Power steering blowing the steering rack seals. -94 456 GT | Page 2 | FerrariChat
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Power steering blowing the steering rack seals. -94 456 GT

Discussion in 'Technical Q&A' started by 456 koirra, Oct 18, 2009.

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  1. F328GTS/GTB

    F328GTS/GTB Formula Junior

    May 3, 2005
    517
    France
    Full Name:
    Denis
    #26 F328GTS/GTB, Nov 5, 2009
    Yes! the steering did feel very light! What does this mean then? too much pressure? I recall that on the pump it was said that it was rated to 90 bar.

    90 bar is a normal pressure for steering system.
    On some system, pressure is increased till 120 bars, but on the 456, I don't know. 90 bar seems Ok for me. I suppose the pressure limitor is located on the pump, which is normal.
    What is important is that IF you notice a reduction of the steering wheel torque at end lock, it means that you had more assistance in the rack cylinder, which is due to more pressure inside the system. (Reason ?).


    ATF 220 is valid oil for steering system, even if not the best one (at cold temperature, the viscosity is very high, which lead to change of steering wheel torque, but you shouldn't use your Ferrari at very cold conditions ...).
    What do you mean by "i've tried a couple of different ones" ?
    Is it requested in the maintenance book to change the oil regularly ????? Steering oil can be used for many many years without any change. It is not like braking fluid with water charging inside oil.

    Normally, even aftermarket seals should be compatible with ATF oils. If all dimensions, correct way of assembling are good, it should work and be tight. But be careful, how did you choose aftermarket seals : did you know the exact dimensions of ZF seals and seal material ?
    Concerning material, HNBR or VITON should be used. Never use NBR material which will have a bad behaviour in severe temperature environnement.

    Still interested to have pics of your racks (close pics of the rack bar, seals, and general view). Next time !
     
  2. 456 koirra

    456 koirra Karting

    Aug 18, 2005
    95
    Finland
    #27 456 koirra, Nov 6, 2009
    By trying different fluids I meant that as I had severe loss of fluids I tried also other ATF manufactured by a Finnish oil company called Neste. Ended up with present due to cheaper price despite good reputation and filling the specs.

    If there turns out to be a problem with the pump, I guess it makes sense to first try the system with the present seals as the rack is in place but if I have to take it out I will definately take pictures of it!

    I will check the material of the seals. And get back as soon as I have some news. from the shop where the pump is or from where ever!

    Thanks for your effort!
     
  3. F328GTS/GTB

    F328GTS/GTB Formula Junior

    May 3, 2005
    517
    France
    Full Name:
    Denis
    #28 F328GTS/GTB, Nov 8, 2009
    Last edited by a moderator: Sep 7, 2017
    for your info, I send you an extract of a hydraulic steering gear drawing. May be your ZF gear is not exactly the same design, but more or less, all steering gears are in the same "easy" structure.

    Tightness is done by the two oil seals around the rack (n°4 and 13).
    The oring n°12 makes tightness between rack bush and rack housing.
    Image Unavailable, Please Login
     
  4. 456 koirra

    456 koirra Karting

    Aug 18, 2005
    95
    Finland
    #29 456 koirra, Nov 25, 2009
    Last edited by a moderator: Sep 7, 2017
    Thanks a lot your reply and naturally for the drawing too! And sorry for the slow reply.

    The pump came back from the service. They found one part that was worn and this part controls the pressure.
    They manufactured a replacement part and after that I fitted the pump back.

    The pressure should be normal now, there is also more resistance and feel in the steering.
    Unfortunately other end of the rack started leaking again. However this is the same end that already started leaking with the last set of new seals before shipping the pump to service. I have been told that once a seal starts leaking it will do that and the rack needs to be rebuilt again.
    When doing this, I wll take pictures and post them. Attached is a picture of the culprit. On the picture you can see wear on the "shaft".

    It is getting wintery here in Finland and it might take a little while before I get this project finished. But I will then get back to you asap! Thanks again for all your efforts.
    Image Unavailable, Please Login
     
  5. PAP 348

    PAP 348 Ten Time F1 World Champ
    Lifetime Rossa Owner

    Dec 10, 2005
    100,234
    Mount Isa, Australia
    Full Name:
    Pap
    #30 PAP 348, Nov 25, 2009
    Thanks for the update mate. It looks like it was sticking, like a few of us thought. :):)

    The 'wear' marks give it away. :D:D
     
  6. anton summerfield

    anton summerfield Rookie

    May 22, 2015
    6
    #31 anton summerfield, Oct 12, 2015
    Did you ever find out what the problem was ,I have just experienced the same thing with my 1995 456 ,not sure what to do ?
     
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