Baystate Jeepers

Hello everyone. I have a 2012 JK 4 door with a 3 inch lift, shocks and coils, stock CAs. I have noticed that the rear coil springs are bowing forward. It is not as drastic as other examples that I have seen in my research but it is certainly noticeable. Is this something that needs correcting?

I have also had some knocking when traveling over bumps. That also seems to be coming from the rear of the jeep. I'm not sure if this has something to do with the coil bowing or a separate issue. Could really use some help diagnosing.

Best,

Bill

Bump stop could be hitting coil. Pinion angle is probably off too. If you correct the pinion angle the bow will be worse. To correct pinion angle need adjustable control arms. They make bolt on wedges to fix bow but they add height. Proper way is to cut top mounts off frame and move back. This is me assuming setup same as a tj. Most just drive with them bowed.

Thanks Mark. I'll be driving it as is for the time being. I'll have to take a look at the bump stops tomorrow.

Also Check your swaybar link bushings, shock mounts and bushing, and even the control arm bushings too they all make banging sounds when get worn and are not so easy to detect by just looking. Need to grab and shake.

Bill : Picture your control arms (all 4 of them) locating the rear differential when it came from the factory. They were pretty much parallel to the ground. Now you put a longer spring in there to lift the chassis. The arms head downhill toward the rear axle . Now on the axle itself is the coil spring bucket which used to be level and right under the upper spring bucket. With the arms pointing downward this causes the spring bucket to be tilted rearward and slightly forward of the upper bucket. Hence the BOW . The taller the lift the bigger the bow will become. Unless , like Mark said, you put in a spring wedge to level the now crooked bucket it will continue to get worse over time. The bigger chore is to move the upper bucket to compensate for the crooked bottom one. With adjustable control arms ($$$$$$$) you can relocate the axle backward so they would be inline , but that bottom one will always be tilted unless you cut them off and have them welded back on to be level again. Sounds worse than it is , but thats the only fix. FjR68

Mark- I checked the rear bump stops and they are located away from the coils and do not appear to be the issue. I gave everything a good shake and nothing would budge. It is a gremlin for sure. Separate issue, my front passenger bump stop has rotted out and is now floating around in the coil. I know sound can travel underneath but Im not optimistic that is the cause of the noise.

Mark/Frank- Thanks for the geometry lesson. The Adjustable arms are on the back burner for right now. It is good to know what it takes to get everything to line up the way it should when the time comes.

How about exhaust hitting something

Good idea. There is only about half an inch between the rear sway bar and the upward bend in the exhaust near the muffler. I went under there with a flashlight and could tell there was wear on the sway bar. Would longer sway bar links take care of that contact?

Cheever3 wrote:I have also had some knocking when traveling over bumps. That also seems to be coming from the rear of the jeep. I'm not sure if this has something to do with the coil bowing or a separate issue. Could really use some help diagnosing.

Hey Bill, Is there any chance that noise is another loose shock mounting similar to the front loose shock we discovered at the end of that run late last year?

That was the first thing that crossed my mind. I went over them and they are tight. Gremlins Ralph. Hope everything got squared away with your driveshaft. See you on the 4th?

Cheever3 wrote:That was the first thing that crossed my mind. I went over them and they are tight. Gremlins Ralph. Hope everything got squared away with your driveshaft. See you on the 4th?

Got it back last Monday and it looks brand new. Hope to get it in this Friday with Kurt's help. Pretty certain I'll be there on the 4th.

You need a hand Friday?

Cheever3 wrote:You need a hand Friday?

As long as Kurt doesn't mind, and I can't imagine that he would, please come by. It would be great to see you again. As I said, we're hoping for Friday at 10:00, but Kurt is getting over stomach flu and not sure if he'll be up for it. Should know Thursday. Bring Jimmy! Never too young to learn! And he'll fit in those tight spots more easily