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  #1  
Old April 15th, 2003, 21:50
Handlebars Handlebars is offline
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Pics of my cracked frame due to steering box brace

Here's the history of my steering box brace. I lifted my Jeep and mounted 33 inch tires in June of 2000 with 96,000 miles on the clock. A couple of months after the lift I added Rusty's steering box brace to strengthen up what I thought was a weak point.



A couple of weeks ago (137k miles) I added a Hansen bumper and a Warn winch to it. Last weekend I took a long trip to the Arizona Strip which included about 350 miles of high speed dirt road driving. I got off the dirt onto the highway and noticed that my steering wheel was off center. I crawled underneath to have a look around and noticed a crack on the bottom of the frame rail right underneath the steering box that ran between the sway bar mounting bolts. Here's a look at the crack:



I checked the steering box mounting bolts- they were all tight, just as they have always been every other time I checked them. Closer inspection showed that the two layers of sheetmetal that formed the frame rail have buckled and split apart.





What I have surmised from looking at the damage and my recent mods and use: The steering box brace caused the driver's side frame rail to flex in a lateral direction whenever the unibody flexed. The body could handle the extra flex with the flimsy sheetmetal OEM bumper tying the front of the body together. Now that I have added the very heavy, very rigid Hansen bumper the front ends of the frame rails cannot flex independently of one another. This stress is now localized at the steering box mounting area of the unibody. The vertical portion of the framerail can still flex in and out but the horizontal portion can't so it buckled and cracked.

My conclusion is that you can get away with running a steering box brace as long as you don't have a stiff aftermarket front bumper. I also believe that there is a lot of flexing going on in that part of the unibody and it is much better to allow it to do it's thing than try to stop it and send the stress in a direction that the unibody wasn't designed to handle.

My first question is- How do I fix this? I do not have access to a welder. I will probably end up taking it to a body shop to have it fixed. Can I be content with having them simply weld the crack shut? Or should I have them weld in a strip of sheetmetal along the bottom of the frame rail? I have removed the steering box brace and placed it in a safe location where it will never harm another Cherokee, so I belive the stress that caused the crack is no longer present. I am also very leery of adding any stiffeners to my frame now that I have seen the consequences of introducing them in places where they do not belong.

The second question is- Do I even need a steering box brace of some kind? I have never found any loose steering box bolts during my routine inspections and there are no signs of cracks or stress around the steering box mounting points. I plan on staying with 33 inch tires and a 4.5 inch lift forever and have no desire to do any hardcore trails.
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  #2  
Old April 15th, 2003, 22:27
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hjeepxj hjeepxj is offline
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would a crok bracke prevent this?
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2000 XJ 5.5" Lift w/Deavers and TNT arms, 30 front w/Super 30 kit, ARB, truss, etc. 44 rear w/35 spline alloys, ARB, Wilwood discs, truss, etc. Hooligan stiffeners front to rear, Hooligan fenders, Trailready front bumper, JCR rear bumper w/tire carrier. *under construction*
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  #3  
Old April 15th, 2003, 22:49
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JEEPZZ JEEPZZ is offline
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Quote:
Originally posted by hjeepxj
would a crok bracke prevent this?
...and if the c-rok bracket would help this situation, would it be compatible with an aftermarket bumper and/or tow hook bracket??


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Old April 16th, 2003, 06:45
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hjeepxj hjeepxj is offline
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jeepzz, I know that it would be compatible with towhooks and stock bumper, it would just go behind all that stuff

bow my custom4x4 and your ARB...I have no idea...

