2X4 frame for my CJ2A

My present frame is in very bad shape. I got it for free, it had rusted out parts which I patched in other sections from other random frames and spliced in 12" in the center to give me extra length. It works ok, but I think in addition to all that it might be twisted. Drives fine, but I am over it. Time to get started on this if I want to be done by mid spring next year.

I have purchased 2 sticks of 24 foot 2X4X3/16 wall rectangular steel tube.


My measurements for my frame will not match anyone else's, so they aren't relevant aside from the space between frame rails. Those I want to keep stock or at least stock enough to install a rear mount gas tank. One thing that may work for others is the length of the angle from the bottom tube to the top. Its about 12". I want to replicate a bit the drop down angles. I think it may help when I stick the fenders and body together.

I could be wrong on a great many things in this thread. I hope some of you with relevant experience or those who have thought of this chime in.

This will be my first cut. I will be using an angle grinder with a cut off wheel. I used to use a worm drive saw with a steel blade for stuff like this, but the chips killed it.

 

You have my attention...

 

Good luck, my brother bought a tubular aftermarket frame for his M38 several years ago. I've helped him move it several times around his garage. Stay after your project.

 

I drive my jeep just about every day. I got it all together and running last year about this time. There are aspects of it that I really do not like that need to be fixed. Taking the whole thing apart again and putting it back together, not as proof of concept but as a "final" product will be nice. There will be significant amount of mission creep in addition to the frame that only makes sense. Swinging pedals, hydraulic clutch, rear mount gas tank, larger wheel wells for big tires... thinking about a rebuild on the SM420 and the D18 while the body is off. trying really hard to fend off the idea of a 25% OD too. 3 grand at 60 is not too terrible, but it won't last and faster isn't so good for the engine.

 

It sounds like you have a plan but don't poo poo the OD unit. I run 5:38 gears and OD in the 3B and have done many trips across this state and to Utah. One of the best things in the Jeep along with the PTO winch. Well, the V6 doesn't hurt either, and two gas tanks.
Keep on with your build.
I can't say much, I have most of the parts out there for another 3B build...

 

The most important bit of advice I could give you is to make absolutely positive both frame rails are identical. This will require a jig of some sort, or at least a very accurate full size drawing on a floor that you can lay the parts out on and pull measurements from. Tack both rails together identically, then weld them both in sections at the same time. If you weld one 2" section on one rail, weld the same section on the other immediately after. This process will ensure that any warpage that happens will be the same on both. Ideally, you'd have a 20' long, one inch thick table to build a jig on... Hey, we can dream, can't we?

 

I am not Poo Pooing the OD. I want one. I just don't want to spend a grand on it. I assume its total worth it.

I have no perfect table. Its not really as flat as it needs to be. It is 12' or so. I will be fine. I don't see a lot of warping because I am not welding long lengths. Simple frame. I might weld the rails together as suggested. I Know one guy who is doing this who does have a frame jig, Tarry99...

Whatever I do its guaranteed to be better than what i am driving now.

 

I worked in one steel shop for a while that built parts for the giant printers that print the wraps that they use on billboards. The printer head would travel back and forth on this 8"x8"X1/2" x 20' long square tube, so it had to be absolutely straight. One small 2"X1/4" bracket got welded on the center of this tube, and it would warp this massive chunk of steel almost 1/4" on both ends. It doesn't take much.

But like you said, it won't take much to be better than what you have!

 

I didn't have a frame jig, but carefully measured tacked, braced, and measured (and checked and rechecked) everything. Use a stick of heavy rectangle or square tube as a flat surface to work and clamp against. The bigger the better to resist pulling forces of the weld cooling. Plan it all out on pieces of wood first, cut them to what you want, lay them out on your garage floor, think about them, let them alone for a few days, look at them again, etc. Then start tacking, bracing, measuring, etc. Also, weld some on one side of rail, then some on other, etc. to keep warpage down. Fillet all welded surfaces. If you can find my Family CJ-6 thread, you will see how I did it. I don't have a jig (wish I had garage room for one but space is at a premium) but my frame is straight and my CJ-6 tracks well and doesn't wear tires badly.

