Help diagnosing sound

thomat65

thomat65

TJ Enthusiast
Supporting Member
Joined
Nov 9, 2019
Messages
351
Location
Southwest MI
It's somewhere in the rear. Varies in volume depending on speed, does not vary in pitch. It does not depend on load, gear, 4WD, or any of that. It does seem to need to get warmed up. First starting out it'll be silent until ~45 mph, but after driving for a mile or two I can hear it as slow as 30 mph. It's sort of how I imagine a stick or leaves would sound rubbing against the smooth inside surface of a wheel, except maybe softer than that. I checked, no sticks or leaves in the wheels! I can't tell exactly where it's coming from, it's just behind me somewhere.

What should I check?

I recently went hooning in the sand with some buddies. I was kind of expecting something to break or fly apart what with almost 200k Freedom Units on the odometer. But no it drove home just fine. So maybe I'm just being a hypochondriac. Maybe this sound has been there all along and I just never noticed it because the top has been off for the past few months until I put the soft top on the other day?
 
thomat65 said:
So maybe I'm just being a hypochondriac.
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This for sure. If you really want to put yourself at ease pull the rear discs and clean out the parking brake assembly just to make sure it's clean and free from debris. Besides that if anything was wrong it'll get worse fast.
 
You need to put the Jeep on a lift to do a visual of underneath the Jeep.
IF nothing is found then have someone start the Jeep, engage the transmission at a slow speed to see if the noise is heard.
Otherwise you will need to do as Pagrey posted; wait for the noise to get worse so you can identify where the problem is.
 
Sancho said:
Ujoints maybe?

Does the sound change when off camber or turning?

Sticky drum brake?
Click to expand...
I do have a full set of U joints ready to go when the time comes. I'm fixing to put the Jeep in the garage for the winter, so maybe this winter is time.

Doesn't seem to change with the slight amount of side loading I'm able to put on it while driving 45.

Disc brakes. But I think the principle might still apply. Maybe something behind the shield or in the parking brake assembly like @pagrey said.

pagrey said:
This for sure. If you really want to put yourself at ease pull the rear discs and clean out the parking brake assembly just to make sure it's clean and free from debris. Besides that if anything was wrong it'll get worse fast.
Click to expand...
Great ideas, both to check/clean the brake assemblies (that'll only be a good thing) and to let it get worse if I don't find anything. It sure is nice having our van to drive as backup! I hate working on a car under a deadline.

SPECWAR said:
Could just be harmonics from wind moving over and around the top.
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Good idea. I bet I could find out for sure if I just rode in the back seat.

CharlesHS said:
You need to put the Jeep on a lift to do a visual of underneath the Jeep.
IF nothing is found then have someone start the Jeep, engage the transmission at a slow speed to see if the noise is heard.
Otherwise you will need to do as Pagrey posted; wait for the noise to get worse so you can identify where the problem is.
Click to expand...
Thanks! I'll keep this in mind if I get access to a lift.



Okay guys, I now have a rough plan:
  1. Find someone to drive so I can sit in the back and listen more closely
  2. Clean and inspect the rear brake assemblies
  3. Keep an eye out for a lift
  4. Just live with it
  5. Probably should replace the U joints anyway
Thank you!!
 
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