Cracked Upper Trailing Arm Mount

[mattusmc]

Cracked a weld and bent the driver side upper trailing arm mount at Windrock this weekend. Time to reinforce the mounts I guess. This is on a 2023 2dr. Noticed after the third trail, the drive shaft would make contact with the fuel tank skid, the contact would get worse and worse. Found the axle to have pivoted to the driver rear. Put it in reverse and the axle straightened out enough I could limp it back to campground where we realigned the axle. Cleaned it off and discovered the crack and slight bend.

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[Tricky Mike]

@popo_patty has a great thread documenting this problem but it was limited to 21s.

 

[popo_patty]

Cracked a weld and bent the driver side upper trailing arm mount at Windrock this weekend. Time to reinforce the mounts I guess. This is on a 2023 2dr. Noticed after the third trail, the drive shaft would make contact with the fuel tank skid, the contact would get worse and worse. Found the axle to have pivoted to the driver rear. Put it in reverse and the axle straightened out enough I could limp it back to campground where we realigned the axle. Cleaned it off and discovered the crack and slight bend.

Rock Krawler setup in the rear?

 

[Mdsuits]

Looks like the rk 4 link. I have a feeling this may become an issue.

 

[mattusmc]

Yep RK 4 link, had it on for a while now. Lift,37s, etc. I’m just gonna drill and fill the crack and add some 1/4” plate with gussets to the frame and mount. Just sucks cause I’m gonna have to drop the tank again and reinforce the pass side for peace of mind lol.

 

[RallyGorgo]

Looks like you’re in the endless loop of chasing the next weakest link.

 

[87-Z28]

Looks like the rk 4 link. I have a feeling this may become an issue.

Indeed. the 4 link setup transfers the lateral loading to the frame hard points. Especially for the upper links. The mounts need to be able to handle the extra loading that is not present with the 5 link since lateral loads are reacted by track bar. Using the factory hard points may be asking to much. Hopefully enough extra support can be welded in to remove this concern.

 

[87-Z28]

Yep RK 4 link, had it on for a while now. Lift,37s, etc. I’m just gonna drill and fill the crack and add some 1/4” plate with gussets to the frame and mount. Just sucks cause I’m gonna have to drop the tank again and reinforce the pass side for peace of mind lol.

I would definitely do both sides and make sure you have some gussets oriented to stiffen the mounts laterally if possible.

 

[Mdsuits]

Cracked a weld and bent the driver side upper trailing arm mount at Windrock this weekend. Time to reinforce the mounts I guess. This is on a 2023 2dr. Noticed after the third trail, the drive shaft would make contact with the fuel tank skid, the contact would get worse and worse. Found the axle to have pivoted to the driver rear. Put it in reverse and the axle straightened out enough I could limp it back to campground where we realigned the axle. Cleaned it off and discovered the crack and slight bend.

Just out of curiosity….you sure it wasn’t making contact before you took it out. This is a know issue with the rk 4-link. If you compress the passenger rear and drop the drivers side it steers the driveshaft and pinion yoke into the gas tank skid. I had to trim mine….plus use the rj sway bar to slightly limit flex.

 

[Copperhorse73]

Just out of curiosity….you sure it wasn’t making contact before you took it out. This is a know issue with the rk 4-link. If you compress the passenger rear and drop the drivers side it steers the driveshaft and pinion yoke into the gas tank skid. I had to trim mine….plus use the rj sway bar to slightly limit flex.

Do you have any pictures of how much you trimmed the gas tank skid ?

 

[Snacktime]

Called it

 

[mattusmc]

May end up getting a tank made similar to this kit, would increase my range a little bit too. Lots of room with the muffler gone.
https://motobilt.com/products/rear-fuel-tank-w-skid-plate-for-factory-frame-for-jeep-jku

 

[popo_patty]

So I’ve been looking at the second picture trying to find the crack you mentioned but I can’t see one. Are you talking about that frame divot with the split looking area? Because if so, we all have that. Here is mine for reference.

 

[mattusmc]

So I’ve been looking at the second picture trying to find the crack you mentioned but I can’t see one. Are you talking about that frame divot with the split looking area? Because if so, we all have that. Here is mine for reference.

Well looks like I need to dive deeper into it when I get it home. The axle is definitely shifting under load to the rear DS. Thought that was it, zoomed in on the picture and it looks jagged not a straight seam.

 

[Snacktime]

Check your snap rings on your johny joints, they have been know not to be seated all the way when assembled.

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