Move fuel tank to inside rail along driveshaft?

[Wincks2]

Have a new 85 gmc crewcab long box. Considering moving the a fuel tank to near its current location except inside the frame and along the driveshaft rather than to at the rear under the bed.

Any suggestions?

[Drzronnie]

Just from looking roughly at my truck it doesn't look like it would fit there. I didn't measure or anything but there doesn't appear to be the room.


Tank is pretty big.

[Wincks2]

I see what you mean.

An article I read http://www.autosafety.org/GMAttR.pdf suggested the tank from an '83-84 Ford Ranger might fit. Maybe they are smaller. I will have to check on how much they hold.

[Drzronnie]

The only problem you would have with a lil ranger tank is you would be filling up constantly.

[Keith Seymore]

Originally Posted by Wincks2

Have a new 85 gmc crewcab long box. Considering moving the a fuel tank to near its current location except inside the frame and along the driveshaft rather than to at the rear under the bed.

Any suggestions?

Why are you thinking of moving it?

K

[cableguy0]

If your scared of the truck blowing up in side impact stop worrying. Those trucks were practically set on fire by the news outlets to look dramatic.

[thrtsxchambers]

I don't think it will fit. I have my batteries mounted there (one on each side) and leaves very little room between the battery and the driveshaft.

[Wincks2]

Yes, I read about the differences of opinions about whether the side tanks cause fires. Ralph Nader, and tv producers setting off charges in the tanks, on one side and GM on the other with the federal government getting in the middle. Big differences in the claimed number of resulting fatalities from the different groups.

Mentioned it to my wife, who worked on the burn ward for 18 years. Although perhaps extremely unlikely, "Gee, I guess I should have moved the tanks." would be a delicate conversation. So now I will be moving the tanks. And mine is a diesel with a higher fire temperature than gas.

The truck has only the one tank on the driver side now, so was thinking about moving it to the rear under the bed, then read the article suggesting along the driveshaft might be better, but have not found any information from someone who has put it there.

[Restrorob]

Don't forget there's a tank that will fit between the rear frame rails where a spare tire would go.....

[bigdnew]

Originally Posted by Restrorob

Don't forget there's a tank that will fit between the rear frame rails where a spare tire would go.....

echo same message. summit sells an aftermarket alluminum tank that mounts where the spare tire would go.

[Wincks2]

To get two tanks, both within the frame, perhaps one under the bed where the spare would go and the other near the original location and inside the frame along the driveshaft.

If only using one tank and a large enough one can go along the driveshaft, the spare tire could remain under the bed at the rear.

Thanks. Will take a look at summit.

[BLE 'BURBAN]

So where would you run your exhaust?

[Wincks2]

Just went for a crawl through the snow to take a closer look.

Drzronnie is right. The original tank is too big to fit inside the frame. It seems not to go much higher than the frame while outside the frame, but inside the frame the cab bottom drops down and there is a piece of metal crossing between the frame sides that is lower than the top of the frame.

Seems to be space on the driver side for a smaller tank inside the frame near the original tank location. Would have to find a way to get the filler tube from outside the frame to inside the frame.

My exhaust runs down the passenger side.

Where the exhaust would go with the rear tank, I don't know. Mine has a 3" tube. Looks like folks are able to have the exhaust get through on some older trucks http://67-72chevytrucks.com/vboard/s...el+fill&page=2 MOved the filler hose to the side tail lights http://67-72chevytrucks.com/vboard/s...ad.php?t=77104

There might be room for a smaller tank in the rear that would be far enough away from the exhaust, or perhaps shielded from the exhaust heat.

[Wincks2]

If a second filler tube is run from the rear under bed tank to behind the rear driver side wheel, perhaps even a swing out light as on the other thread, it might be possible to fill both tanks from the driver side of the truck

[Keith Seymore]

Wincks -

You didn't ask for my opinion, but - because this is a topic I get somewhat emotional about (...I apologize in advance...) - I'm going to give it to you:

If your motivation in moving the tank is because of safety I think you are wasting your time.

It sounds like you may have done some reading, and so you may have already seen this thread, but I would ask you to read it again:

http://67-72chevytrucks.com/vboard/s...d.php?t=379580

My editorial comments are documented there, although perhaps not as eloquently as I would have liked.

Secondly, your comments re-piqued my curiosity about this topic, so I did some (hopefully detatched and unemotional) research:

I wondered "...how many deaths were there, really, as a result of this?". So I did a quick internet search.

The National Highway Traffic Safety Administration (NHTSA) has documented what they believe to be 1800 fire related fatalities in '73 - '91 C/K and R/V trucks, from 1973 through calendar year 2000.

