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Thread: DIY Guide: Z3 Differential Removal & Installation

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    DIY Guide: Z3 Differential Removal & Installation

    This guide is now available to download in a .pdf

    CLICK HERE TO DOWNLOAD
    Last edited by mcoupemindy; 03-19-2013 at 01:42 PM.

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    mcoupemindy is offline Senior Member BMW CCA Member
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    This guide is now available to download in a .pdf

    CLICK HERE TO DOWNLOAD
    Last edited by mcoupemindy; 03-19-2013 at 01:42 PM. Reason: Automerged Doublepost

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    Great DIY - thanks!
    Brian

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    Sweet dude, when I grow some bigger stones, this will be helpful.

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    Interesting, your diff has some different bolts on the top then mine does.

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    Quote Originally Posted by The ZED View Post
    Interesting, your diff has some different bolts on the top then mine does.
    I bet yours is just missing the spacers that sit between the bolt head and the subframe. I've seen several like that.

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    Mscire2 is offline That one RS'd Coupe BMW CCA Member
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    do those spacers make a difference? because mine keep coming loose. I am about to put some lock washers in there.

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    Quote Originally Posted by The ZED View Post
    do those spacers make a difference? because mine keep coming loose. I am about to put some lock washers in there.
    From all the cars I've done I've noticed that it really doesn't matter of the spacers are present. I've seen cars with the spacers come loose also. Lockwashers or blue loctite would be my recommendation.

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    Quote Originally Posted by mcoupemindy View Post
    From all the cars I've done I've noticed that it really doesn't matter of the spacers are present. I've seen cars with the spacers come loose also. Lockwashers or blue loctite would be my recommendation.
    Do you know the correct torque setting for the diff bolts?

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    Good info - Thanks
    2000 Z3 MCoupe, '01 LSB E46 M3, '99 GTI VR6, '06 Audi A4, Andrew '95 Avus M3

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    I've actually been considering making an access panel to get to those upper bolts from inside. It's just so much work to lower the subframe!
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    Nicely done. I have to mine again, as the 3.73 i dropped in is making noise now...not looking forward to it.
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    Awesome write up, I will keep this handy thanks! You can never have too many floor jacks ehhh? I love my Arcan (made in the Good Ol' USA), I stuck with the steel as I didn't want to step down from 3.5 tons though.
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    Quote Originally Posted by The ZED View Post
    Do you know the correct torque setting for the diff bolts?
    They remove with between 50-80 ft.lb. and seems to depend on each car. It's been quite some time since I looked up the recommended figure, but I typically go by as tight as possible with an 18" breaker bar in the limited space. Maybe someone else can chime in (or look up in the Bentley) the specific torque spec for these.

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    110 Nm.

    Z3s don't have the spacers, ///M cars do.

    The spacers allow more bolt stretch, presumably, so they don't come loose.

    Some cars have been easier to remove the bolts than others, but I've never found any that were "loose" even on cars that I know the differential was swapped.

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    Quote Originally Posted by Randy Forbes View Post
    110 Nm.

    Z3s don't have the spacers, ///M cars do.

    The spacers allow more bolt stretch, presumably, so they don't come loose.

    Some cars have been easier to remove the bolts than others, but I've never found any that were "loose" even on cars that I know the differential was swapped.
    Thanks Randy! You saved me looking it up.

    ... I'm not sure if use has anything to do with it, but I've seen a few with "finger tight" bolts. To me, that qualifies as loose. Mind you the cars that I help tinker with are really never just street driven.

    Additionally, I've seen non-M's with spacers and M's without spacers. With most of the cars being not one-owner cars, it's hard to tell what previous owners did or the shops that previously serviced the car. I actually heard of one M owner removing the spacers so that the bolts were more easily tightened with the subframe up. Diff bolts are on my inspection list when I have my car on a lift - my OCD has saved my butt a few times.

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    very nice write up

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    Excellent DIY, very well done.
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    Not bad, but I can get to the top bolts without dropping anything, and that's with the spacers.

    Rob - 2000 BMW Z3 M Roadster | 1986 Porsche 944 5.3L LM4

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    Great write-up. So, the first time this was done, how long did it take? I'm really tempted to give it a shot if I ever find the $$ to source a new diff.



    EDIT: Please place a link to this in the DIY sticky too. I'd do it, but have found some people prefer to link their own threads.
    Last edited by lokijibber; 12-12-2010 at 08:27 PM.

  22. #22
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    Quote Originally Posted by Robstah View Post
    Not bad, but I can get to the top bolts without dropping anything, and that's with the spacers.
    Yes you can do it, but it's a PITA for most. Well worth the extra 30 minutes for the steps to loosen the subframe IMO.

    Quote Originally Posted by lokijibber View Post
    Great write-up. So, the first time this was done, how long did it take? I'm really tempted to give it a shot if I ever find the $$ to source a new diff.



    EDIT: Please place a link to this in the DIY sticky too. I'd do it, but have found some people prefer to link their own threads.
    If you take your time and clean everything as you go, it will take between 3-4 hours on both the removal and installation for a first time. You'll need additional time to seal the diff case, etc.

    I would be more than happy to help you do it if you want to come a bit south. Just let me know.

    I'll post in the DIY thread.
    Last edited by mcoupemindy; 12-12-2010 at 10:14 PM. Reason: Automerged Doublepost

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    Quote Originally Posted by mcoupemindy View Post
    Thanks Randy! You saved me looking it up.

    ... I'm not sure if use has anything to do with it, but I've seen a few with "finger tight" bolts. To me, that qualifies as loose. Mind you the cars that I help tinker with are really never just street driven.

    Additionally, I've seen non-M's with spacers and M's without spacers. With most of the cars being not one-owner cars, it's hard to tell what previous owners did or the shops that previously serviced the car. I actually heard of one M owner removing the spacers so that the bolts were more easily tightened with the subframe up. Diff bolts are on my inspection list when I have my car on a lift - my OCD has saved my butt a few times.
    I found one (1) like this:





    Same car:



    When I was doing the reinforcement work, nothing was lining up; the suspension carrier was bent, and had to be replaced.

    As was discovered during the project, the car had been rear-ended so bad, that the back half of the car had been replaced (sectioned with another one). Since the suspension carrier mounts were on the main part of the tub, everything that was critical lined up, once the new carrier was installed.

    Interesting viewing in this album... http://www.rfdm.com/gallery/album68

    Every car is a mystery; some are pristine (most, really) and some leave me wondering...
    Last edited by Randy Forbes; 12-13-2010 at 03:13 AM.

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    Thanks for doing a great write-up. I'm looking to put a 3.4 or 3.6 diff someday.
    -Phil

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    Quote Originally Posted by Randy Forbes View Post
    As was discovered during the project, the car had been rear-ended so bad, that the back half of the car had been replaced (sectioned with another one). Since the suspension carrier mounts were on the main part of the tub, everything that was critical lined up, once the new carrier was installed.

    Every car is a mystery; some are pristine (most, really) and some leave me wondering...
    How many cars that have had a full repaint don't have something sketchy about them?
    I like the unicorns.
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