2x4 frame questions

My frame is a pieced together POS. It is remnants of a 2a, 3b and maybe early 5. All I am certain of is that its slightly twisted and not the kind of work I am capable of doing now.

So, the question is "do I start down the road of building a 2x4 frame for it"?

I have looked at others builds and it seems pretty straight forward for the most part, but i have some questions. The tub mounting is simple, but the fenders seem to need some modification to the inner portions. I have fender headers for my 225 so thats already been done.

I guess I just need some insight from others that have done this before about some of the problem areas they encountered during this fabrication. I do realize this will have a good bit of "mission creep" as I dive in. I am sure I will go hanging pedals and power brakes, although I really like the floor pedals...

To fix all the not so good aspects of my jeep would be nice.

I would like to drive my jeep around while I make the frame and weld in mounts, then in the winter swap stuff over. I assume by late spring I would be close to finished, maybe?

Thanks

 

My philosophy is do it right or don't even bother.
If I was going to build a custom frame I would have the complete jeep fully detailed in my head or better yet on paper.
The build jeep is completely held together by the frame so all minute detail should be foreseen before starting.
I would start with 2" x 4" chromoly tubing @ 1/8" wall thickness.
Chromolybdenum withstands flexing exceptionally well.
I would cut and tig weld to reach the desired form.

1/8" not 1/16"

 

there is some good info on Pirate4x4 on cj frames and builds , chromoly is good if you tig and have the budget and are racing it

 

2x4 mild steel rectangular tubing is your best choice.......for either TIG or MIG with at least a .188 wall thickness........some folks have tried using .120 wall but do to the normal bracketry required for the motor ,transmission & suspension mounts which all need to be at least .188 or in some case's .250 thickness material , while attaching those brackets to a lighter .120 wall frame tubing leaves your connection weld point at risk for cracking and eventual failure................not building a Race Car here so a little extra weight is not your enemy!

 

Thanks. You might know something bout this. I will probably TIG weld the whole thing. I could MIG weld it, but that welder lives outside and my TIG welder lives inside with a nice table to fabricate stuff on. Plus I really like TIG welding. Makes me happy when it looks nice.

I have looked on pirate, i have seen some good ideas, but this is my forum of choice. Questions I have are, how difficult is the body and fender mounting since the fame is 2 straight lines and not the rounded old style frame? Does it even matter? This solution to a terrible frame seems so easy. tell me why I am wrong.

Thanks

 

Maybe it is not a concern to you, but I have found modern mild steel is extremely prone to severe corrosion.
For example I have built trailers that have been completely destroyed by rust within ten years, here in the Salt Belt.

Perhaps due to recycled material and loose manufacturing standards - but it has definitely gone downhill in recent years.

I would give plenty of thought to wall thickness and corrosion protection. Or finding a solid original frame to reuse.

 

I still think full chromoly with double and triple butted joints.
Tig welded chromo is extremely strong.

Or just find, fix and modify an original frame.
Those are generally around .140 thickness (?) and were never factory butted.
Much, much easier to go with an original frame !

 

Tig welding is fine .........but the A-500 Mild steel rectangular tubing is Hot rolled , and there will be some carbon flashing left on the surface .......so good clean ground joints are a must for Tig welding.....the same can be said for most Mig welding also. I like using the MIG to tack the chassis together.......then switch over to the TIG if you want to finish.

I'm not sure I understand your next question regarding body & fender mounting........Jeep main frame rails are pretty much straight , short of the kick ups at either end. In some cases a kick in and up helps for inside wheel tire clearance for turning when axle width and tire stick out are a concern......a wider frame in the middle is more beneficial for roll bar support and larger drive trains with auto transmissions especially when exhaust systems may be sharing the same corridor. It also helps to be a little wider in the middle of the rear for a larger shallower fuel tank...............In my build I'm using all of these things to take advantage of space while using larger 1-ton components......

The frame building part is a moving target, main rails are pretty much straight forward , but no cross members should be permanently installed until every thing else has been worked out for placement and width.........your body as will as the drive train will probably be on / off or in / out of your chassis several times before it's finished.

As far as rust or corrosion , you folks in the east obviously have some issues with salt.......Modern ASTM steels are far better than the low quality scrap metal being used on early Jeep frames. If your going with Rectangular tubing you have two choices 1) seal it off or 2) if you feel that it will be run in deep or salty water allot then leave the ends open and flush it out after it's been used.....in either case when that new frame finally fails due to rust you'll probably be just a memory.

I like using Chrome moly and use it all the time in the Race Cars.........but that is only for the weight saving benefits of that material. On a Roll cage in the race car I use 1.625 OD x .083 wall Chro/Mo @1.384 lbs per foot..........using DOM Mild Steel If I remember correctly the specs for the same strength would be 1.750 x.120 wall..at about 2.0795 lbs per ft.......so a swing of about .69 lbs per foot heavier for Mild Steel and half the price of the Chro/Mo.......as I mentioned before weight is normally not your enemy in a Jeep , but if your looking to put that race car on a diet that .069 pound swing over a 200 ft full cage average material length needed is about 14 lbs...........and will worth the savings!

