Modified JK fuel cell?

10494 Views 33 Replies 12 Participants Last post by Ruskin, Nov 17, 2007

fr33land

Discussion Starter · Oct 31, 2007

I just got done reading the skid plate thread and was wondering if its possible to replace the fuel cell and create a new skid plate for it? Has anyone looked into it? I fabbed up a 3/16" plate to skin the existing fuel skid but I still feel that I need more break over angle.

I feel that this is the only design flaw that is glaring and even would be willing to go to a 15 gallon tank or even try to put it in the back behind the seat. If anyone has idea's or suggestions on how to deal with the fuel pump or any thoughts...
Please help me brainstorm.
Oh... I have the CAD drawing for this plate if anyone is interested. I bought the steel and had it jetted out for just around $150. Mine is completely hammered and still is holding up. I have high centered on it several times and it easily holds up the weight of the JK.

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007JOE

· #2 · Oct 31, 2007 (Edited)

To help you brainstorm although my purpose is a bit different, I was thinking of moving the Evap Canister to the back and in it's original location making an auxiliry fuel cell to add more distance and avoid carrying an extra fuel can for the long tips. With that thought, I did think about making the factory tank shorter height wise for more clearance and then adding the auxilary tank to the other side to not loose driving distance. So far per my measurements, it can work fine. The biggest problem I see though is getting the 2nd tank to drain properly into the main tank.

The best way that I can think of doing that is cutting the stock tank in half creating a top and bottom and removing about 2+ inches off of the midle then just tig welding it back together. That would also avoid fitment issues and would look stock.

Have fun trying it if you do and take some pics durring the process.

RedRockJK

· #3 · Oct 31, 2007

I would like to take a stock tank, and section about 2" out of the middle (thickness of it) and weld it back together. That would tuck it inside the frame rail nicely. I've been thinking about this for a while now.

Who wants to donate a stock fuel tank for an Unlimited ?
.
.

PhilD

· #4 · Nov 1, 2007

RedRockJK said:
weld it back together.

Not sure I'd trust welded plastic with my gas.

I've had exactly th same thought thought, I'd happily accept a smaller tank to get it tucked up by the frame rail. A decent skid would be much easier to make then as well.

RedRockJK

· #5 · Nov 1, 2007

PhilD said:
Not sure I'd trust welded plastic with my gas.

I've had exactly th same thought thought, I'd happily accept a smaller tank to get it tucked up by the frame rail. A decent skid would be much easier to make then as well.

Damn I forgot the tank was plastic. :bawling: Heck it may be just as easy to measure the stock one, and have a custom fuel cell built for it.

MichaelW

· #6 · Nov 1, 2007

If Gen-Right can make one for the TJ that fits in the rear frame rails and has some serious protection and carries 31 gallons of fuel why can't we have one for the JK? I've asked Gen-Right and they said they have been asked by DC to not build a tank for that location. However if we all send an email asking for a larger capacity heavily protected fuel tank to fit in the traditional TJ location maybe, just maybe they will build us some. I'd gladly loose that little trunk area for 10 or more gallons of fuel set in the middle of my JK and with some serious protection.

G

· #7 · Nov 1, 2007

MichaelW said:
If Gen-Right can make one for the TJ that fits in the rear frame rails and has some serious protection and carries 31 gallons of fuel why can't we have one for the JK? I've asked Gen-Right and they said they have been asked by DC to not build a tank for that location. However if we all send an email asking for a larger capacity heavily protected fuel tank to fit in the traditional TJ location maybe, just maybe they will build us some. I'd gladly loose that little trunk area for 10 or more gallons of fuel set in the middle of my JK and with some serious protection.

I agree completely!

paragon

· #8 · Nov 1, 2007

MichaelW said:
If Gen-Right can make one for the TJ that fits in the rear frame rails and has some serious protection and carries 31 gallons of fuel why can't we have one for the JK? I've asked Gen-Right and they said they have been asked by DC to not build a tank for that location. However if we all send an email asking for a larger capacity heavily protected fuel tank to fit in the traditional TJ location maybe, just maybe they will build us some. I'd gladly loose that little trunk area for 10 or more gallons of fuel set in the middle of my JK and with some serious protection.

