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Thread: Early Steering box

  1. #1
    Join Date
    Nov 2014
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    New York City
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    BMW 750il (e32)

    Early Steering box

    I'm looking for an early Steering box. Nothing wrong with mine in my 1993 750il however I prefer the lighter steering of the early box in my old 1988. I recently looked at a 1988 750il and the steering was lighter as I prefer. Does anyone know when BMW increased the steering effor?. I know by observation that MY 88 was a light steering year but perhaps other years were too, knowing this would help me find the right box.

  2. #2
    Join Date
    Jan 2005
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    11/88 E32 750iL+98 E36M3
    Has nothing to do with the steering gear box, the support/power comes from the servo unit. Clean the filter for the power steering fluid and maybe you try different servo control modules. Location of the servo control unit ist inside the cabin, left front behind the speaker in the footwell.
    Also clean the filter at the bottom of the steering gear box, you have to remove the torque converter servotronic. The torque converter motronic has 4 bolts, the 2 longer ones are the ones you have to remove to get the unit out, behind that converter is a metal mesh screen. I also had the same problem years ago and cleaned the filter and all worked well again, see my website, I posted that there.
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
    Join Date
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    11/87 735i & 735il P/C
    @Shogun I'd bet it's the servo control module if he notices that much difference.

    When I got my current 88 735 running it had much heavier steering than I remembered on my first 88 735. After much searching on this forum I discovered it was the module. If you remove the two orange plugs that go into it, they plug into one another. Then your steering is always lighter. The downside of that (as I discovered) is over-sensitivity on the highway - the point of a working module is to make the steering heavier when you're going over ~50mph (might even be 40mph, anyone know exactly???) and improve handling.

    So as long as your PS fluid looks clean and is at the correct level, I'd start by going through the hassle of removing the speaker in the driver's footwell to get at those two orange connectors (the module they're plugged into is mounted up and to the left on the inside of the sheet metal where the speaker hole is... kind of hard to describe and a huge PITA. Disconnect them and plug them into one another to see if you have lighter steering... then find a replacement module. I was lucky because I had a parts car... not sure if the modules are repairable.
    1983 4-spd Mercedes 240d w/403k - Sold!

    11/87 E32 735iA w/45k - Daily Driver (finally!)

    04/88 E32 735iL - Parts Car

  4. #4
    Join Date
    Nov 2014
    Location
    New York City
    Posts
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    BMW 750il (e32)
    Quote Originally Posted by CamE32 View Post
    @Shogun I'd bet it's the servo control module if he notices that much difference.

    When I got my current 88 735 running it had much heavier steering than I remembered on my first 88 735. After much searching on this forum I discovered it was the module. If you remove the two orange plugs that go into it, they plug into one another. Then your steering is always lighter. The downside of that (as I discovered) is over-sensitivity on the highway - the point of a working module is to make the steering heavier when you're going over ~50mph (might even be 40mph, anyone know exactly???) and improve handling.

    So as long as your PS fluid looks clean and is at the correct level, I'd start by going through the hassle of removing the speaker in the driver's footwell to get at those two orange connectors (the module they're plugged into is mounted up and to the left on the inside of the sheet metal where the speaker hole is... kind of hard to describe and a huge PITA. Disconnect them and plug them into one another to see if you have lighter steering... then find a replacement module. I was lucky because I had a parts car... not sure if the modules are repairable.
    Thanks, I'm going to dig deeper in to the screen and perhaps an early servotronic unit before I try a new steering box.

  5. #5
    Join Date
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    11/88 E32 750iL+98 E36M3
    Over the years BMW had different control modules with slightly different power support curves, some numbers
    BMW 1134310 -> ZF 7038 900 142
    BMW 1134315 -> ZF 7038 900 143
    BMW 1134338 -> ZF 7038 900 144
    BMW 1134870 -> ZF 7038 900 145
    On the German forum they have made some extensive test and even read the curves. Alternatively you can use modules from Audi such as
    Audi Nummer -> ZF Nummer -> Kennzahl -> Herstellung -> Verwendung/Herkunft -> Nummer
    Audi 4A0 907 307A -> ZF 7038 900 206 -> 3X2 568 -> 29/95 -> Audi 100 C4, Audi V8 D11 -> 357
    Audi 4D0 907 307 -> ZF 7038 900 207 -> 3X2 569 -> 11/94 - 46/97 -> A6 4B C5, A8 4D D2 -> /
    Audi 4B0 907 307 -> ZF 7039 900 209 -> 3X1 448 -> 50/90 - 20/99 -> A6 4B -> 392
    Audi 4D0 907 307A -> ZF 7038 900 215 -> 3X6 120 -> 42/99 - 37/00 -> A4 B5, A6 4B, A8 D2 -> 605

    one Audi unit decoded:
    ich konnte nun endlich mal ein Steuergerät auslesen, hier also der Inhalt des 93C46 EEPROMs aus folgendem Servotronicsteuergerät von Audi:
    Audi 4D0 907 307 -> ZF 7038 900 207 -> 3X2 569 -> 38/96 -> A8 4D D2 -> 356
    0123 2C33 3A40 4A62 768F A3B2 BECC D7DE
    E3E7 E9EB ECED EE00 EF00 00F0 0000 F1F2
    040B 1374 2800 2800 2800 0000 AD52 6900
    2034 4430 3930 3733 3037 2020 3130 3861
    2030 3031 201E FFFF FFFF FFFF FFFF FFFF
    FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
    FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
    FFFF FFFF FFFF 0004 3C41 0007 6914 681A

    BMW module decoded
    BMW Servotronic Steuergerät 7038 900 222
    32.43 - 1 162 703 (leider nicht vom V8)
    :10000000 0129 516A 7984 9BB6 C0CD D8DD E2E5 E8EA
    :10001000 EBEC EEF1 00F2 0000 0000 F300 0000 00F4
    :10002000 040B 163D D4CF 1400 1414 0000 AD52 6900
    :10003000 3131 3632 3730 3320 3130 3663 2032 3232
    :10004000 2D30 3031 201E FFFF FFFF FFFF FFFF FFFF
    :10005000 FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
    :10006000 FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF
    :10007000 FFFF FFFF FFFF FFFF 44CF 0003 411A 3C08
    :00000001 FF

    here is the long thread https://forum.e34.de/thread.php?thre...ht=servotronik

    The old version modules are NLA, that is the module in this shape for fitting the 2 round yellow plugs http://www.kawasuki.net/fotos/servo2.JPG
    normally there is an adapter loom to modify from the 2 yellow plugs to the new module connector, if you want to go the cheap way, here http://www.kawasuki.net/fotos/servotr.JPG
    Not to difficult, on the old relay there are the terminal numbers mentioned such as 15, 31 etc...
    And then there are 2 larger pins left for the valve at the steering gear box and a smaller pin for the speed signal.

    repair of the module I posted here http://www.bimmerboard.com/forums/posts/1268590/
    some use a fixed resistor http://www.bimmerboard.com/forums/posts/1268588
    and here is the training manual I sent by email to Patrick, he uploaded it http://www.bimmerboard.com/forums/posts/1268618 9 pages, download it, there you can also see the power support curves (German language training manual Servotronic - die elektronisch gesteuerte Servolenkung
    Last edited by shogun; 10-05-2018 at 03:35 AM.
    Shogun tricks and tips for the E32 series are HERE!

  6. #6
    Join Date
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    11/87 735i & 735il P/C
    Great info Shogun! Thanks for sharing
    1983 4-spd Mercedes 240d w/403k - Sold!

    11/87 E32 735iA w/45k - Daily Driver (finally!)

    04/88 E32 735iL - Parts Car

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