Originally Posted by GunsOfNavarone
The Bonneville was built on GM'* H- platform (really the G platform but GM continued to label it H). This platform was shared with the two following vehicles: Buick Park Ave, LeSabre Cadillac Seville, DeVille Olds Aurora
These vehicles all share one major common issue- vibration from the front end while driving. What they don't share is the cause of the vibration. Vibration is most notable between 60-75 miles per hour.
But one factor in the vibration is constant in the chassis they share: the light weight of the moving suspension parts. That made their smaller mass easier to move with slight variations in up-and-down movements in the tire/wheel assembly. So Road Force balancing became important. Getting the road force effect below 10-12 ounces was necessary.
GM also switched to Michelin tires. My leSabre came with Symmetry tires same as shipping and being switched on Cadillacs to abate the symptoms.
[quote] The vibration has caused dealers and GM engineers much frustration. Seems every fix identified for one vehicle, did not solve the issue for another vehicle with the same symptom. [/quote
Requires analysis just as all of us here have been suggesting to determine weak spot.
Fixes have included replacing tires, wheels, alignments, wheel hubs- the list goes on and on. No dealer will commit to replacement of any part, or any one service as a fix to the vibration. It is a matter of looking for something out of spec and/ or replacing a part and testing to see how the replacement impacted the vibration.
I'd suggest jonniewalker check the new hubs for any movement in or out.
I'd suggest switching all 4 wheels with a known good set of tires to eliminate those. Of course most of us don't have a 2nd car with same rim bolt pattern nor a tire shop or car dealer willing to switch for testing. But that works to eliminate a belt or wear pattern in tires.
I was fooled by noise and vibration from aged tires and replaced a Timken front wheel bearing on my 98 under warranty. My neighbor, who had worked in a tire store earlier in his shade tree life, could feel the problem was tires when he drove it and felt the tire. Aged belts and hard tread on OLD Michelins.
On my own new 03 leSabre and less than 10K miles with Symmetry Michelins a variable vibration was felt from tires at 62-72 at times, especially under slight acceleration on slight uphill grades (changes the pull on A-arm bushings and alignment slightly) but not on downhill. Service manager checked alignment; rear was off on toe-in, but within the wide specification. That fixed it.
My guess for jonniewalker'* problem if tires are not the fault is play in the front alignment, tie rod ends, ball joint, or wear in the A-arm bushing.