Gas tank relocate, frame strip questions

[R&B51]

Gas tank relocate question:
51 - 3100, plan LS/LQ4 swap, TCI 4 link in rear and really want to keep room for spare but want tank under bed, good sized 18-23 gallons for driving range, and pump inside tank (my 73 Bronco with 5liter fuel inj. Has external pump and is a little noisy and slow to prime/start in hot weather). Any body done this or know if a link?
Also, tearing down front to rear and not sure what all comes off frame to make all this happen?

[dwcsr]

I doubt that you will get an 18 - 23 gal rear fuel tank and spare tire under the bed.

this is a 50 with a rear tank and an LS, 68-69 Camaro tank side fill and can be a rear fill easily or a bed fill

[OrrieG]

Yep. you can have a spare tire OR gas tank there. Most aftermarket ones are 19 gallons, which keeps the bottom up out of harms way. Some guys use larger capacity 70's Blazer tanks. Fill options are up thru the bed, back over the bumper, or thru the side. Using the box above click 67... and search for "1950 under bed gas tank", lots of threads will come up for you to review.

If you want to keep the spare there and get the tank out of the cab you can add one in the bed, guys use old footlocker, coolers, tool boxes, etc. to hide them. Or you can look for an early Suburban that mounted in front of the passenger rear tire and fill above the step. I think the big trucks from then also had the side tank but can't remember if anyone has used one.

[Root2812]

I don't know your budget but I have a 1950 and its getting a LS. I used the tank from Brothers. http://www.brotherstrucks.com/prodin...number=SGT4753

The tank fit awesome. I picked up an Aeromotive Phantom kit to put the pump in the tank but I haven't fitted the pump yet. Here is the tank installed.

[wolffcub]

Originally Posted by Root2812

I don't know your budget but I have a 1950 and its getting a LS. I used the tank from Brothers. http://www.brotherstrucks.com/prodin...number=SGT4753

The tank fit awesome. I picked up an Aeromotive Phantom kit to put the pump in the tank but I haven't fitted the pump yet. Here is the tank installed.

Just thought i would post a heads up for people who might be running the same style of tank under the bed of a 47-early 54 truck. I did like the style of the tank and such but found out yesterday that where they welded on on the mounting tabs to the tank has caused a rip in the tank.

It was the furthest forward tab on the left side. Looks like this style of mounting tabs is not the best because it appears to not allow flexing at the tabs if the chassis twists or flexes.

Need to find a different tank now with either a single tab per side or possible a unit that uses a strap style hanger system.



I think the issue with this is the poor design of the front tabs. They are welded at a angle to supposedly match the angle of the chassis wheel hump. Problem is that the wheel hump is a curve and the tabs are flat so when you tighten up the bolts as instructed is causes the tab to flex and follow the curve of the chassis. This would then in turn put stress on the welds where the tabs is attached to the tank sides, and with any possible chassis twisting over time rip out the weld as it did on mine.

[Root2812]

I forgot to comment on on your spare tire. I had three ideas because I also want a spare. My parts truck is a 53 and had the spare tire that mounts on the bed side with the dimpled fender. I am leaning toward using that bed and sporting the side spare. I also toyed with the idea of fining a donut tire in the junk yard that would work and putting that behind the seat for when I'm in a pinch but then I figured why do that when I could just keep a can of that fix a flat stuff. I hate the mess that stuff makes in the tire becuase I'll have to clean it out to patch the tire. All three of those options and I think the side spare is going to be the best for me. I still have time to decide.

[YukonXL04]

Roadside assistance? Lol

[jbarron]

Could it be that they designed that tank thinking that you would move the rear cross member back allowing the tank to sit in the flat section of frame. I can't tell from the pictures but it looks like the gap between the side tank mounts might line up with the rear spring mount.

[wolffcub]

The tank fits good but its a design flaw in the mounting tabs. I will draw up what i did as a after mod and something i highly recommend doing.

[wolffcub]

nope. The tank is made to sit right where its shown. The front tabs are angled to try to follow the wheel arch curve. If you move the tank back those tabs will be nowhere close to hitting the chassis rails correctly. The tank would be angled downwards at the front.

[wolffcub]

Here is a rough drawing of whats happens. The front tab is flat and the chassis is curved. As you tighten the bolts the tab will bend to conform to the chassis but that puts major stress on the tab where it is welded to the tank. The pad part of the tab that is actually welded to the tank will actually start to distort causing the welded perimeter to start to pull apart.



The easy fix is to allow it to conform to the chassis and them re-weld just the tab portion.