maybe someone will shime in with good news for us
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2000 XJ 5.5" Lift w/Deavers and TNT arms, 30 front w/Super 30 kit, ARB, truss, etc. 44 rear w/35 spline alloys, ARB, Wilwood discs, truss, etc. Hooligan stiffeners front to rear, Hooligan fenders, Trailready front bumper, JCR rear bumper w/tire carrier. *under construction*
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  #5  
Old April 16th, 2003, 07:52
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BillR BillR is offline
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I installed my C-Rock this past weekend, and I have a C4x4 bumper. You just need to use some washers or bar stock to shim the bumper mount on that side out a little for the CRock to go behind it. I used washers, and I needed them on the 4 front mounting bolts on that side. The washers go between the bumper mounts and the winch cradle.
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  #6  
Old April 16th, 2003, 08:00
Paul S Paul S is offline
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Alex, while I would agree that your steering box brace added to your problem, it was probably not the only factor. For whatever reason, this exact steering box/frame tear seems to be a problem on 97+ XJ's. The easy fix (hopefully preventive for others) is to cut away 3/16" from the edge of the sheet metal from the bottom layer of sheet metal. Cut from the front crossmember back about 8" or so. This will give you a nice surface to weld the bottom & top layers together, much more so than the few factory spot welds. Since you already have a problem, I'd also take the opportunity to reinforce the entire area, you could probably buy the new ORGS or C-Rok plate for cheaper than having someone local make you something.
Paul
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Old April 16th, 2003, 08:43
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Quote:
Originally posted by Paul S
Alex, while I would agree that your steering box brace added to your problem, it was probably not the only factor. For whatever reason, this exact steering box/frame tear seems to be a problem on 97+ XJ's. The easy fix (hopefully preventive for others) is to cut away 3/16" from the edge of the sheet metal from the bottom layer of sheet metal. Cut from the front crossmember back about 8" or so. This will give you a nice surface to weld the bottom & top layers together, much more so than the few factory spot welds. Since you already have a problem, I'd also take the opportunity to reinforce the entire area, you could probably buy the new ORGS or C-Rok plate for cheaper than having someone local make you something.
Paul
Paul-
It sounds like you have some experience in this area. In your opinion, will the C-Rock brace prevent this from happening if installed prior to frame cracks?
TIA.
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  #8  
Old April 16th, 2003, 09:40
SeanP SeanP is offline
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been there, done that on my 97.

I kept hearing creaking and my steering box broke loose from bolts on two occasions. I finally found a crack in the same spot as you. Ground it down and made a valley that I could weld into (gotta love welding upside down with .025 wire). Finally, I cut a piece of 2" .25" strap and covered the bottom of the rail (drilling holes for the sway bar bolts to go thru). I also cut some .25" plate to cover the inside and outside of the frame rail, drilling holes for the steering box bolts and butt welding this to my Tomken bumber mount plates (which dont extend back like your hanson mounts).

Everything is very solid right now. I still have the steering box brace. The next mod will be to tie in the two frame rails behind the track bar mount (under the oil pan).

Alex, I just posted something on PBB to see if anyone there in ALBQ has a welder and a torch that can help you out for not much $$. If I get a response, I'll PM you.

SeanP
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  #9  
Old April 16th, 2003, 09:49
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Goatman Goatman is offline
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Alex, I think you have made a very good analysis of what caused your problem. It looks like you won't need the steering box brace with the type of wheeling you do if the frame is repaired and reinforced properly. You will need a welder, they should grind a V in the crack and weld it up, then weld together the two layers of frame on the inside seam, then add a strip of thin metal along the bottom of the frame in that area.

Cracks in the frame around steering boxes are a universal problem with 4x4 vehicles, and each vehicle has it's proper solution. On an XJ, it appears that either the entire structure must be allowed to flex, or everything needs to be braced. Bracing one section just makes a shorter section take all of the abuse causing problems. I went for years without any cracks, and I thought I was doing real good, but the metal eventually fatigues, and once I started getting cracks I got tons of them. I have repaired at least 6 different cracks in my frame around the steering box, top, bottom, inside and outside. My bumper mount has had one of the steering box bolts run through it, but I should have had them all run throught it, and I had a steering box brace. I now have plated the frame on the bottom, and I formed a plate that I welded to the inside of the frame. Personally, I think a reinforcement plate on the inside is better than one on the outside, but it's not flat in there and no one makes a plate for that. The C-rok plate should work, but I don't know if all aftermarket bumbers will fit with it, I know mine won't. Mark at ORGS has considerable experience with this situation and he also has a fix. BTW, I'm not running my steering box brace any more, either.

