Interesting noise in the rear of my 04

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wolf_walker

Junior Member
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So over the last 20K miles, this noise has been growing.
Only I could hear it, sometimes, early on but now anyone with decent hearing can hear it.
It is audible most from 30-45mph, it's likely there below that but not audible, and above that
I'm sure it is but wind and tire noise fold it into the mix.
At 35mph, it is rhythmic, somewhere around twice a second, and it does seem to vary in
frequency with speed but it somehow does not seem to vary as much as it should.
On/off throttle makes no difference, gear makes no difference, loading the chassis one side
or another makes no difference, braking makes no difference, road surface makes no difference,
temperature makes no difference.
But it is, slowly, getting louder.

I've been monkeying around with cars for decades, and I'm pretty good at describing
stuff but I can't find an English language combination of letters that match it.
Early on it was almost like wind noise, like a gust of wind across the rear C pillar.
Now it's almost like the sound of a lid for a mason jar being spun on a counter till
it stops, if that makes any sense at all. Whaka whaka whaka but without the K and
more wind across the exterior like, and a regular frequency, is as close as I can come.
I'm pretty sure wheel speed isn't two revs per second at 35mph so I don't believe it's
tire or wheel. My best guess is a rear axle bearing but other than a bad pinion bearing
here and there, I've never heard a bad solid axle bearing. And the pinions I've heard were nothing
like this. It's such a slow noise for the speed of everything in the driveline at 30-40mph
I can't imagine what it is. The only other thought I have, is I do have bad bushings in one
of my (fairly new Moog) rear control arms that I guess could possibly be transferring sound
in an odd way into the chassis? That's a reach, I know.

My plan is to stick it up jack stands and run it up to the speed where it makes noise and
go under and have a listen. I need to find a fuse that will disable the ABS since I'm pretty
sure it'll have a fit doing that. Failing that I'll rotate the tires and see if it follow, but I really
don't think that's it.

Any of this sound at all familiar to anyone?
Car has 246K as of todays 300 mile drive so it could be about anything.
I changed the rear axle fluid at 220K but that was likely it's first change.
 

Hound Dog

Active member
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Reading this I was starting to think axle bearing too.

One thing more you might check is the emergency brake. If a liner came loose from a shoe or a spring popped loose it could make this noise. How does the pedal feel? Loose or tight? If it is tight maybe the adjuster over did it and they are rubbing a bit.
 

wolf_walker

Junior Member
684
446
63
Haven't ruled out tires, but I'd be a little surprised.

I did the rear brakes not long ago, pedal good, did the ebrake too and they worked last time I used them.
The stock shoes had fallen off the backing, I replaced everything at the time. Good thought though, I'll check em.
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Hound Dog

Active member
129
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28
Thanks for following through with the answer.
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