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Frame X-Member Q: What's needed to install a rear fuel tank?

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Bronco638

Frame X-Member Q: What's needed to install a rear fuel tank?

This time my question is regarding the frame cross member for trucks with a rear fuel tank. The cross member in question is the one above and just behind the rear axle.

But, I also found this image:

of an '80 F-150 Flare Side 4X4. That truck has a different cross member and does not appear to have a rear tank. My '80 F-150 Flare Side 2WD is in storage so I cannot easily check it.

If an F Series truck that does not have a rear tank, then it does not have the cross member as shown in the first image? It also appears that the frame is bent upwards, just aft of that x-member, as well.

Since that cross member bolts in, is there a separate part number for it?

What I'd like to do is remove the side/mid tank and replace it with a rear tank(only).

Dave A
'80 F-150
'11 Ranger
'17 Expedition

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

Dave - What you are wanting to do has been done, but not by the factory. The Flareside trucks came with the midship tank but not the rear tank.

However, Dave/Fuzzface2 has added a rear tank to his Flareside, and I do mean "added" as he kept the midship tank as well. So he's the guy to ask the question of, and I've tagged him to come to help you.

Said another way, I cannot answer your question as all I know I learned from the documentation and since Ford never did it there is no documentation on it. But I know Dave can, so let's await his arrival.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Dave and I have been going back-and-forth over on FTE, too. Not having my truck in the garage, for reference, is a bit of a PITA right now because I have so many thoughts/ideas of what I'd like to do with it.

Dave had the benefit of having a parts truck with the rear tank. So, he just unbolted that cross member, from the parts truck, and installed it into his flare side frame.

Another inmate on FTE fabbed up his own cross member using 3" C channel. I don't know how to weld but I can use his idea and make it work for me. It would be nice to have the Ford cross member but if I can't source one locally, I may have to make one. Being in northern Illinois, these trucks are few and far between.

So, if there was a Ford part number, at least I could search the internet to see if anything popped up.

Appreciate the reply/help Gary!

Dave A
'80 F-150
'11 Ranger
'17 Expedition

FuzzFace2

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

In reply to this post by Gary Lewis

Dave is in the house

Dave has a thread going over on the other Ford truck forum and thought I answered the questions but he dose bring up something.

That bolt in cross member that sits in front of the rear tank I know is different on trucks with and with out a rear tank.
With a rear tank it has the slots and holes for the straps that hold the tank in place where the non-tank truck do not have them. I also cant remember if the shape is different?
They both bolt in.

That something brought up - dose the 2 different cross members have apart number being they are different and bolt in? Also would the rear tank cross member for the 87> truck use the same cross member?
Dave ----

Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100

FuzzFace2

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

In reply to this post by Bronco638

I just checked my build pictures and the non-rear tank cross member is a little thing of a cross member like the one on the truck in the 2nd picture and looks to bolt to the bottom of the frame rail.

The rear tank cross member is beefer to support the weight of a full gas tank and bolts to the top& bottom of the rail.

Still like to know if the 87> rear tank cross member could be used on the <86 trucks.
I think it can as I dont see why not?

I used all factory parts to mount the rear tank, cross member, top & bottom straps but that is where it ends for a flare side.
Filler neck and door on the fender will have to be made from parts gotten.
I also said the door has to be from a flare side because of the size and shape to fit the contour of the fender.
I posted pictures on FTE post he started. https://www.ford-trucks.com/forums/1744451-gas-tank-swap-side-for-rear.html
Dave ----

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

Dave/FF2 - What crossmember did you use? More specifically, what wheelbase truck was it off of?

Gary, AKA "Gary fellow": Profile

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

By the way, I think 1987 parts can be used in most cases. In the listing below from our page on crossmembers you'll see that the MPC says things like "80/". That means 1980 through at least the end of the catalog's range, which was 1989. So with the exception of the F100's and some of the F350's the parts should swap. (And they may well swap for the F100's except that they disappeared after 1983 so they are shown for just the 80/83 years.)

Gary, AKA "Gary fellow": Profile

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Gary, I'm having a hard time understanding that MPC chart. Which Parts List No. number is in question? I've seen images from the MPC that show how the cross members are numbered but without that, there doesn't seem to be any context. My truck is an '80 F-150 2WD Flare Side. According to the chart, that should be cross member #12, right?

