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  • Drivetrain / diff clunk?

    Done a search on this and can't find any posts with the same concern...

    Often when I reverse I get a clunk from the rear - feels like it's in the area of the diff/propshaft. It doesn't happen as you select reverse, nor when you start to move, but when you ease of the throttle it happens then & feels like quite a shunt.

    Doesn't do it every time but this seems to be a new sensation that's developed in the last few weeks. Diff clunks as the clutch is engaged seem to be a common "characteristic" but that's not what I'm getting.... just wondered if anyone had any thoughts?

    As an aside, I also get an "ease-off" or "sudden throttle" knock sensation when travelling forward, e.g. being at 50mph in 5th - sudden let off of throttle a slight "knock" is detected - sudden floor of the accelerator and the same "knock" - almost as if something vibrating along the drive train line.

    Not sure if this is connected? Thoughts anyone?
    Just a little nervy about such issues give the boot floor problem, though mine has previously been strengthened....
    ----------------
    David
    1999 M Coupe (S50)
    >>Read my journal here<<
    2005 Smart Roadster-Coupe Brabus
    2022 Range Rover Evoque PHEV

  • #2
    Guessing from the lack of response I have a unique issue here?
    ----------------
    David
    1999 M Coupe (S50)
    >>Read my journal here<<
    2005 Smart Roadster-Coupe Brabus
    2022 Range Rover Evoque PHEV

    Comment


    • #3
      Mine had a bit of a clunk/shunt although it was pretty much stopped when i removed the clutch delay valve which I felt made the clutch too slow/unresponsive when you change gear quickly.

      Braided line with no CDV made quite a big difference.

      I'm expecting the driveline to be further improved now I have replaced the guibo, centre bearing and the boot floor is re-inforced and has a new diff support ear, and Polybushes in the subframe to stop the subframe whipping about. Haven't got her back on the road yet though.



      Other possible causes:

      Worn Guibo/Donut
      Incorrectly fitted Guibo/Donut
      Worn Prop centre bearing.
      Misaligned prop and or wear in the non greasable Universal Joint
      Excess Backlash or play in the diff (unlikely unless abused)
      Boot floor welds and or diff mount just starting to come away.

      Guibo wise here is a useful video:

      https://www.youtube.com/watch?v=Vw7Zbp1rfGI

      Comment


      • #4
        The guibo was replaced a few months ago - also had the braided hose fitted.
        The boot floor welds are my main concern - hopefully not that as it was all reinforced by a previous owner!
        ----------------
        David
        1999 M Coupe (S50)
        >>Read my journal here<<
        2005 Smart Roadster-Coupe Brabus
        2022 Range Rover Evoque PHEV

        Comment


        • #5
          Crossing my fingers for you, it's worth a look at the boot floor no doubt.

          I had to look at mine very closely to spot the spot welds that were starting to fail.

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          • #6
            I would say clunking just as you come off throttle/dip clutch and unload the driveline are common traits of the Z3 in general.

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            • #7
              Defo, mines always done it. It can be disconcerting though...
              S54 Seca Blue - ACS Short shift and Exhaust. Luverly.

              Comment


              • #8
                Originally posted by c_w View Post
                I would say clunking just as you come off throttle/dip clutch and unload the driveline are common traits of the Z3 in general.
                I’d agree, mine has always done it, even when it was new to me at ~3.5 years old
                2002 '52 S54 - Titanium Silver with 18" BBS LMs, AP Racing BBK, KW V3, H&R anti roll bars & ACS flippers (previously 2000 'X' S50 - Arctic Silver)

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                • #9
                  Mine does it, but its done 160k The garage said it was a bit of backlash in the gearbox.

                  It's fine once your rolling, but if you come on the throttle hard initially in any gear you feel the take-up.

                  All my diff bushes were fine and not holes in the floor etc
                  2001 E46 M3 Coupe for me / 2007 E91 335i for the Dogs.

                  Comment


                  • #10
                    Sorry bit late to the party...but did you get this sorted?
                    I had something similar and took the coupe to a couple of my local indys.....
                    ML were the ones that sorted it straight away.

                    Mine was a combo of things, mainly weirdly it need an uprated diff oil!
                    Had the noise mostly of right hand turns.

                    Defo get in touch with Munich Legends....70mile trip for me but that's where I always end up getting my issues resolved.

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                    • #11
                      Changed both gearbox and diff oil on mine, not difficult and well worth doing :)

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                      • #12
                        Having had a 2.8 , M Roadster and now the Coupe , they all have had a slight clunk when you take up the drive . Taking into account the amount of CV's within the drive chain and the fact that you are virtually sitting on top of the diff is perhaps why you tend to notice it all the more

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                        • #13
                          Originally posted by ///Juttla View Post
                          Sorry bit late to the party...but did you get this sorted?
                          I had something similar and took the coupe to a couple of my local indys.....
                          ML were the ones that sorted it straight away.

                          Mine was a combo of things, mainly weirdly it need an uprated diff oil!
                          Had the noise mostly of right hand turns.

                          Defo get in touch with Munich Legends....70mile trip for me but that's where I always end up getting my issues resolved.
                          Thanks I use them also and will be booking in for a service in the spring so will ask them to do a diff / gearbox oil change - that said it seemed to go away the last few weeks before I put it away for winter!
                          ----------------
                          David
                          1999 M Coupe (S50)
                          >>Read my journal here<<
                          2005 Smart Roadster-Coupe Brabus
                          2022 Range Rover Evoque PHEV

                          Comment

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