Saltynutz

It's the brakes, have some one check the brakes carefully. Check to see if brake shims or fitting kits are in good shape and aligned probably. Sometimes aftermarket pads don't fit well with other parts.

skysurfing

Mine was the transmission but it went about 10,000 miles before it was ready to die. In addition I did have to have the bearings and brakes done but the sound I posted about was the tranny. This RX330 must have been abused because it's a lemon and I so regret buying it. I would have thought 90,000 on a "toyota" was nothing but these sure aren't like my first Corolla.

Kendig

Our 2007 rx400h (fwd) developed a whine which was most obvious while driving 28-32 mph on a flat road, so that the accelerator was being ever-so-gently feathered. Took it to Lexus of Orlando. They test drove it with me, heard the noise, and diagnosed it as a problem in the transaxle. (No surprise; I've had a Corvette and a Mercedes which serenaded me like that until the differentials were replaced).

Anyway, at 88,000 miles and still under the extended warranty, we now have a new transaxle whose replacement cost was listed as $5500.

By the way, with reference to the earlier comments about Lexus of Tampa & Clearwater, I've been to Lexus of Tampa and I won't be back. If our RX broke down in that part of the state, I'd call up Lexus of Orlando and willingly pay extra to have them come and pick it up.

Heypresto

I have very similar problem on my RX 300. It is so annoying, I do not know what to do.
I have replaced the transaxle oil but the noise still persist.

Audiqv8

First, you have to determine the problem. You can try to determine if it is coming from the right or left side. I just replaced the rear passenger side bearings on my RX two days ago. I determined that the humming noise was loudest when I was turning left while moving. This indicated to me that I had a problem with a right wheel bearing. The hardest part was trying to free the rusted wheel bearing from the backing plate. Using an air hammer solved that problem, and torquing the axle the nut to 217 ft/lb was solved with a torque multiplier.