How far can I move my rear axle back?

[crawln68]

With a BC Broncos 24 gallon gas tank, how far can I move my rear D60 axle back without hitting the tank? I don't have my tank from the mass buy yet to meassure. 2 inches, 2 1/2 inches, 3 inches? What do you guys think would be safe? I don't want to get into fuel cells and all of that. Just want to gain a couple of inches of wheelbase. Thanks.

 

[Socal Tom]

I've got the BC tank, it fits tight against the rear cross member. And hangs down quite a bit below. I think you first need to deal with that cross member. You will hit that with the rear axle unless you do something about it.
What ever you do. leave the two holes in the cross member there, or be prepared to fab something for the tank to mount to .
Tom

 

[crawln68]

Are you saying that the rear diff is going to come up high enough to hit the frame cross member? If so, what is the solution? How close is your tank to the very end of the frame rails? Can I move the cross member back without the tank extending beyond the end of the frame rails? (where the bumper bolts on)

 

[Tgure]

Patrick,

I thought about moving my axle back a few inches and my front forward an inch but in my research the consesus was that a few extra inches wouldn't make enough of a difference to out weigh the work etc. I don't really think it would be worth it unless you could increase your wheelbase at least 6" but more like 10" to make it worth it.

Anyway I can mock up my tank and measure for you but I think the tank will get in the way before anything else.

 

[SaddleUp]

I moved mine back about 2" and there is still another inch or so before I would get close enough to the tank to worry. Not sure about the difference with the Dana 60 vs. the 9" housing though.

 

[tonto]

The most you can move the rear axle back with the cross member & 23 gallon tank is 2”s.
If you go any further than that you run the risk that you will get the top rear part of the diff into the cross member and the backside of the diff into the tank,All though you can notch both the cross member & tank for clearance.
Remember the leafs flatten out and the axle moves back a little on hard upward movement.
I moved my front end forward 2”s and my rear back 2”s and it did make a definite difference, it comes down to how much work vs. what its worth to do.

 

[bigpappa]

Like others have said 2" or 3" is all you are going to get before your axle will get into the cross member.

I am looking at doing the same thing. I am just going to go ahead and extend the frame and move the rear back 10" - 12". I decided to do this so I would not get into the cross member and could still use a large tank. Pluss this is going to give me a little more interior room. (I am extending the body as well).

 

[Socal Tom]

Are you saying that the rear diff is going to come up high enough to hit the frame cross member? If so, what is the solution? How close is your tank to the very end of the frame rails? Can I move the cross member back without the tank extending beyond the end of the frame rails? (where the bumper bolts on)

Dusty is running f150 springs. They move the axle back a couple of inches. In order to ensure clearence, he notched the rear cross member significantly to do this.

The BC tank hangs down 6 to 8 inches below the frame rails on my rig ( I'm about 3000 miles away or I would measure it). I have no body lift, the tank does move up with a body lift.
Tom

 

[Gummi Bear]

If you're staying with leafs, you're not going to be able to move it very far back, regardless of whether the tank and crossmember are in the way. There's just no place to move the rear shackle back.

I'm thinking hard of doing a 4 link rear on mine this winter. I'll remove the tank all together, and put in a fuel cell or fab a custom tank. I will move the rear axle back between 6 and 8 inches.

The front axle will be moved forward also. I believe that I can probably do it in a hard weekend of work.

I'm shooting for 100-102" wheelbase.

 

[welndmn]

I made a new cross member and put it ontop of the frame( I have a body lift)
moved the axle about 4-5 inches back, it now just rubs the gas tank

 

[crawln68]

I made a new cross member and put it ontop of the frame( I have a body lift)
moved the axle about 4-5 inches back, it now just rubs the gas tank

Hey Welndmn,

Do you have any more pics of your crossmember and gas tank? What tank are you running?

That is what I was thinking of doing too. I am going to be running a 2 inch BL, so I thought that I could move the crossmember up 2 inches and maybe even notch it for diff clearance. If the crossmember is up and out of the way, that should allow me to move the axle back 3 inches or so. I think that a 3 inch gain in wheelbase would be worth the effort.

