Frame cracks / fixes needed

Attached are pics of the front frame horns on my old 67 cj5. We just returned from running the Con, and in trying to figure out what needs work, we decided that it was past time to fix these cracks. The jeep sports an old Warn 8000 winch (5674?) probably a good thing we didn't need to use it.....

I did a search on frame cracking on the forum, and found several helpful posts using different techniques. Also lots of cautions about not causing additional cracks down the line.

And I guest thats my question, can I get some feedback on what has worked well over time, and what hasn't? Also any pics you have of completed work would be helpful.

craig

 

I welded 1/8" plate on the inside and outside of the frame rails. it really stiffened up the frame. the holes for the tow hooks have a piece of pipe welded in the frame to prevent pull through as well.

 

That looks like a pretty good repair. JMO - I'd try to add as little metal to the frame as possible. Depending on your philosophy, you may want to keep the flexibility, and boxing will stiffen the frame a lot.

This failure, cracks where the hangers attach, is quite common. You can see how the force of the spring twisting the hanger would make the bottom frame rail crack.

If I were to repair it, I'd add a boxing plate that is not much longer than the length of the spring hanger on the inside of the frame horn. This would transfer some of the twisting force of the hanger to the top rail.

I'd remove the hanger, weld up the crack, and put a plate on the inside of the frame rail (bottom of the U) over the cracks, welding only along the length of the rail. Don't weld across the rail except to weld the crack - only weld along the length. You might drill a hole at the end of the crack to stop propagation. New hangers are cheap and available, so I wouldn't make any effort to save the old hanger. You can bolt the new hanger in the same location, and weld along the length of the hanger as the original had.

There are a couple of articles on frame repair at the CJ-3B page:http://www.film.queensu.ca/CJ3B/Tech/Frame.html

 

66CJ5 / Timgr Thanks for the pics and advice, If I read you correctly, you are each hitting on the two schools of thought on this repair. ie. box/plate to the max. Or plate only the area needed the minimum amount.

What isn't that obvious in my pics is that the Lt Spring hanger is cracked almost 360 degrees around the hanger. For that reason I was considering removing the spring hanger, boxing the entire front of the horn, and then trailing a piece of the box back to the outside of the frame near the cross member, using a fish end > and stitch welding it to the frame.

thats probably clear as mud.... scratching that idea for the moment, would repairing the cracks and adding only a small plate to box the end, hold up for long?

craig

 

As a welder, I can tell you that it depends on the quality of your welds. If your proficiant with a MIG and do the prep work right it will last a lifetime.

Greg

 

I've been chasing cracks in my frame for way too long. My experience is that if you partially box the frame you just guarantee it's going to crack where you ended the boxing. I'm pulling my tub this winter to box the whole thing and be done with it. Of course it depends on how much you wheel it and how difficult the trails are you run. I believe the suspension should be doing the flexing, not the frame/tub. Just my .02
If you do put in short sections of plate, don't weld all the way to the end. Stop the weld about 1/4" from the ends.

 

I agree with Lynn:

"For yours, nothing so drastic should be required. Drill a hole at the end of the crack to stop propogation, then grind the crack slightly into a V... preheat it to somewhere around 250*, and weld it up. Mine was welded that way about 15 yrs ago, crack never came back (almost exactly the same crack)"

I think boyink did the same thing, mine also is the same and this is what I plan to do.

 

thanks for the input, and pics...

To get some more ideas, I also took it to the local welder, he thought the frame should not be welded on unless absolutely necessary, which in my case it is. his plan was to add box metal inside the rails then partially box the rails and make it a noseeumm..... $500 give or take...

craig

 

The compromise approach may be the worst option. IMO the most likely place for cracking is the junction between some flexible part of the frame and a rigid part. If you box the frame horns, they become rigid and concentrate the stress of flexing at the junction between stiff and flexible.

My notions of this are based on my physical intuition, what I've read, and what repairs I've seen while I worked at the Jeep dealer. The race cars there weren't boxed, but instead strapped. Strapping puts, say, 0.125x1.5" stock (straps) along the entire length of the top and bottom rails. This stiffens the frame some, but not like boxing, since the x-sec of the U isn't closed. It also prevents having a very stiff boxed section that abuts a more flexible open U section. Jeep also uses strapping to strengthen the CJ-6 factory frame. Straps are stitch-welded along the length of the frame, not the width. This places stress parallel to the weld direction, not perpendicular, preventing concentration of stress at a single spot (and starting of a new crack).

IMO Greg's comment about weld quality is central to a long-lasting repair. I don't really understand Posimoto's comment about stopping the weld 1/4" from the end. To me this seems like the opposite of what you'd want to do - concentrating the stress at the weld in the resulting gap. It seems the same as what the CJ-3B page tells you not to do, sp. undercut the ends of your welds.

 

I like this idea for a repair. I have a crack on the frame where the leading spring hangar is located. Would this repair (cut out the rot and crack) and weld in your own 1/8 inch steel work in that area?

 

I had another question: Would a 110 volt welder be enough to weld the frame up? I only ask cause I dont have a convenient 220 receptacle near the carport. Im planning on taking a welding course at the local com. college and then maybe buy a decent rig at the local home depo. Are the Harborfreight units anygood? I would normally buy the good brand but I dont know how much I would use the welder...

 

Mine was cracked almost identical to CI CJ (on both sides). I cleaned the area up with a wire wheel and grinder to give a fresh surface, then had my friend/co-worker weld it up with a 110V Hobart flux core unit (model 125?). It has held (with some abuse on the trail) the past three years. I didn't drill the start of the crack, but I did grind it pretty decent.

I think it is stronger than before (my co-worker welded for a living for ~8 years). He grunted about the flux core unit, but honestly he had no splatter and the welds penetrated like crazy.


IMO, the boxing/plating is not really necessary. If it is properly welded and cracks again , then I would consider it.

For $500 he is talking about boxing the WHOLE frame? No way would I pay that for just this area.

 

Just so I get this right, he welded right into the crack? No cutting, just grinding and cleaning the area right?

 

yep...not saying it is the best way, but it has worked for me. I wouldn't have attempted it, and I still wouldn't, but a skilled welder should have no problem.

 

hmmm....many different views here. i had the same cracks also. i used a 110 turbo mig. i ground the v shape, welded the crack, then boxed the frame with 3/16. but only boxed about the length off the spring hanger. i never heard of drilling a hole at the end off the crack but it seems to be a decent idea. i have alot to do before i put mine on the road to see how my repairs hold up. but the mig did do a nice weld

 

yea same here, I have many repairs to do before mine hits the road as well. I appreciate all your input.

 

Wont that cause another crack just outside the boxing though?