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550 motor mounts upgrade: Urban Legend?

Discussion in '456/550/575' started by Vereeken, Aug 20, 2017.

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  1. Vereeken

    Vereeken Formula Junior

    May 16, 2014
    264
    Belgium
    #1 Vereeken, Aug 20, 2017
    Ok, so I did the 550 to 575 mount upgrade.

    I fail to see how a failing mount can cause catastrophic failure to the engine.

    (I am not debating that it is good practice to replace, that is something else).

    My 550 mounts where original I think. The funky yellow cross on the bolt was still present stating that it was torque checked.

    Maybe the design is not NASA but I think it is safe and works even when it fails.

    The nut on top has a big washer (but really big and thick) so even should the rubber completely fail the engine can not drop any further because the washer will fall in the "cup" of the motor mount and stop there because the cup of the motor mount is tapperd towards the bottom.

    If that all fails the engine will ride lower but it will not go below the stabilizer bar. SUre the oil pressure sender gets close to the bar but still has enough clearance and nothing is going to rip it off. If you do rip it off you have other issues, like a busted bumper plastic cover and maybe even sump. I think the sender will be the least of your troubles.

    What would concern me more is the hard line from sump to oil cooler. This will rub on the chassis, no doubt. Also the serpentine cooling from the steering housing will get trapped between engine and steering rack. But surely if this happens you must have felt something wrong earlier.

    Am I missing something?

    For reference. I had 3 mm more clearance between pressure sender and stabilzer after the installation of the 575 mount.

    BTW the hero that succeeds in doing this in 4 hours without removing/relocating the steering rack should go and work in an F1 team.
     
  2. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,368
    Frederick, Maryland
    Full Name:
    Brian Brown
    #2 Motob, Aug 20, 2017
    Last edited: Aug 20, 2017
    I have worked on 550's where the engine oil pan was sitting on top of the steering rack, and you could actually feel engine vibrations in the steering wheel while driving the car and the oil pressure sending unit. While it might not be a catastrophic failure, having the steering rack support the weight of the engine is not a design feature of the car, and if the motor mounts got worse, then the oil pressure sender could break off, causing a catastrophic failure of the engine.
    The original design of the 550 mounts had nothing to stop the motor from going lower and lower once the mount failed. The new 575 mounts have a plate integrated into them so if they fail, the plate stops the motor from getting too low.
    I can replace the mounts in less than 4 hours without even disconnecting the steering rack, let alone removing. It is all about technique (you jack up the motor for clearance.)
     
  3. Vereeken

    Vereeken Formula Junior

    May 16, 2014
    264
    Belgium
    #3 Vereeken, Aug 21, 2017
    I am depressed.

    With 5 cm of upward movement I could not get anything on the driver side bolt to get full leverage to break the bolt free. Sure the PAX side I could do without moving the steering rack.
    But on the driver side I had to revert to the airgun and even cranked up to max before it gave way. The steering rack had to go in order to do that.

    I will make a picture of the mount so you can see what I mean by the washer blocked in the cup. Good it ain't but I think it prevents the catastrohic failure.
     
  4. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,723
    Amsterdam
    #4 166&456, Aug 21, 2017
    Do we know of engines that actually failed because of this?
    Also, can't you just have four plates laser-cut and put them in between mount and engine? Provided the mounts aren't perished.
    I believe I have seen very similar mounts somewhere as industrial silent blocks.
     
  5. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,368
    Frederick, Maryland
    Full Name:
    Brian Brown
    #5 Motob, Aug 22, 2017
    Why are you depressed. Have you not been able to install new 575 mounts to correct the problem? if so, then you are good to go.
     
  6. Vereeken

    Vereeken Formula Junior

    May 16, 2014
    264
    Belgium
    #6 Vereeken, Aug 22, 2017
    No the depressed referred to your 4 hours and not needing to move the steering rack.

    I looked for maybe 2 hours to understand how I could do it without disturbing the rack but could not figure it out.
    I could reach the bolts but could not get enough swing to break them loose so I needed to get the airgun on them.

    The 575 mounts are in so I am good from that perspective.
     

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