400i rear suspension self leveling

Discussion in '365 GT4 2+2/400/412' started by KLHarper, Aug 11, 2021.

  1. KLHarper

    KLHarper Rookie

    Sep 4, 2009
    Mebane NC
    Full Name:
    Hello, I know this has been posted in the past but I am trying to find current status on a few items.

    I have a 1984 400i in the shop and I am in the process of rebuilding the suspension. The self leveling works fine, but he self leveling unit leaks profusely.

    Is there someone who rebuilds these units now or are their kits available to rebuild them?

    I know there is a conversion kit for early 2 shock suspension, but this is a 4 shock, is there a kit available to convert it to non hydraulic.

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  3. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    Is your leak in the central control lever or the shocks themselves? There are a few shops that say they can rebuild any Koni shock (and these levers). I had a pair of shocks rebuilt at FJB Shocks in AZ. Since I had bought a pair of NOS shocks that I put on the car, I was not in a hurry to get them back and they have not been on the car so I can not vouch for quality. They did take a long time and a lot of prompting to get them back. I would look for alternates via this forum. Thew units can be rebuilt; it is just a matter of o-rings and seals.
  4. 57Wayne

    57Wayne Karting

    Mar 29, 2015
    Wilbraham MA
    Full Name:
    Wayne Thresher
    Someone had posted that they used Performance Shock Inc, 29139 Arnold Drive, Sonoma, CA 95476. I bookmarked it and still have their page open on my phone, so it was within the past year. Looks like just for the web site. 1-800-965-5664. They have a downloadable service request form online.
    I have a pair of Q1 coil over shocks and the forward pair of self leveling hydraulic shocks in place. That way all the hydraulics except for the rear pair of shocks is in place. Sits nice, and the rear height can be adjusted. Rides nice too. I think though that there is a restriction or something in the circuit as I get a hydraulic squeek (like fluid through a restriction) on some bumps somewhere around the passenger side front seat.
  5. KLHarper

    KLHarper Rookie

    Sep 4, 2009
    Mebane NC
    Full Name:
    The leak is in the control unit itself. The shocks are in good order and I replaced the accumulators during the rebuild. The accumulators are for a Mercedes and I was hoping that Ferrari had just borrowed the Mercedes actuator unit but alas that is not the case.
    The control unit is just a hydraulic actuator, and it might be simple to rebuild, but I am out of my comfort zone to start experimenting with seals and O'rings, if I had a kit of known good seals my confidence would be higher. I might take it to someone who rebuilds industrial actuators to see if they could rebuild it.
  6. ONSilver

    ONSilver Karting

    May 26, 2008
    Oakville, Ontario
    I sent the rear shocks and self-levelling valve control arm for my 1986 412 to Ferrparts who had Performance Shock in Sonoma do the refurbishing last year. They were about the only source in North America able to do the work (lots of stories about how Koni are very difficult and basically refuse to let their distributors provide any kits, parts, and service both here and also in Europe).

    I was very pleased with their work, and relieved I could keep my 412 in its original specs.

    To your point, before the refurb, my 412 sagged at the rear whenever parked and engine switched off, even though there were no leaks as such from the system or components. When engine was started, the car rear raised itself to the standard height and worked well with different load weights in the trunk, and with different number of passengers too, so very good and comfortable when driving it.

    Of note is after the refurbishing, when the engine is switched off, it no longer 'sags' at the rear and maintains the standard ride height when parked. I'd recommend them to you and think you'll be happy with peace of mind.

    My approximate cost for all was US $2500 which I thought was very reasonable, and probably compares well to your other alternative choices.

    Cheers Oliver
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