Well, now I'm in deep! :D

I welded up a temporary crossmember to the frame and cut the actual front crossmember off, in preperation for the lengthening process. (1976 CJ5, if that is important. :rasta: )

Got a couple of q's, if you all don't mind.

Here is my plan.

The frame is 3x1.5" (ID) right where I cut the crossmember off. My plan was to get some 3x1.5 (OD) about 6-8" long, and shove it in there. Weld.

Then take a piece of 3x1.5 (ID) the length that I am going to stretch it and weld that on the inner "new" piece that I just put in.

After that, take a piece of 3.5x2(ID) and basically put it completely over the "joint" that I just made.

Then, make a new 4x4 crossmember and weld that shit in.

Now, I know that my ID/OD shit is confusing, but I wanted to get this up for consideration before I lost my train of thought. :flipoff2:


So, here are the Q's.

1. How's the plan? Any forseeable problems? Concerns?

2. I know that you are not supposed to weld a completely vertical piece on another, cracks will happen, and I believe that a 45* angle is preferred. But I don't have alot of room from where I cut the crossmember off and a bend in the frame begins (prolly about 4") and I want to keep as much of the original frame material available for strength. Is a 30* angle acceptable? Or just any angle, as long as it's an angle?

3. Finally, what thickness of tube would everyone recommend? 3/16, 1/4 or should I "mix and match" (1/4 inch for the inner sleeve, 3/16th for the rest?)

Thanks for the help dudes.

Out

Sounds like a good plan if the 3x1.5 od piece is a snug fit. I'm not sure on the angle thing, but something else you could do is cut the frame (and extension piece) in a half circle at the end to increase weld area. Kind of like this
___ ___
___((___


Also you might want to put some plug welds on both sides of the joint for added strength.

The way you described is almost the exact same way I stretched my YJ frame.
I have older posts describing it in more detail.
I used 2X4x3/16 tubing, turned out to be same dimention as my frame on the 4" side but was 1/2" narrower on the 2" side.
I centered the tubing on the rail end and butt welded the top and bottom and lap joint welded the sides. Then I used 1/4 " plate over the piece of tubing (braught me out to same width as frame rail) and butt welded that in at the splice.
Used 2" straps along top and bottom that overlaped the splice.
Ground everything smooth, you can't tell where I added the length.
You only have to worry about fish plating the sides when you plate over your existing frame rails, not with the method described above. The top and bottom straps prevent the joint from opening up or cracking.
Your crossmember in close proximity to the splice will also help prevent joint failure in case it would encounter a side load.
All the strength you need is there so no worries. :D

i would think you would be fine with using the 3x1.5 od (at least .120 wall) and then use the 3x1.5 id to sleeve it. that should be plenty strong. i've heard the angle cut thing and i think most of that came from guys who used plate to patch repair a broken or severly cracked frame. i think you'd be fine with straight cuts, but thats my .02.;)