On Wed, 2 May 2018 14:43:04 -0500, dpb wrote:

On 5/2/2018 2:28 PM, trader_4 wrote:
On Wednesday, May 2, 2018 at 2:29:13 PM UTC-4, Tekkie® wrote:
...

The dealer just called. Diagnosis: alignment. My wife has an $80 coupon
which they will honor. They tested it at 80 mph. Will return loaner and pick
up. No damage to any suspension parts. They left the new tires on the right
side because they measured the tread depth and found no difference.

Thanks everyone for their posts.

--
Tekkie

That explains all the symptoms except the vibration. IDK how alignment
would cause vibration, you should ask them that.

I'd wager they rebalanced as well just didn't say so, specifically.

Most times I find the service rep that calls is just that; all he has to
go on is the service order, he didn't do any of the work and just reads
off the highlights, not necessarily every minute detail...if there's
something need to know specifically usually ends up having to actually
talk to the tech/mechanic to find out just what they actually did in detail.



From a tech article in HotRod Magazine's site

Alignment

Sometimes an elusive shimmy or vibration stems from an improper wheel
alignment. The two main culprits are toe and caster.

Toe


Toe describes the longitudinal relationship between two wheels on an
axle. Toe-in: wheels point toward each other in the direction of
travel; toe-out: wheels point away from each other in the direction of
travel.

The front wheels on most rear-drive road cars benefit from a touch of
toe-in. It compensates for the road force that can induce a toe-out
condition. Toe-in also eliminates lash in the various components,
which enhances straight-line stability.

Excessive toe-in can induce a bear of a shake. It causes the tires to
fight each other for traction and the rapid release/traction cycle can
cause a shake. It also wears tires unevenly, which causes its own
problems.

Toe settings vary by suspension design so start with the specs that
the original manufacturer determined for the suspension under your
car. But don’t treat these specs as if they’re set in stone. Your
vehicle’s dimensions may differ considerably from what the
manufacturer intended so you may have to slightly alter toe settings.
Remember that bias-ply tires neither need nor tolerate as much toe as
radial tires do.

Caster


Caster in a roundabout way generates tracking stability. It refers to
the Steering Axis Inclination (SAI)—the line plotted through the
kingpin or through both ball-joint centerlines—as viewed from the
wheel face.

What actually generates the stability is the relationship between the
point where the SAI intersects the ground and the tire’s contact
patch. Most vehicles feature negative caster, meaning the tire follows
the point where the SAI intersects the ground. In fact, motorcyclists
express this tracking-stability dimension by the distance that the
tire “trails” the SAI where it intersects the ground. Increasing this
distance increases the force by which the front wheels center
themselves. That makes a car feel more stable at speed.

But that force sword has a second edge: excessive caster/trail can
generate enough force to steer the wheel beyond center and slightly
into the other direction. If conditions are just right the centering
forces can volley the wheel rapidly left and right in a shimmy.
Motorcyclists have a more descriptive term for this too: Death wobble
or tank slapper. Anyone who’s experienced it in a car or on a bike can
testify that it’s terrifyingly scary and it goes away only if you
reduce speed dramatically.