Also in order to properly weld chrome moly, one has to pay close attention to a host of other issues like the shielding gas used , the proper filler materials for each application, there is also a need for post heat normalizing of joints and some folks even use low pressure shielding gas inside the tube to keep the weld zone inside clean..........totally acceptable in the Racing World where ultralight materials are being welded together.........But hardly worth it in a normal Jeep.

 

Interesting specs there Terry. Thanks. 14 lbs is nuthin' in a driver jeep. I can see it in a race application. Sure doesn't make financial sense, to me, considering what I suspect to be a substantial cost difference between the 'moly and mild steel.

:lurk: Can't wait to watch this build thread. I love this stuff. Often thought and dreamed of doing this also. Maybe someday.

 

Hey hey now. ....i haven't bought the steel yet. Just thinking about it before i go do anything foolish.

You make a good point about the mill scale. In order to TIG well I really need that stuff gone, lots of grinding and a good chamfer is needed to have full penetration on the welds anyway. Outside work and tacked with the mig is a good idea.

Making the frame perfectly straight from one end to the other is easy, but maybe not the best idea if I want to inboard exhaust and go out the back instead of the side and the addition of a rear mount gas tank would be nice not to mention the ability to tie in a roll cage easily and effectively to the frame.

I am not concerned bout rust. everything is gonna be fully welded shut with any through bolts welded with tube or pipe inside.

So, rear mount tank, points for roll cage. the project creep is creeping..

 

Plus If you weld all the tubes closed then the frame itself could be used as an air storage tank.

 

Wait, i thought I was the hot air storage tank?

 

No, that is your seat cushion.

 

Its real slow at work. I have free time and building the frame is easy. The hard part is planning. I have to decide things like tank placement, shock mounts and if I want a full cage. Everything comes apart to do this after the frame is done and there could be the mission creep. Rebuild the SM 420 and the D 18, do i use sliders instead of shackles? The body need cut for big tires to clear etc.. I want to drive this thing too with minimal downtime but this could stretch out for a year or 2 easy.

The good thing is that i know all the mechanical aspects of my jeep work great aside from a funky 3rd gear shift with the SM 420. The body is already stretched 12" and is ok with the exception of the bed which i did a poor job of 8 years ago. I know I had an exhaust valve that needed to be replaced, but I didn't. I lapped the valves really well and it runs strong anyway. the rabbit hole is deep..

Its hard for me to NOT just go out and buy 3 sticks of 2x4 tube right now.

 

You can buy aftermarket frames made of tubular material. Matkins? My brother has one in his garage, a real pain to move around. I don't know why he hasn't got it under his M38 yet. Yet,again, I have most of another 3B back there and I'm not putting it together so as the old joke goes, "People who live in glass houses shouldn't stow thrones". Yeah, a groaner and I don't remember the lead in to it anymore.

 

Another option is to find a CJ-5 frame and use that. There's an article on the CJ-3B page about putting a CJ-5 frame under a flatty. The rear of the CJ-5 frame sticks out a little, or you could trim it off. http://cj3b.info/Tech/FrameCJ5.html Used to be that M38A1 frames were pretty easy to come by - they have extra boxing already. And a handy machine gun mount.

 

I have and am seriously considering this. i know of a pretty solid one for cheap, but i gotta drive 150 miles to get it. I also need to hack it up anyway to get the extra 12" in the middle and i am running 2.5" springs so the stock mounts go away. The other issue is that welding old steel never is easy and TIG welding is pretty much out since the rust never goes completely away. In the end I am still dealing with a host of similar issues that i have now, albeit less so.

I will say one thing though, a nice machine gun mounted 30 cal persuader would really make those traffic altercations MUCH easier to deal with. That could be the deal maker!

 

Here is a PDF for a jeep frame. You can skip the full length side plates and just fish plate the joints as needed. This frame has been wheeled all over the southwest and on two ultimate adventures. Search username Meiser and his build thread rango for the full plan.

http://www.expeditionportal.com/forum/threads/58343-Rango-1942-Willys-MB?p=1074445#post1074445

 

I read that guys stuff. Its fun to read and he has a good writing style. I and almost everyone in the known universe loves that jeep. I need to sign up to view his PDF though. The basic frame is really easy, its the details that I need to think out. Like i said, I could build it in a day, but then I would be back tracking if i don't plan ahead things like if I want a rear tank. The under the seat thing is fine, but I really want to lower my seat to allow for a better lower position. I would also like more than 10 gallons of fuel. Changes right now that deal with my frame are a PITA because the PO either welded on angle all over or I welded in patch pieces or there is a rust that blows up when you try and weld etc.

I would really like to build a finished frame before taking any piece of my jeep apart then in the winter take off the body and fix some poor quality stuff and cut out the rear wheel wells to accommodate the 35" tires i am running. i also want a real swing out spare tire mount too on the rear. I will need to repaint the fixes at that point and welding the tailgate up would be nice as its useless for me.

If I go body off then it will probably be a great time to go swinging pedals and power brakes. Hydraulic clutch will facilitate that as well. None of this is difficult, just time consuming and I don't want to NOT drive my jeep around.