rumble noise and vibration from driver side rear
 

Car is having a little issue. Could use some help diagnosing. Thanks in advance for the help!

Issue: feels like I'm running over cables or small rumble strips. Sound and feel like coming from rear driver side.

Frequency: often, almost 100% replicable at highway speed.

Occurance: prominent when off throttle slowing down, gets muffled a bit when on brakes, the frequency of "bouncing" is lower at lower speeds (occured as low as 5mph).

Diagnosis attempted so far: swapped wheels/tires, no OPR present on previous tires. Tightened lugnuts. No obvious damage or visual cue.

When it started happening: after Track Night. It wasn't as prominent, I thought lugnut was loose, but it wasn't. It got significantly worse tonight.

Next step: tighten all linkages, including shock nut of rear struct...

[ame]https://www.youtube.com/watch?v=ftz-Q_fwlig[/ame]

Could it be from the trunk area where the spare is kept?

My guess, lose underbody panels and or fender liners.
Did you happen to go off track, or hit a deep pot hole?

did not go off track, no under body panel hanging (from the rear???) the rumble can be felt though pedals and steering wheel, so i don't think its something inside the car causing it.

If you feel it in the steering wheel and while at a crawl, I'm going to say you have a bent or out-of-balance wheel. It may also be structural failure of a tire. If the latter, you are in danger of a blowout.


I hear only rattling of some panel which I am guessing is due to wheel wobble.

its not wheel or tire, i swapped both. rattle and vibration can be felt through steering and pedals. latest diagnosis... not sure if this is normal, but it seems like a sloppy U-Joint.

[ame]https://www.youtube.com/watch?v=YDaQy9hu_Ps[/ame]

That sure sounds like the same slapping sound heard in your first clip.

Check out this section of the manual. My take is forget the dial indicator. If you can feel it give in any direction, it's toast.

DRIVE SHAFT / PROPELLER SHAFT: PROPELLER SHAFT ASSEMBLY: INSPECTION; 2013 MY FR-S [03/2012 - ]

we tried turning the shaft by hand, there were definitely some play rotational wise before it actually actuates the diff. not sure if thats normal.

That's normal gear lash. Look for failures in the u-joints themselves.

Dam that vid make me to think it's maybe the lsd is toast

so we tried to repeat what we did in the video again. same clunking. but if i turn traction control off, its smooth. lead me to think the ECU is freaking out cuz wheel is spinning but car is not going anywhere since its jacked up... probably normal? on the other hand... i haven't able to recreate the same clunks in the first video when i drove it friday night... gonna take it to my mechanic's shop sometimes this week.

I had a loaner Volvo some time back that rumbled and rode roughly with spin control on but when it was off all was well. :iono:

Issue has been fixed. Driver side rear CV joint was bad. Driven on "new" axle for over 2000 miles now, no rattle of any kind.

Thank you! Much better when there is closure on such things.