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400i Series 2 Self Leveling Suspension

Discussion in '365 GT4 2+2/400/412' started by miami355, Mar 20, 2020.

  1. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL
    I have a 1984 400i and suddenly the rear bounces like crazy when I hit a bump. It did not do that previously. It also doesn't seem to raise when started, but then again it could be at proper level and not need to raise? I think the self leveling system is broken, but not sure how to diagnose which component. It doesn't appear to have any leaks.

    I know there are swaps to conventional coilovers from T Rutlands, but those are for series 1 cars. Series 2 cars have all 4 shocks that are hydraulically connected, where as series 1 cars have 2 conventional and 2 hydraulically assisted. I also can't find anyone who rebuilds the series 2 shocks, assuming that is what is wrong. I tried Performance Shock Inc, and they don't work on them. Any ideas on how to diagnose, and who rebuilds the series 2 shocks if necessary?

    David
    Miami, FL
     
  2. wrxmike

    wrxmike F1 Veteran
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    Mar 20, 2004
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    Michael
    Most likely a failed hydraulic sphere, read this thread.
    https://www.ferrarichat.com/forum/threads/rear-suspension-behavior.517419/#post-144587819
     
  3. christc

    christc Karting

    Mar 3, 2013
    207
    Germany
    You can check your self leveling on an S2 easily.

    1. With the car on the ground loosen and remove the bolt 4 of the self leveling valve 1 in enclosed picture. Remember position of arm 3. Move valve stem in and out with car running. Car should raise or drop depending on movement.

    2. If this works remount arm in original position. Car should be raised to normal driving height.

    3. Leave car as is. Measure distance of wheelarch to ground. If it drops after short time it is very likely that your spheres have gone. Replacement of spheres is possible with mercedes spheres. Have done it myself. - see threads here on fchat.

    Hope it helps
    Christopher


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  4. dstacy

    dstacy F1 World Champ
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    Jan 23, 2006
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    It’s the accumulators
     
  5. christc

    christc Karting

    Mar 3, 2013
    207
    Germany
    Accumulators = spheres for those who wonder
     
  6. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL
    Thanks everyone for their help. I'll have my mechanic test using the self leveling valve. I agree, it must be the accumulators.

    Are Series 1 self leveling? Don't they have some kind of hydraulics going to two of the four shocks?
     
  7. dstacy

    dstacy F1 World Champ
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    No, just Series 2 cars.
     
  8. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL
  9. dstacy

    dstacy F1 World Champ
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  10. raemin

    raemin Formula Junior

    Jan 16, 2007
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    Lyon (FR)
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    R. Emin
    #11 raemin, Mar 23, 2020
    Last edited: Mar 23, 2020
    Whichever sphere has the proper built-in pressure would do. From then on If you can choose between several layouts, just buy whichever is easier to install. The other route is to buy a sphere with the best possible bracket and have a specialist perform a clean refill with the appropriate pressure. I've posted a link to MisterAuto website, where they list many accumulators, these are French and do not ship overseas, but they are courteous enough to provide cross references and pressure for each of the sphere they sell, so you can easily identify the best possible part for your project.(https://www.mister-auto.com/spheres-accumulateur-de-suspension/febi-bilstein/)

    The sphere you quoted is rated for 23bars on their website, looks on the soft side. The followings do have a nicer bracket (https://www.mister-auto.com/spheres-accumulateur-de-suspension/febi-bilstein/01915/).

    As a side note Serie 1 car had a "self contained" self leveling unit, not as sophisticated as series 2 & 412, but still effective. This primitive system does manage "rebound" more gracefully, but it is not as efficient as the later variant under heavy load. It's also prone to fail and so to say impossible to fix (a few die hard enthusiast did succeed though).
     
  11. dstacy

    dstacy F1 World Champ
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    Jan 23, 2006
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    Sorry, no. Series 1 cars had NO hydraulic self leveling system.
     
  12. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL
    I already ordered these: https://www.fcpeuro.com/products/mercedes-suspension-self-leveling-unit-accumulator-1233200215?

    raemin, where do you show they are 23 bar?

    I need to plug the top port, as shown in the arrow and install a banjo from what I am reading.





    View attachment 2912077
     

    Attached Files:

  13. raemin

    raemin Formula Junior

    Jan 16, 2007
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    I've been careful not putting hydraulic in my remark, so yes no HYDRAULIC self levelling, but still fitted with self levelling shock absorbers (as per workshop manual F24).
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    Calling the later variants hydraulic is a bit misleading, as that's the gas pressure on the sphere that dampens the suspension, the exact term is "oleo-pneumatique" (oil and gas). On the negative side these setups are quite "bumpy", and whoever was passenger in a Citroën (with self leveling on all corners) can testify that one would get sea-sick in no-time! The Ferrari is marginally better (much more stiff and only 2 corners do help), but a Mercedes M100 does feel much better than the 400i gen2. The upgraded aerodynamic of the 412 provides more down force on the rear wheels, so probably better, but had no occasion to test a 412 at high speed so far :)

    A very few cars reportedly had no self levelling absorbers "out of the factory". I never actually saw such a setup "in person", but I consider this as a really nice feature nowadays.
     
