NorthernRX

I'm a new first-time Lexus owner and recently bought a beautiful Matador Red 2009 RX350 about 3-4 months ago. Has 141k miles on it currently. For the last 2 months or so, it has developed a odd drivetrain vibration. I've read threads on here about wheel bearings, CV axles, driveshafts, etc. but need a little help figuring this one out. It vibrates/give a rumbling sound similar to that of a bad rear u-joint right around 2000rpm at 30mph, and again at any speeds over 60mph. It's not a terrible vibration but just annoying after enjoying the Lexus-quiet ride for the first month or two. It's a seat of the pants type of vibation/rumble that is not felt through the steering wheel - akin to the sound of a helicopter flying overhead. Lifting on the throttle at these times seems to give a decrease in vibration/noise. It can even be felt when the vehicle is up on a hoist, spun up to 60-70mph while in the air. It did have a preexisting slight rear diff whine ever since I bought that's not terrible but is noticeable at certain speeds. Wondering if my rear diff could be causing the vibration?

I have had the driveshaft taken off, inspected, and rebalanced by a driveline specialist, have had all 4 tires rebalanced (18" Conti ExtremeContacts with good tread and no unusual wear), and had the shop even pull out the rear CV axles to see if there was any tell tale signs of anything. So far no luck and no change in vibration. FWIW, this all started (whether coincidentally or not) right after having one of the driveshaft center support bearings changed out that had begun squealing, it has been rechecked and rebalanced since that time, no trouble found. The shop (independent shop - the best place in the area for diagnosis stuff) is baffled and says I need to let it develop, but I just worry about something coming apart on my wife when she's using it, or on one of our upcoming summer road trips. I've also tried the veering one way and the other at 60-70mph to see whether it could be a wheel bearing issue, but it's tough to say whether it really changes any while doing that.

I'm totally fine with having to install a good used rear diff or whatever it takes to get rid of the issue, but I just don't want to keep throwing parts at the problem, guessing at the issue. Anyone have any ideas of what to look for and how to test it? I'm new to the Lexus family, so maybe there's something I'm missing?

nwfsnake

Well yours is 4WD obviously, which I do not have. However, since you can feel the vibration through the steering wheel I am going to guess that your front inner CV joints are dry and failing. If it was the outer joints, you would get noise when turning. Just a guess, though. Good luck and please post whenever you do figure out the problem and solution.

NorthernRX

It cannot be felt through the steering wheel, but....that same thought occurred to me the other night. At first I thought the noise was coming from the rear, but now I'm not so sure. The front inners have never been pulled out and checked.

nwfsnake

Sorry, I read that you could feel it through the steering wheel. My bad, probably not the front axles then.

05RX330AWD

In my case (RX330 AWD), the vibration but no noise was at 60 MPH, my mechanic greased the U-joints & the vibration is much less pronounced, I may need the driveshaft balanced as you did for a complete cure.
As I do mostly city driving & need to pay $45.00 for the bridge to get off this island to get that done, that could wait for now. Although every case may differ, probably a good idea to check the differential also.

RedGemini

$45 to cross a bridge? OUCH!!!

05RX330AWD

The bridge is 8 miles long, that's $5.63 a mile, total ripoff
All included, bridge, the fuel & the service, it could cost around $200. to have the driveshaft balanced....
certainly do not leave this island much, only in summer, although this summer it will be for good.
Time to move on, it will be the last time I get soaked.

DavidTB

Had a similar problem with my 08. It started after an oil change. Would start at about 30 mph. At first I thought the dealer tighten somthing. After a couple time back, found out it was a loose bracket near the gas tank. They put a small piece of foam there and problem was fixed. No charge.

BlackLexRX

^^^^ mine had that vibration too when i bought it. Was gas tank plastic shield that rattled. Check yours OP. It is located drivers side rear just in front of rear tire. Look under there and you will see it. Lexus has a TSB for it; http://www.revbase.com/BBBMotor/TSb/...dPdf?id=142846. They replace the whole shield with a new one, but you can fix yours if it has the problem by adding foam around the edges like myself and others did. Some have cut the edges where they contact frame, but just put some sticky weather strip tape around leading edges and vibration is gone.