I have picked up a 2004 AWD wagon with the sport suspension. It exhibits what I'll call a "hip wiggle" when going over bumps at an angle to the road, such as expansion strips on a cloverleaf. If I go across a bump that is perpendicular to the road, there is no problem, but if it is at an angle then the rear of the car feels squirmy. The car definitely doesn't go straight across the bump.

So far I have replaced both rear shocks, and the lower rear forward control arm on the right side ( I didn't have a second arm on the shelf, another is on order). I also had a 4 wheel alignment done and everything is in spec. I also have a 2007 sedan and I swapped wheels and tires from the sedan which drives perfectly, and that made no difference, so I think we can rule out anything with wheels or tires.

Any ideas where I should look next?

 

Jagboi64, something I would ask you to try is to drive on a long sweeping curve like that of getting on a highway. But, in this case, take it a little slower than normal and then in the middle of the turn, step on the gas (in a controlled manner) like you were going to pass someone on this curve. Did the rear end step out a little bit on you. If so, then you have a bad arm in the rear end. May need to replace the upper control arm. Next, I would be looking at the lower A-arm on the front where it attaches to the frame (by the firewall). If that is loose/worn out, I could see that causing what you are seeing. Finally I would give the strut bushing a look over and make sure that is not worn. That can be checked by simply opening the hood/bonnet and then pushing on the car sideways. If you see the nut in the center move, it needs to be replaced.

 

There has been freezing rain, so not the time to try applying power on curves! Later this week I'll try that. I rocked the car tonight and the strut nut didn't seem to move, so that might be ok.

The previous owner left the wheels out of balance for a long time, it shook the pinch bolt loose on the steering column, which left a large dead spot. Was "fun" to drive that home for 1000 km through the Rockies. After you mentioned it I was actually a bit surprised the strut bearing wasn't loose. The rear wheel bearings had flat spots, I have replaced those. The fronts seem ok, the car is quiet and smooth on the highway.

 

And when you replace the rear upper control arms, "thermo" them. Do a search under his name and you will see what and how to purchase them. It also adds the ability to adjust them in the future. Nearly all of us older owners have done it.

 

You mean the Mazda/Volvo ones? I have seen those posts.

 

Volvo ones. Yes. We call them "Thermo'd" as he pioneered them.