First off, in looking at the data, from what I can tell they don't distinguish between pickup, Blazer and Suburban - the later two which would not have side saddle type tanks - so the actual number will be somewhat smaller than the 1800.

Secondly, if you read through the data, it does not distinguish between "fire" as the cause of death vs "fire as a result of side saddle tanks" as a cause of death. Many of the fatalities occurred as a result of single vehicle accidents where the truck struck a tree or a pole or a bridge abutment. One could assume that in those cases the vehicle was moving forward, likely longitudinally (and perhaps at a moderately high rate of speed), and the fact that the tank was mounted on the side of the vehicle would be moot. (That is, these were not situations where the victim vehicle was T boned in the side - specifically the side that the tank was on - resulting in fire). This would also reduce NHTSA's number of fatalities directly attributable to side saddle tanks.

Lastly, in reviewing their data, in some cases there were two, three or even four people involved some of the vehicle incidents. So - the number of vehicles impacted (ie, specific crash events) was something less than 1800, like 1200 or so.

However, for the purposes of this discussion, let's do some math and use their number of 1800:

NHTSA estimates there were roughly 10 million of these vehicles produced (Note: I think that's low, 15 plus model years many of which were more than 1 million per year - but again we'll use their number). If we assume each of those vehicles traveled 50,000 miles in their lifetime (again, I am choosing a low number on purpose, as mine has nearly 200,000 miles) then the number of miles traveled in these types of vehicles would be 500,000,000,000 - hopefully that's 5 with 11 zeros behind it, or 500 billion miles.

I am relating it to miles traveled because that's the factor that causes you to be "exposed" to something bad happening. Said differently, there's really no danger when the vehicle is just sitting in the driveway. 500 billion miles - that's a lot of "exposure".

Your odds of dying in a fiery death, then, according to NHTSA would be that number divided by 1800 or 1 in 277,000,000. One in 277 million.

Just to give this number some perspective, I did a quick check on some other comparable statistics: your odds of winning the lottery, according to one website, are one in 120 million. Your odds of being killed on a commercial airline flight are one in 19 million. Your odds of being struck by lightning, the standard of measure in this type of thing, are one in 750,000. If you prefer a "straight up" numbers-to-numbers comparison, I found that there are roughly 12,000 deaths attributed to "slip and fall" incidents each year.

So basically you are twice as likely to win the lottery, 14 times more likely to die in a plane crash and 370 times more likely to be hit by lightning than to be killed in one of these trucks as a result of fire, according to data from the National Highway Traffic Safety Administration.

[Keith Seymore]

Now - let's talk about the design process itself:

GM barrier tests dozens of new vehicles every day - and has since the mid 60's. During the development phase of these tests designs are modified to improve the vehicle's ability to pass the final validation test. Brackets are modified, shields put in place, the style of the end of bolts changed, etc, to ensure a robust design. That's a lot of testing - and a lot of little details.

These pickups had to pass every federally mandated test and regulation that was on the books at that time (Note: had to pass, or we could not legally sell vehicles) - plus, the more stringent internal GM testing. The internal tests are more stringent because GM wouldn't want to show up for a federal test not knowing what is going to happen: much testing would be done in advance to ensure a "pass" when the formal witness test was to be run.

Additionally, part of the test requirement is that after the barrier incident the vehicle has to be turned upside down and there can be NO leakage of fuel. These vehicles passed that test, verified during each of the model years, as well.

You are about to embark on a path where you are going to use a homemade tank, or an aftermarket tank, complete with your own design fuel lines, vapor lines, fuel fill, etc.

How do you know your design is "safe"? How are you going to ensure fuel system integrity? How do you know that in a barrier event the drive shaft is not going to pop up and poke a hole in your tank? Or that the tank itself is not going to be pushed into the end of a bolt, or bracket, rupturing the tank? Or pull a hose off a fuel line?

I would propose that, without some type of testing, you are not going to know. And, I very much doubt, that you are going to be able to do hundreds and hundreds of side impact barrier tests to prove out your design.

So - you would be moving away from a known commodity (ie, the GM design) and into a complete unknown. I think that would nag at me.

Bottom line: I would recommend you leave the tank and fuel system where it is, and if you really feel that strongly about it - either create or purchase one of those steel guards/structures that goes around the outside of the tank.

My $1.00 -

K

[Drzronnie]

Originally Posted by Keith Seymore

You are about to embark on a path where you are going to use a homemade tank, or an aftermarket tank, complete with your own design fuel lines, vapor lines, fuel fill, etc.

