Shimmering

[Harry8160]

After driving for 60-90 minutes a vibration begins in the rear of car (feels like a flat tire) and slowly moves to front where it gets so bad I have to stop the car. When applying brakes there is excessive front wheel shimmering. There is nothing wrong with the tires after stopping. When I resume driving the shimmer is gone and does not starrt again for another hour.  I had the wheels balanced, alignment checked and brakes checked. All OK. Any suggestions as to cause or solution. Thanks

[RX400h]

Based upon your description, I'd guess that something is loose or badly worn. I recommend taking it to a shop that is experienced working on older vehicles. For something like this, I'd take our RX to a trusted alignment shop. 

[rjleo24]

Long shot here. If you had tire work such as new tires, or a re-balance of the wheels, it would require a removal of the wheels from the car. When the service tech torqued the wheels back on the car he may have over tightened the wheel nuts. I've seen it where the torque applied is double the spec due to using a pneumatic device common in tire shops that are not calibrated to the specified torque. These nuts should always be set to the specified torque using a torque wrench! Over torque of the wheel nuts can result in warping the rotor, which will cause simmering in the wheels. You can check the torque by marking where a wheel nut is positioned on the wheel and then loosening the nut. Re-torque the nut so the lines are in the position they were before loosening. Don't be surprised if they read well above the specifications.

Hope this helps.