Belt stretching clarification? | FerrariChat

Belt stretching clarification?

Discussion in '348/355' started by kenneyd, Oct 19, 2017.

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  1. kenneyd

    kenneyd Formula 3

    Sep 30, 2014
    2,028
    NE FL
    Full Name:
    Ken
    I am following ferrari's instructions:
    Stretch the belts as follows: lever in holes 3and4 on the belts-stretching bearing. Rotate towards the engine inner side until the catch 5 is free to slide in its housing, then lock the bolt 1. Let engine run for some minutes(not sure how to do that lol) and check the distance 6 on the mule guide should be ~= 2.5mm and the catch 5 free to slide.

    The "mule guide" is stepped. one side can be almost flush and the other side fully compressed is about 2.5mm.

    I Rotated the bearing until the pin moved freely and tightened the bolt.
    I've met 1 of the two requirements, i can still slide the pin in and out of the catch freely, but im getting ~1mm on the flush side and ~3+mm on the higher stepped side. I am kinds thinking ferrari just eyeballed the gap and wrote ~2.5mm

    I just dont want to assume anything, (the picture below is not mine) Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
     
  2. taz355

    taz355 F1 Veteran
    Owner Silver Subscribed

    Feb 18, 2008
    6,059
    Indio Ca/ Alberta
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    Grant
    The bottom one
     
  3. yelcab

    yelcab F1 World Champ
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    Nov 29, 2001
    13,654
    San Carlos, CA
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    Mitchell Le
    And that is the dilemma, Grant. If the bottom thinner slot is adjusted to 2.5mm, then the pin no longer slides easily in and out of the locking holes.
     
  4. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,389
    Frederick, Maryland
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    Brian Brown
    Are you replacing the belts and reusing those nasty old tensioners and tensioner bearings? They should be replaced along with the belts. I set the tension so that the pin can slide in/out of the hole without too much trouble, and the smaller gap is usually very close to 2.5mm
     
    taz355 likes this.
  5. SoCal1

    SoCal1 F1 Veteran
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    Jun 14, 2011
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    Tim Dee
    Good question I have 2 EO to do myself in 355s
     
  6. kenneyd

    kenneyd Formula 3

    Sep 30, 2014
    2,028
    NE FL
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    Ken
    #6 kenneyd, Oct 20, 2017
    Last edited: Oct 20, 2017
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    Haha, of course not. That was just some random picture from the internet. Here is the picture of mine, you can actually see through the pinhole to the other side

    The only thing I can thinkthat may be lost in translation is the 2.5mm shows up while ruining
     
  7. taz355

    taz355 F1 Veteran
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    Feb 18, 2008
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    I am not sure I understand Mitchell?
    When I did mine aftr removing the pin and turning engine over several times it was very close to 2.5 mm. It was between 2.5 and 3 for sure.

    Am I missing something??


    ?
     
  8. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
    2,389
    Frederick, Maryland
    Full Name:
    Brian Brown
    The tensioner is what tensions the belt. The adjustment required to get the tensioner into the beginning of its working range,so it will still tension the belt as the belt stretches. it is not super critical adjustment, but you need to have some kind of gap between the bracket for the belt idler and the body of the tensioner, otherwise it will be metal on metal, and the tensioner will not be doing its job.

    As long as the pin can slide in/out of the hole, then the tensioner is right where is should be. If the gap is a little larger or smaller than 2.5mm, you are ok.
     
    Qavion, Dave rocks and SoCal1 like this.
  9. kenneyd

    kenneyd Formula 3

    Sep 30, 2014
    2,028
    NE FL
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    Ken
    Awesome! thanks for the reply
     

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