 

[crawln68]

Anyway I can mock up my tank and measure for you but I think the tank will get in the way before anything else.

Hey Aaron,

That would be great if you don't mind. Thanks man.

 

[Dusty]

Dusty is running f150 springs. They move the axle back a couple of inches. In order to ensure clearence, he notched the rear cross member significantly to do this.

Just a little clarification on what Tom said. Yes I do run the F150 springs but I currently have them set at the stock wheelbase, which required placing the forward perches a few inches further forward, and the rearward perches all the way back, almost inside the bumper. I built my own rear corssmember rather than notch the stock one. I made it out of rectangular tubing, which I notched for diff clearance. It does take advantage of the body lift by going high up over the frame rails as it crosses over the pumpkin. I do also run the BC tank, which also takes advantage of the body lift. Here is a pic of my current setup. Note that the custom crossmember I built is a couple inches forward of where the stock one was. I did that for clearance for my old shock setup but I'll probably move the crossmember back in the future:

There are more pix of it on This Page, just scroll down to them.

Tonto and I are going to 4-link my rear here in a few months and when we do I'm going to move it back a few inches. I'll probably notch the tank and skid plate some to do so.

Dusty

 

[MikeM]

Can somebody post up a pic of their rear suspension at full stuff? I'm having a hard time seeing the pumpkin into that cross member. When I ramp mine the leafs will invert, this means the axle returns to a more forward (nuetral) position. In other words full stuff is not when the axle is at it's furthest back.

 

[crawln68]

Dusty...Your the man! That is exactly what I was thinking of doing. How much body lift do you have? How far above the frame does your crossmember go? Awesome job!

 

[welndmn]

I don't have any other pics I can think of at work.
But I have the WH gas tank.
I like the notched crossmember better, but did not work for me because the picup on the WH tank would be in the way (form the pic its what the tube is protecting.

 

[sstlaure]

Can somebody post up a pic of their rear suspension at full stuff? I'm having a hard time seeing the pumpkin into that cross member. When I ramp mine the leafs will invert, this means the axle returns to a more forward (nuetral) position. In other words full stuff is not when the axle is at it's furthest back.

Stock you've got ~3" clearance between the back of a 9" pumpkin and the x-member. If you want to see it yourself, take apart your leaves down to just the main leaf. Put a spacer block into the pack to make up the missing leaves, reattach it to your truck and ratchet strap the axle to the frame. Crank it down until you're at full stuff. I don't have a pic from the side, but this shows how far the axle can stuff up. (I think I had 2" clearance frame to axle tube, I believe 68Ford has his down to 1/2" clearance between the frame and axle tube.

Oh yeah, watch out when you release that strap...

 

[MikeM]

Great pic Scott! There must be some serious fender well hacking going on there, I like it.
Yep, I did all that a one leaf action a couple years ago. I just wasn't getting that much stuff and it seemed like the gas tank was going to limit it first anyway.

 

[crawln68]

Does anyone know how much clearance there is between the top of the stock crossmember to the bottom of the bed with no body lift? I have my body off right now and I will be running a 2 inch body lift. I'm trying to figure out how much I can raise the crossmember without hitting the bottom of the bed when I put the body back on.

Example: If there is 2 inches between the top of the crossmember and the under side of the bed and I have a 2 inch body lift, I should have 4 inches to play with. I would probably raise the crossmember 3 1/2 inches.

 

[md_lucky_13]

Whoa Whoa Whoa..

If you are going to go to all the trouble to move an entire cross-member, just stretch the axle back a full 8-10".

It would be just as easy, if not easier, to remove the stock gas-tank and build fuel cell as it would to completely move the crossmember.. Then, you probably will not have to even move the crossmember. We never touched it, and the 4-link has never come close to hitting the cross member at full compression. If you are going to go through the trouble, at least make it worth your time, in my humble and un-biased opinion... %) %) (Right? hehe)