Hi all. Ima noob on this forum but have been lurking for some time.
I have an RX350, 120,000 miles never a major problem it’s entire existence. Proper dealer service completed at 90k.
until 4 days ago.... The entire front end shakes badly only when accelerating getting past 40 up to 70mph causes the vehicle to shimmy( mostly on the front passenger side. It hasn’t got worse or any better since this started.
Things to note.
Newer tires from Tire rack, balanced and rotated (again just yesterday) The tires have 15k on them and are still in great condition.
Newer struts and sway bar links at the same time as the tires were replaced. I've crawled under and inspected as much as I could. Loose or damage and found nothing out of the ordinary. CV joints/boots are in good repair(solid and no clicking noises), and the drive shaft carrier bearings seem solid.
The vibration mostly goes away when above 60mph and cruising. The vibration completely goes away when foot is off the gas and decelerating. The brakes are newer and do not pulse or make any noise when braking. The rotors show no sign of overheating or caliper issues ( used a temperature gun and checked this morning)
Has any owner experienced this. Solutions? I’m planning on putting it up on jacks to further inspect the driveline/undercarriage tomorrow but if anyone has suggestions, I’d certainly appreciate them. Thank you
Worst case, an expensive trip to Lexus of Madison

 

I trust you had an alignment after the new struts were installed. They should have inspected all of those suspension components at that time. Were the tires road force balanced?
How are the wheel bearings?
You should next check your motor and transmission mounts.
Maybe check the torque on the driveshaft bolts as that is part of the 30,000 mile check up.

 

Have you changed (right) driveshaft?

 

It sounds like you've checked all appropriate suspension components. I would look at the engine mounts. I believe you can open the hood and have someone rev the engine while in park to see both the initial torque flex on the mounts as well as any inability for them to control wobble from particular RPM bands. Perhaps you can note the RPMs while you're in the 40-70 MPH range and have your spouse / friend target that RPM band while rev'ing the engine in park.

I believe there should be two lowers and one upper (passenger). There are some posts on DIYing the top one, and it shouldn't be too difficult. My experience with lower mounts is outdated, so I don't have first-hand advice. I'm not sure about transmission mounts.

 

rotate tires front to back on same sides, see if it goes away in the front . If it does buy 4 new tires.If not look into the drive shaft and transfer case and axels

 

My 2011 had nasty vibration due to transmission oil was never changed. With new oil and antishudder additive it runs mint.

 

Sounds like a very slightly delaminated tire is a possibility. I bet it's Michelin.
I'd be taking it back to the shop that did the front end work and asking them to do a quick check on their tightness and they can likely diagnose it for almost free.

 

From your description, this very much looks like a front axle problem. The boots do not have to show visible damage to have a problem. It may be one or both axles. If you feel it more on one side then that is the likely culprit. It is common to replace both when one fails, but not necessary.