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Thread: 540iT M5 Diff Swap with Auto

  1. #1
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    540iT M5 Diff Swap with Auto

    02 E39 540iT Auto with SLS.

    Considering doing a tranny and/or diff swap not sure both yet or which order really. I've got a possible donor 00' M5 with a transmission, driveshaft, complete rear diff and subframe.

    Been reading up on the links, mostly this one, which explains the majority of it and has helped a lot in even considering it.

    http://www.bimmerforums.com/forum/sh...-Wiring-Coding

    I'm not sure I will be able to do it all at once due to cost/time, but here's my question, I couldn't find a definite answer with my searches.

    If I keep the Auto tranny for the time being - Can I swap just the Diff, with either the included M5 half shafts and or finding flanges(sounds like the easier route)? Is it even possible to do that on the Auto? Everything I've found seems to already have a manual in it then they try the diff.

    Thanks!

  2. #2
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    Figures I find something right after posting.

    Reading this, sounds like if I already have the Auto, all I need for the diff swap is the diff end of the M5 driveshaft, and the M5 Diff itself, no flanges or changing half shafts needed as the auto already shares the same half shafts as the M5?

    https://www.bimmerforums.com/forum/s...6#post26247706

  3. #3
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    Quote Originally Posted by Passta View Post
    Figures I find something right after posting.

    Reading this, sounds like if I already have the Auto, all I need for the diff swap is the diff end of the M5 driveshaft, and the M5 Diff itself, no flanges or changing half shafts needed as the auto already shares the same half shafts as the M5?

    https://www.bimmerforums.com/forum/s...6#post26247706
    You are correct. The axles are 102mm input flange size, just like the M5, but the M5 axles do have beefier shafts. I believe it's like 31mm for 540iA and like 37mm for M5. Probably nothing to worry about if you're not producing a ton more power than a stock 540i motor.

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  4. #4
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    540iT M5 Diff Swap with Auto

    I’m planning this also and have all the parts. I was told that you need the M5 axles as well...which I also have. Is this true?


    Update - never mind I checked all the links. Thanks

    Sent from my iPhone using Tapatalk
    Last edited by Dvbimmerk; 09-18-2018 at 11:40 AM.

  5. #5
    geargrinder's Avatar
    geargrinder is offline Having No Trouble Here BMW CCA Member
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    Quote Originally Posted by Dvbimmerk View Post
    Update - never mind I checked all the links. Thanks
    Even without links the last 2 posts explained your question explicitly.

    Touring owners are lucky in that regard (flanges). I would not fret for one second over the M5 / 540iT axle diameter issue. If the axles (CV's) wear out on you... well sure then you can put either one in but the 540iT axle is already bigger than the sedan and not sure I can ever remember an E39 axle breaking (wearing out, CV going, sure, but not "the diameter was insufficient and it snapped").
    2003 M3CicM6 TiAg
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  6. #6
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    Quote Originally Posted by geargrinder View Post
    Even without links the last 2 posts explained your question explicitly.

    Touring owners are lucky in that regard (flanges). I would not fret for one second over the M5 / 540iT axle diameter issue. If the axles (CV's) wear out on you... well sure then you can put either one in but the 540iT axle is already bigger than the sedan and not sure I can ever remember an E39 axle breaking (wearing out, CV going, sure, but not "the diameter was insufficient and it snapped").
    Thank you


    Sent from my iPhone using Tapatalk

  7. #7
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    I installed an M5 diff, M5 axles, M5 driveshaft in my 6MT 540iT and found the following:

    * Diff is a little longer so the shorter M5 driveshaft was needed.

    Your 5AT driveshaft is shorter than both M5 and 6MT driveshaft but you'd also have to consider that the trans is probably longer.

    * Output flanges are indeed the same size so you could reuse the 540 axles.

    * My car is a rust free CA example and pulling the stock axles is probably one of the toughest jobs I've done.
    Current:
    Alpine White E46 325i Touring S54 6MT
    Titanium Silver E39 540i Touring M-Sport S62 6MT

    Past:
    Alpine White E46 330i ZHP Sedan S54 6MT
    Interlagos Blue E85 Z4 M Roadster 6MT
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    Estoril Blue Individual E46 M3 Coupe 6MT
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    Alpine White E92 M3 6MT
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    Laguna Seca Blue E46 M3 Coupe 6MT
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    Lagoon Green E36 325is 5MT

  8. #8
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    Sorry to revive and I've searched heavily. With my 540iA sport, using 540i axles given the same flange size on the diff - what about the c-clip and positioning of to secure? Running into this right now at the shop.

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