OK i have been through alot with this car.....
at 60k miles i bought new tires all the way around because I hated the All seasons that i had on there....
Keep in mind that the all seasons HID this problem from me untill i repurchased performance tires. I thought i was getting sidewall flex so i ended up getting the OEM bridgestones back on there at 61kmiles (begged America' Tire Co to swap them) ok there was an improvement with the Stiff sidewals, but i would still get wobble on the freeway....i swapped out the swaybar bushings with urethane bushings and the ride improved greatly!
Now it still wobbles on the freeway a little, but not as bad as before, so now i replaced the front struts and rear shocks with NEW ones thinking this would solve my problem! I WAS WRONG! Turns out that it is the swaybar endlinks causing the swaybar to sli around back and fourth and the steering feels sloppy AKA Swaybar Walking!....here is a cut and paste of the problem as described on another forum (yes i was desperate to find an answer and NEVER do this, but i was desperate)
"I am experiencing an odd "swaying left and right" motion... while driving in a straight line! Yes that is correct, straight line driving, not during cornering. My end links are still in place and nothing is broken. My first guess was perhaps a loose bolt ever since I installed my suspension? (Cusco Zero II's dropped 0.5 inches, Hotchkis sway bars - hard front med rear, GT Spec front/rear lower tie bars, tanabe underbrace) However, a loose bolt would make a noise from the extra play or at least a *clunk* when it sways, in my case, there is ZERO noise... the car drives straight, the wheels are straight, but the body itself leans from left to right. The shocks are basically brand new and the up/down rebound motion is perfectly fine. My BEST guess was because of the sway bar.. but what could possibly be wrong with a sway bar besides the... END LINKS! I just received my SPL rear links in the mail the other day and will install them by the end of today, but until then, any suggestions? BTW: I just had my alignment done 3 days ago and my mechanic got everything back to spec and he noticed this odd swaying motion, 3 days later (today) it got worse than ever. Hopefully end links will solve the issue.
I've been reading about people who "hit a bump on the highway and the rear end seems to lose control" this happens as well, perhaps it's all part of the same equation, who knows, any suggestions guys?"
THEN A FIX FOR THE PROBLEM!
"Just got back from the shop and installed the other rear SPL end link... Night and Day difference over the wimpy stock ones. The SPL's have a ball joint design with a polyurethane "cover" to protect the ball joint from any debris that might enter the mechanism. I took some pics of the install and I'll post them up when I get home. I replaced the front end links with new OEM factory links and the car doesn't shift from left to right anymore! So glad this issue got fixed within a day... driving around with broken end links was very dangerous and I felt as if the tail end would've whipped out any second during normal driving. Thoughts after driving:
Regular street driving - everything feels firmer again, no more wobble, solid! Lets hope these dont wimp out on me after I install beefier solid sway bars.
Highway cornering @ 80mph+ and hitting bumps while turning - STILL solid! Very well engineered product! I am satisfied... for now!"
AND ANOTHER GUY SOLVED HIS PROBLEM ON HIS G35
"I just replaced all 4 of my endlinks on my '04 G35 sedan with the supposed oem beefier links for an '05+ model. The old endlinks were definitely shot and the balljoints moved around too freely. Probably a combo of 4 track days, numerous canyon runs and crappy cali roads. After the install I could immediately tell the car felt much more solid and the slop had gone away. But the question is how long will these new oem end links last? Would be nice to go with a solid aftermarket end link that can take abuse."
OK so most of these guys bought aftermarket endlinks for over 300 bucks...ME i'm going to the dealer to buy stock ones for 60.00 for the whole set....and will post my results up soon!
here is a link to the thread..VERY interesting read!