Same issue on my '13 GX I purchased two months ago from Carmax. I was getting a vibration on the steering wheel once I would hit 60 mph on the highway. I had the wheels balanced at both tires plus and Carmax but still had the vibration, so I took the truck to the dealer and had them road force balance the tires, which solved the issue.

 

I've seen alot of issues lately with Michelins on the GX. For some reason the tires either don't totally seat the beads, or need to be flipped to achieve a lower road force.

 

Been on highway most of the time and it's a distinct vibration randomly around 60-75 mph. The steering wheel doesn't shake. But very noticeable in passenger seat

 

My video..see seat vibration. It may be hard to see

 

2nd video I made

 

Wow. I can see the vibration clearly. After I saw your video, I did a short drive with mine at the same mph range and didn't see it. I made a video too lol.
Does the whole truck vibrate or just the passenger seat?
What happens if you shift to S and go down to 5th gear or 4th. Does it vibrate at the same range? How about in 6th in S?

 

The whole damn truck feels like it's vibrating. What a situation I have

 

How old is your truck? Mines 4 days old, has a bad pull to the right and bad vibration. It also has less than 300 miles on it.
Its been to the dealer 3 times, if they cannot fix it today, i'm hiring a lemon law attorney to get me out of it.

 

My gx still under Full warranty if they don't fix it in 3 times it's a lemon. I will get the Jeep track hawk then. Done with Lexus. They can't make vehicles that ride nice or trouble free any more it seems

 

Please keep us posted on the dealer's attempt to fix... I have the same issue in my 2015 CPO, and am taking it in for 1st service next month.

 

Did you not test drive the car before you bought it? And the dealer has to make 3 repair attempts. Plus its pretty normal for an unloaded seat to shake. I'm sure its not a big deal whatever it is, but you are jumping off the bridge rather quickly don't ya think?

 

I wonder if it is bushings or bearings. Was Lexus able to reproduce the issue? I know you replaced the tires, were they the same brand? all Michellin?

i hope you can resolve it soon.

 

Tires are normally the culprit, good luck with a resolution. We've had our GX for a few months and had an alignment issue. Never noticed it on the test drive, shame on me I guess. But when shopping for a vehicle for my wife, there's a lot going on. Plus it was difficult to find the exact (pre-owned) model we wanted. Once we did, I was mainly concerned about the cosmetics as the vehicle is under CPO warranty.

Anyway, it took two trips to get the alignment right. On the last visit, they adjusted the caster on the front passenger side. It seems to have resolved all of our alignment issues. Truck tracks straight.

I've had my share of problems with vibrations on a previous sedan (BMW 550). Holy **** was is a pain to get resolved. It turned out to be the tires (Conti DWS). They would balance just fine...but you can balance an egg too. That doesn't mean it is perfectly round. I wish you were closer, we could swap wheels/tires and see what happens. I would tell the Dealership that's what you want done. Not necessarily long-term, just long enough to see if that resolves the issue. If it does, you (and everyone else) will know it's a tire and/or wheel problem. If the loaner set (tires and wheels) still has the vibration, then it must be something in the drive train.

 

That vibration looks to my untrained eye like it's drive train related, especially since you mention there is noting in the steering wheel.

If the front or rear drive shaft has ever been off, they may have been put back in out of phase:

Other things to consider:
Make sure the drive shaft splines have been greased. Check that the U-Joints are good (no play). Check the drive shaft for any signs of missing weights (unlikely) or any damage (dents etc.). If those are OK, check the front half-shafts' CV joints (unlikely at your mileage). Exhaust system hangers in place? Any weights that the factory have added to dampen vibration on the exhaust system or transmission/transfer case are still in place? (I don't know if the GX has any, my other car does). Mounts ok on the engine, transfer case, and transmission?

Additionally, shops have a tool called chassis ears.
http://www.buffaloscoop.com/the-caus...ain-vibration/

This will provide some evening reading:
http://ctoprework.lms.nnanet.com/Tec...n_Sept2011.pdf


Good luck and please let us know what you or your dealer discovers is the cause.

 

The dealer did do an alignment again. It was way off the first time but was in the green the 2nd read. They did replace all 5 tires (spare included with a set of the best Michelin tires available for my truck and did a road force balance. It seems to be 90% better but not perfect. At this point I really like the truck and for my inconvenience the next 4 services plus 1 year extra of Enform are going to be free. So though not totally fixed I like the vehicle enough to live with it