Dno36

OK, this will be kinda long as I have been stumped...maybe someone can find a possible solution.
I've maintained dozens of vehicles with my business and extended family, and done about every repair possible over the last 30 years,
I've inherited the Equinox 16 Months and 35K miles ago.
2013 Equinox AWD 2.4L., 170K miles.

Developed a vibration when accelerating about 3 months ago. Getting worse.
It will happen at ANY speed, from start to 70 MPH, if there is a moderate throttle increase.
Higher acceleration and the shake won't start until about 50 MPH.
A slight throttle can make the shake happen right from a dead stop.
A turned wheel makes it worse, both left and right turns are the same.
A subdivision left-hand curve, 20MPH, always makes the shake appear.
I ease off the throttle, and it goes away.
I gently accelerate, and the shake remains the same with the transmission shifting normally through the gears. (Ruling out inner transmission)
Sometimes I can let off the throttle and re-accelerate and the shake is greatly diminished or gone.
The vibration is felt in the steering wheel, but not prominently. Feels like the front drive-line.
The shake does not seem to be from the rear shaft as the seat shake is not evident. Had another Equinox with bad mid-bearing and the seat was shaking badly.

Basic info:
Newer tires all around. Oil & water vapor catch can for direct injection vehicle.
I was getting ready to make a series of normal year/mileage part replacements, so I got to it.
New Plugs and VVT solenoids.
New Front CV shafts, wheel bearings, lower control arms, sway bar links, calipers, rotors, and brakes.

Trans service, checked tie-rods(tight and right), motor mounts(newer), sway bar (newer). Struts seem fine.
Tires are tight, shaking at 12 & 6, and 3 & 9 have zero play.

Through all of the replacements, done over about 2 weeks, most notably, wheel bearings and drive axles, the vibration has NEVER changed... at all.
No difference.

Could this be the Intermediate shaft? Is there a check for this?
That or maybe a bearing at the end of the transmission is all I can think of...

Any reasonable ideas?

Thanks in Advance,

One-Stumped-Dean

Dno36

OK, Here is an addition to my ongoing vibration issue...
It has gotten worse. As expected.

A right-hand sharper turn at lower speeds is worse than a left-hand turn.

Here is a strange fact: When the car is vibrating badly, if I hit resume on the cruise control to accelerate to a previous higher speed, the vibration goes away, completely!! If I just keep my foot on the throttle, the vibration continues.

ac9934

I have the same problem in my 2020 Equinox. My dealer told me that GM is aware of the problem. They claim it's because the two front drive axels are different lengths. One will spin faster than the other. They told me there is no fix for it at this time. Apparently, a BMW (or something like that) has the same problem.