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    Something is shifting around...

    So Im trying to pinpoint a problem with my car. Here is the issue.

    At low speeds, like parking lot driving or taking a corner very slowly, I feel something shifting around in what I believe is the rearend section of the car, like the subframe or something. It makes a loud thud and is very noticable. As if the subframe is pivoting. It is very hard to describe. Also, the car pulls to the right pretty badly. When I give it gas it wants to track to the right and when I let off it tracks left.

    Heres the setup:
    2JZGTE
    R154 Trans
    Condor Speed Shop RTABs, Diff, and Subframe bushings with riser kit
    Welded Diff
    BC Racing Coilovers
    E36 Rack
    Tii Brakes

    Front end has stock control arms, bushings, tie rods, ball joints, but they all seem to be pretty tight.

    So my question is what should I check on? This has happened since ive owned the car, before the bushing installs. Alot of people say its just the welded diff, but it doesnt feel like thats the issue, although im sure its not helping. Any ideas guys?
    - AXIS POWERS - 2JZ E30 Build
    Current Project - 87 325is 2JZ Swapped with M4 DCT

    #2
    Originally posted by SLEEPYDUB View Post
    So Im trying to pinpoint a problem with my car. Here is the issue.

    At low speeds, like parking lot driving or taking a corner very slowly, I feel something shifting around in what I believe is the rearend section of the car, like the subframe or something. It makes a loud thud and is very noticable. As if the subframe is pivoting.


    This part sounds exactly like the behavior of a welded diff.
    Lorin


    Originally posted by slammin.e28
    The M30 is God's engine.

    Comment


      #3
      Ok I can agree that the welded diff is causing the shifting feeling. But can anyone help me understand what exactly is going on to make this car feel that way?
      - AXIS POWERS - 2JZ E30 Build
      Current Project - 87 325is 2JZ Swapped with M4 DCT

      Comment


        #4
        When you turn a corner your left and right wheels are rotating at different speeds because the circles they are describing are of different diameters. The tighter the turn, the greater the percentage of difference.

        When you are at low speed your tires have very good traction and since your left and right rear tires are turning at different speeds they build up a torsional (twisting) load through your half shafts and welded diff UNTIL the torsional load becomes greater than the traction available and a tire (usually the inside one) violently, briefly spins and everything unloads (unwinds). The cycle repeats if you continue in a circle.

        This is why most vehicles intended for high traction surfaces have a differential.
        Lorin


        Originally posted by slammin.e28
        The M30 is God's engine.

        Comment


          #5
          That helps, thanks. So then this is just something I will have to "live with" as long as I use a welded diff. It just sounds so harsh. I guess the popping and clunking sounds are just axles and the diff, and are a "normal" sound with this setup.
          - AXIS POWERS - 2JZ E30 Build
          Current Project - 87 325is 2JZ Swapped with M4 DCT

          Comment


            #6
            Originally posted by SLEEPYDUB View Post
            That helps, thanks. So then this is just something I will have to "live with" as long as I use a welded diff. It just sounds so harsh. I guess the popping and clunking sounds are just axles and the diff, and are a "normal" sound with this setup.
            It is harsh and adds extra strain and wear particularly to the halfshaft assemblies.

            I would recommend you run a limited slip diff, the E30 lsd unit is very easily upgradable to high performance standards.

            EDIT: I forgot to add another annoying feature of a welded diff on the street. It causes severe understeer at low speeds as well because the locked together rear wheels are trying to push the car in a straight line.
            Last edited by LJ851; 04-11-2013, 10:58 AM.
            Lorin


            Originally posted by slammin.e28
            The M30 is God's engine.

            Comment

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