Car feels as if it sways from the rear, HELP?

batman_4

Let me get started with the car facts. Bear with me please, I'm not suspension savvy and really have no clue what I'm looking for here.

1) My car was taken to Monterrey, Mexico (current city I live in) about 8 months ago. I live in a certain area where the roads are not the typical torn up Mexican roads we all know off, but they are also not decent like the ones State-side.

2) I've clocked about 3k miles on Mexican roads, car is at 63,005 as it sits today.

3) Before taking the car down I took off my coilovers and re-installed my stock suspension which, was taken off at 12k miles and paired it with Eibach springs (forgot which one, but it was a small drop)...a slammed Z would not survive the speed bumps over there.

4) About a month ago I started feeling something loose...so I started paying attention. A few miles later I came to the conclusion...every time I hit unevenness on the road, whether it be a slight change in pavements, small bumps, etc...the rear feels as if it sways from side to side slightly. I figured...maybe a bolt of some sort has come loose since the car has to deal with shittier roads now. Stupid me took it to the "best" suspension shop in Monterrey and lets just say it was the first 370z they had ever touched....end product was no improvement on the sway, if anything got worse.

5) After that shop experience I took it to Nissan, long story short, they denied work on my Z...the head mechanic wanted to blame it on my rims because they sat flush with the fenders, "and if you look at that Nissan Versa with the rims tucking, that is how rims are supposed to fit, your car has the wrong size wheel"...quoting him.

6) Came back to Texas, took the car to get an alignment to a guy I have taken my cars for the past 10+yrs, was corrected (mentioned Toe was off bad) but car still felt loose on the rear. Asked friends and nobody really has an idea of wtf it is....so I took it Nissan (have a good relationship with them).

7) 1st visit (w/SSR wheels): Nissan says after full suspension inspection, it is probably my tires (Birdgestone Potenza S-04's) and their asymmetrical tread pattern = issue not solved. So I decide to slap the stock wheels and tires to test their theory....same problem.

2nd visit (w/stock wheels/tires): they said it was my alignment now, which they corrected aaaaaand car STILL feels as if it sways.


I've looked online and "bushings" keep coming up a lot...any opinions/idea/experiences would be GREATLY appreciated!

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'09 6spd. Touring: Eibach / SPC / Motordyne / Berk / Z1 / Oneighty / Mines / SSR / Stillen / CFE