My first chassis crack

I guess I knew the day was coming.

I was up under the rear of the car and noticed that there is a crack on the pass. side that starts right on forward edge of the rear crossmember/shock mount, and goes forward right were the rise under the back seat is. It is only a few inches long right now, but there seem to be some more starting around in. I can see daylight through all of them. I guess I was surprised that the crack wasn't at a joint or corner, but right on the flat part of the cars floor.

I'm frustrated. But I'm also wondering what I should do about it. What do you guys do with cracks? Just pinch them together and weld them up? Add some extra metal as reinforcement? Any ideas are welcome.

Thanks
Marcus

you got the answer your self. but run that extra metle down the intire leanth of the beast and don't worry about it againe.
just so ya know it's a jeep not a car. if it was a car you would take it to the junk yard. hehehe

Drill a hole at each end of the crack, to keep it from going farther, and then weld them up. It helps to grind a little V in the crack if you can get to it, but it's not necessary. Adding reinforcement needs to be thought out carefully, sometimes it just moves the stress point somewhere else, or cracks develop in the weld at the edge of the metal that has been added.

That does seem like an odd place for a crack, but then again I see you have a 99 XJ, seems that the newer XJs are more crack prone than those of old.

XJguy

Looks like it may be my fault after all. I moved my upper shock mounts towards the center, and while the crack doesn't start right at the mount... it's pretty close. So it seems like more force was being put in that area than I had predicted (My hint was the rear cross member, which the shock is bolted to... just more towards the center, is bending right at the shocks mount.) I'll see what I can do.

Richard, the reason I asked about reinforcement was exactly what you talked about. I was wondering if It would stress something else. I'll drill like you said and weld and see how it holds. Since I'm almost finished with new shock mounts that won't put any force in that area, I think it'll be ok.

Just got back from the desert races and it killed having to drive slow all week to keep from making it worse.

Marcus