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Thread: Lad Shock lower seal replacement

  1. #1
    Join Date
    Jan 2013
    Location
    Australia, Geelong
    Posts
    11
    My Cars
    E32 740ial

    Lad Shock lower seal replacement

    Hi All

    I have a leaking rear LAD on the car, BMW E32 740ial, de73350, that needs to be repaired. After some considerable googling I have found this http://www.bimmerboard.com/forums/posts/779720 by Ken on bimmerboard should do the trick. This is a really good write up and I feel that I could do this rather than remove the LAD from the car. I have cleaned the LAD and I have identified the oil (Pentosin 11s) is leaking from the bleed hole at the large nut at the bottom of the LAD. I have two questions.

    1. Has anyone completed this procedure/fix?? - any advice..
    2. Has anyone been able to get a set of o ring seals that last the distance (as indicated in the fix). I am happy to send $$ to anyone who has access to a seals to complete the LAD repair.

    I will share the experience as I have a go at this repair. Any advice received and faithfully applied..

    - Phil

  2. #2
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,655
    My Cars
    11/88 E32 750iL+98 E36M3
    There are no complete sets, you have to find the single seals/gaskets. We have done some in our wrenching group like this, works since years. bottom Seal: we used O-rings from a large box of o-ring assortment in metric dimensions, just check what you have available or visit a hydraulic shop and show them the seals/O-rings samples.
    The bottom is the easiest to fix, even if you fail with the first replacement o-ring, no big deal, try another one.
    Or contact our member Legoman in Perth, he has a expert on hand which fixed his LAD shocks nicely.
    For the top of the LAD, if that is leaking, I might still have some seals on stock, but maybe you can also get them locally, we talked in this thread about it https://www.bimmerforums.com/forum/s...light=LAD+seal
    here another thread http://www.bimmerforums.com/forum/sh...-My-SLS-Struts

    and here more pics from Ken https://www.bimmerforums.com/forum/s...light=LAD+seal
    Last edited by shogun; 03-18-2018 at 09:01 AM.
    Shogun tricks and tips for the E32 series are HERE!

  3. #3
    Join Date
    Jan 2013
    Location
    Australia, Geelong
    Posts
    11
    My Cars
    E32 740ial
    Hi Shogun and All

    Thanks as always. I have PMed Legoman over in Perth and I appreciate the contact. The leak is definitely at the bottom of the LAD. I am keen to learn from people's past experience of the size and type of seals that have worked on the LAD. Keen not to reinvent the wheel if I can. I have notice that in the bimmerforum conversation the type can have an effect on the longevity of the fix. i.e., Buna-N versus FPM seals. So any advice will be greatly appreciated, as is Shogun's comments and guidance.

    - Phil

  4. #4
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,655
    My Cars
    11/88 E32 750iL+98 E36M3
    Searched a bit more, here some info:
    As for the shocks, leaking + some 'sweating of oil" is different, BMW even had a TIS on this, here coped from the German info I have
    Niveaulift Schwitzöl : An den hinteren Federbeinen der Niveauregulierung ist generell ein leichter Oelaustritt ueber die Kolbenstangefuehrung vorhanden. Die Kolbenstange schleppt einen duennen Oelfilm mit, der sich ausserhalb der Dichtungs- und Fuehrungseinheit sammelt. Diese Oelleckage ist prinzipbedingt durch den hohen Systemdruck gegeben und ist im Gegensatz zu herkoemmlichen Federbeinen, die unter keinem oder geringem Systemdruck stehen, normal. Ausserdem kann beim Anheben des Fahrzeuges mit haengenden Raedern durch Schraegstellung der Federbeine ein momentanes Ueberlaufen des angesammelten Oeles beobachtet werden. Auch dies ist normal. Das uebergelaufene Oel ist vor dem Ablassen des Fahrzeuges unbedingt abzuwischen, um keinen wirklichen Oelverlust vorzutaeuschen! Oelstand im Ausgleichsbehaelter pruefen, ggf. nachfuellen. Federbeine fuer Niveauregulierung mit nach oben ausfahrenden Kolbenstangen duerfen bis maximal ueber die halbe Daempferlaenge am Aussenrohr oelfeucht sein - sie duerfen "schwitzen".

    brief translation
    At the rear LAD shocks there is in general a slight oil leak via the shock pistons. The shock piston/rod pulls a thin oil film, which is collecting outside of the seal- and guiding unit. This leak is design related by the high system pressure compared to normal shocks, which are under no or low pressure only. Besides that when the car is lifted and shocks extended, there can be a slight overflow of this collected oil. also this is normal. Before letting down the car from a car lift, clean this area on the LAD shocks, otherwise it looks like real leaking (to the customer). Check oil level afterwards in Pentosin container. LAD shocks with pistons going upwards are o.k. that they are covered with "oil mist" up to half of the total LAD shock length, they are allowed to 'sweat'.

    Then I found on the German E34 forum the following data for E34 LAD seals and the regulating valve (all in mm):
    Niveaudämpfer Kennung "73" (sportliche Fahrwerksabstimmung, sollten aber baugleich sein mit den normalen 72ern bis auf eine kuerzere Kolbenstange)
    je Daempfer
    1x 38x2mm
    1x 30x3mm
    2x21,81x2,62mm

    Regelventil:
    1x 12,5x1,5
    1x 16x2,6
    1x 13x2
    1x 9,52x1,78
    1x 6x3
    difference between E32 and E34 LAD
    http://www.bimmerboard.com/forums/posts/1261417/
    http://www.bimmerboard.com/forums/posts/1260639
    Shogun tricks and tips for the E32 series are HERE!

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