Vibration at speeds above 70 MPH, seat shaking, 2003 Bonneville
 

Well I broke a spring,replaced it and had the jack in my trunk,i have a shaking at 70-75,very common as i see here..with the jack in the trunk and airgun and other tools,,the car was much smoother on the highway..took it out and its back..have to retest this,i changed the right axle shaft..didnt fix it...lost on this shaking..bought new rims and tires,thats now it..

Lets look at all the likely possibilities:

Inner tie rod
Outer tie rod
Worn control arm bushings
CV axle (you already replaced)
Ball joint
Hub bearing
Another bad balance on your new tires

You may want to start to eliminate the above one-by-one. The ball joints and tie rods you can check at same time. Pop off the tires and then check the bushings. With new tires, you can swap them front to rear and see if any change.

Note I have the same issue in my 2001 Bonny. It only happens on some roads when driving above 60. I changed tires two weeks ago and the problem has not come back. I did a ball joint check and notice by right side ball joint is failing.

In my case I think i have two issues causing the vibration (even though the new tires ares somehow masking the problem). Right side ball joint and worn control arms bushing.

Thread title has been updated.

I changed 2 struts and got it lined up,rotated the tires and it seems better..now 1 of the bolts on top of the sturt I cannot tighten up the insert spun,and now i got a banging noise going over a speed bump..got to check that..

I replaced both my struts a year ago with "quick struts". In my vehicle, the struts were not a factor in the intermittent vibration at higher speeds.

thats what i put in...rockauto 61 bucks...autozone 202 bucks

I think you installed just the struts, which run around $60 at Rock. The quick struts run over $100 at Rock, and include new springs, all new hardware, etc. What caught my eye was when you mentioned that you can't tighten down one of the strut mounts. That is eliminated as a issue with the quik struts.

these are quick struts...all 1 piece w spring etc...monroe.

You got an awesome price. I bought them for well over $100 at Rock.

our cars are getting older,234 at advanced auto..geeze..

Al, please take a look at this thread:

https://www.gmforum.com/2000-2005-90...aurora-305177/