Boxing the frame

Well now what to do. I liked the idea of boxing for addl strength and to be honest I like the way it looks. I plan on using the jeep to mostly drive around in the summer a couple trips to the sand dunes a year and occasional winter cruises. Since a don't plan any serious rock crawling and under normal driving the suspension will absorb most of the travel I may try boxing the frame and see what happens. Any more input is always appreciated. Any one have negetive results after boxing the frame?

Henry

 

Well heck Hank. If you're not planning on doing any trail riding with it, why bother with the boxing? Man that's like an oxymoron. You need to box the frame if you're going to trail ride. Or... If you're going to trail ride you don't need to box the frame.

I'm still confused.

Sparky. Tell us again why to box or not to box? And I'm not being facesious (sp?)...I really am wondering. I'm assuming there are benefits and deficits, but if the deficit is the loss of flex, how does that happen? Does an open "C" style frame flex more than a box frame and if so why?

 

That was me that said that but thanks. Now I'm convinced that if I had the chance to with a clean frame and the will to do it, I'd box the whole frame and if I wanted flex, I'd set up a flexy suspension. I've experienced those cracks @ the front horns where the hangars are. Remember Tellico in May of 04?

 

Back in the old days, flex in the frame was a good thing, as no one had long travel shocks, or even decent springs. Nowadays, the rig that wins the RTI comp every year in our club is a Samuri on spring over stock YJ leaves. (My TJ spanks everything else, but doesn't come nearly close enough to matching the flex of his rig)

I'm all for partial boxing of the frame, to keep it from cracking at the hangers if you are looking at getting decent flex. Here's why-

It's not the flexing of the frame so much as the fact that when the suspension flexes a great deal, you are actually twisting the springs longitudinally. What do you think the effect on the spring hangers is??

Yup, they are being twisted as well. The hanger is a big lever working against the lower flange of the frame. Partial boxing is needed to keep the hanger from fatiging that section of the flange.

Now on the later CJs with boxed frames, cracks come for a couple different reasons. The main one is the fact that the spring hangers are riveted to the bottom of the frame, and then have a very short section welded to the outer side only. Most of the cracks on 'wheeled rigs with this setup start right by this weld. The other reason (Besides rust from the fact that the boxed CJ frame is impossible to clean crud out of) is that instead of boxing in the "C" channel, Jeep just added another, thinner "C" to the inside if the first one. The rivets are on the outer channel, and along with the fact that the inner and outer don't flex the same way, both combine to seperate the weld between the innner and outer channel.

After that, the hanger is able to work against the outer channel the same way it would on an open channel frame, except for the fact that that only part of the weld is conpromised, and the outer channel only flexes up to the end of the seperation. Usually a crack forms on the bottom of the frame where the channels are still welded to gether, and then the crack run vertically up the frame. (Where it is impossible to stop without drill stopping, welding, and fishplating)

I personally don't like full boxing, as it adds too much weight, is a pita to bolt a crossmember to, and makes the frame a safe harbor for salt, mud, hornet's nests, and small rodents.

 

I must go back to the cj-5 we have here. most of the cj-5 are military, and we have a lot of them. parts imported to israel, here they added some improvements and assembled them. those jeeps participate wars, parachuted, carry heavy weight and weapons and all kinds of weird things. after about 10 years of service they sold to private hands.

Back to our subject: all frames are totaly boxed and they had more spring leaves on front and rear. i dont know of any critical problems on their frames, they regarded to be strong, after many years. driving in such a jeep is very tough !
(those days i restore a 1960 willys cj-5 (open frame), so i will be able to compare the two frames, in 2 years from now...)


Ziv

 

I say box it if your going to trail ride alot. If not then dont.
Flex should come the tires, leaves, shackles and the shocks help control all this.
These frames and these old Jeeps were not built with what some us do to them.
Tellico is a prime case here. Years back 15/20 years ago, the trails were not as hard as they are now.
30" and 31" tires were large. Nobody ran lockers etc.
From my dragracing days frame flex is bad as it cause body parts to rip and break, much like flex on our Jeeps do. Joes Jeep flexs unreal, and he has the cracks in the fenders to show for it.