Quote:
Originally Posted by Silverpike
God I can't believe there are 3 pages on this and nobody got the answer yet:
IT'S THE DIFFERENTIAL
I guarantee this is the answer. How do I know? My Subaru WRX has the exact sound you guys are describing. The reason comes from a firmly mounted rear subframe. The diff has a resonance right at about 60mph for me, and it got 10x louder when I installed subframe bushings. The resonance is anywhere in the 60-70mph range for all Subarus (newer subarus have slightly higher resonance points). It sounds like a loud, resonating pitch that fills the whole cabin of the car. The cabin acts like an amplifier unfortunately.
Unfortunately for me, it's very very loud. Nothing I can do, since I'm not pulling the bushings back out.
The way to mitigate this is twofold:
1. Buy high quality gear oil for the diff.
2. Add audio damping material to the car, around the rear subframe and the lower cabin.
I doubt anyone here will get a resolution from Subaru. This is not something easily fixed at the source.
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I'm pretty certain it's the differential but I won't say it
is the differential until the car's been checked out and the noise pinpointed by an experienced mechanic; that will hopefully take place in under a week's time. There ought to be something that can be done to remedy or mitigate the noise on Subaru's part; not everyone is reporting this issue which makes me hopeful that not every car suffers from this issue. I know for a fact the car I test drove way back when did not make this noise.
Quote:
Originally Posted by sdshores08
Thanks! I'll let you know if I decide to call Scion. I haven't been driving on the freeway lately, but it'll probably aggravate me again the next time I do. I hope something comes from your case, please keep us updated.
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Will do.
Quote:
Originally Posted by Silverpike
Sorry I should add one more thing:
You can tell if it's the diff if the noise changes pitch and loudness depending on how hard you are on the gas. Both on acceleration and deceleration, the noise is loudest for me. Steady state cruising the noise is soft. All of this is inside the 60-70mph window, so if you test make sure to keep it in this range.
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It's much more speed dependent than anything else. I'll experiment, possibly tomorrow, with different loads to see if the noise changes: I don't believe it does. There's a load-dependent whine from the transmission but it's not bothersome like this noise is since it 's ever-present when I'm in the speed range. The presumed differential noise is just slightly there outside of the small speed window, but it's very gaussian in that the intensity rapidly increases as I approach 70 MPH and then tapers off again.