How far can I move my rear axle back?

[Socal Tom]

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.

Well, I knew there was a notched cross member under there.
Tom

 

[sstlaure]

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.

No hacking (yet). With the 33's everything still clears (5" susp, 2" body), but when I go to 35's (or the paddle tires) I'll need the clearance. (the wheelwell placement on my glass body is screwed up anyway, the RH wheelwell opening is 1.5" further rwd on the body, so I'll straighten those out with cut-out flares

 

[Projp]

I moved mine back 7", which is about the limit without extending the frame. I cut the 23 gallon tank to fit between the crossmenber and rear of the bed and raised it so it was flush with the crossmember. I havent had any problems hitting the crossmenber or tank. I have set my bump stops so that it won't happen. The only possible issue might be if I was into jumping it, (which I am not, it is a crawler). Crossmember clearance is usually only an issue on full compession of the whole axle. Usually in crawling only one side is stuffed thereby reducing by 1/2 the amount or uptravel. I have a 3.5" lift which factors in. The bump stops will limit my stuff a little but I can ony use so much running 37" tires.

 

[crawln68]

I moved mine back 7", which is about the limit without extending the frame. I cut the 23 gallon tank to fit between the crossmenber and rear of the bed and raised it so it was flush with the crossmember. I havent had any problems hitting the crossmenber or tank. I have set my bump stops so that it won't happen. The only possible issue might be if I was into jumping it, (which I am not, it is a crawler). Crossmember clearance is usually only an issue on full compession of the whole axle. Usually in crawling only one side is stuffed thereby reducing by 1/2 the amount or uptravel. I have a 3.5" lift which factors in. The bump stops will limit my stuff a little but I can ony use so much running 37" tires.

Nice job! I noticed that you added a little rear fender skirt to center your wheel in the wheel well and added to the length of your inner fender wells, looks great. What else did you have to modify? Did you cut and weld in material to extend the tub too? Or did you just do the outer fenders and inner fender wells?

 

[Projp]

I didn't do anything with the tub, just the wells and fenders. I will see if I can get a couple of pictures of the finished product.

 

[crawln68]

I didn't do anything with the tub, just the wells and fenders. I will see if I can get a couple of pictures of the finished product.

That would be great. If you went back 7 inches, you must have gone right to the very end of the frame rail, huh? Did you reinforce the frame right there at all?

 

[Projp]

That would be great. If you went back 7 inches, you must have gone right to the very end of the frame rail, huh? Did you reinforce the frame right there at all?

I went right to the end of the frame then filled in the holes with 1/4". My bumper inserts quite a ways into the frame rail so it is double thick there really stiffing things up.

 

[crawln68]

I went right to the end of the frame then filled in the holes with 1/4". My bumper inserts quite a ways into the frame rail so it is double thick there really stiffing things up.

Cool man, I like what you did. Did you notice a difference having the extra wheelbase?

 

[Projp]

The extra wheelbase IS noticeable, it is alot more stable, and I didn't have a problem with breakover. We went to Moab for E*S and ran Cliffhanger, Behind the Rocks, and Hells Revenge. Before the stretch I was always slamming my 23 gal. tank, I didn't touch anything on the rearend this time. The pictures are not to good, it is snowing and dark.

 

[Madgyver]

Projp,
Looks really nice. I think I'll be doing this with the 77 frame I'm working on.