Snap ring size differences | FerrariChat

Snap ring size differences

Discussion in 'Technical Q&A' started by FF8929, Sep 14, 2009.

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  1. FF8929

    FF8929 Formula Junior

    Apr 12, 2008
    799
    Livonia, Michigan
    Full Name:
    Fred Flynn
    These snap rings hold the CV joints onto the half shaft, on a 308 QV Mondial:
    I distorted the OEM snap rings getting them off. The replacements, obtained locally, are a bit different in dimensions as follows: Original ring is 1.43mm/.057" thick vs. the new snap ring thickness of 1.22mm/.048" thick. Also the new ring has an ID of 24.94mm/0.98". The shaft snap ring groove is 26.88mm/1.058".

    Seems close enough to me. Comments?
     
  2. Brian Harper

    Brian Harper F1 Rookie
    Owner Silver Subscribed

    Feb 17, 2006
    4,078
    San Jose area
    Full Name:
    Brian Harper
    I would have one concern. On the six 308 CV joints I've been intimate with the CV inner presses on a cupped washer (belleville) that rides on a shoulder on the shaft. This is on the side opposite the circlip. This washer acts as a spring, always applying a little pressure to the joint and circlip. The distance that the spring is compressed is very little. If your new clip is thinner than the original then you might not be putting any pressure on the spring. Is this important? I don't know, but if the cupped washer wasn't important then it probably wouldn't be there.

    I would guess that your local BMW or Porsche dealer could supply the snap ring since they used the same CV joints if your usual Ferrari supplier can't.
     
  3. mackb61

    mackb61 Karting
    BANNED

    May 17, 2008
    80
    Snap rings are directional. One side is ground flat and the other side is convex. Make sure they are installed in the correct orientation.
     
  4. FF8929

    FF8929 Formula Junior

    Apr 12, 2008
    799
    Livonia, Michigan
    Full Name:
    Fred Flynn
    I've never seen a snap ring, and I've seen quite a few, ground on one side and convex on the other. Live and learn. OK then, what would be the correct orientation? I suspect that the ground side would be againest the groove in the shaft?
     
  5. mackb61

    mackb61 Karting
    BANNED

    May 17, 2008
    80
    #5 mackb61, Sep 15, 2009
    Last edited by a moderator: Sep 7, 2017
    Top picture is showing flat/ground side. Bottom one shows convex side of same snap-ring. I'm having a problem putting into words how to install a snap-ring correctly. The ground side goes in the direction of "force". Example: If the snap-ring was retaining a spring, the spring would butt up against the convex side of the ring. The ground side would butt flush in the groove stopping movement. I hope this makes sense. I'm really having a problem explaining it. I don't remember ever seeing a snap-ring that didn't have one side ground flat.
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  6. 2NA

    2NA F1 World Champ
    Consultant Owner Professional Ferrari Technician

    Dec 29, 2006
    18,221
    Twin Cities
    Full Name:
    Tim Keseluk
    #6 2NA, Sep 15, 2009
    Last edited: Sep 15, 2009
    It's a function of the stamping process used to make them.

    Just like a typical washer, there's typically a flatter side and a more rounded side depending on which side faced the dies. I don't think any grinding was involved.

    You are correct that the sharper edge should be in the direction of force.

    I think you'll be fine with those snap rings.
     
  7. mackb61

    mackb61 Karting
    BANNED

    May 17, 2008
    80
    Makes sense. I always thought they were ground flat.​
     
  8. FF8929

    FF8929 Formula Junior

    Apr 12, 2008
    799
    Livonia, Michigan
    Full Name:
    Fred Flynn
    Brian: Your comment about the slight compression of the washer is spot on. I was aware of that. I dry fitted the Belleville washer, inner race and the new snap ring to the shaft. While there is no end play, the washer is just able to turn. Hummmm.

    Mackb61: I think that most snap rings are "tumbled" after they're stamped out. This removes the burr on the "breakout" side of the ring, making it appear to be finished. Thinking more about it, I have seen rings that were ground on both sides. They were for aircraft and other high tolerance applications. Also, your orientation explanation did make sense.
     

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