Problem indicator:
Noise only (so far)
From a stop, light acceleration and there is a clunk from center to back of car in first gear (flipped to manual to confirm current gear); next hit second and it changes to a steady vibration until somewhere in 3rd at 50 mph and then it balances (guessing) out to smooth to faster highway speeds.
Under continuous hard acceleration until 50 mph little to no vibration and no clunk at all.
In breaking and deceleration little to no vibration and no clunk.
The clunk and vibration seem to be independent of the engine rpm but relative to the road speed.
Turning has no bearing on the issue.
CV joints seem and look good.
No issue in reverse.
No leaks under car.
Idles fine.
Engine mounts look okay, but haven’t fully tested.
Transmission cushion has yet to be inspected.
Rear differential stayed warm for a while after driving (not sure if that’s normal, first time to need to check rear end of car I owned)
Picked up a a/c part (unrelated to clunk) from my closest Subaru dealer/shop, after leaving the shop the clunk/vibration got worse. (a hour one way at highway speeds, i.e. two hours per trip) Asked the Subaru shop the next time and they said that’s weird never hear of such and issue. Seems to not have changed significantly on the second trip, but concerned that driving may worsen the issue.
After discussing with a local gearhead/shade tree mechanic and inspecting the underside of the vehicle we decided most likely to be relating to prop shaft/center bearing. I removed the prop shaft and found the u joints to be showing signs of failing according to my research (forums and vids by quality mechanics). I bought and installed replacement. No change in the clunk and vibration.
At the moment I can’t get it to a shop without driving and considering the it may be unsafe to drive trying to figure it out myself.
Any help or thoughts would be much appreciated.
