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If you are experiencing body rips or bulges with your FJ, what setup are you running?

  • Stock bumper, no lift

    Votes: 147 28.9%
  • Stock bumper, w/lift

    Votes: 51 10.0%
  • Stock bumper, w/lift and 285/70 17's

    Votes: 51 10.0%
  • ARB bumper, no lift

    Votes: 6 1.2%
  • ARB bumper, with lift

    Votes: 22 4.3%
  • ARB bumper, w/lift and 285/70 17's

    Votes: 44 8.7%
  • WARN bumper, no lift

    Votes: 7 1.4%
  • WARN bumper, w/lift

    Votes: 14 2.8%
  • WARN bumper w/lift and 285/70 17's

    Votes: 18 3.5%
  • ARB bumper, w/lift, and 255/85 16's

    Votes: 3 0.6%
  • ARB bumper, w/lift and 315/75 16's

    Votes: 8 1.6%
  • Demello bumper, no lift

    Votes: 2 0.4%
  • Demello bumper, w/lift

    Votes: 12 2.4%
  • Demello bumper, w/lift and 285/70 17's

    Votes: 14 2.8%
  • Road Armour bumper, no lift

    Votes: 0 0.0%
  • Road Armour bumper, w/lift

    Votes: 10 2.0%
  • Road Armour bumper, w/lift and 285/70 17's

    Votes: 12 2.4%
  • All-Pro Bumper, no lift

    Votes: 5 1.0%
  • All-Pro Bumper, w/ Lift

    Votes: 16 3.1%
  • All-Pro Bumper, w/ lift & 285s

    Votes: 32 6.3%
  • Stock with Skid Plates

    Votes: 34 6.7%

  • Total voters
    508
3481 - 3500 of 3504 Posts

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Thanks for the heads up Kurt. This is fascinating. I just went down and inspected mine too. What I found on mine is that there isn't any crack there, but if I look down from the top, I can find a subtle buckling in the sheetmetal, bowing inward toward the engine compartment on both sides. Just as everyone else here is showing, it's at the crumple zone closest to the firewall.

I'm running the ARB bumper with winch.

I have 3" of suspension lift and 35" tires.

I've carved crap out of the way to make the wheels clear all the way around, but in deep compression, I can still just get the top of the tire to kiss inside the well. It's a rare event, and I don't think that it imparts any force of significance.

Irrespective of bumper choice, the 4500 pound vehicle has all the ingredients necessary to flex the frame a bit when it gets into a twist. Although the body mounts are rubber, they still impart a force. If the bumper is brought up against the body, I'm sure it can impart even more force, but I don't think it's a deal breaker. The beauty of physics is that there is no "immovable object", there are just limits to the sensitivity of measuring tools.

This is flex fatigue. Note that the crack is happening ON TOP. Ask yourself how to apply a one-time force necessary to get the metal to TEAR at that location. It would have to be bent OVER something with down pressure in front and behind, while up pressure is applied beneath ... or some equivalent mechanism to get this to be a point of bending. That was the thinking in guessing about wheels hitting inside the well. If the body is supported in front and behind, and the wheel pushes up in the middle, that would explain it. Unfortunately there are crumple points that are much closer to the place over which the wheel touches, and if you push up inside the well at the point of contact, you can flex the actual well, without moving the stiffer support box above. The wheel wouldn't be able to do it.

That's NOT what is happening here. The twisting motion of the frame in offroad driving conditions is only partially being damped as it is transmitted to the body. The rest of the body has a lot more stiffness because of the height from floor to roof. The engine compartment is much flatter and therefore has less vertical stiffness. The body is getting "flexed" up and down (and probably in TWIST) just like the toe of a well broken in running shoe. This bending effect is amplified at the level where the low profile engine zone meets the high profile body zone. High flex meets low flex.

When metal is bent back and forth, it ANNEALS. This is a process of work-hardening that uses heat and compression to pack the crystal structures closer together. Annealing trades ductility for hardness. This is why medieval blacksmiths heated the steel bar red hot and hammered it thin before sharpening it into a sword. This is why bending coat hanger wire back and forth eventually warms it and then snaps it.

