Some recent developments:
I had to go to the same dealer where I bought my ride (Puente Hills Subaru, PHS) twice and they gave me that typical BS runaround about how it’s “normal.” How can it be normal when during acceleration a wobble shakes your butt like the car wants to dance. One tech even said he could live with it. So here is the symptom that started about two months ago in case any of you have it:
Slight to moderate vibration/shake during acceleration from a stop or during traffic crawl, up to about 15-20 mph. Not an engine hesitation or stumble. Vibration felt at the seat/butt area and not the steering wheel.
Occurs most under load, when full of people, and during right turns. After 15-20 mph the car always drives smooth. The heavier the car, the more acceleration vibration.
Symptom occurs only **after** the car engine/CVT are at operating temps. Will not happen when driving from a cold start. It seems like very hot days trigger more acceleration vibration.
Finally, during my second visit they relearned, or “flashed,” the computer. Then I was told it was “fixed” and all’s well. I drove off the lot gushing with joy and then the darn shake returned immediately. I was so darn pissed I didn’t even bother driving back. Why? Because the first time they said it was three flatspots on my tire that caused it. So, on both diagnoses they were wrong. I intuitively sensed it was either the axle or CV joints given the threads I read here and on other websites. Thanks for all your help everyone! My personal inspections of the engine and transmission mounts were correct: no problems with those. I didn’t think it was the suspension because I’ve not had any of the telltale “clunks” people describe on here (well, at least not yet since I have only 9500 miles on the odom).
I finally did a few searches on the best dealership in Southern California, in LA county, and it was a place called Subaru of the Pacific (judging from all the positive reviews I’ve read I had high hopes; had they not fixed it I would have simply voided my warranty and paid for the part to be replaced). I woke up at 5AM this morning and drove during rush hour to get to my 8:30am appointment. The service rep actually listened to me and had the mechanic ride with me. Then the mechanic drove it himself. I told him to drive a certain way to put the car under load and sure enough the acceleration vibration was duplicated. They determined it was the axle and replaced the front one. All is cured now. After the axle was replaced, the mechanic asked me to drive it with him on board to see if I could trigger it. I couldn’t so it’s fixed! Then I had to drive about 2 hours home in 90+ degree heat (~33 Celsius) and can confirm that the wobble is gone.
It’s all about the dealership when you’re still under warranty. Now I’m just wondering if I should critically assess the first dealership in an online review or through Subaru USA. As for the first dealership (PHS) I did buy my car through them in a very smooth transaction; indeed, the salesperson I worked with was a very professional and nice guy. However, their car servicing sucks so bad it’s unbelievable. I really just want to say how incompetent they are but then I don’t want to get people fired (that said the service reps there have attitude, thinking you’re an idiot with their “oh, it’s normal" BS). I’ll definitely leave a positive review about the second dealership though—they completely are worthy of it.
I do have a quick question though: what causes the axle to go out of balance? This wobble didn’t occur until about 2 months ago and I bought my 2015 in October of last year, so what wore off the part to throw it off balance? Thanks for reading this lengthy post!!