My car has a moderate shake/wobble when I'm on the highway at 60+mph on a LEFT curve/slight corner. Otherwise there are no wobbles going straight or on right corners at high speeds
This one is difficult to diagnose, but at the same time narrowing it down/finding the culprit might not be as difficult considering it only happens when left cornering at high speeds.

Additional info: Car is on coilovers, 15mm wheel spacers front, 25mm spacers rear. I've owned the car for under 3 months and the previous owner already had the coilovers and spacers installed. I haven't commuted on the highway much since then and it was only recently that I discovered this issue.

I don't know if the previous owner got the tires balanced and aligned after any coilover height adjustment he has done, I don't know if it's a spacer thats failing, or if it's a bad bearing or axle, ball joint. Where should I start?

 

where do you feel the shake coming from...front or rear?
I'd get the wheels off and inspect everything from the wheels/tires/spacers/hub/brakes/suspension...etc
Somewhere along the way you'll find the issue.
If you can feel it from a certain spot that will help narrow it down. Since it's only left turns, I'd guess it's the passenger side seeing as it's getting more stress.

 

Every town across our country has a qualified "Independent" brake/alignment shop, find yours if you haven't already. These shops deal with suspensions every day and wouldn't be in business if they weren't good! Shakes at high speed turns are a very bad thing, they need to be corrected!
Gary

 

sounds like ball joint(s) is(are) starting to fail.

 

I just started having the same problem on my 03 G35 with 168K. I just put new tires on my aftermarket wheels & performed an alignment. Going 60+ MPH later that day to test them out, I noticed it was vibrating horribly while veering left (just changing lanes caused the vibration) I took it back this morning and he said they're perfectly aligned and balanced, they even did a road force balance, and it's most likely the aftermarket wheels, since they're bigger you get more vibration, but I call BS. Did you ever figure out what was wrong?

Update: So I took it to a trusted friend who works on Nissan's, we put it on a lift and inspected it, while the lower ball joints looked rough, he said they were ok, the main problem was a leak from the rack and pinion assembly. He said the whole thing would have to be replaced and to prove it, he showed me the play in the tires, while lifted he rocked the tires side to side & up and down. there was a lot of play in the tires going side to side, but no play going up or down. He said the side to side play was indicative of a bad rack and pinion, and up & down play would be the result of bad ball joints.

 

Just an update on my situation, I hope this helps somebody with the same issue in the future...

I replaced my steering rack & pinion and both outer tie rods (found OEM reman R&P on amazon for $350, both AC Delco Outer Tie Rods for $38/E) That fixed the vibration. Unfortunately there was some collateral damage to my driver front wheel hub bearing, so I replaced that as well. With this being my daily driver and it being an expensive job (I also had a small leak in the valve covers, and wanted to replace the drive belts) I had to wait a little too long to save up to do everything, but everything is good now & my G is riding smooth

 

Glad to hear it, love it when people actually FIX the problems

 

Glad to hear. Next time ask about where to find deals on those parts though... I found my rack for $160 with a lifetime warranty.