What you're seeing is an annealed flex point which eventually got too brittle to flex, and subsequently parted.

I think that the bumper may contribute to this to some degree, but my guess is that you've uncovered a design flaw that could become evident in any FJ after the right number of twisty trail runs. I'll guess that it happens sooner if the bumper design transmits more bending moment, but like the coat hanger... big bends or little bends... it eventually parts.

Ok... if that's the diagnosis, then what's the management?

My guess is that if you try to weld some sheet metal over that area, you'll just move the flex point to one of the welds and repeat the cracking process. You'd also de-engineer the crumple mechanism to some extent. I doubt it'll mean a thing if you actually wreck, but when your passenger is killed and their lawyer gets ahold of the investigator's report, you could be doing a lot of explaining. Realistically, for me, though... I doubt this would be a problem in the face of all the other massive offroad modifications I've got going on. When they get in underneath and see where I've actually cut and welded on structural points, I think the body issue would be pretty trivial.

My first thought was actually to go the other way. If this is where it's going to flex, let's not fight it, let's actually free it up to do what it has to do. I was thinking about actually completing the fracture by grinding out a quarter inch gap and then affixing a sandwich in the gap made of two pieces of sheet steel and a layer of urethane. However, I don't see that as being any better than the welded repair in the scheme of liability (which bothers me a little bit) and urethane has a habit of squeeking (which actually bothers me more). In the end, this seems like more work than it's worth!

Therefore, my plan will be to let it happen and then just leave it. If there has to be flexion at that point, then thats what it will be allowed to do. I looked at all the parts anchored onto the body forward of that location on both sides, and absolutely none of it would suffer. There's the radiator (which is attached to everthing else by flexible hoses) the battery (attached with wires) and some various other tubes and wires that I can't see having a problem with additional flex. The air system is rubber. My ARB compressor is on top of the wheel well, but its connected with wires and hoses.

If there's annoying flex and rattle after that, I'll weld on some supports and destroy the flexion point... and I'll just see what happens.

It's only body metal. ;)
Well, I think this is a very good post. Torsional rigidity of a ladder frame is not the best and why monocoque construction is much better for torsional rigidity. I have read where some of this ends up splitting the outside fender too.

Adding more weight to the front with heavier bumpers and equipment only adds to the problem.

The best fix is to fix the frame and that could be done but it would take a separation of the frame from the body to achieve. Evidently the engineers understood this and changed the frame. How do you achieve more torsional rigidity with your ladder frame?

If you build a simple four sided frame out of wood, you can flex it easily. Add an X between two of the sides and it adds some torsional resistance. The bigger the X the better. You will notice that the FJ has no X between the frames.



Back to the wooden frame. If you add a panel across the whole frame and attach it to all of the sides, you add the most torsional resistance you can. I don't know if it could be done but welding sheet metal across much of the frame would add more torsional rigidity. Another issue would be the front body mounts to the frame. Like you said, it is obviously cracking at the crumple zones which have already been work hardened by the stamping process. Any push on the corners at the front will exacerbate the issue whether it is from body mounts or bumpers. It is the continual flexing that weakens the area, not one push.

You could strengthen the inner fenders which would reduce the crash worthiness to something like a Jeep.

BTW, this is not a serious structural issue but a design flaw. Ladder frames flex in torsion. The crumple zones are doing what they are supposed to be doing, flexing under pressure. They are just not designed to flex all of the time. When they do, like BellyDoc said, the work harden. Work hardened steel is much more brittle and can crack under stress. Just driving on washboard roads would be a problem. The inner fender is just a weak point in the design.

Just my two cents.

FYI: My 08 has a build date of 11/07. 97K and no bulge or crack. I bought it used and don't believe it has been off road.
 

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Frame flex? What frame flex?
 

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I just learned that I too have a pair of these body rips in the 5th crumple zone from the front. I guess I will just let it play itself out until I hear of a reasonable solution. :(
 

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Add me to the list :) LOL

I am not worried as there is a frame on these and it is not a UNI-Body.

But non-the-less, if something does come of this in a form of a recall or TSB, I would like mine fixed.

Thanks
 

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Looks like the crack on my passenger side is heading south.
 

