Here's the story.

I did my polyurethane bushings over a month ago. At the same time I installed solid REAR delrin mounts on my differential (not the solid steel front one that is common, but 2 solid delrin rear ones). Got everything finished, put the car back together, and drove it home.

On the way home I noticed a weird sound coming from the rear. It was kind of like what rushing (whooshing) air sounds like. This sound increased with speed and decreased on decel. I decided to put the car down until I could figure it out. I jacked the car up and spun the rear tires by hand and noticed that it made a rubbing sound, so first thing I tried was new brake pads, but those didn't fix it. Then I noticed that my calipers were pretty shitty and the piston seemed to be frozen, so I got new reman calipers. After the calipers were put on, today, and I bled the brake system, I took the car out for a drive and it STILL makes the sound.

The sound, like I said, still increases with speed, sounds like rushing air over something, etc. My friend stuck his head out the window of my car the entire time and while driving, coasting, anything he could not hear a single sound from the outisde of the car, it is very noticeable from inside the car, though. It comes from the center of the rear, could it be the differential possibly? All we did to the differential was to take the stock mounts out and replaced them with the solid rear ones.

Here I am over a month since I put in the bushings with barely anything changed. Thanks to midterms, Napa ******* up my parts orders, and incompitent people I have not been able to get a whole lot done.

What's next to change/check? Rotors? I don't know how the rotors could just die or get warped while sitting, though.

Any help appreciated.

 

It may be just gear noise from the diff coming through the body. Can your friend ride in back with his ear over the diff mount area (pressed to the floor) and hear it better? Welcome to the world of compromise, performance/comfort!

 

Yah I was wondering about that precisely, but a friend also brought it to my attention that I should get a full alignment and get the specs back to stock first. After going to coilovers, camber adjusters, and ropping the whole subframe/suspension for bushings, somehting could've gotten screwed up even though I made marks to keep it as much the same as I could. I think my next step will be an alignment and checking a few things.

Opinions still welcome though!

 

Dude...I been driving RX's for 20 years and own two 88 S4's now...one that that all of mine have had in common is when the tread on the rear tires gets low...it has a terrible sound...now I don't mean down to the threads....but one half to two thirds wear they get noisy....maybe its just me but I have noticed that for quite a while and new tires solves my noise problem >>>for a while anyway...hope thats all it is....but I don't hear much about it on the Forum so I don't really know...good luck
'

 

Tires are fine, hardly used, like 3k mile, Goodyear Eagle F1 GS-D3's with awesome tread still.