It's a safety issue. If you get rear-ended hard enough by some idjet, the fuel cell will compact and likely cause a fire in an otherwise survivable crash.

Placement of the fuel cells in vehicles have become a bigger issue due to a few lawsuits where someone sued due to a fire resultant from a crash. Notably GM trucks where their saddle-bag tanks were on the outside of the framerails and the multi-billion Dollar Chevy Malibu lawsuit where the fuel cells were deemed to be too close to the rear of the vehicle.

PhilD

· #9 · Nov 1, 2007

RedRockJK said:
Damn I forgot the tank was plastic. :bawling:

I think plastic can still be "welded", but I don't think I'd want to risk on the gas tank.

PhilD

· #10 · Nov 1, 2007

paragon said:
It's a safety issue.

Plus with a rear bumper, a big spare back there, I'd rather have the weight of the fuel tank between the axles than hanging out at the back.

nam6869usmc

· #11 · Nov 1, 2007

PhilD said:
Plus with a rear bumper, a big spare back there, I'd rather have the weight of the fuel tank between the axles than hanging out at the back.

Agree,...when I wheeled at Rausch, the thing that stopped me the most was being high centered on the Gas Tank Skid, so I would anticipate a hit on the tank & use a dab more skinny pedal to go up & over. If that tank was 2" farther up in, that would solve a lot of our problems, and an aftermarket Skid wouldn't even be an issue. At this point I was using the Skid as a Slider all day long. An aftermarket Skid of that size would weigh a ton, because I know my "Skidrow" Engine Skid is pretty heavy at that size, we all would need Hemi's installed.

. I would take the reduction in capacity(thinner Tank) for the tank to be recessed 2".

paragon

· #12 · Nov 1, 2007

PhilD said:
I think plastic can still be "welded", but I don't think I'd want to risk on the gas tank.

I've seen those plastic "welders" and have considered buying one. Especially as bad as I am about chopping stuff up. But my artistic skills are really too lacking to make use of one.

paragon

· #13 · Nov 1, 2007

nam6869usmc said:
Agree,...when I wheeled at Rausch, the thing that stopped me the most was being high centered on the Gas Tank Skid, so I would anticipate a hit on the tank & use a dab more skinny pedal to go up & over. If that tank was 2" farther up in, that would solve a lot of our problems, and an aftermarket Skid wouldn't even be an issue. At this point I was using the Skid as a Slider all day long. An aftermarket Skid of that size would weigh a ton, because I know my "Skidrow" Engine Skid is pretty heavy at that size, we all would need Hemi's installed.. I would take the reduction in capacity(thinner Tank) for the tank to be recessed 2".

I'll preface to say that I don't have my JK just yet and certainly haven't wheeled it. But, honestly, regardless of what you do, you are going to use something as a slider. You are going to belly up on stuff no matter what, because you will be trying different obstacles due to the different abilities offered. So if you were to change it up, you would likely just be doing something you couldn't do before.

What appears to me to be most advantageous is a tank that is shorter in the front and taller at the rear and slightly longer. It is now high in the rear anyway, but if the bottom front of the tank was tucked up further and the tank itself was a little longer, it might accept the same amount of fuel but have a higher clearance that at the most critical point.

The rear part of the tank hanging low is not as critical as the forward portion since it's getting closer to the rear tires and you have the Dshaft dropping anyway.

MichaelW

· #14 · Nov 1, 2007

I built a custom tank for my Isuzu. It held over 40 gallons of gasoline. It was mounted in the back and between the frame rails. I never had an issue with this arrangement. Couple this with a solid steel bumper, an excessive skid plate for the already 1/4" thick gas tank, I don't think any vehicle on the road today could puncture my gas tank, unless they were traveling at missile velocity or were significantly larger than me such as a 25 ton semi. Then at that point I think survivability would be a non issue as the difference between being compacted into a 2'x3' square verses being compacted into a 2'x3' square then catching on fire is mute point.

I say let everyone else crumple.