Simply cut the tab along the green lines right up next to the pad portion. Leave about 1/4" uncut in the center. You want to do this from both ends of the tab. Then re-bolt the tank on the chassis and tighten the bolts. You can see how the tab will then bend up to follow the chassis curve. Once you are all tight you just have to tack up the bent up tab portions back to the pad from the underside then remove the tank and fully weld the tabs back to the pads.



In my opinion this is a must as mine cracked on both sides very bad. and this would have been avoided if i did this mod to begin with.

[R&B51]

Thanks for replies. This gas tank thing seems to be a complicated subject. I see what has worked and what you're having troubles with. I really wanna try to have my cake and eat it too, so will try to find/fab a tank to save spare space. Saw two possibilities, cheapest is a long skinny tank inside frame beside drive shaft. I measured the space in front of rear end between frame and old drive shaft and 14" wide x 60" long and depth is determined by ground clearance. Not sure what minimum should be-how far below frame rail is safe. Drive shaft would hit before tank if tank was about 8-10". This is closest prefab tank I could find and 11" depth (if it is 14" wide and 11" deep" and not other way) is one concern and 14" width only gives an inch to clear driveshaft. Shaft doesn't move side to side. Could install heavy steel safety plate between it and shaft.
Anybody seen this done?
Here's tank info off Raybuck: 81973-81 C/K Series Chevy/GMC Fullsize Pickup Ahead Of Rear Axle 20gal.
Dimensions: 56" x 14" x 11"
Strap Set: ST01

[R&B51]

Another option I saw on 1952Chevytruck.com build thread. He had a custom tank made against the bed above the axle. It looks great but probably is $1000 plus project this is a picture of it and it looks really slick. Have any of you custom make one for the space?
http://www.1952chevytruck.com/images3/tankincradle.jpg

[dwcsr]

I tried that one and its way to big, its to wide, long and tall, it also has a hump in the top where it would hit the cross member. If your dead set on a tank ahead of the axle get a panel truck tank from Jim Carters. Just remember that the original tank was designed for a driveshaft tube next to it not a spinning driveshaft

[Gippetto]

Wolffcub: Nice use of Solidworks to present you fix for the problem you encountered. Whose tank did you use?

[mr48chev]

I'm just wondering, has anyone tried an S-10 tank on a stock AD frame? or an S-10 Blazer tank for behind the axle. I'm thinking about sticking the little skinny spare that came off an Olds 88 that I used to have behind the seat in my 48 with a cover on it. It isn't the ideal thing but at least I'll have a spare and I carried it on several road trips already.

[dsraven]

is it possible to just fab up some tank straps and use that mounting technique? cut the tabs off and go?

[R&B51]

Great thread. Trying to make a decision. I did a pretty expensive online search of driveshaft and gas tank positions in modern cars and also the history of gas tank disasters. Wow, take a look at this link, pretty interesting considering the trend toward rear mounted gas tanks in these old trucks:

http://www.autosafetyexpert.com/defect_fueltank.php

Especially The comment:
"The auto industry has known for decades that the fuel tank for passenger vehicles should not be located behind the rear axle ... as was done in the Ford Pinto and Mustang and Crown Victoria, and many other Ford, GM, Chrysler, and Japanese vehicles up through the mid-1980's and beyond. Instead, the fuel tank should be located in the safety zone forward of the rear axle, where it is protected by distance and structure from collision damage."

Looks like there are quite a few modern cars with gas tanks in front of the rear end and beside the driveshaft. I initially had the same reservations that probably everyone has about driveshafts next to gas tanks but there seem to be far more references to explosions, fires and recalls in vehicles with gas tanks positioned behind the rear from collisions (remember those Pinto and Mustang issues years ago and more recent Crown Vic, Jeeps) . Couldn't really find any references to fires from driveshafts hitting gas tanks. Did see some issues with four-wheel-drive's and rock crawlers rubbing on gas tanks. I know driveshaft can come apart, but I've only heard of a few of those and lots of people get rear ended. I know driveshaft can come apart, but I've only heard of a few of those and lots of people get rear ended. I bet you can't have a pretty high quality driveshaft manufactured and this is not going to be a real high horsepower build. I think I will likely pursue having one made like Rick's tanks down in Texas did for the guy at build thread 1952Chevytruck.com. Maybe add a protective steel plate on the bottom of that frame he had constructed.

