Rotational Clunk somewhere in the rear end

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  • robo_trigger
    Wrencher
    • Oct 2011
    • 210

    #1

    Rotational Clunk somewhere in the rear end

    So my girlfriends A/T 325e is making a strange noise and after a few days of searching around the net/doing what driveway diagnosis I can in 20 degree weather I'm looking for a little help.

    What : It's a clunking sound, I first noticed it when I was driving close to a wall on the passenger side of the vehicle. It seems like it occurs with every wheel rotation. It could also be described as a really loud click, but its more of a clunk.

    Where: It seems like its coming from the passenger side rear wheel area. I know this could be half shafts, wheel bearings, parking brake hardware. Possibly diff or driveline issues. All of the parking brake components are brand new in the past 2000 miles, and the sound doesn't have any metal on metal scratching characteristics and occurs too reliably on rotation to seemingly be ebrake stuff so I ruled that out off the bat. I got under and pulled around on the half shafts and they seem okay, nothing seems out of place. I couldn't see the CSB with the heatshields on so I know not of its condition. I know that occasionally she had some vibration under load (right around 2k).

    When : Any time under load, especially loud when trying to go up hills etc. If I punch it for a bit its really loud and if I let off the gas the pitch of the noise changes and it's softer but I can still hear it (clunk clunk clunk). However if I feather off the gas I can usually find a sweet spot when I can make the noise disappate or disappear altogether.

    Now I know the normal culprits (halfshafts, csb, guibo [she has an early eta guiboless driveshaft so this is a moot point]) but I'm wondering if this symptomatically (the frequency of the noise, the ability to produce it under load) might be some sort of differential issue? similar to diff backlash?

    Any help would be awesome.
  • jlevie
    R3V OG
    • Nov 2006
    • 13530

    #2
    That noise is unlikely to be the differential. A half shaft or drive shaft problem is more likely, especially since it is influenced by drive train torque.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

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    • robo_trigger
      Wrencher
      • Oct 2011
      • 210

      #3
      Sounds good to me, sounds a lot better than a differential. Thanks man.

      Comment

      • robo_trigger
        Wrencher
        • Oct 2011
        • 210

        #4
        How about this, She said she tried to park on a rather sizeable snow mound on the side of our street today, which might have been a little taxing on the suspension. And when she pulled away the sound was gone. I thought this was probably shenanigans so I drove it around. It has indeed abated for the time being.


        I don't like it.

        Comment

        • robo_trigger
          Wrencher
          • Oct 2011
          • 210

          #5
          half shaft in case anyone was interested. when she backed up over the snowbank she re-sat it towards the diff. a little daily driving loosened it. clickity-clack

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