Dave A
'80 F-150
'11 Ranger
'17 Expedition

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

Bronco638 wrote

Gary, I'm having a hard time understanding that MPC chart. Which Parts List No. number is in question? I've seen images from the MPC that show how the cross members are numbered but without that, there doesn't seem to be any context. My truck is an '80 F-150 2WD Flare Side. According to the chart, that should be cross member #12, right?

Not "cross member #12" but "Parts List No 12". And yes, that appears to be the right parts list for your truck.

Gary, AKA "Gary fellow": Profile

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Any chance you could post an image of Parts List No. 12? I'd like to see what it illustrates. Thanks!

Dave A
'80 F-150
'11 Ranger
'17 Expedition

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

It is on the page at Documentation/Suspension And Steering/Crossmembers, down below the table that shows which trucks use which parts list.

Gary, AKA "Gary fellow": Profile

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Sorry, I didn't even think to look. Thanks again!

Dave A
'80 F-150
'11 Ranger
'17 Expedition

FuzzFace2

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

In reply to this post by Gary Lewis

Gary Lewis wrote

Dave/FF2 - What crossmember did you use? More specifically, what wheelbase truck was it off of?

It is the bolt in cross member that fits just in front the rear tank that the straps fit to.

The cross member I used was from a 2/81 F100 style side long bed dual tank truck.

It bolted in place on my 11/80 F100 short bed flare side, no rear tank.
Dave ----

salans7

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

This post was updated on .

This crossmember can be sourced from some Styleside trucks without dual tanks as well, as my old parts truck only came with the front tank, but still had this crossmember as well as the lower supports for the rear tank.

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

OK, looks like I'm going to need to visit some local wrecking yards when the weather improves (single digit high temps coming for the next week +

). I know there's a '87 Brick Nose with a rear tank in the closest yard. I wonder how rusty it will be...

Dave A
'80 F-150
'11 Ranger
'17 Expedition

FuzzFace2

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

In reply to this post by salans7

salans7 wrote

This crossmember can be sourced from trucks without dual tanks as well, as my old parts truck only came with the front tank, but still had this crossmember as well as the lower supports for the rear tank.

Are you sure on that

I only say this because that same cross member on the flare side, a non-rear tank truck, is not the same cross member used with the rear tank.

If you look at the pictures the non-rear tank CM is a little thing and looks to be bolted to the lower part of the frame rail. The rear tank CM is a beefy one and bolted top & bottom.

Also the tank CM would have slots & holes for the straps that go on top & bottom of the tank.
So look the CM over closely to make sure it will hold a rear tank.
Dave ----

mat in tn

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

in the two pictures at the intro there were two different frames. on the first frame which looked to have just been refinished was the one with the asked about cross member/ tank support rail. in the second picture was a spare tire upper rail for use without a tank. on the models with rear tank, the spare tire holder holds the spare against the bottom tank rails. without a tank there is still a need for the upper half of the spare support. this frame member being asked for is also the part which the brake line (soft hose to rear axle) is mounted. then the hard line is fitted. on the ones without this there is a short (4") flat stock bracket in lieu of it for the rear brake hose to anchor to. if you do decide to add this cross member then you will swap over the brake attachment at the same time. perfect time to install new hose. also, you are looking for top tank straps and bottom tank rails to go along with the new tank and I'm sure you need the filler neck and internal tube too. buy a new fill hose.

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

in the two pictures at the intro there were two different frames.

I thought the exact same thing. It seems as if those frame rails are slightly different. There doesn't seem to be two "kick ups" above the rear axle on the rusty frame whereas the re-coated frame has them. Are there "non-rear tank" AND "rear tank" frames? Those two pics would seem to indicate that there are.

Dave A
'80 F-150
'11 Ranger
'17 Expedition

Gary Lewis

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

Administrator

The picture below is mine and is of Dad's truck: 1981 F150 regular cab long bed 4WD with a 133" wheelbase and two tanks.

Gary, AKA "Gary fellow": Profile

Bronco638

Re: Frame X-Member Q: What's needed to install a rear fuel tank?

This post was updated on .

Yes, and if you look at your frame just aft of the cross member in question, you'll see that it has two areas, one on each side, that are (slightly) bent upwards. Looking at this frame, those areas don't seem to be there:

The two areas back by the rear cross member are the same, on both frames. Your frame has two of these areas near the rear axle, the other frame does not.

Dave A
'80 F-150
'11 Ranger
'17 Expedition