Just finished up some maintenance on my 2011:

Front sway bar end link replace (left and right)
Rear diff fluid change
Front diff fluid change

On the maiden voyage, everything was fine up until about 70mph. Then I start to get a vibration in the steering wheel....the steering wheel doesnt SHAKE but you can feel the vibration. The car was driven all winter on my winter wheels with no vibrations, but thinking maybe they were flat-spotted (and its about the time anyway) I changed over to my summer wheels which also never vibrate. But the vibration remains.

Under 70mph the car seems fine. I cant really feel the vibration anywhere else other than the steering wheel so I was thinking SOMETHING up front, but not sure what. Could it be related to the diff fluid change? I used 75W-90 full synthetic (I know the FSM calls for 80W-90 but I wanted to go full synth which Ive only found in 75W-90).

EDIT: some more observations - the frequency of the vibration seems too high to be wheel/tire balance...its more the feeling of going over rumble strips. It happens when on or off the throttle. Once it does start to happen, its not consistent....its like an on again off again thing, but no regular pattern to it (other than 70+mph speed). Did confirm I cant really feel it anywhere other than the steering wheel (felt brake pedal, gas pedal, dash, floor,. console and seat while it was happening but could not feel it in those). The frequency does not seem to change with speed...once the vibration happens it feels the same at all speeds until under 70 when it stops (or I cant feel it anymore)

Thanks in advance.

-Chris

 

Wheel bearings are a common issue on AWD sedans. Generally one side goes before the other, so the best way to diagnose is to see if the vibration lessens when turning. if it's only happening at speed they might be in the early stages of failing. Take to the highway late at night so you're not causing a hazard and when you get up to speed and feel the hum, cut one way and then cut to the other, noting if the vibration gets better or worse. You don't need to cut hard, but just enough that the weight transfers off one side to the other. If there's a stretch of highway with some sweeping corners, that is ideal.

If it gets better when cutting left and the weight comes off the left side, it's your left wheel bearing, same applies to the right.

 

I was able to try this last night and it does not seem to be affected going right or left when its already doing it. Even going perfectly straight, the vibration just comes and goes by itself. No elevation change, no throttle change, but the vibration changes.....its really strange. I did have a wheel bearing go on my old 2001 i30. It would vibrate at a certain spot when turning left....before and after that spot, nothing. It did feel similar to what Im feeling now, but what I feel now is no matter which way Im turning or even if going straight.

I forgot to note that I have not reinstalled the under-engine plastics yet....I will do so later today and if for some odd reason that makes this all go away, I will have a beer and come back here admitting Im an idiot

 

Well....its beer time and I must be an idiot!

All I did today was release the sway bar because I needed to lubricate the bushings. Reinstalled the bushings and brackets, then reinstalled the under chassis plastics I removed.

Aaaaaand....no more vibration. Not quite sure which thing fixed it, but at this point Im just happy its fixed.

-Chris