 gal of usable volume because I think that would be more than sufficient for our needs.

Can you take the material thickness and a divider and the Space for the spare tire mount mechanism into account on your model? I didn't get under and measure but I'd be curious how much you could shave from the total depth. Would 7" still provide enough volume and eliminate any clearance departure angle concerns?
 
fireball said:
My rough calcs were 4.2 cf of space and 7.5 gal per cf. I then rounded fine to 20 gal of usable volume because I think that would be more than sufficient for our needs.

Can you take the material thickness and a divider and the Space for the spare tire mount mechanism into account on your model? I didn't get under and measure but I'd be curious how much you could shave from the total depth. Would 7" still provide enough volume and eliminate any clearance departure angle concerns?
Click to expand...

If I remember tomorrow, I do a re-model and calc it out again.
 
Ok, here's the deal:
with a 32" diameter and a 2" hole in the middle (for the spare tire chain) at 7" high. I will assume 1/4" 6061 aluminum plate for the building material. The "interior" volume will be (a little drum roll please...): 5360.34 cu or 3.10185 cf or more plainly: 23.20 U.S. gallons.

Now if you do not want to do all that rolling of material for a 32" diameter and do something simpler, say just using a hexagon shape, with the 32" diameter being point to point and the distance from flat to flat being 28.15" (still at 7" high). This is still taking into account all the above parameters of material and thickness. So here is the interior volume: 4427.45 cu, 2.5621 cf or 19.17 gal.
 
Last edited:
r2m - thanks for the helpful calcs. Definitely sounds doable! Now we just need someone to make it happen!

Points to consider:
1. how would you fill the water tank?
2. how will you get the water out of the tank? RV pump, hand pump?
3. what constructions requirements/materials if we want it to hold potable water?
3. If you use part of the space as an air tank, can I plumb my ARB compressor into it to keep it filled? I think a lot of us have one of the two smaller ARB compressors that are adequate if not terribly speedy for filling tires.
 
$1787 for an aux fuel tank?! Wow!

Christo- do you think there's a market for the fresh water/air tank idea we're discussing above? Was hoping you'd chime in and say you've got one in the works :)
 
paflytyer said:
Unless you're gonna spend the big $$, why not just use a $15 Aqua-Tainer like mentioned above? I use mine all the time. My kids have no trouble turning the spigot. Couldn't get any more simple and it holds 7 gallons. Turn the spigot and like magic, water comes out. You'll have to lift it into your truck initially and you may have to slide it to the tailgate so the spigot overhangs the edge. That may be a concern if you're not into doing that. Downsides are.... it's heavy when full, it takes up space inside and it's not nearly as fancy as the high dollar stuff. I put some cool stickers on mine so it looks fully expo. If an interior mountable water container (like the one tried a few months ago) were made to fit and was affordable, I'd consider that. But I like the ability to move the Aqua-Tainer around as needed.
Click to expand...

Stickers to make it fully expo! HA!
 
bringing this back up for discussion.....stainless would be great for water or gas. I have material and plasma to prototype and a certified welder on staff to fab up....if your serious about trying it. thinking 16ga 304......
 
r2m said:
Hey Fireball,

This is an idea I've been thinking about for a while and it could manifest itself into several different options.
If you could get someone to fabricate (or do it yourself) a hexagonal or octagonal (heck, it could even be round) tank about the diameter and height of a stock spare tire, have a hole down the middle of the tank (think torus or doughnut shape but with vertical sides), then one can use their factory spare tire chain and crank to hoist it nice and snug into the stock spare tire position!
Click to expand...
I've had similar thoughts involving 2 aluminum tank-ends together, and ending up with something about the size of a tire...maybe with a spacer between the two.??

Steve
 
I really like that! Did you remove the plate that holds the stock wheel in place and replace it with a "washer"? I can't tell from the pic how the tub is being held in place. Thanks!!
 
A friend of mine had it made. It makes good use of the space. It also has drawbacks, but it's a pretty simple mod. I'm leaning towards a small 10-15 gallon plastic tank that fits up tight to the underside. Don't want to lose any departure angle. I've already cut off the resonator and rerouted the exhaust.


...via IH8MUD app
 
You must log in or register to reply here.

Share this page

Back
Top Bottom