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Thread: Missing Negative Post Under Hood

  1. #1
    Join Date
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    Missing Negative Post Under Hood

    Another post triggered this post about battery posts under the hood. (Redundant?)

    My 1990 E32 750i (shorty) (German National) car does not seem to have an under-hood negative charging post. It does have the positive B+ post in the normal position, but looking around the engine bay and at both front strut towers, there is no large negative post mounted. I have been using a strut mount nut/bolt as the negative for my battery maintainer, but I was wondering if the real post is in some "secret" place due to it's being a euro spec car.

    As an alternative, if in fact there is no post, can I just drill a hole in the strut tower sheet metal and bolt one in? Yes, I am stretching here...

    Ideas and suggestions are always gratefully received and appreciated.

    Thanks,

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  2. #2
    Join Date
    Jan 2005
    Location
    Japan
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    My Cars
    11/88 E32 750iL+98 E36M3
    Nothing is missing on your car. My 11/88 750iL also does not have that negative post, no need, I also use a strut mount nut or any other chassis part as a negative point. Seems, some built years years have them, others not.
    Just leave it as is, I would not drill another hole in the strut tower sheet metal, that only weakens it, think about the problems in other models where they even install strut mount enforcement plates.
    Last edited by shogun; 04-04-2019 at 07:41 PM.
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
    Join Date
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    Thank you Erich. As usual excellent information and advice.

    I didn't really want to drill any holes as I want to keep it original as possible, which (unfortunately) includes the radio (a work in progress).

    Thank you again,

    Mike
    Mike Drives:
    BMW's
    E24 - 635CSiA - (1) 1985 (US)
    E24 - 635CSi - (1) 1985 (EC)
    E31 - 850iA - (1) 1991 (Black)
    E31 - 850iA - (1) 1991 (Calypso Red)

    E32 - 740iA - (1) 1994
    E32 - 750iA - (1) 1990 (Not an "L") (EC German National)
    E32 - 735iL - (2) 1990
    E32 - 750iL - (1) 1990

    E38 - 740iLA - (2) (1) 1997 & (1) 1998
    E38 - 750iLA - (1) 1998
    E38 - 740iA - (1) 2000 "Short Sport"
    E39 - 528iA - (2) - 2000 & (1) 1997
    Also:
    2015 Ram 3500 Dually, Cumins 6.7, Std.Cab. Long box 4x4 (To haul all this junk when necessary)
    2014 Dodge Dart Rallye (Daily Driver)
    2007 Mercedes Benz CL600 (Brabus SV12S)
    Mercedes Benz SL's - (1) (2002) & (1) 1999 500 - (1) 1999 600
    1967 Buick Riviera (2)

  4. #4
    Join Date
    Apr 2004
    Location
    Hamburg, NY USA
    Posts
    1,583
    My Cars
    e23, e32, e34, e39
    An easy post to add would be one from an e39 passenger side shock tower. Screw off junk yard car, screw on yours some where.

  5. #5
    Join Date
    Jan 2005
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    Japan
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    My Cars
    11/88 E32 750iL+98 E36M3
    Actually no need, I just recharged the battery of an Alpina B12 which is parked in my garage since some weeks, connected to B+ and for the ground I used some of the hood lock mechanics next to the fuse box, because that was nice blank iron and good contact.
    Shogun tricks and tips for the E32 series are HERE!

  6. #6
    Join Date
    Jan 2005
    Location
    Japan
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    11/88 E32 750iL+98 E36M3
    alternatively you could use this one: BMW Hex Nut M8 x1.25 - Genuine BMW 07149125856 , OE Numbers 07149125856, 12521719648, 12520141131.
    That is as far as I understand the original hex nut on the B+ post in engine bay. On the German E34 forum they just mentioned that the M8 nut fits onto one of the 3 bolts of the shock mounts as negative post.
    Last edited by shogun; 04-21-2019 at 10:13 AM.
    Shogun tricks and tips for the E32 series are HERE!

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