Passenger seat Vibration @ 69-75

[05+CTS+V]

07 1SG STS4

Anyone else have this? I don't have the sqeaking passenger seat issue that many have mentioned before. However, when on the highway I feel a slight vibration and when no one is in the passenger seat it vibrates pretty badly.

However, you don't feel it in the wheel at all and the car tracks straight. The pass seat doesn't make any noise just shakes and is annoying out of the corner of your eye. Also I feel a slight chassis vibration.

Above or below those speeds it's smooth as ice.

Anyone else see this?

Thanks in advance.....

[05+CTS+V]

Forgot to mention it has 15k.

I'm wondering if it needs a wheel balance.....

[MARKVIII]

My 'o5 V8 does it also. only the seat shimmys nothing else. the car rides smooth as glass and there is no vibration in the chasis. i cannot explain it....

[Benjamin Simon]

My Lac has been doing that for the last 51K miles. Evidendly, the car is designed to do this. Let me know if you find someone to tell you a different answer.

[MARKVIII]

I also have a little play in my drivers seat. Its been addressed (tightened) several times and then they finally told me its designed to move a back and forth a little...

[HexWarrior5]

WOW...I'm glad other people see this cuz I thought I was going crazy when i first noticed it...it's so strange, all symptoms are exact...my car is an 05 sts v8 with 20000 mi and same thing: car rides very smooth and no vibration in wheel or chassis except this goddamn passenger seat!!! but i guess that's good ol american design...oh well, please, if anyone acutallly solves this issue, post it!!!!! this little thing is quite annoying!

[WillySTS]

Originally Posted by HexWarrior5

WOW...I'm glad other people see this cuz I thought I was going crazy when i first noticed it...it's so strange, all symptoms are exact...my car is an 05 sts v8 with 20000 mi and same thing: car rides very smooth and no vibration in wheel or chassis except this goddamn passenger seat!!! but i guess that's good ol american design...oh well, please, if anyone acutallly solves this issue, post it!!!!! this little thing is quite annoying!

Well I'm glad you all are satified with that, I was about to to tell you that your rear wheels are slightly out of balance and that's how it shows up...not through the steering wheel as that is for the front wheels, but it can be felt through the seat...how else could you feel it?

Tires/wheels NEED to be balanced regularly, they do not keep their balance forever or past 15,000 miles, even though you don't rotate them. Have them done on a GOOD balancer, you'll see wht I mean.

[05+CTS+V]

Willy,

Thanks for the replies. I was figuring it was a balance issue as I haven't had the car balanced since I bought it 3k miles ago. I will get a 4 wheel balance in the next week or so and post back the results for everyone.

Thanks