One question that I think is still out there to be answered is if the combination of a stout front bumper, a steering box brace, and a track bar mount brace, will solve the problem. There is considerable flex in the frame around the track bar mount, if you look down the side of the frame while someone turns the wheel lock to lock it will scare you. When the front frame is reinforced with a strong bumber and mount, and the box is braced, the frame will still flex around the track bar mount adding a lot of stress to the frame, so maybe adding the track bar brace will keep the whole area from twisting. Of course, then you may add more stress around the A pillars which are also prone to cracking. T and J makes a chassis stiffener that runs between the LCA mounts and the rear leaf spring hangers which also could be a very good idea to add. But, I think the bottom line is to make critical areas stronger but allow them to flex, or brace and support everything. I have added a full cage AND chassis stiffeners along the side of the frame rails, now I have NO flex whatsoever.
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Old April 16th, 2003, 09:59
SeanP SeanP is offline
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Alex, here's the link on PBB.

http://www.pirate4x4.com/forum/showt...09#post1452009

Richard,

Chasing the weak areas is scary. I have the bumper, the steering box brace, a soon-to-be added track bar brace (tonight if all goes well), and my subframe/crossmember for the long arms. Do you think I will still have flex issues? Can you notice all the stiffening from your cage?
SeanP
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Old April 16th, 2003, 10:10
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Goatman Goatman is offline
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Oh yeah, no comparison to before. You know how you can feel the body flex if you put your hand around the top of the door and the roof? You can feel the door move relative to the roof. Now, mine doesn't move AT ALL. I've had so many cracks in my A pillars I wanted to fix the problem for good, and I think I have. But, I give some of the credit to the chassis stiffeners/frame reinforcement that I added as much as to the cage. I need to take a few pics and post them of what I did. Plus, I welded the interior A pillar down bars to the inside of the A pillars, so there is a lot of support in that area.

Too bad you missed JV, we had a very good trip. Can you believe we had no breakage (just one cut tire) with 13 rigs and two night runs?
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Old April 16th, 2003, 10:17
SeanP SeanP is offline
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looking forward to seeing closer pics of the A pillars and chassis work.

Sorry I missed it. Gary E came over last night and showed me his cut sidewall and door "enhancements"

SeanP
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Old April 16th, 2003, 10:27
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EricsXJ EricsXJ is offline
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You guys are starting to scare me! (I have the BPI bumper with add'l welded on brackets like tow hook brackets and Rusty's steering box brace) I really need to learn how to weld so I can do some custom strengthening.

In trying to understand exactly how the brace is responsible, I have a little skeptasism still. It seems to me that if you had a rigid front bumper and NO steering brace, the cracking would be worse. The front bumper eliminates any lateral (side-to-side) movement of the frame rails as you point out. But without a steering brace the steering box is pulling at the frame rail and would result in more cracking because the frame rails can't flex due to the bumper. So in my mind, it seems logical that with a rigid front bumper you would want the steering box to be as stationary as possible so the brace can only help.

Also, are you sure the swaybar doesn't have anything to do with it, since the crack is under/near the swaybar mount? I would imagine that the swaybar is adding a lot of stress to the frame when it has big tires pulling on it. With the cracks under the swaybar mount, wouldn't it be easy enough to add a metal strip between the swaybar mount and the frame rail? That is something I could fab up without any welding. Do you think that would help?
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Old April 18th, 2003, 22:53
C-ROK C-ROK is offline
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I do believe that our frame plate would help out here.

I know there are mixed opinions about the cross frame box braces. I personally think they are beneficial but I know for a fact that they do not prevent frame failures like these.

What I've seen with the cross frame supports that grab the box at the sector shaft output is that they hold that portion of the box rigid but the box pivots about that point and still allows noticable flex at the bolt locations.

Our plate stiffens the entire area where the box bolts to and distributes the point forces from the bolts over a much larger area which reduces the stress concentrations that cause the cracks.
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Old April 19th, 2003, 00:03
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EricsXJ EricsXJ is offline
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Quote:
Originally posted by C-ROK
...What I've seen with the cross frame supports that grab the box at the sector shaft output is that they hold that portion of the box rigid but the box pivots about that point and still allows noticable flex at the bolt locations...
hmm seems like some replies in this thread have disappeared! Anyways thanks for the explanation above! Now I finally understand how the steering box brace can still allow cracks to happen. If my bumper mounting brackets weren't in the way, I'd buy that C-ROK frame plate in a second!
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