  14. dstacy

    dstacy F1 World Champ
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    Ok, no sense in arguing about if cars had them or not. I owned one but that must have been a figment of my imagination.
     
  15. raemin

    raemin Formula Junior

    Jan 16, 2007
    390
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    R. Emin
    https://www.mister-auto.com/spheres-accumulateur-de-suspension/febi-bilstein/03276/ ( " Pression [bar] : 23 " )

    You could always compensate the lower pressure by adjusting the length of the connecting rod on the sensor (under the spare wheel) in order to achieve the proper ride height. Maybe that the lower pressure could be beneficial in the end (the shocks are vertical and the rear A-Arms are quite long).
     
  16. samsaprunoff

    samsaprunoff F1 Rookie
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    Jun 8, 2004
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    Good day Dave,

    I wonder if you are referring to the early 1983 or so 400i cars? I mention this, as the 1983 400i parts manual show onloy two shock absorbers only (see pic below) with no leveling system. The 365 GT4 2+2 and 400GT do have a self leveling shock made by Koni (item 4 in the parts diagram below ... 2nd pic), but are quite a bit different (e.g. self contained... see 3rd pic) to the later self leveling systems.

    Cheers,

    Sam

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  17. rovexienus

    rovexienus Formula Junior
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    Jean-Michel Savary
    Hi Sam, for the 1983 400i (from chassis number 42705), there are three tables to describe the rear suspension system: table 047 (oil tank and oil pump), table 048 (self levelling valve and oil lines) and table 050 (levers and shock absorbers).
     
  18. samsaprunoff

    samsaprunoff F1 Rookie
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    #19 samsaprunoff, Mar 26, 2020
    Last edited: Mar 26, 2020
    Good day Jean-Michel,

    This is interesting and a mystery to some degree. Given your comments and I dug a bit deeper and found that within the 1979 400i parts manual (Table 44) that it uses the same self leveling system as the 365 and 400GT (one shock and one self contained leveler). I then reviewed the 400i shop manual and found on page F24 the following:

    "Rear Suspension (up to vehicle no 42705)
    The rear suspension is fitted with two telescopic shock absorbers with coaxial spring, with two self-leveling shock absorbers which keep the vehicle at a constant height regardless of the load or speed. The self-levelers need no adjustment and are to be replaced when irregular functioning occurs. Self-leveling shock absorbers type Koni 7100-1012, shock absorbers Koni 82 T-1825"

    On the next page (F25) it basically says that you stated from vehicle 72705 and onward and a diagram shows the accumulator setup mentioned within this thread.

    What is odd is that another 400i Parts Diagram as provided by Eurospares (the image I included in my previous post ) contradicts the shop manual's statement about chassis nbumber 42705 and earlier in that the diagram shows and lists a single part number (117722) for each of the shocks on the rear suspension (for a total of 4 per car).

    And the mystery continues...

    Cheers,

    Sam

    <Edit>... I see where the mystery leads... When I was looking at part 117722 the image provided by the Ferrari UK simply showed a shock absorber when in fact it is not a regular shock (see pic) ... So... The parts manual and the shop manual are correct and that self levelers looked to be present throughout the 365/400/412 series, but with different designs.

    Mystery solved...

    Cheers,

    Sam

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  19. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL

    Attached Files:

  20. miami355

    miami355 Karting

    Sep 2, 2006
    130
    Miami, FL
    Comparing the original and the Mercedes Corteco 1233200215 accumulators, I need to order an M10 1.0 plug to plug one of the holes, then get an adapter or insert to put the Ferrari's M10 1.0 banjo screw in the to the Mercedes Corteco 1233200215 M12 1.5 hole. Can anyone share how they made the adapter?
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  21. christc

    christc Karting

    Mar 3, 2013
    207
    Germany
    Just ask a local machine shop to do it for you. Its an easy job using a lathe and some tap dies. Just make sure that you use a good thread sealing and composite washers (combination of aluminum and rubber) to mount unit.
     
  22. Jasonberkeley

    Jasonberkeley Formula 3
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    Apr 23, 2017
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    Jason Berkeley
    I just got my 1984 400i back yesterday after having Bill at GT Car Parts in Scottsdale, AZ rebuild them and re-powder coat all of the pieces.

    https://gtcp.com/

    One of them had developed a leak and the rear would sag. I havent driven it yet, but after sitting in the garage for 24 hours, rear is still up at normal height.

    I will report back after the rainy weather clears and I take it for a spin. Pics below are from this morning, riding high!
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