Besides, I'd much rather have the weight of the gasoline centered over the middle of the vehicle than only on one side such as is the case now with the factory tank.

Plus added weight just behind the rear axle will add down force on the rear axle and provide more traction on the rear tires.

And yes, excessive weight the further away from the rear tires could make it easier to flip over backwards, unless you provided some sort of rear stinger to stop you from flipping so easily.

I'm going to be building my rear tank as a custom project. I'll be able to hold more gas than all of you and go on longer desert excursions without the need to have more gas cans.

So in other words, you haven't convinced me this is a bad idea yet.

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paragon

· #15 · Nov 1, 2007

MichaelW said:
I built a custom tank for my Isuzu. It held over 40 gallons of gasoline. It was mounted in the back and between the frame rails. I never had an issue with this arrangement. Couple this with a solid steel bumper, an excessive skid plate for the already 1/4" thick gas tank, I don't think any vehicle on the road today could puncture my gas tank, unless they were traveling at missile velocity or were significantly larger than me such as a 25 ton semi. Then at that point I think survivability would be a non issue as the difference between being compacted into a 2'x3' square verses being compacted into a 2'x3' square then catching on fire is mute point.

I say let everyone else crumple.

Besides, I'd much rather have the weight of the gasoline centered over the middle of the vehicle than only on one side such as is the case now with the factory tank.

Plus added weight just behind the rear axle will add down force on the rear axle and provide more traction on the rear tires.

And yes, excessive weight the further away from the rear tires could make it easier to flip over backwards, unless you provided some sort of rear stinger to stop you from flipping so easily.

I'm going to be building my rear tank as a custom project. I'll be able to hold more gas than all of you and go on longer desert excursions without the need to have more gas cans.

So in other words, you haven't convinced me this is a bad idea yet.

Well, personally, I'm not here to convince you it's a bad idea. But I think it is a bad idea.

A fuel tank is not going to tuck nicely behind a fabbed rear bumper and the dynamics of a crash are not simply about linear bumper to bumper impacts. A fuel cell hanging low in a potential impact area has been shown to be a bad idea, through lawsuits.

You will be driving a lifted vehicle. IF you try to build a cage to protect the cell from a crash, you are then impacting the departure angle. If you simply utilize a typical bumper, a car is likely to make underneath the bumper.

But on to the point PhilD brought up, which is what I would also consider. It's not as much about flipping over backwards. It's about maintaining a F/R weight balance for stability, traction, etc. But, the CoG will be changing dramatically which will throw the suspension dynamics off which will likely mean making adjustments to the suspension to accomodate the change (if you want to maintain the the suspension dynamics). A question would be how big of a change to the suspension would have to be made to make the Jeep still work.

I don't know... if it was a trail-only rig, it might be different. But just a little food for thought.

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MichaelW

· #16 · Nov 1, 2007

I agree with your logic, but again this doesn't convince me but actually reinforces (in my mind) the justification for having it in back.

The 2 heaviest pieces underneath the JK is the engine and a full gas tank. The engine is right above the front wheels. Placing the tank in the old muffler spot will have the tank just behind the rear wheels. Plus it will be centered over the left and right side of the vehicle as opposed to one side that makes the left and right characteristics different from left to right. It is easier to roll on a side hill if the down side is the passenger side vs the opposite.

Having the tank in the back opens up a more likely chance of it being hit in an accident where you are rear ended. However my tank has a significant frame mounted skid plate plus the tank it self has a gap between the plate and tank and the tank is 1/4" thick. I have dropped off of 4' ledges onto my gas tank and have only managed to merely mar the skid plate and in one occasion put a crease into the skid plate. However nothing yet has penetrated through to the gas tank. So this isn't the average joe factory skid plate that yes if my tank was a factory flimsy pie tin and plastic tank I would have damaged the tank.

Now using the same situation, so now with a low hanging side mounted factory gas tank you are just as vulnerable from a broadside impact such as those that take place at intersections.

I'll take my heavily reinforced rear mounted and protected tank with a skid plate/super slider any day over the way the factory tank is currently mounted.

Just my 2 bits. Again I'll let everyone else crumple.

