xj frame stiffining

I'm going to be putting a hp44 & 9' off a 79' full width bronco under my xj. I'll be running on 37's or 38's. Before all this I will be getting some c-channel and pretty much box in the whole frame rails. I'll run plug welds front and rear to hold it in and use bolts and a couple welds on the strait parts. That way I can still have access to the tranny and t case. I'm wondering how thick of metal I should use. I was thinkin 1/4 would be good, but that might be a little overkill. I will also be tieing a cage later on. so I'm trying to keep the weight down as much as possible with out comprising strength. Let me know what you think.

3/16" would probalby work good.

I just finish the d44/9" swap myself. While I was at it I used a piece of 3x3 3/16 angle and bolted it in 12 places to each frame rail. If you want to see pics I could probably post some tomorrow after work.

Bryan

that would be great. you should post some pics of your steering set up. If you need to you can email to me to.
[email protected]

I'm doing similar to my MJ with 1/4". The only section that needed to be done was from where the LCA pockets used to be to where the unibody widens on a MJ (just behind the tranny Xmember), only 21" total. I bought some 4x4x.250 box and cut the top off, then realized that it wont fit over that section. So I bought 4x6x.250 angle and some .250 plate to build my own channel, but with a weird ass taper... I also cut some 1" holes in the bottom of it and welded 1 1/8th nuts to the inside of it, then cut 1 1/4" holes (had to be bored out) in the unibody to recess the nuts in. It gives a really solid place to mount skidplats (future) and my stupid rusty's Xmember. I'm going to reuse the box and plate farther back from there, no sense wasting the steel.

1/4" is way overkill. Like, stupid overkill; especially if you're going to bolt a skidplate underneath it. I'd suggest cutting lots of holes in the sides of the box/channe/angle for rosette (is that how it's spelled?) welds, so you can get more surface area to spread the welds over the thin unibody. I'd weld along the top for 2" every 3" or so too; although I just said f'ck it with mine and laid 21" of weld. For stress dissipation that assumably is a no-no, but I doubt it's going to be an issue. Oh yeah, don't bother with rosettes on the bottom, welding upside-down above your head is just plain not worth the trouble...

Using channel is probably the easier way. I was just afraid it wouldn't fit because of how it was tapered, and didn't feel like buying a peice to find out.

While you'll get some stiffening benefit out of adding steel to the frame rails, it will be minimal. Structure, rather than a little thicker metal, is what is really needed to add rigidity. We need to plate our frames to keep them from getting crushed, but the cage is what will really add rigidity. Or, doing something like the T and J stiffeners that tie the suspesnion mounts together. To gain the most stiffness without a cage, my opinion would be to run a strap of 3/16" down the bottom of the frame to protect it, then run a section of boxed or round tubing along the outside of the frame from the leaf spring hanger to the lower control arm mount.

here are the pics of what I did
driver side

pass. side

my steering- I swapped out to chev knuckles for high steer

I plan on tying a cage to the angle plate in the future.

That tie rod doesn't look very high.

Lonestar said:

my steering- I swapped out to chev knuckles for high steer

I plan on tying a cage to the angle plate in the future.

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David Taylor said:

That tie rod doesn't look very high.

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The "high steer" goes hand in hand with the "shackles".






The frame boxing does look good though.

Lonestar said:

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call me nieve but where is the track bar or does the ford radious arm set up not need one?

I was wondering how long it would take for someone to notice that there is no track bar. It is not a radius arm setup. Its a unique design that only uses 2 links. It flexes like crazy, but I get really bad bump steer that I am still trying to fix.

I like what you did with the frame & the axle swap looks good as well. I dig the Ford axles under my 87 soon to swap under my '01.

Lonestar said:

I was wondering how long it would take for someone to notice that there is no track bar. It is not a radius arm setup. Its a unique design that only uses 2 links. It flexes like crazy, but I get really bad bump steer that I am still trying to fix.

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it looks like a ford radious arm on the drivers side and a long LCA on the pass side, are those cables in the center what keeps the axle centered?

Those cables are a cheap limiting strap. I used them because I was running out of time and couldn't get a real one. The big arm on the driver side is welded to the housing and then trussed though the cast diff, and that is what keeps the axle centered side to side. I know it odd and I'm certain to get some crap for the way its set up, but its different and it works really well.

could you take more pics of your front suspension. Also, how bout splurging for some real shackles?

Lonestar said:

I was wondering how long it would take for someone to notice that there is no track bar. It is not a radius arm setup. Its a unique design that only uses 2 links. It flexes like crazy, but I get really bad bump steer that I am still trying to fix.

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How in the world do you locate the axle laterally with that?????

Is your "really bad bumpsteer" your entire front axle shifting from side to side perhaps?

With a linked axle, in order to locate the axle laterally you HAVE to have some kind of structure in the Y vector; angled links or panhard.
My guess is right now it's nothing more than some minimal resistance from the arm bushings and the lateral rigidity of the coils holding the axle in place.

Greg, sounds like he's depending on his weld joint from the large control arm to the housing. This means that the weld is holding both the axle torque (rotation) AND the sideways movement. Niether are being held with a structural member, both are being held by a welded joint between the large arm and the housing.........if I understand it correctly. If nothing breaks, I guess it would work, but it's kind of taking a chance as far as I'm concerned. The bumpsteer should be coming from the vertical axle movement and the angle on the drag link.

Goatman said:

Greg, sounds like he's depending on his weld joint from the large control arm to the housing. This means that the weld is holding both the axle torque (rotation) AND the sideways movement. Niether are being held with a structural member, both are being held by a welded joint between the large arm and the housing.........if I understand it correctly. If nothing breaks, I guess it would work, but it's kind of taking a chance as far as I'm concerned. The bumpsteer should be coming from the vertical axle movement and the angle on the drag link.

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Correct. But then that means you're relying on the thrust load of the spherical bearings to resist lateral.
Those looked like 1" rod ends. I don't what the rated thrust load for them is but I suspect it's well, well below the shear rating on a factory track-bar end link; which would be the MINIMUM I would think you'd want to achieve.

In general, if you've designed a spherical bearing to resist a thrust load, you've designed it incorrectly.

I apologize for being blunt with it, but that is not a safe setup.

And I will add to compliment the rest of the work. How the frame substructure was done looks great and it's clear the owner has a pretty decent knowledge of fab work.

Edit:
I'd add too that without a panhard, your vertical axle travel will not match the arc travel of the drag link and bump steer will occur. He has a good flat drag link which should minimize it through the typical suspension travel range you'd see on the road. Since he said the bump steer is really bad, I suspect it IS the axle moving laterally causing the bump steer.

I realize it is an unsafe setup. I was my first attempt at fabing a suspension. Thou mistakes were made, I will not repeat them when I redo the front end this spring.