Our 2001 RX300 (182K) has a front right suspension rattle at low speeds (under 30mph). It's more heard than felt. At higher speeds it disappears. Sometimes (not always) the steering return is notchy. Also, front passenger side tire had very uneven wear. FWIW Sway bar end links are new and bushings look good. I'm guessing it's the strut mounts. Struts themselves were replaced with KYB about 70K / 8 years ago but (as far as I can remember) I did not replace the mounts. Yesterday I was looking at the strut tops (from under the hood) and noticed the passenger (noisy) side center nut is noticeably off center in its opening. Driver's side is perfectly centered. Makes me think right side upper mount has lost bearings. Anyone ever seen this? Will be taking apart soon.

 

The strut mount do go out (that's why it's recommended to change them along with the struts). If you replace them, use OEM mounts, not aftermarket.

 

Took noisy side strut out. Strut mount bearing looks better than expected and moves smoothly. Strut mount itself is pretty rusty. I suppose it could be flexing and making noise. Strut (KYB G2S) seems good - difficult to compress by hand and takes about 1 minute 30 seconds to go from fully compressed to fully extended. From what I understand that's normal for a low gas strut. Attached pic shows bottom of mount. Seems strange that the "flats" which sit against the flats on the strut rod are rounded - but maybe it's normal. Could be my issue is lower control arm or ball joint.

 

As I recall those flats slide into notches on the strut rod so that you can tighten the strut nut without the allen wrench typical in most strut assemblies. I suspect that yours was not properly inserted when the struts were replace 70K ago.

 

I'm hoping this is what happened (even though it was me 70K ago) and that the curved flats on the inside of mount are munged and are the source of the noise and replacing will solve the noise.

 

Replaced strut mount and tie rod end. All quit now. Likely the real issue was the tie rod end.