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paragon

· #17 · Nov 1, 2007

MichaelW said:
I agree with your logic, but again this doesn't convince me but actually reinforces (in my mind) the justification for having it in back.

The 2 heaviest pieces underneath the JK is the engine and a full gas tank. The engine is right above the front wheels. Placing the tank in the old muffler spot will have the tank just behind the rear wheels. Plus it will be centered over the left and right side of the vehicle as opposed to one side that makes the left and right characteristics different from left to right. It is easier to roll on a side hill if the down side is the passenger side vs the opposite.

Having the tank in the back opens up a more likely chance of it being hit in an accident where you are rear ended. However my tank has a significant frame mounted skid plate plus the tank it self has a gap between the plate and tank and the tank is 1/4" thick. I have dropped off of 4' ledges onto my gas tank and have only managed to merely mar the skid plate and in one occasion put a crease into the skid plate. However nothing yet has penetrated through to the gas tank. So this isn't the average joe factory skid plate that yes if my tank was a factory flimsy pie tin and plastic tank I would have damaged the tank.

Now using the same situation, so now with a low hanging side mounted factory gas tank you are just as vulnerable from a broadside impact such as those that take place at intersections.

I'll take my heavily reinforced rear mounted and protected tank with a skid plate/super slider any day over the way the factory tank is currently mounted.

Just my 2 bits. Again I'll let everyone else crumple.

We'll disagree on the "safety" stuff as there's too many variables to keep in play.

But, my point on location is that your suspension setup will have to change. When setting up a suspension the CoG is calculated so that the instant center, anti-squat and all the other junk can be dialed in. You are significantly changing that by moving all of that weight, therefore you will need to re-tune your suspension to accomodate the change.

And I really think I am simplifying it quite a bit through my ignorance.

fr33land

Discussion Starter · #18 · Nov 1, 2007 (Edited)

paragon said:
We'll disagree on the "safety" stuff as there's too many variables to keep in play.

But, my point on location is that your suspension setup will have to change. When setting up a suspension the CoG is calculated so that the instant center, anti-squat and all the other junk can be dialed in. You are significantly changing that by moving all of that weight, therefore you will need to re-tune your suspension to accomodate the change.

And I really think I am simplifying it quite a bit through my ignorance.

Good discussion... :smokin:

:smokin:

Not to butt in... but how is the COG changed all that much by shifting weight? By the fuel consumption the COG changes as the weight of the gas is lessened, coupled with the fact that you maybe carrying tons of gear and spare part in the back behind the seat (my spare **** and tools = 30lbs). Take along some camping equipment... This wouldn't require suspension mods.
My JK squats a little to the side when I fill up already.
More info please...?
I have been on the trail with several loaded JK's and they only squat a little.
Wouldn't the Airlift 1000 air springs remidy this squating problem?

toadontheroad

· #19 · Nov 1, 2007

Dual tanks?

Guys,
What obstacles are there to losing the OEM and replacing with a smaller one that fits inside the frame and joining it to a slightly smaller auxilliary tank on the other side next to the exhaust? Could a pump be placed so that it drew fuel into the primary tank? Or is that too complex? I've heard that the CARB (Ca Air Resoures Board) won't allow some aux systems. Maybe because there isn't enough tax money in it? :shaking:

:shaking:

PhilD

· #20 · Nov 1, 2007

fr33land said:
Not to butt in... but how is the COG changed all that much by shifting weight?

It moves it towards the rear, you can compensate with taller springs etc, but the CoG will now be further back. Not by much I guess, but maybe enough to effect going up some steep obstacles. Of course it may help with coming down some

By the fuel consumption the COG changes as the weight of the gas is lessened,

I tend to always wheel with a full tank, to avoid the pickup sucking air at the wrong time. That said, yes, it does change and my vehicle will lean slightly when it's got a full tank of gas.

Given the choice I'd take a smaller tank tucked up inside the frame where the current tank is. But I wouldn't say no to a rear mounted tank either, and will be happy to see any solution available on the market place. Apart from the cost of a new tank and protection, you may also have to factor in new skid plates and mounts etc.

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