04 LS Vibration in rear after car sits for a couple of days plus

[Marshallt]

I love my 2004 LS 6Cyl Basic, 2 owners, 32,000 miles. Everything works but:
If the car sits for a few days (as it frequently does) I have a vibration from the rear end. It is a rumble to a shimmy. It goes away after driving the car for 15-30 minutes. I have new Michelins and TSW wheels. The problem does not move after rotating wheels. The TSW wheels have the centering rings installed. Car has never been wrecked and is garage kept. The under-carriage is literally like new. The longer the car sits the more significant the vibration is.

I am stumped. Help, please.

 

[joegr]

It's pretty normal for tires to get a bit of a flat set after sitting a while (especially when cold) and cause some shaking/vibration of the car for the first few miles, but it doesn't seem like this is what you are describing. Have you checked the alignment, specifically the rear toe? The center bearing on the driveshaft? The rear CV joints?

 

[Marshallt]

It's pretty normal for tires to get a bit of a flat set after sitting a while (especially when cold) and cause some shaking/vibration of the car for the first few miles, but it doesn't seem like this is what you are describing. Have you checked the alignment, specifically the rear toe? The center bearing on the driveshaft? The rear CV joints?

Yes on the alignment, no on the driveshaft/CV joints. They are now on the check list. Would both/either of those items settle down after driving for a reasonable period of time? Thanks!

 

[joegr]

I really don't know. Maybe after they heated up?

 

[Marshallt]

I really don't know. Maybe after they heated up?

I will certainly look into it. I know something about an engine bay, brakes and suspension. I am lost with drive trains.

Thanks again.