I'm trying to chase down some noises and vibrations toward the rear of my car that aren't always the same or consistant. I've done my best remember all the scenarios in which the different feel/sound has happened. So, here goes...

• When I first get on the freeway my car vibrates at what feels like a wheel rotation frequency. It pretty much goes away within a mile. I assume it's related to tire flat spotting since the vibration feels busier than tires that are out of balance.
• When I am on the freeway (especially after I just get on the freeway) I also typically get a higher frequency vibration which can be heard (like a subwoofer rumble) and felt. It's typically only above 60mph. This one sometimes goes away just as quick as the first bullet point. Other times it seems to continue on for longer. I believe that it greatly reduces or goes away if I let off the gas. When it's happening the amplitude typically comes and goes every 2 to 4 seconds.
• When driving above 65mph I also get a vibration that feels like about the frequency of tire vibration. I want to believe that I can rule the tires out after have the tire balanced>noted bent wheel fixed (to "better-than-new") and re-balanced>all 4 tires re-balanced with road-force balance. This one also seems like it reduces or goes away if I let off the gas.

My thoughts are that it might be the guibo(s) and/or driveshaft center support since I do get a higher frequency vibration and it seems to go away if I let off the gas. I'm not sure how this would cause 2 frequencies of vibration though. Possibly the higher frequency vibration becomes harmonic at a certain speeds causing a slower vibration... probably a stretch.

Has anyone had and fixed similar issues?

 

I would say flat spotting for the first one, second and third really sound like wheel balance.

 

It's a two piece drive shaft, the vibrations will occur at every order of harmonics on both halves.

I would check it since anytime you left off and vibration reduces/changes it means something in the drivetrain that alters it state from load/absence of load is the generator of the noise. Also check the input bearing of the rear diff and rear trans bearing endplays.

This is assuming you are certain it's not the wheel/tire packs, did you already swap rear to front and see if it followed? It's usually in the tires as stated above

 

I'm not certain it's not tire balance issues. I've had them balanced by two different shops recently and I feel like there second shop did a good job. They explained the details of what they did and they have a good rating on Google.

 

Move the tears to the front yourself or mark them with a paint pen to ensure they move them and see if the steering has vibration and if the noise in the back stopped. If the issue moves around with the tires/wheels the issue is there no matter what the shop might say.

 

Good point. Free and easy. I'll give it a shot.

 

Finally got a chance to do this.
Vibration is still happening at the rear. I did seem to reduce it some by cleaning up the mating surfaces of the hubs, rotors and wheels.

Continuing to investigate...

 

Might have to take my last post back.

On a trip today it was as bad as ever again. Not sure what to make of it.