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cruiserlarry previously said:
I, too, have stress cracking in the exact same area, and it is growing quickly. Anyone with an aftermarket bumper (or who uses lights on the stock bumper) knows how much vibration is present in the body of the FJC when driving. My guess is this stress cracking is due to the excessive frontal vibration present in the vehicle due to extremely soft / tall body mounts designed for flexibility. While a stiffer suspension and additional weight on the frame may increase the vibration of the front end, I, in no way, believe it would be solely responsible for this type of stress cracking alone.
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BellyDoc previously said:
This is flex fatigue. 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. 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 know a lot more about fighter jets than I do about trucks and I'm also (uhhh) drunk right now, but what CruiserLarry and BellyDoc said makes a lot of sense to me. Which means this will probably happen to every FJC that gets flexed a lot eventually, it's just that you guys and Air2Air reached the metal fatigue / breaking point before everyone else. (Hope you guys will pardon me for the partial quotes.)