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I noticed on my 07MT with 100,000 miles that I have fender cracks/inner body rips on both sides, but no bulge. I may have overlooked one (pic #2 that is more wavy) of them before thinking it was a seam.





Very fine cracks, easy to overlook, but continue from top to bottom.

I think I heard the left side crack when I hit a massive pot hole. A little louder than normal :lol:

Would be nice to get it repaired for free but I don't expect it.

It also doesn't concern me in the least or make me like the FJ any less. I've driven it hard, and I admit it :lol:

Most 7 year old cars are already in the junk yard :lol:
 

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There are plenty of other threads to read about this. It is a bummer, but doesn't really change the structural integrity of the vehicle. You do not have to jump your vehicle to get this sort of damage. If you put the chassis through a lot of off road stress, the ladder frame will transmit the forces of impact and twisting to the very front of the fender aprons like a lever. since the other main and solid point of contact for the fender apron is the firewall, which is directly connected to another body mount, the force being transmitted needs to dissipate its energy at the weakest point between these two junctions. The crumple zone just forward of the firewall is where this failure occurs.

Because the front suspension is directly bolted to the frame, and not the body, This failure, though ugly, should not affect the the overall performance of the vehicle. It is a real eyesore however, and I would love the opportunity to chat with a high ranking Toyota executive, about it.
 

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There are plenty of other threads to read about this. It is a bummer, but doesn't really change the structural integrity of the vehicle. You do not have to jump your vehicle to get this sort of damage. If you put the chassis through a lot of off road stress, the ladder frame will transmit the forces of impact and twisting to the very front of the fender aprons like a lever. since the other main and solid point of contact for the fender apron is the firewall, which is directly connected to another body mount, the force being transmitted needs to dissipate its energy at the weakest point between these two junctions. The crumple zone just forward of the firewall is where this failure occurs.

Because the front suspension is directly bolted to the frame, and not the body, This failure, though ugly, should not affect the the overall performance of the vehicle. It is a real eyesore however, and I would love the opportunity to chat with a high ranking Toyota executive, about it.

Thanks for the info. Yea mine might turn into more of an eyesore, but now it's pretty unnoticeable. I don't know if there is any precedent for a similar issue on other vehicles well past warranty, and 7 years later.

I looked at an Audi A8 for a friend a few years back, and the shock towers had cracks inside the engine bay that didn't appear to be collision damage. I wonder of that was a known issue, for example, and if Audi did anything about it if so.
 

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Looks like there is some sort of fix for this now. Another member posted these pictures up and I was wondering if anyone had information?

-B
 

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Looks like there is some sort of fix for this now. Another member posted these pictures up and I was wondering if anyone had information?

-B
I would like to know where to purchase these also. This looks better than just welding plates over the rips. Mine are completely torn on the inside and are traveling down the outside fenders now.
 

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Hey guys take a look at the thing I bought in Europe. These are inner fender reinforcements to prevent or fix existing bulges/rips for FJ Cruiser. Manufacturer declares easy bolt-on installation with no drilling or welding (if rip is no longer then 2 inch).

It's intended to be installed on existing factory bolts using PU sealant. I'm going to install them this weekend although there are no visible rips or bulges on my '07 FJ.
Did this fix work?
where can I order it? can you share a link to where you bought it?
thanks!
 

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I would be very interested in knowing where to purchase a structural reinforcement piece. I filled my body panels with expanding foam and I haven't seen any movement in the existing tears/bulges or any new ones show up but I would feel better with something a little more substantial in there.
 

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Yes...there was a redesign in late 2008 that fixed this issue.
....
I wish, my 2011 built FJ has a crease at the same point as my 2007 model had...been driving this one in the dunes for about 1 year and the crease is now slowly increasing in size (by the crash crease under the bonnet)
Also I have a tear on the wheel arch on one side :grin

Still a great 4x4 leaves ALL the Jeep JK2012 models for dead in soft sand and climbing the ridge dunes...
 

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Sorry don't yell at me because I didn't read the other 350 pages, but that is most definitely fatigue cracking. I am kind of surprised they didn't do a better job designing it. It is a relatively easy thing to design for.
 
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