How do you know your design is "safe"? How are you going to ensure fuel system integrity? How do you know that in a barrier event the drive shaft is not going to pop up and poke a hole in your tank? Or that the tank itself is not going to be pushed into the end of a bolt, or bracket, rupturing the tank? Or pull a hose off a fuel line?

I would propose that, without some type of testing, you are not going to know. And, I very much doubt, that you are going to be able to do hundreds and hundreds of side impact barrier tests to prove out your design.

So - you would be moving away from a known commodity (ie, the GM design) and into a complete unknown. I think that would nag at me.

Bottom line: I would recommend you leave the tank and fuel system where it is, and if you really feel that strongly about it - either create or purchase one of those steel guards/structures that goes around the outside of the tank.

My $1.00 -

K

Just to add on that note. I had to put a fuel cell in the bed of my S10 when I body dropped it. If you fill it up all of the way fuel will slosh out of it when you drive down the road. (ie, leaks) If you are that worried about it I would just replace the tank with a stock replacement plastic one, no mods, problems, and you will save money in the long run. There is next to no room between the frame and driveshaft as you can see in my pic above. Plus if your truck is like mine with a drivers side fill you would need to re route the exhaust because it runs on the drivers side between the frame and driveshaft.

[Wincks2]

What an excellent discussion forum! Real expertise right here!

Regarding Mr. Seymore's first detailed post: And as we currently have only a single tank on the driver's side, our risk is probably only about half of what your math has predicted. So our risk should actually be proportionally less than that of competing trucks brands that had the tanks within the frame by then (assuming, without evidence, their risk did in practice turn out to be lower due to having already moved the tanks within the frame).

Regarding Mr. Seymore's second detailed post, supported by Drzronnie's most recent post: What are the odds of me, with my thumb, drill, and new ratchet set and having read that some have moved tanks within frames designing something as safe as Mr. Seymore with his engineering degree, years of industry practice, and teams of people with thousands of hours of expertise considering the questions and designing to meet federal safety standards. Man, optimism can be a dangerous thing. Thanks for the reality check. And thanks for saving me the time I now wont be spending moving a fuel tank. Although, my guess is my wife may now have me spend it looking for an 88 model on which the factory put the tank within the frame. The latter even though, with NHTSA saddlebag numbers as low as 1800 or in practice lower, there may not be any statistically reliable evidence that the factory move to within the frame reduced the risk of death by fire in identical situations.

Seems like my time right now would be better spent making my diesel engine start better in our Manitoba February weather

[Adams74Chevy]

Originally Posted by Wincks2

... And mine is a diesel with a higher fire temperature than gas...

I believe Keith sums everything quite well, but this little piece caught my eye. Not trying to sound like a jerk but have you tried to catch diesel fuel on fire? It takes a much hotter spark than gasoline does...therefore harder to ignite. I know in accidents (from VFD family members) spilled diesel is worried about less than spilled gasoline from the ignition after the accident point of view. I'd say go with what GM designed and don't worry about.

[bigblock73]

Dodge trucks of the same era had their plastic tanks inside the frame rail, with the exhaust on the other side of the DS. Not sure of their frame width (it could be wider). It can be done I suppose, but as Keith mentioned, it is likely more effort than it is worth IMO.

[3r!c84]

Originally Posted by Keith Seymore

Wincks -
http://67-72chevytrucks.com/vboard/s...d.php?t=379580

i started that thread

Originally Posted by Keith Seymore

My $1.00 -

Keith seymore..you are a big help to this forum.

[Keith Seymore]

Thank you.

BTW - as a result of this investigation I won't be playing the lottery any time soon, either...

[MrBeast]

Keith, very well written.

I say leave the tanks be, im a perfectionist, and I am leaving my tanks be, well atleast the drivers side tank, I am swapping in a 40 gallon suburban tank and putting the filler on the drivers side so I dont have to fill both tanks from either side. So that will give me 60 gallons, I dont know what your MPG is, out of my 454 im pulling about 10, that is just under 600 miles or so before you have to stop for go go juice. and a $160.00 fillup when you get there.

[JohnC]

Originally Posted by MrBeast

Keith, very well written.

I say leave the tanks be, im a perfectionist, and I am leaving my tanks be, well atleast the drivers side tank, I am swapping in a 40 gallon suburban tank and putting the filler on the drivers side so I dont have to fill both tanks from either side. So that will give me 60 gallons, I dont know what your MPG is, out of my 454 im pulling about 10, that is just under 600 miles or so before you have to stop for go go juice. and a $160.00 fillup when you get there.

[grinch4om]

you really want to be safe? put a 22 gal fuel cell with the metal surround(ala nascar) behind the axle...problem over