Serious Frame Crackage

I am just getting started on my frame and need some serious help. The frame of my '66 is cracked in 1/2 on both sides by the rear spring hanger (see pic). Currently there are two large pieces of steel holding the frame together with ugly arc welds. I took the frame to a guy who builds street rods and race car frames and he thinks he can fix the frame like new. The frame is very solid with only little surface rust. The frame has also been fixed above the front spring hangers. As it sits now, he is planning on welding up the cracks and then welding 3/16 plate inside the c-channel for support. I am wondering if I anyone has had to fix an issue as severe as this and what has worked? I am also contemplating adding 3/16 plates to the outside with fish-mouth openings on each side for support as well. Like I mentioned before, the guy seems to think the frame is more than salvageable, but I wanted to see what everyone on here thought.
Thanks,
:v6:
BenF
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In addition to the repairs you have planned, I would remove the spring hangers and weld a 3/16" or 1/4" thick strap on the bottom frame rail flange. That's what Jeep did to CJ-6 frames.

 

On the inside of the C-channel? I found a source for the inner spring hangers, but cannot seem to find a source for the outer ones. Any ideas?
:v6:
BenF

 

On the outside lower flange of the frame rails. Make the strap the same width as the flange then replace you spring mounts, redrill your transfer case bolt holes, etc. I'm trying to remember if the strap on the CJ-6 went the full length of the frame.

 

Here some info for you Ben I have done this in the past and works very well. And Both sides would make it stronger but you may not need it.

 

really dont look that bad to me, yes its broke and all, but the frame looks solid, i would say the guy you are talking to can make it as good as new or better, one thing though, if you plan on driving it on the street you may want to check your state laws, VA wont pass it for the yearly saftey inspection, no frame repairs on autos, other than straightning a bent frame, but they can get by with frame mods on coaltrucks:? and all depends on who you know too:twisted:

 

We don't have vehicle inspections in Iowa. If they started doing that at least 1/2 of the cars on the road would be taken off immediately.

 

I was thinking of making essentially the same plates but inverting the angle to form a fish-mouth. Any benefits of doing it either way? Either way I think I am definately going to have some pieces water-jetted out and welded on. The only issue I am facing is I am trying to make the jeep look as original as possible so I am trying to make the plates look a little more aesthetically pleasing. Thanks for posting the pic.
:v6:
BenF

 

The fish mouth is used to make the angle of the weld less perpendicular to the long axis of the frame. Welds parallel to the frame rails are in tension or compression along their axis, and are less likely to generate new cracks. Welds perpendicular to the frame rails should be avoided.

Sounds to me like this guy who want to repair the frame has some experience. I'd follow his advice and not go wild with extra metal.

If you can picture this, the cracks form where the frame flexibility changes, ie at the spring mounts and at the cross-members. Stiff next to flexible causes a stress riser, and this promotes metal fatigue. My intuitive understanding of this suggests that you don't necessarily want to add metal to the web of the frame (C-channel = 2 rails connected by a web). It's the rails that provide most of the strength in the frame - the web only spans the distance between the rails and acts as a fulcrum to put them alternately in tension and compression. If I were adding more steel, I'd weld new steel to the insides of the C-channel, along the rails. I'd also box the C at the spring hangers, with a piece of steel about the length of the hanger, to reduce the twisting of the bottom rail by the springs.

Look at the M38A1 frame for an example. There's also some discussion of frame repair on the CJ3B site: http://www.film.queensu.ca/cJ3B/Tech/Frame.html

 

I don't recommend this. I re-inforced the areas around my spring hangers with plate (boxing) and my frame continued to break at those plates. Doesn't matter where you start or end them. That's where you next crack will form. Also, any unused holes in the bottom rail will tend to form stress risers and subsequent cracks. I wheel the dog snot out of my rig so if yours is going to be a street Jeep you may not need to re-inforce the frame all that much. In my opinion, you either box the entire frame or leave it alone. Partial plating will guarrantee future cracks. The break shown in the pic is parallel to the plating on the inside of the "C".

 

I don't plan on off roading this jeep once I get done. It will be a pavement-only vehicle (which is why I have been looking for another cj5 that I can play with). I just figured because I am doing a frame-off I might as well fix things the best way possible. Thanks for the replies.
:v6:
BenF

 

I ended up replacing my frame with a better one but before i started on it i boxed the frame with 3/8" plate from the front to the rear. It will out last my lifetime for sure and the added weight is great for snowpolwing.