 

I cut out the pieces with an angle grinder. The cuts are ok, not perfect, but will be fine as the thing is going to get 3/16 or 1/4 strap in the angle. depends on what I find or buy. The length of the angle is too long for me to use any other tool I own. I can make the straight cuts with the portable band saw. Since I cut some of the pieces long by mistake I used it to shorten them up. Works as good as a hack saw but is a whole lot easier and faster.

This is the initial mock up.


It looks strange. Remember my frame and body are 12 inches longer in the center. I need to have approximately 57" in the center from where the frame starts to angle up from one end to the other. What I find is that I need 40" front and rear for the OAL of the top rails. The angle is 12" long, so thats 28" that is fully 4" taller than the bottom rail. I have made this measurement at least a dozen times. What I also find is that my present frame is different by an inch or so on one side compared to the other. Spring mounts aren't in the same places either. Drives fine though. How is that possible? Who knows..


Its all my fault as I am the P.O. that everyone laments ad infinitum. I would say I am Bubba, but that name is already taken here...so I am just PO Chris....

 

None of this is ready to be tacked. Just clamping it up to take a look. Everything needs to be clamped together, the angles ground evenly and the mill scale ground off in prep for welding anyway.
The OAL length of the rails is about 137". my present frame is 136 OAL. That can be trimmed later. The important part, I think, is the distance between where the top piece starts to angle upward. I need to be able to clear a part of the body in the rear and in the front I want to make sure the headers clear the frame with minimal inner fender work. The long angle also gives me 12" to weld instead of a shorter run if the angle was shorter. It will get plated in addition to that.


I can't get any side view shots because thats all the wide my work area is. Thats quarter sawn white oak in the background. Boy will that burn hot if I light it on fire.

 

Totally makes sense. I will probably use 3/16 steel. That gives me 3/8 I need to make up for. I haven't cut it that close, I don't think, and i plan on putting the tub on this frame before I do any finish welding of body mounts for sure. Plan is to weld it all up except for body mounts, engine mounts and spring mounts. At that point I will take apart my present jeep and fit it all together, then finish weld. I most likely will be doing a significant modification on the tub anyway, so if i don't get it right, I will make it right. If all that fails I can reuse my 1" body lift. I would rather not though.

 

Looking good to me so far Chris. I wonder if it would beneficial, while you have the two rails lined up together, or maybe after the initial welding is done and they are side by side, to make a few scribe marks across the top and bottom of the rails, with a square, as reference points for later. I am watching this thread closely. Good luck, sir, on your latest adventure.

 

Yes, I have already scribed the center of the bottom rail. The top rails can move in or out a bit and still give me about 4" thickness through the angle. I will DEFINITLY make witness marks to measure from that are square to each other. I plan on using the extra 20' of 2x4 tube for cross members. If after all is welded and If I am only out 1/16 or 1/8 I will be very happy. I am coming to the realization that I will not be able to finish weld this frame and just plop the drivetrain and body on the rolling chassis. It might be less than cold out when i start taking this jeep apart.

 

Chris...........With all that metal your going to cut one of these Evolution 15" cold saws might be something to look at? Cuts that tubing like Butter.

 

Yes, I would love to have a cold saw. They are very nice. I used to use a steel cutting blade in a worm drive saw. That worked well too, but I killed both my worm drives. 250 bucks for the saw and the blade buys a lot of cut off wheels. I also have a 14" abrasive cut off saw. For the straight cuts the hand held milwaukee portaband works ok. I have a 20" bandsaw that if i either found a transmission for or fabbed up some jack shafts or bought a variable speed drive for the 3 phase motor on it, could maybe get the speed low enough to cut steel. I just don't want a project so that I can do my project.

 

I've always thought about tubular crossmembers, passing through both walls of the box steel frame rail, when i think about building my own frame. I don't know, from an engineering stand point, if this is a good idea or not. Just something I have thought about. Welding it at both pass through points (both walls of the box steel) on each rail.