Rear end out of control and sometimes "shimmies" hard to the left

[hawkman71]

My 2011 Expedition has a terrible bounce in the rear. It's almost out of control at times. In fact, one some occasions, the right kind of pothole causes the rear end to "shimmy" hard to the left. It feels like the back end is going to come around while I'm driving straight. This has happened at 35mph as well as 70mph.

The dealer I bought it from (used, it's a Dodge place that has horribly handled the stalling issue I told you about in other threads), told me there is nothing wrong with it.

I once had a friend following me and I noticed the "shimmy" thing happen. I mentioned it to him when we parked and he said he noticed it, too, and that it looked strange.

What should I be checking?
I'm going to replace rear struts - what else should I be looking at and/or replacing along with them?

Thanks.

 

[1955moose]

Besides new struts, be sure you don't have something loose or broken back there. I'm not sure on newer ones, but earlier models used control bars that rot out. Basically go under there and shake everything down. That dealer just doesn't want to warranty anything, is why all is fine. You can be sure if you said I'm looking to fix this bouncing problem, how much? They'd have a laundry list of parts/labor for you. If your SUV has more than 50k, the original struts are worn.

Sent from my N9131 using Tapatalk

 

[Trainmaster]

Anything that controls lateral movement in the rear end can be at fault. Some cars, particularly Jeeps have a panhard rod between the frame and the differential that locates the rear axle. When that wears, the axle vibrates laterally, creating what's often called the "death rattle". See what suspension parts are designed to restrict this movement in the rear and you'll locate your trouble.

Ask another shop to diagnose the problem, give 'em twenty bucks for their time and go back to the dealer and fight your fight.

 

[hawkman71]

I had hope to get under the Exped this weekend, but did not. Thanks for the tips.

As for the dealer, there's no fight there anymore. This is on me to fix and I'm fine with that.

 

[hawkman71]

Took a quick look right after supper before the missus I had a meeting and saw a piece of rubber hanging below the strut! The bushing is shot, that's for sure.

Right side, rear




Right rear, but different joint.


Left rear lower strut, for comparison

 

[hawkman71]

I've been under the beast and the only thing that I can find that moves is one of the stabilizer links. It doesn't rattle (not that worn out) but it can be twisted as it pivots on the ball socket relatively easily. It seems hard to believe that it could cause a problem. I'm surprised they are about $50 apiece. The sway bar bushings appear to be fine but are inexpensive to replace I guess. I'm in a no-rust area and everything is clean under there. Nothing appears to be 'rotted out'. I do not hear a rattle when I drive so I do not feel that I have ball joint issues but that is not the diagnostic I should use I guess. I did try to twist the tire side to side and up to down when on the jack and did not feel any play.

 

[hawkman71]

I thought I saw a youtube video that described the bottom nut of the strut to be a 31mm yet when I'm in stores I see sets and individual sockets that include a 32 but no 31. Just wondering if you know. (Bilstein 4600 I believe)

 

[hawkman71]

Update: Long story short with other threads here handling the details: I replaced four shocks with Bilstein 4600s, keeping the rest of the assembly original. Drives like a dream now. Thanks for your help and suggestions!

 

[Bain64]

Thanks for following up with the fix! Glad it worked out

 

[hawkman71]

Thank all of you for your help! I'm sorry there are periods of time where I don't respond. Everything was coming to a head there before Christmas. I was stressed, etc.

Sincerely appreciated. Merry Christmas and Happy New Year to all.