[R&B51]

I had not even considered the fuel filler tube- maybe making it pull loose from the body shell and stay with the tank along with a one-way flapper or filler valve near the top ( it will have to have a modern click tighten fuel cap - probably behind a nice looking sheet metal door like a more modern car anywayIn frontal crashes, high-pressure fuel system components can rupture and tear and separate, spewing out a geyser of gasoline, with an immediate fire in the engine compartment, which spreads to the interior and the passengers. A simple fuel shut-off inertia switch, which automatically stops the electric fuel pump at the start of a crash, has been used in Ford vehicles worldwide for many years, and in many European cars... but there are many vehicles that do not have this safety feature. Automatic fire-extinguishing technology has also been available and practical for many years for usage in motor vehicles, but has been ignored as a "fail-safe" design feature. because of the pressure) and possibly even an inertia switch added since this will be an LS conversion and the tank will be pressurized. I bet this is not real complicated to at least make some efforts to do it right. Couple of more quotes from that article:
"Filler tubes are often separated from the tank, and need a safety "break-away" feature at the fender, and one-way valves to prevent leakage. One such recent case involved a full-size multi-passenger van with its fuel tank located vulnerably behind the rear axle, with the filler tube inserted through a rubber grommet into a hole located near the bottom of the tank. In the rear-impact collision accident, the filler tube immediately pulled out, and the ensuing fuel-fed fire quickly engulfed the van and its occupants. Mr. Bloch testified as a court-qualified expert in the trial, and the case settled shortly after his testimony began."
And,
"In frontal crashes, high-pressure fuel system components can rupture and tear and separate, spewing out a geyser of gasoline, with an immediate fire in the engine compartment, which spreads to the interior and the passengers. A simple fuel shut-off inertia switch, which automatically stops the electric fuel pump at the start of a crash, has been used in Ford vehicles worldwide for many years, and in many European cars... but there are many vehicles that do not have this safety feature. Automatic fire-extinguishing technology has also been available and practical for many years for usage in motor vehicles, but has been ignored as a "fail-safe" design feature."
Interesting stuff, I just want to do it right because my boy and I will both be driving this thing. Sure a lot of great guys like you guys out there driving these trucks daily and two shows.

[R&B51]

Because of all the LS swap going on right now with pressurized fuel situation is, does a fuel shut off switch get installed and is that part of the computer swap?

[R&B51]

This is my first week or so join you guys on this forum. Sorry about the long posts - hope that's OK? To get extra input or feedback from people who might not follow the gas tank thread, Is there a way to post a fresh thread that will get people to see these questions on the general forum that relates to LS swaps and this inertia switch fuel shut off valve And fuel tank placement, fuel filler construction safety issue? I'm not real savvy on these kind of things.

[Foot Stomper]

I think a "behind rear axle" tank may be an issue in a passenger car but I believe these old trucks of ours are far more hazardous with "in cab" tanks than the risk of lighting our bed wood on fire in the event of a catastrophic rear end collision.

My vote is 100% in favor of a under bed/behind rear axle tank. No hesitation.

[R&B51]

I agree, getting tank out of the cab is a must! I was looking at the option of trying to get a tank constructed like the one in 1952Chevytruck.com build thread that is above the driveshaft and below the bed. So many of these model trucks being built and tanks being relocated, if that ends up being a good location and custom tank makers could make a bunch of them the price would come down. I will probably be willing to pay the extra to have a custom one made. I also totally get it that most of you guys are really good defensive driver with these dream trucks and all that work so you're even less likely to get rear ended by the way you drive.

[Foot Stomper]

R&B51 don't over think this.

These old trucks with no seat belts, rattles, loud road noise "no crumple zones" are what they are... old nostalgic/time capsules. Enjoy them for what they are and not what they aren't.

Don't ruin it for your boy and your family by worrying about gas tank explosions killing. My boys (in their 20's) are going to learn to drive the foot start/manual choke/throttle/manual clutch/manual drum brakes/manual steering (huge wheel) and a multitude of other "inconveniences" that I hope with carry the heritage of these old trucks into future generations.

[50 Chevy LS3]

I used the Nolimit, aluminum, tank in my 1950 project. It is similar to the steel one, with frame tabs described above, except that the tabs are one-piece, straight welded aluminum. They conform to neither the frame or the rear crossmember. Nolimit instructs you to form wooden blocks to allow mounting. Maybe a good enough solution, but, I was less than impressed. I instead mounted mine, inside the channel frame rails on a self fabricated "ledge". On final assembly, a thin rubber pad will be used between this ledge and the tank. Mounting higher in the frame keeps the tank less visible from the rear. Caution must be taken, however, as mine is very close to where the bed floor will be. Less than 1/2" from the wooden bed floor.

Some pics.are available on my build thread over at Classic Parts...starting page six, post 107, I think...