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    Failed rear diff bushings?

    What are the common symptoms of failed rear differential bushings?

    Thanks.

    Jesse
    Old, not obsolete.

    #2
    Usually a clunk in the rear.
    You can feel it/hear it as you let go of the throttle.


    A lot of times the front differential bolt is not torqued to spec (as it’s a high torque spec) and this easily causes the differential clunk as well, even if the differential bushings and bolts are in good shape.


    Hope this helps.

    Comment


      #3
      Thanks.

      This morning I got a fairly loud knocking in the driver's side rear when applying throttle in a corner. Not heavy throttle but not just a tiny bit either. At first I thought it was the DSC kicking in, but it was dry and I was not on the the throttle enough to get it out of shape. I got on it a bit in the next right hander and got the same sound but confirmed that the DSC light was not flashing. Sort of like someone knocking rapidly on a door.

      This morning's noise was on top of noticing some new low speed snapping and popping sounds from the rear yesterday....

      Jesse
      Old, not obsolete.

      Comment


        #4
        Hmm that doesn't sound like what I heard when mine failed. To me, it sounded like someone was kicking the trunk floor really hard from the bottom. It was a super noticeable single deep thud whenever I got on or off the throttle.
        2002 Topasblau M3 - Coupe - 6MT - Karbonius CSL Airbox - MSS54HP Conversion - Kassel MAP - SSV1 - HJS - PCS Tune - Beisan - MK60 Swap - ZCP Rack - Nogaros - AutoSolutions - 996 Brembos - Slon - CMP - VinceBar - Koni - Eibach - BlueBus - Journal

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          #5
          Definitely not a single thud.

          The car sat for most of the winter until I found time to do the rod bearings, control arms, steering rack, ps hoses, valve adjustment, etc. It sat up on the quick jack with the suspension hanging for about two weeks while all that went on. I did no work on the back end and had no noise from the back when I took it off the road. I am skeptical of coincidences, but what else can it be? The car is 18 years old and it seems anything is possible .

          Jesse
          Last edited by D-O; 05-18-2021, 10:21 AM.
          Old, not obsolete.

          Comment


            #6
            Originally posted by heinzboehmer View Post
            Hmm that doesn't sound like what I heard when mine failed. To me, it sounded like someone was kicking the trunk floor really hard from the bottom. It was a super noticeable single deep thud whenever I got on or off the throttle.
            Thats exactly how I would describe it to others when my rear diff. bushings were shot.
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              #7
              Originally posted by D-O View Post
              Thanks.

              This morning I got a fairly loud knocking in the driver's side rear when applying throttle in a corner. Not heavy throttle but not just a tiny bit either. At first I thought it was the DSC kicking in, but it was dry and I was not on the the throttle enough to get it out of shape. I got on it a bit in the next right hander and got the same sound but confirmed that the DSC light was not flashing. Sort of like someone knocking rapidly on a door.

              This morning's noise was on top of noticing some new low speed snapping and popping sounds from the rear yesterday....

              Jesse
              This sounds like a bad axle CV joint, and not the diff bushing/bolt. Get under the car and check CV joints for any rotational backlash. Should be none.

              Comment


                #8
                To identify if it's the diff bush/bolt issue: pull hand brake to create drag, drive the car reverse and slowly engage clutch, then do the same in first gear. If no clunk then no issue.

                Comment


                  #9
                  Originally posted by sapote View Post

                  This sounds like a bad axle CV joint, and not the diff bushing/bolt. Get under the car and check CV joints for any rotational backlash. Should be none.
                  Roger Wilco. Thanks.
                  Old, not obsolete.

                  Comment


                    #10
                    Originally posted by sapote View Post
                    To identify if it's the diff bush/bolt issue: pull hand brake to create drag, drive the car reverse and slowly engage clutch, then do the same in first gear. If no clunk then no issue.
                    I can test this when I leave work tonight. Thanks.

                    Jesse
                    Old, not obsolete.

                    Comment


                      #11
                      Originally posted by D-O View Post
                      I am skeptical of coincidences, but what else can it be? The car is 18 years old and it seems anything is possible .
                      Binding cv joint, rear shock mount, RACP cracked, limited slip chatter.
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                        #12
                        Originally posted by oldFanatic View Post
                        Binding cv joint, rear shock mount, RACP cracked, limited slip chatter.
                        Yup. These are all running through my mind now.

                        Anyone know if the suspension hanging while the car was in the air for a couple of weeks could damage the cv joints?

                        Jesse
                        Old, not obsolete.

                        Comment


                          #13
                          Originally posted by sapote View Post
                          To identify if it's the diff bush/bolt issue: pull hand brake to create drag, drive the car reverse and slowly engage clutch, then do the same in first gear. If no clunk then no issue.
                          No clunk.

                          I will be having a look at the axles tomorrow. On the drive home I got it to act up a bit more, and can say that the noise in the rear is more severe vibration than it is noise. I can feel it more than I hear it. It only happens while turning right and applying power, but once it starts it feels like the entire back end is vibrating.

                          Jesse
                          Old, not obsolete.

                          Comment


                            #14
                            Originally posted by D-O View Post

                            No clunk.

                            I will be having a look at the axles tomorrow. On the drive home I got it to act up a bit more, and can say that the noise in the rear is more severe vibration than it is noise. I can feel it more than I hear it. It only happens while turning right and applying power, but once it starts it feels like the entire back end is vibrating.

                            Jesse
                            You have described exactly the issue I am facing. Sharp turn, light throttle result in the rear end binding and making all sort of noises.
                            Soon I'll be dropping the rear end to rebuild and upgrade my diff [4.1], change out bushings [subframe/diff], and take a look at the axles.
                            2002 M3 | 1986 R80 | 2001 EuroVan

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                              #15
                              Originally posted by cudzich09 View Post

                              You have described exactly the issue I am facing. Sharp turn, light throttle result in the rear end binding and making all sort of noises.
                              Soon I'll be dropping the rear end to rebuild and upgrade my diff [4.1], change out bushings [subframe/diff], and take a look at the axles.
                              It sure seems like my diff has had enough. Anyone know a way to positively determine that the diff is the issue. The axles seem fine - no slop.

                              Jesse
                              Old, not obsolete.

                              Comment

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