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UPDATE: Fixed - Driveline vibration.. what'd I do wrong?

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    UPDATE: Fixed - Driveline vibration.. what'd I do wrong?

    Ok so.. I am having a problem with my driveshaft.. I think..? HALP.



    Setup:
    s52
    getrag 260
    3.73 medium case diff
    325i driveshaft
    new revshift flex disk
    brand new CSB

    Ok so, I was having a vibration problem coming from the area around the CSB at 25 to 30 mph.. after that it dissipates. The CSB was completely destroyed, as was the flex disk. So, I replaced the CSB and FD.. put it all back in the car. Drove the car, still had the same problem. So I said "fuck it, I'll just get a whole new driveshaft."

    Called Portland Driveline.. had them ship me a rebuilt 325i driveshaft with the normal u-joints. Happy as a bird, put it back in the car... drove it.. WHAT THE FUCK, still vibrating at 25mph to 30mph. Feels like there is a midget under my floorboard banging through up through the middle of the car. It's not HAMMERING it or anything, but it is definitely noticeable and driving me mad..

    What the hell should I do? The whole rear end is tighter than a little girl's tuna.. tried 2 different sets of balanced wheels, no different. It does not shake after 30mph but there is a slight vibration that can be felt in the steering wheel, not the shifter. Everything feels tight back there.. 2 brand new rear axles..

    No grinding/stuttering.. no different if accelerating or decelerating.. not RPM based, happens strictly at about 25-30mph. Car was JUST aligned and it did not affect the problem at all.
    Last edited by Nairb; 12-01-2011, 06:47 PM.
    My 1991 318is Progression Thread

    #2
    Engine/tranny mounts?
    Downpipe touching firewall?

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      #3
      Engine mounts are custom.. tranny mounts are green poly.. transmission is currently leaning 10 degrees.. which is pretty standard for s5x with 260.

      Downpipe is not touching firewall either.. plenty of clearance and no play.
      Last edited by Nairb; 10-17-2011, 04:33 PM.
      My 1991 318is Progression Thread

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        #4
        Oh so if you flip into neutral and just cruise, it keeps vibrating till it slows down under 25?

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          #5
          What did you torque your tranny mounts to? If you put your old ones back in, does the vibration go away?


          Project log -- DIRTY 30

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            #6
            Originally posted by Fusion View Post
            Oh so if you flip into neutral and just cruise, it keeps vibrating till it slows down under 25?
            Yes.

            Originally posted by Cronopoulos View Post
            What did you torque your tranny mounts to? If you put your old ones back in, does the vibration go away?
            The tranny mounts are bolted in the stock position.. it is a Getrag 260. I think it might be the OEM tranny mount.. which I'm thinking could be the problem?
            My 1991 318is Progression Thread

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              #7
              Originally posted by Nairb View Post
              The tranny mounts are bolted in the stock position.. it is a Getrag 260. I think it might be the OEM tranny mount.. which I'm thinking could be the problem?
              That would be your problem. You need a modified brace to correctly run the g260 with a 24v motor.
              88 325is - S52 powered

              Originally posted by King Arthur
              We'll not risk another frontal assault, that rabbit's dynamite!

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                #8
                Straighten up the mounts. One either needs to be much longer than the other, or you need to make/buy a custom trans x-member. The stock g260 x-member and mounts, one will be stretched like a rubber band on a 55gallon drum, the other compressed like a skinny guy stuck under "Gertrude".
                john@m20guru.com
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                  #9
                  ^That.

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                    #10
                    I was going to ask if you put the correct pilot bearing in...but,you may have found the issue
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                    1997 M3 sedan
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                      #11
                      try rotating your driveshaft 90 degrees. if it doesn't go away, another 90. and another. until youre back where you were and then you completely ruled out your driveshaft as a source of vibration.
                      Function.
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                        #12
                        I will definitely try all of your suggestions.. I am pretty sure the OEM e30 transmission mount is in place.. not good. Going to order a White325is tranny brace and I will get back to you guys.

                        Just wondering though.. why is it that you cannot use the e30 mount? Does it throw off the geometry of the tranny/driveshaft/diff or is it just because of the angle of the driveshaft? Curious..
                        My 1991 318is Progression Thread

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                          #13
                          Originally posted by e30s50dan View Post
                          I was going to ask if you put the correct pilot bearing in...but,you may have found the issue
                          What would be the symptom of an incorrect/incompatible pilot bearing? Good to know for future reference.
                          My 1991 318is Progression Thread

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                            #14
                            Sure your wheels are straight and balanced?

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                              #15
                              Yes, just got wheels balanced and tried 2 different sets.. same exact symptom of driveline vibration.
                              My 1991 318is Progression Thread

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