So my car makes a rear end whining noise from zero to about 50 mph, much louder when engine braking but still present to some extent while accelerating.

I couldn't hear it when I bought the car because of the loud exhaust, I first noticed it when I put on the magnaflow x pipe but didn't care much because it wasn't loud compared to all the creaks and clunks I could now hear coming from the suspension. Then, I fixed the blown diff bushings with Whiteline poly bushings and it got a lot louder due to more of the vibrations being transmitted to the chassis. This is what makes me think that it's diff noise and not wheel bearings, combined with the fact the noise doesn't change on cornering loads and that the wheels are on nice and tight.

Then, I fixed all the creaks and clunks in the suspension, put 10k miles on the car, and now the whine is noticeable enough to bother me while cruising around town at a constant speed even with the radio on a normal volume... Time to fix that too!

After some research on the internet symptoms seem fairly consistent with loose pinion bearing preload, has anybody experienced and fixed this before? I also noticed when I was under the car troubleshooting I could slightly move both diff flanges where they connect to the axles axially. Is this normal too?

It's also possible that this is just normal poly bushing diff noise and I'm just being OCD, so I made a video. The mic doesn't pick up the sound very well but it's much louder in person. In the video you can only really hear it at ~40 mph, starts around 10 seconds and goes on and off as I play with the throttle for the rest of the short video.
https://www.youtube.com/watch?v=uXsI...ature=youtu.be
Is this something others have experienced with their Gs when upgrading to poly/solid bushings?


The input of this site is greatly appreciated!


EDIT: And yes I changed the diff fluid the day after I bought the car, my tires are brand new.

 

There really isn't an upgrade option aside from switching to a mechanical unit UNLESS your VLSD is shot and replacing it with a good VLSD would be an "upgrade", there should be stiff resistance when you try to turn the axles in opposite directions. As far as the whine in the video it's a little bit different than mine, I have whine that starts about 30mph and lasts until 60mph but it doesn't change pitch or tone at all by playing with the throttle (it gets a little louder from 30-60 though) so you might have something off inside the diff. I know mine is just gear whine echo'ing out of the diff so I just ignore it...

Just as a precaution I would definitely check the fluid level in the tranny and diff in case there's a small leak you aren't aware of.

 

My VLSD appears to be function from the axle turning test. Are you also able to slightly move your axle flanges on the diff?

My noise changes in both pitch and loudness depending on speed and direction of drivetrain load, I think it may have been caused by the PO driving (and probably racing given the former state of the suspension) the car for 50k+ miles with a blown diff bushing...

 

I had no play on my differential axle shafts, they were pretty much rock solidly attached when I had it out for diff bushings.

 

Did you ever figure out what the problem was!?! I’m having this exact problem