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  • Diff bearing position

    Hi Guys,

    In the last month i revise the complete rear axle from mit Z3M.
    Now i put all together and was a bit suprised about the Diff bearing position.

    Is it right that the bearing will touch with the metall cover the diff holder ?

    Iam not sure... maybe somebody have some picture so that we can compare.

    THX and Greats from germany

    Oliver
    Last edited by Dave P; 19-01-2023, 05:57 PM.

  • #2
    The backplate doesn't seem to be sitting at the right angle. The outer metal of the bush shouldn't be touching the body otherwise noise/vibration will just get transferred in to the cabin.

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    • #3
      Doesn't look correct, are the upper diff mounting bolts positioned correctly?

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      • #4
        Similar problem?,


        http://www.bmwfanatics.co.za/showthr...d=64543&page=3

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        • #5
          Thanks for your posts.

          Do i understand right that i need an new rear axle carrier ?! :-(

          Or maybe with the Diff bolts it is possible Boy correcting the position ?

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          • #6
            Originally posted by Dave P View Post
            Doesn't look correct, are the upper diff mounting bolts positioned correctly?

            Dave, the question is: what is correct in this case ? Or Just open and Try ?

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            • #7
              Originally posted by Olified View Post
              Thanks for your posts.

              Do i understand right that i need an new rear axle carrier ?! :-(

              Or maybe with the Diff bolts it is possible Boy correcting the position ?

              I would doubt its the rear axle but more likely something not correctly seated? as c_w says the diff cover appears to be at a odd angle

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              • #8
                Hopefully youre right... i will Try to correct it without putting the axle out of the Car... if i will have an soloution (or maybe Not) i will Tell you that !

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                • #9
                  I can't work out how it is like this - the diff mounts on the boot floor aren't bent are they?

                  The bolts that go through the subframe in to the diff are very tight tolerance (anyone refitting a diff will know they can be fiddly as they have to go in dead centre!).

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                  • #10
                    So just putting the diff on subframe and under the car was maybe to easy for the first step.

                    In Daves link the guy wrote something very interesting:

                    If the bolts from the diff are not in centre with the black covers, there is a big chance that the subframe is bent.

                    See picture: http://smg.photobucket.com/user/gizm...00335.jpg.html

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                    • #11
                      Originally posted by c_w View Post
                      I can't work out how it is like this - the diff mounts on the boot floor aren't bent are they?

                      The bolts that go through the subframe in to the diff are very tight tolerance (anyone refitting a diff will know they can be fiddly as they have to go in dead centre!).
                      Im not really sure if it is bent. I does not look like that. But perhaps you cant See it

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                      • #12
                        Olified, if you could perhaps take more pictures from underneath your car it might help to find the problem ?

                        Here are some pictures from mine (scroll down to see the rear end subframe related ones) : https://plus.google.com/photos/11351...LXkmuWj46W42wE

                        The diff is attached to the subframe with those four bolts from the top. As c_w said, there is not much (if any) play in these and therefore the diff can only have one position in relation to the subframe.

                        Then the subframe/diff combination is attached to the car at three locations :
                        2 x front subframe bushes + 1 x rear diff bushing.

                        This gives us basically the following theoretical places to have an issue :
                        1) Front subframe bushes are shot or the bolts in the bottom of the car to hold these are bent -> the whole subframe becomes incorrecty positioned respect to the car body. If you remove the diff bushing bolt, in theory at least, you could bend the front bolts when you bush the subframe downwards ?

                        2) The subframe is bent (very unlikely if it came out ok and the car has not been severely crashed ?)

                        3) Diff endplate is incorrectly assembled to the diff body (this may not be even possible without having oil leaks ?)

                        4) The attachment in the car body for the diff bushing is bent. It is rather thin sheet metal and could happen.

                        5) The diff is not correctly attached in the subframe but has incorrect angle respect to the subframe (= tilted respect to the subframe). Cannot recall if there were any shims in between the diff and the subframe but with those you could incorrectly angle the diff in the subframe ?
                        Some pics that might help :

                        https://v2tre.wordpress.com/2016/03/...d-and-updated/

                        https://v2tre.wordpress.com/2014/02/01/pera-irtaallaan/

                        https://v2tre.wordpress.com/2014/03/...menna-ajetaan/

                        Good luck. Hopefully it is some minor hick up.

                        br, JuhaV
                        The older I get, the faster I was ...
                        BMW HP2 Sport
                        ex- BMW Z3 M Coupe - Cosmosschwartz Metallic

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                        • #13
                          If there is a problem with the alignment of the beam and the diff is sitting in the wrong position it should show up as in this picture as the upper diff bolts should be centred in relation to the recess?


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                          • #14
                            Hi Guys,

                            First of all a big thanks for all that detailed and great informations !

                            Today i made a plan and will go on step by step to check all the options you told to me. Unfornately i will see my Z3M on friday because i am in beautifu munich.

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                            • #15
                              Today i checked the subframe. What should i say? Its like on the pictures from the guy with the white Z3M

                              So i will buy next week an E30 Subframe to make sure, where the problem is. What ever the previous owner did


                              I will keep you up to date !

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