Fear of Fire

[NorCal_Prerunner]

Is there a higher chance of a cab fire in the event of a roll over with a fuel cell mounted behind the cab VS. mounted at the back of the frame? I assume the risk is the same if the cells are properly installed. I assume mounting a cell at the back of the frame will just buy the driver and co-driver a few more seconds if disaster strikes. Any advantages to either mounting location other than the obvious, more weight in the back? But then again, all that weight from in the back from the full cell goes away as gas is used.

 

[Kritter]

Higher CofG

 

[DANKFAB]

I mounted my fuel tank as far to the rear and as low as I could go without causing any ground clearance issues. I don't know if it will eliminate a fire hazard, but having the weight further back will act like leverage on the rear suspension. True it does lose weight, but it will lose weight behind the cab too, so for C of G purposes, I recommend locating it way back and low as possible without wreaking havok.
You'll just have to extend the lines a few feet further, which isn't rocket science.
Brandon

 

[tedmales]

i would figure the risk of fire would be the same, but i f there was a fire , then i would rather it be farther away from me.

 

[MH20]

Since we started this, what about the possibilty of gas dripping onto a hot muffler? Seems like another reason to have it mounted in the rear.

 

[kjmiller1]

"True it does lose weight, but it will lose weight behind the cab too, so for C of G purposes, I recommend locating it way back and low as possible without wreaking havok." Your probably right for most of us, but I would think their would be advantages of locating it up towards the cab when it comes to fine tuning your springs and shocks. Since the front to back weight distribution changes less, you don't wish your rear was firmer on full tank and lighter on empty as much.

 

[drtdevil93]

putting the cell farther back increases polar moment of inertia. heavy engine up front, heavy fuel cell out back. polar moment of inertia increases stability. while having the cell behind the cab causes less change in F/R weights balance, the weight balance probably wont be as good. my 2 cents.

erik

 

[curt]

Balance is important, anything mounted in front of the front axle and behind the rear axle according to this page http://www.jeepaholics.com/tech/cog/#_Toc535118739 it becomes cantilevered weight and has a larger impact on whatever end it's on(in the jeepers case on rollover agles). It's all leverage, you could hold 5lbs all day long but try to hold it at arms extension, you won't last 5 minutes. Also inertia from the weight can drastically alter your handling, after we moved our cell from the very back of the truck to as close to the rear axle and as low as we could get it, the tendency to oversteer was substantially reduced. Curt

 

[Kbach66]

Along with an increased polar moment of inertia comes "lazier" handling. If you're looking for good straight line stability move it back....want the truck to steer quicker, move it in towards the cab. I feel both locations have advantages and disadvantages. You just need to think of things like intended use (long sandwashes, or short courses), and packaging. You may think you can help keep the CG low by putting it low in the back...but then you go and mount a spare or two flat on top and there goes the CG! I'm putting the cell behind the cab, but 2 37" projects are hangin' off the rear. For me, I think it's the best because I like the fact that the weight bias and CG will remain fairly constant. For somebody else....everything could be different.
I think with the design of cells these days, that if you're in bad enough wreck to puncture the bladder, you're going to be worrying about other things than fire!!!

Just my .00002 pesos

 

[geoff]

that is what i was thinking too, i have the cell hugging the rear axle, and at full bump, the cell will be just close enough =) i hope i dont touch any rocks!!

I personally have no desert experience at all, but from the extensive bench/internet racing ive done, this seemed like a good idea =)


Actually... this brings up another thing i have been wondering about -- why do most prerunners set their trcuks up to be so damn tall? Why arent people racing lower trucks? It seems like a good idea, and of course youre going to have to pay for some real shocks, but look at every fast truck out there, theyre all pretty low. With the exception of the AVALANCHE truck built by FLY-N-HI at the bilstein boost at SEMA this year

 

[FABRICATOR]

Probability of fire is related more to the quality of installation than the location of components. A common mistake is to under estimate the volume and weight of fuel in the fill hoses and tubes, and poorly mount them. After a fill, there can be 2 to 3 gallons of fuel in some fill systems. That and the hoses can weigh 20 pounds or more. Many crashes are within 4 miles or so of the start or a pit stop, making this something to consider. Another problem area is someone going to dump in gas and missing the fill altogether. This is easy to do and on a buggy often causes gas to be splashed directly on the driver. This is good reason to use dry breaks. There are also dry break fuel line fittings that should be used in certain locations.

There is no better place to put a fuel cell than near the middle of the car and on the floor. This is generally only possible with a rear or mid engined car that uses a transaxle. Having a huge 70 gallon cell all the way in the rear only points to the lack of sophistication of many of these vehicles. It's not that having that kind of weight back there is necessarily bad. It's the fact that having 400 pounds there one minute and not having it there the next does'nt make a gigantic difference. In most any other form of motorsports racing, this situation would be intolerable.

 

[drtdevil93]

the person who was asking has a reg. cab toyota. these have a relatively short wheelbase, and as such dont need to be any dartier than they already are. on mine, i put the cell directly behind the axle, as far forward and low as will clear and have decent clearance. at full bump the bottom of my fuel cell is about an inch above the bottom of the diff, its about as low as i felt would be safe. unless josh wants to move his engine to the middle of the truck, id say just behind the axle is the best place to put the fuel cell.

erik

 

[ACID_RAIN28]

I look at it this way, putting it in the rear will do more good than bad, the weight will be better distributied, and for note Chevy did a recall on all the side saddle tanks cause they would blow up in a side impact and people burned alive. good enough for me.

 

[fnkrngr]

NASCAR,ARCA,BUSCH etc. doesnt have a problem with the weight hanging off the rear maybe they know something we don't?Downforce from the spoiler maybe?And as for tanks blowing up on impact as i recall, those tanks didnt have bladders.

 

[ACID_RAIN28]

I fiqure the chances of someone hitting a tank buried inside tubing behind the cab, but that is too close for comfort.

 

[geoff]

another east coast boy hooked on desert racing =)

join the club... where in az are you? im in phx, i own a shop in mesa.

 

[NorCal_Prerunner]

Thanks for all the replies. Just doing some home work for the new truck before I start building. 4.0 Ranger Xtra Cab.