Rear suspension...calling GT Jones | FerrariChat

Rear suspension...calling GT Jones

Discussion in '365 GT4 2+2/400/412' started by Jagbuff, Dec 10, 2016.

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  1. Jagbuff

    Jagbuff Formula 3

    Jan 13, 2004
    2,267
    Site of US F1 Race!
    Full Name:
    Franck
    I am in the process of doing a partial restoration on my '80 400iA (pictures forthcoming) and trying to sort the rear suspension which has always felt rather weak/saggy. By the look of things the rear shocks have been rebuilt (not sure when, but compression and rebound feel good) but the Konis have these lime springs. Found a thread by GT Jones mentioning that these were for 308 and not up to par for the car but didn't see any conclusion about whether they were a/ correct for the 400i and b/ what the correct combo/ replacement.

    Appreciate any direction and suggestions!
     
  2. GT Jones

    GT Jones Formula Junior

    Oct 15, 2011
    669
    Lincoln, MA
    Full Name:
    Christian J
    I think the green color is actually oem and just oddball fiat inconsistency. Why are my front brake shields teal?
    If your self levelers have crapped out then you are missing the spring rate that they should provide. I've got adjustable perches now on all 4 rear shocks and have experimented with several spring rates (using 2.5" eibach springs) and the green rate that my car originally had isn't too far off where I am now. Keep in mind that I no longer have self levellers. I finally found a shop with a shock dyno and they matched all of my Konis and set them for slightly more compression and rebound than stock to go along with my stiffer springs. The car is really stable and solid at higher speeds. Send me a pm or email and we can chat.
     
  3. Newman

    Newman F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 26, 2001
    14,159
    Canada
    Full Name:
    Newman
    Off topic I know but the teal shields were on boxers as well to 78 and I suspect the same part on both cars. The springs and sway bars were made by another company whos name escapes me but I have reproduced the decals for restorations I perform. I can give that info tomorrow if anyone wants to know. 308's and boxers have the red apparent spring rate paint.
     
  4. Jim575

    Jim575 Karting

    Sep 26, 2011
    154
    Sydney Australia
    Full Name:
    Jim K
    Hello Gents
    My car has green springs. So when restoring the suspension and repainting the springs should I repaint them the green again?
    Jim
     
  5. Newman

    Newman F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 26, 2001
    14,159
    Canada
    Full Name:
    Newman
    I would say yes.
     
  6. Jagbuff

    Jagbuff Formula 3

    Jan 13, 2004
    2,267
    Site of US F1 Race!
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    Franck
    For cost reasons and adjustment ability, I have opted to go with the QA1 & 250lb springs as it looks pretty much plug and play...there goes the Classiche certification ;)
     
  7. GT Jones

    GT Jones Formula Junior

    Oct 15, 2011
    669
    Lincoln, MA
    Full Name:
    Christian J
    I think 250# is the wrong spring. I'm not near my notes but i think that's much too high.
     
  8. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    34,119
    Austin TX
    Full Name:
    Brian Crall
    I have the manual and all the specs if needed.
     
  9. jacques

    jacques Formula Junior

    May 23, 2006
    877
    Los Angeles/Florida
    Does QA1 make a direct replacement for our Koni shocks (dampers, excuse me)? I think that would be a very interesting alternative, if indeed they do. Thank you. Jq.
     
  10. Jagbuff

    Jagbuff Formula 3

    Jan 13, 2004
    2,267
    Site of US F1 Race!
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    Franck
    ...hum, I going off a write up that was done a while back - the spring that was used was spec'd out a 250lb though after some investigation it looks like it's actually a progressive spring that ranges 130 to 250lb. RD does your reference provide any guidance - I presumed that the leveling system changes depending on load, is there a ballpark that would work?
     
  11. 57Wayne

    57Wayne Karting

    Mar 29, 2015
    127
    Wilbraham MA
    Full Name:
    Wayne Thresher
    I used the QA1 with the 250# springs. Said I would provide my version of the prior pdf instructions, but have not yet. I have not driven it a lot yet, but it felt pretty good over bumps and curves as well as on limited straight smooth sections.
    Still thinking I might find a rebuilder or instructions to rebuild my original Koni parts, so everything is reversible.
    My one warning; make sure you have tightened the large banjo bolts to the accumulators fully and then checked it again before you tighten the small banjo bolts on the top of each. I didn't do my check before tightening the top on one side...good news is with a bubble flare brake line and a torch you can solder the old fitting onto the new line and be back in business.
     
  12. Jagbuff

    Jagbuff Formula 3

    Jan 13, 2004
    2,267
    Site of US F1 Race!
    Full Name:
    Franck
    My '80 MO does not have the hydraulic leveling system, just the high pressure shock levelers so it's pretty simple change over!

     
  13. 57Wayne

    57Wayne Karting

    Mar 29, 2015
    127
    Wilbraham MA
    Full Name:
    Wayne Thresher
    #13 57Wayne, Jan 5, 2017
    Last edited by a moderator: Sep 7, 2017
    In the attached .pdf which is for the 412, it shows what should be a similar setup to the 400i but using a different leveler. The accumulators and shocks, I imagine, should be the same. I removed hose 31 (both sides) and replaced it with a spacer (could use a bushing) of about the same height. (I machined a 17mm nut, but it is not necessary).
    There is an o ring in the stack that is the same as an Acura fuel injection o ring PN, and the replacement sealing washers came from eBay.
    What I've thought about since completing this, is that the original system had two shocks on each side feeding into the accumulator (nitrogen charged ) providing force from the entire rear of the car into the accumulator (volume of fluid x pressure associated with full weight). With the coil over shocks replacing one original each side, the volume is reduced by half and the force is reduced by half (simplify that the mechanical shock takes half the force of an incident), so the displacement in the accumulator is less...but without the forces associated with the entire mass of the rear of the car, is the remaining hydraulic shock portion now stiffer?
    Still feels good to drive, and looks great being at a proper height when I see it sitting in the garage!
    Image Unavailable, Please Login
     
  14. Al Campbell

    Al Campbell Formula Junior
    Owner Silver Subscribed

    Nov 22, 2013
    574
    Australia
    http://www.ferrarichat.com/forum/365-gt4-2-2-400-412/527434-replace-self-leveling-suspension-something-modern-need-steps.html

    Post #12 is what I have used & is identical to the leveller replacement units that are on the market for the series1 400i. This setup is easily set to the heights listed in the repair manual & handles well.

    Cheers,
    Al
     

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